WO2008106964A1

WO2008106964A1 - Releasable fully automatic mechanical coupling

Info

Publication number: WO2008106964A1
Application number: PCT/DK2007/000110
Authority: WO
Inventors: Thorkild Stokholm; Khaled Alsofi
Original assignee: Fractum Aps
Priority date: 2007-03-02
Filing date: 2007-03-02
Publication date: 2008-09-12
Also published as: CN101627165A

Abstract

The invention relates to a releasable coupling between a heavy object and a locking arrangement (2), said heavy object being provided with a locking member (5) com prising at least one suspension surface (6), and said locking arrangement (2) compris- ing at least one holding arm (8) displaceably arranged on said locking arrangement (2) and release means (88, 90) for releasing said coupling, characterized in that said lock ing arrangement (2) comprises a toggle joint (75) which in a locked position thereof holds the locking arrangement (2) in locking engagement with the locking member (5) when the two are coupled together, and said release means (88, 90) comprises means for shifting the toggle joint (75) to an unlocked position thereof.

Description

RELEASABLE FULLY AUTOMATIC MECHANICAL COUPLING

Field of the invention

The present invention relates to a coupling in particular for facilitating a releasable coupling between an object, preferably a heavy object, and a lifting arrangement and to an apparatus for incorporating such a coupling. Moreover the invention relates to a method of engaging and disengaging a heavy object and the use of one or more couplings in a pile driver, crusher, demolition hammer, stone or aggregate crusher.

Background of the invention

These types of couplings find particular use for hammers or pile drivers where the object is to lift a heavy object, such as a very heavy hammer head, to a certain height whereafter the hammer head is released and by free fall is brought to impact on an object whether it be a pile, a rock or other objects which need to be crushed or im- pacted.

Typically, the hammer head will have a weight of from a couple of tonnes to more than 10 tonnes. In order to create a feasible routine, it is necessary to provide an apparatus which is able to create a certain number of blows per minute in order to make it economically feasible.

For pile drivers and hammers, it is known to have a system where the lifting arrangement for example in the shape of wires and pulleys are connected permanently to the hammer head. This in turn provides a number of disadvantages such as for example it becomes very difficult to replace the hammer head if the need should arise.

During operation, the hammer head will deform and become worn in or adjacent its impact zone. This may cause that the hammer head will not be able to be elevated in the apparatus where the hammer head is usually elevated along a given path for ex- ample inside tubular member which tubular member guides the hammer head both in its upwards direction as well as its downwards direction. A deformation in the hammer head may cause that the hammer head becomes stuck in the tubular section of the apparatus such that the machinery and thereby the working process will have down- time while the hammer head is loosened and replaced. Also during the free fall part of the process where the energy gained from the lifting and elevation of the hammer head is released, the wires and pulleys may absorb a part of this energy such that not the full possible impact is achieved but only a reduced impact due to the energy ab- sorption by the movement in the pulleys and wires as these follows the hammer head down.

This is further aggravated over time in that dust and other debris from the process becomes integrated in the wire structure and the pulleys and may interfere with the ball bearings in the pulleys such that excessive wear in the ball bearings of the pulleys and thereby absorption of energy and eventually failure will occur.

Another prior art coupling is the electromagnetic coupling, in which the heavy object is lifted by the use of a strong magnetic field. A problem with this kind of coupling is the time it takes to build up a sufficient strong field for lifting, which sets a limit for the number of strokes available per minute.

Other coupling arrangements depend on an active energy supply. This is usually provided in the shape of wires, hoses, pipes or other physical means connecting a power plant and the coupling arrangement. These, however, constitute a major drawback in that wear and tear in these conduits eventually will cause them to break or tear, and thereby cause downtime for the apparatus and repairs. A problem of fluid hoses leaking is especially present when dealing with the commonly used technique of a hydraulic releasable coupling.

Furthermore, the conduits may hamper or otherwise interfere with the proper workings of the apparatus into which the coupling is built.

It is an object of the present invention to provide a coupling whereby it becomes pos- sible safely, efficiently and quickly to engage and disengage the heavy object such that the drawbacks mentioned above are alleviated. Summary

The invention relates to a releasable coupling between a heavy object and a locking arrangement, said heavy object being provided with a locking member comprising at least one suspension surface, and said locking arrangement comprising at least one holding arm displaceably arranged on said locking arrangement and release means for releasing said coupling, characterized in that said locking arrangement comprises a toggle joint which in a locked position thereof holds the locking arrangement in locking engagement with the locking member when the two are coupled together, and said release means comprises means for shifting the toggle joint to an unlocked position thereof.

With the present invention, a remarkable quick and low-friction release of the heavy object is obtained through the fast transition of the holding arms from a firm grip below said suspension surface of said heavy object to a relieving action of the toggle joint, whereby the at least one holding arm release the firm grip of said heavy object. Further with the present invention a quick, low-friction and reliable coupling process between the locking arrangement and the locking member is obtained.

In this context, the meaning of the term "heavy object" is an object weighing above 100 kg, preferably above 500 kg and most preferably above 1,000 kg.

With the present invention it may be possible to achieve around 7 strokes per minute or more with the heavy object which, compared to prior art techniques, has given a considerable increase in efficiency.

Moreover with the present invention a construction has been obtained, which is very durable and low- wear during use. This ensures that a coupling of the present invention outlasts couplings of prior art in that the coupling may perform as many as one million coupling processes or more before worn out.

When said at least one holding arm is adapted to quickly and reliably release said locking member, an advantageous embodiment of the invention is obtained. When said locking arrangement is lifted, carrying said locking member in connection to a heavy object, said locking member and heavy object will be lifted until a point of release by relieve of said toggle joint, as carried out by means of said release means.

With this releasable coupling is has become possible to quickly engage and disengage said heavy object without the drawbacks as mentioned in the background. Furthermore a coupling is provided which can be activated without the necessity of being connected directly to a source of energy.

In an embodiment of the invention, said at least one holding arm is pivotably arranged on said locking arrangement.

When said locking member is held between said at least two holding arms during lifting of said locking arrangement, said holding arms are locked from turning around on their pivotable axes. Following relieve of the toggle joint, the holding arms release their hold on the heavy object and through a pivoting of the holding arms, the heavy object is given a gravity induced free fall towards an object which is needed crushed or impacted. Hence with a pivotable arrangement of the holding arms a very simple and efficient arrangement is obtained.

The pivotable arrangement of the holding arms is preferred; however other ways of arranging the holding arms may be employed within the scope of the invention when capable of holding around the locking member in one position and quickly releasing the grip when activated.

In an embodiment of the invention, said releasable coupling comprises at least two holding arms displaceably arranged on said locking arrangement.

In a preferred embodiment of the invention, said locking arrangement comprises two holding arms displaceably arranged on said locking arrangement. With two holding arms the acting forces are symmetrical around the toggle joint and the tensions in the system are easier handled. In an embodiment of the invention, said locking arrangement comprises at least one locking HnIc.

In an embodiment of the invention, said locking arrangement comprises at least one link lifting.

In an advantageous embodiment of the invention said locking arrangement comprises a system of a toggle joint, two locking links, two link liftings and two holding arms as seen in the attached figures.

In an embodiment of the invention, said at least one toggle joint connects at least two locking links.

In an embodiment of the invention, said locking arrangement comprises at least one link lifting to connect one locking link to one holding arm.

In an embodiment of the invention, said releasable coupling comprises at least one double pivot joint comprising the pivotable holding arms and the pivotable link liftings.

The double pivot joint provides a very advantageous release, in that it ensures that a small turning of one joint allows for the turning of another joint. Hereby only a small opening of the coupling is necessary and a more compact system may be obtained.

In an embodiment of the invention, a lifting force is provided through wires and at least one pulley when lifting said locking arrangement.

In a preferred embodiment the lifting of the locking arrangement is provided through wires by means of machines such as excavators.

In an embodiment of the invention, said locking arrangement comprises a bridge for supporting the element of said releasable coupling. In order to couple said locking arrangement to said pulley an element in one or more parts capable of comprising said attachments points and said fastening points and to create a connection from these points to a holder of the pulley should be provided. The term bridge should in this context be broadly understood as any element fulfilling these needs.

In the embodiment shown in the figures said link liftings are attached to a bridge via attachment points, and the bridge is connected directly as an element in one part to the holder of the pulley.

Obviously the bridge, whether in one or more parts, may be designed in many different ways. Parameters possibly to be changed are e.g. the distance between the locking arrangement and the pulley and the mutual rotation between same.

In an embodiment of the invention, said releasable coupling is adapted for use with excavators, e.g. in combination with a pile driver, a crusher, a demolition hammer, a stone or aggregate crusher

In an embodiment of the invention, said at least one suspension surface is part of a protrusion, an indentation, a recess or a conical shaping.

In an embodiment of the invention, said at least one suspension surface is essentially rotational-symmetrical .

A clear advantage by using an essentially rotational-symmetrical suspension surface is that the holding arms are always capable of grabbing around said locking member, even if the heavy object has rotated an arbitrary angle e.g. during the impact on the object which is needed crushed or impacted.

In an embodiment of the invention, the engaging surfaces of the at least one holding arm and the locking member are designed so that the action of gravity on the heavy object will affect the at least one holding arm from the locking engagement with the locking member and thereby aid to release said coupling when said generated radial locking force is released by relieving said toggle joint. When the toggle joint is relieved, the pivoting of the holding arms downwards will ensure a quick and low-friction release of the locking member as mentioned above. Further the release may be facilitated by having engaging surfaces between the at least one holding arm and the locking member, which are angled relative to the axial lifting direction in which way a radial outward directed force will be present from the locking member, which will aid in pushing the holding arms outwards during the release phase.

When said engaging surfaces are angled at about 90° relative to the axial lifting direction, essentially no radial outward directed force is present. Therefore it is advantageous to have an engaging surface angle of less than about 85° or preferably less than about 70° to aid the locking member to push the at least one holding arm outwards when releasing the coupling.

In an embodiment of the invention, said release means are adapted for automatically relieving the toggle joint when said locking arrangement has reached maximum height.

In order to allow the heavy object to be released again and again, the toggle joint is relieved when said locking arrangement reaches maximum height via contact with e.g. stop pads. Hereby the at least one holding arm will be able to become disengaged from below said at least one suspension surface of the locking member such that decoupling of the locking member is effected and the hammer head or heavy object may free fall towards the object which is needed crushed or impacted.

In an embodiment of the invention, at least one of the engaging surfaces of the at least one holding arm and the locking member comprises at least one roller so as to facilitate the release of the coupling.

When at least one of the engaging surfaces of the at least one holding arm and the locking member is provided with rollers, an advantageous embodiment of the invention is obtained. With rollers a much easier release is obtained when releasing said locking member from said locking arrangement due to the fact that the locking member can then roll off the rollers the instant the grip is released with markedly lesser friction problems than seen in prior art.

In an embodiment of the invention, said one or more rollers are provided on the at least one holding arm.

Preferably each holding arm comprises a roller, and hence in this preferred embodiment the locking arrangement will comprise at least two rollers, although a higher or lower number of rollers may also be applied within the scope of the invention.

In the embodiment shown in the attached drawings rollers are placed on the holding arms to facilitate release. In other embodiments however, the rollers may be placed on the locking member or both, whereby a rolling off in the same sense may be obtained.

When said at least two rollers of said locking arrangement is placed below said at least one suspension surface and locked in mechanical engagement by said at least two rollers and controlled by locking means, said heavy object is lifted when lifting said locking arrangement.

When said at least one holding arm is provided with rollers, an even more quickly and reliably release of said locking member is obtained, and thereby an even more advantageous embodiment of the invention is obtained.

In an embodiment of the invention, the radius of said at least one roller is slightly smaller than an approximated radius of curvature of said at least one suspension surface of said locking member.

When the radius of said rollers is slightly smaller than an approximated radius of cur- vature of the suspension surface an easier roll off is achieved with less friction involved. Thereby the release phase is further facilitated. In an embodiment of the invention, said link liftings, locking links and holding arms following release of said releasable coupling through relief of said toggle joint are brought back to initial position by a holding arm return means and a toggle joint return means.

In order to obtain a hammering cycle with a satisfying number of strokes per minute, a fast and reliable return mechanism to bring the elements back into initial position is necessary. This return mechanism can be provided by several kinds of pulling/pushing or biasing means, such as a hydraulic or pneumatic cylinder, a spring or the like.

The return means and may advantageously be arranged between the holding arms and said bridge and the toggle joint and said bridge, respectively, in order to control the pushing/pulling. However other ways of fastening the return means by which the result is a reliable return mechanism will also be within the scope of the invention.

In an embodiment of the invention, said holding arms are brought in below said at least one suspension surface by said holding arm return means during coupling of said locking arrangement with said locking member.

In the coupling phase the holding arms are pushed apart when moving said locking arrangement towards said locking member, and said holding arms are afterwards brought in below said at least one suspension surface by said holding arm return means.

In an embodiment of the invention, at least one of said holding arm return means and said toggle joint return means are springs.

In a preferred embodiment of the invention all the return means are springs.

In an embodiment of the invention, said releasable coupling is adapted for handling a heavy object with a weight above 1 tonne, preferably above 2 tonne. Typically when using the coupling for crushing or impacting, a weight of the heavy object will be around 5 tonne. However the coupling according to the invention may be able to carry weights of up to about 20 tonne or more.

The coupling according to the invention is in particular suitable for very heavy objects due to the improved locking mechanism for higher weights. The heavier the object the firmer the holding arm will be engaged below the suspension surface provided in the locking member.

Therefore it is favourable according to the present invention when the coupling is used in a device for lifting a heavy object, where the application provides the possibility of utilising the force of gravity as a part of the action in the coupling and decoupling procedure. However, for other applications where the force of gravity is not suitable, secondary means, for example in the shape of actuators or other suitable means, may be used in order to bring the locking member and the locking arrangement into and out of engagement.

In an embodiment of the invention, a dampener is provided on the locking arrangement to decelerate the relative movement between the locking arrangement and the locking member.

In use the dampener is active in a substantially vertical direction, and the locking member abuts the dampener during engagement of the locking arrangement and the locking member. The dampener serves to slow down the relative movement of the locking arrangement with respect to the locking arrangement as this arrangement is lowered towards the heavy object in order for the locking arrangement to engage the heavy object by means of the locking member and the holding arm as described above. During operation, a number of lifts are performed every minute which requires the locking arrangement to be able to move very quickly. This is achieved by substan- tially allowing the locking arrangement to free fall behind the heavy object which heavy object will transfer its energy achieved due to the force of gravity to the object which is needed crushed or impacted, such that the hammer head will substantially come to a complete stop. The locking arrangement following the heavy object close will thereby impact the heavy object at a relatively high velocity such that a substantial amount of energy is being built up in the locking arrangement due to the weight which is under the influence of gravity. In order to not damage the locking arrangement or the locking member in the heavy object, the dampener will absorb the impact energy between the locking arrangement and the heavy object such that negligible energy needs to be distributed in the locking arrangement upon impact and thereby the potential damaging influence from the impact is minimized.

In this connection, the dampener is described as being active in a substantially vertical direction, but it should in this context be noted that as both the heavy object and the locking arrangement is activated due to the force of gravity, the expression substantially vertical direction should be interpreted such as also slanted directions which will provide sufficient energy generation by the heavy object are contemplated within the scope of the present invention.

In order to be able to absorb the energy in an economically feasible manner, the dampener may be in the shape of a hydraulic or pneumatic telescopic cylinder, a resilient device such as for example a spring, preferably helically wound in a casing, or a resilient compound such as for example rubber or other resilient polymer based or polymer modified material.

In an embodiment of the invention, said locking member comprises a tapering end.

When said locking member comprises a tapering end an improved engagement be- tween the locking member and the holding arms is obtained, as the tapering end helps to push the holding arms aside during engagement due to the slanted surfaces of the tapering end.

Moreover the invention relates to an apparatus comprising one or more couplings ac- cording to any of claims 1-24, where the apparatus is a pile driver, crusher, demolition hammer, stone or aggregate crusher. Moreover the invention relates to a method of engaging and disengaging a heavy object by means of a release coupling according to any of the claims 1-24.

In an embodiment of the invention, said engaging of said method comprises the step of coupling together said locking arrangement with said locking member, after which said locking member is lifted with said locking arrangement.

In an embodiment of the invention, said disengaging of said method comprises the step of lifting said locking member with said locking arrangement until a desired height where the locking member is released from said locking arrangement.

Moreover the invention relates to a use of one or more couplings according to any of claims 1 -24 in a pile driver, crusher, demolition hammer, stone or aggregate crusher wherein the weight of said heavy object is above 1 ton.

The Drawings

The invention will now be described with reference to the drawings of which

Fig. 1 shows a coupling according to the invention, and Figs. 2-4 show different steps of a coupling/decoupling sequence.

Detailed Description

Fig. 1 illustrates a cross-section through a coupling according to an embodiment of the invention. The elements of this embodiment will be explained first with reference to fig. 1.

The coupling is intended for coupling the locking arrangement 2 to a locking member 5 of a heavy object. The heavy object, e.g. a hammer head, is not shown in the figures but any type or shape may be employed within the scope of the invention. In common for all possible heavy objects is that they are provided with a locking member 5, which typically will be connected to said heavy object by any ordinary connecting means; however employing a heavy object with an integral locking member 5 is also within the scope of the invention.

The heavy object can be held and lifted by two holding arms 8 provided with rollers 50 at the one end, said holding arms 8 are in the other end pivotably fastened in joint 52 to one end of two link liftings 80 and said two link liftings 80 are at the other end pivotably fastened in joint 86 to two locking links 85, said two locking links 85 are connected in a toggle joint 75, which in fig. 1 is shown in a locked position. The dis- tant ends of said two locking links 85 are provided with rollers 88 fastened in points 87.

Said link liftings 80 are attached to a bridge 25 via attachment points 81. Said bridge 25 can be designed in numerous ways as long as the functionality is present, i.e. it is capable of comprising said attachments points 81 and to create a connection from these points to a holder 15 of the pulley 14. This connection can be obtained in the form of a single object or more objects connected. In the embodiment shown in the drawings, the bridge 25 is connected directly to both the attachment points 81 and the holder 15 of the pulley 14.

The holding arms 8 are provided with arms 51 by which the rotation of the holding arms 8 are partly controlled by a spring 70, said spring 70 is fastened between the end of said arms 51 in fastening point 71 and the fastening point 72 of said bridge 25.

Moreover a spring 17 is arranged between the toggle joint 75 and a fastening point 18 of the bridge 25 to pull the toggle joint 75 downwards into the locked position.

The toggle joint 75 is designed such that only a slight movement of the toggle joint 75 will cause the toggle joint 75 to leave the locked position and be relieved, i.e. a preferred angle between the two locking links 85 should be close to 180°, e.g. from 160° to just below 180°. In this way the toggle joint 75 is effectively locked by the angling and the downwards biasing caused by said spring 17 when a locked toggle joint 75 is desired, and the toggle joint 75 can easily be relieved through a relatively small movement when a relieved toggle joint 75 is desired.

On top of said rollers 88 rests a cover plate 90. This cover plate 90 is free to move upward and downward relative to the other parts of the locking arrangement 2.

In this specific embodiment lowering/locking and lifting of the locking arrangement 2 is carried out by means of wire 13 and pulley 14, however obviously other lowering and lifting arrangements may also be used with the present invention.

The locking member 5 of the heavy object is provided with at least one suspension surface 6. The purpose of the at least one suspension surface 6 is to provide a place for the holding arms 8 to grip around the locking member 5 before and during lifting. A suspension surface can appear in a plurality of different ways e.g. in the form of a pro- trusion, an indentation or a conical shaping. In this specific embodiment, the suspension surface 6 is part of an annular recess provided in the locking member 5. A clear advantage by using an annular suspension surface is that the holding arms 8 are always capable of grabbing around said locking member, even if the heavy object has turned an arbitrary angle during the impact on the object which is needed crushed or impacted.

To further improve the coupling process said locking member 5 is provided with a tapering end 7, whereby the contact process between the locking arrangement 2 and the locking member 5 is facilitated, which will be explained in more details with reference to fig. 2.

The holding arms 8 are pivotably fastened to link liftings 80 and biased towards an initial position by means of a spring 70 fastened to said bridge 25. In this preferred embodiment said holding arms 8 comprises rollers 50 to facilitate the coupling process and in particular the decoupling process in which said locking member 5 so to speak rolls of the holding arms when said coupling is released.

In the shown embodiment a housing 100 encloses the releasable coupling. Encircling said housing along the top thereof a stopper 23 is provided in order to set a lower limit on the mutual distance between the housing 100 and the cover plate 90. Furthermore the bridge 25 may be provided with shock absorbers 22 in order to minimise the damage and absorb part of the energy which arises from the cyclic use of a coupling.

The functionality of the coupling according to the embodiment in fig. 1 will now be explained with reference to figs. 2-4. The crushing cycle to be described here starts with the heavy object and the locking member 5 arranged on said heavy object and ready for being coupled to said locking arrangement 2 and lifted. The elements of the locking arrangement 2 are in initial position as shown in fig. 2 and the locking arrangement is being lowered to couple to the locking member 5.

When the toggle joint 75 is in locked position (as in figs. 1-3), the two locking links 85 are kept locked in this initial position, and thereby said link liftings 80 are held in locked position too. This means that during the turning of said holding arms 8 back and forth to couple to said locking member 5, the toggle joint 75, locking links 85 and link liftings 80 are fixed. As the locking arrangement 2 is lowered over the locking member 5, as seen in fig. 2, the tapering end 7 of the locking member 5 force the two holding arms 8 slightly upward and outward, until the rollers 50 have passed the most wide part of the locking member, after which the two holding arms 8 are rolled in below the suspension sur- face 6 by the aid of springs 70. Hereby said locking arrangement 2 and said locking member 5 of said heavy object are coupled together.

During the coupling phase it is essential that the holding arms 8 are kept fixed except for the pivotable movement. This is in fact the case as the link liftings 80 are kept firmly in a fixed position as long as the locking links 85 are kept in a fixed position by the toggle joint 75 in locked position. Thereby the joint 52 is fixed with respect to the bridge 25 and movement for the holding arms 8 is only possible as a pivotable movement around the joint 52.

In this preferred embodiment gravity facilitates coupling between the locking member 5 and the locking arrangement 2 in that the weight of the locking arrangement 2 in free fall will cause the holding arms 8 to quickly move apart when hitting the locking member 5. Coupling may, however, be carried out in a number of other ways providing a force necessary to move the holding arms 8 apart.

No matter how the coupling process is carried out, but especially when high impact velocity between the locking arrangement 2 and the locking member 5 is present, it is advantageous to dampen the relative motion between these, when the coupling process is complete. Moreover, with the coupling of the present invention, a relatively high number of cycles can be completed every minute. This entails that the locking arrangement 2 impacts with the locking member 5 a relatively high number of times such that high energies arise.

For this purpose a dampener 20 is arranged to receive the locking member 5 during coupling and absorb the energy quickly and effectively in order not to damage the coupling. In this embodiment the dampener 20 is a block made of a suitable flexible material, however other dampening means, e.g. a pneumatic or hydraulic cylinder, may also be used within the scope of the present invention. At a point in the lowering process, which advantageously will be shortly after the coupling is completed, the locking member 5 will engage said dampener 20, which will decelerate the relative velocities between the locking arrangement 2 and the locking member 5 of said heavy object. This is advantageous in that the locking member 5 typically will be stationary during the coupling phase, whereas the locking arrangement 2 will more or less fall freely towards the locking member 5 in order to couple the two together in order to be able to lift the heavy object when lifting said locking arrangement 2.

When the locking arrangement 2 has been dampened in the lowering process and the holding arms 8 are below the suspension surface 6, the coupling between the locking arrangement 2 and the locking member 5 is completed and the lifting phase may begin, as seen in fig. 3.

When lifting said locking arrangement 2, said locking member 5 and thereby said heavy object will be lifted. Due to the pivotable fastening in joint 52 of said holding arms 8 on said link liftings 80 in combination with the rigid system when the toggle joint 75 is in locked position, the weight of the heavy object will at least substantially not alter the position of the link liftings 80 relative to each other.

The inclining upward placing of the holding arms 8, as seen in the initial position in fig. 2 and during lifting in fig. 3, is very advantageous during the lifting process. As can be seen from figs. 2 and 3 the spring force from the springs 70 and the gravity on the heavy object during lifting will collaborate in rotating the holding arms 8 as much as possible towards the locking member 5 and thereby hold the locking member 5 tight below said suspension surface 6.

In a desired height for the lifting, stop pads 95 are positioned (cf. fig. 4), which will engage the cover plate 90 positioned on top of the locking arrangement 2 when this desired height is reached. Hence in this height the heavy object and the locking arrangement 2 have been lifted to their maximum height, and when the locking arrangement 2 is lifted slightly further, the cover plate 90 cannot move higher and in- stead causes the rollers 88 to be pressed downwards relative to the bridge 25 and the elements fixed on the bridge 25.

The rollers 88 being pressed downwards relative to the bridge 25 and as well relative to the attachment points 81 will, due to the bended shape of the locking links 85, cause a rotation of the joints 86, whereby the force directed opposite the spring 17 force to the toggle joint 75 is increased. When the upward directed force exceeds the downward directed force on the toggle joint 75, the toggle joint 75 is relieved.

It is noteworthy that the forces acting upward and downward on the toggle joint 75 are not affected by the massive weight gained to the set-up when the heavy object has been coupled to the locking arrangement. This is caused by the fact that the massive weight is transferred via the holding arms 8 through the lifting links 80 to the attachment points 81 on the bridge from which it is directed to the holder 15 and the wire 13. Hence this weight will not influence the force upward/downward on the toggle joint 75, whereas some force sideways on the toggle joint 75 will be present as a result of torque around the attachment points 81. However this, and hence the massive weight of the heavy object, has no influence on the locking/relieving of the toggle joint 75.

The relief of the toggle joint 75 opens for the pivoting of the double pivot joint consisting of the pivotable holding arms 8 and the pivotable link liftings 80. This double pivot joint is a central element of the invention in that it allows for a very advantageous release. The instant the toggle joint is relieved, as seen in fig. 4, said link lift- ings 80 leave their fixed position, and are now able to turn a little around the attachment point 81 in connection to the movement of the locking link 85 and the toggle joint 75. A very advantageous feature of the invention is that due to the double pivot joint only a slight turning of the link liftings 80 is sufficient for creating enough space for the holding arms 8 to rotate downwards, due to gravity on said heavy object, al- lowing the locking member to be released from said holding arms 8, whereby said heavy object is able to fall freely from the locking arrangement 2 and reach the object which need to be crushed or impacted. A very advantageous feature of the invention is that due to the specific configuration only a slight turning of the link liftings 80 is sufficient for creating enough space for the holding arms 8 to rotate downwards, due to gravity on said heavy object, allowing the locking member to be released from said holding arms 8, whereby said heavy ob- ject is able to fall freely from the locking arrangement 2 and reach the object which need to be crushed or impacted. This feature is enabled through two elements, the above-mentioned double pivot joint and moreover by designing the distance from joint 52 to attachment point 81 greater than the distance from attachment point 81 to joint 86. In proper adjustment of these two distances the lever principle is used to en- sure that a small displacement of the toggle joint 75, the locking links 85, and thereby the joint 87 results in a larger displacement of the joint 52 and thereby the holding arms 8 to facilitate a quick release of the locking member 5.

The problem of wear described in the background is often caused by friction during the coupling phase and friction during the release phase. The use of rollers 50 on the holding arms 8 of the locking arrangement 2 decreases this wear markedly. In the coupling phase (fig. 2) neither the holding arms 8 nor the rollers 50 will make any substantial sliding, which decreases wear of the involved elements. In the releasing phase (fig. 4) the same applies with no need for any substantial sliding, as the turning of the rollers are capable of providing the needed relative movement.

The transition of the holding arms 8 from a firm grip below said suspension surface 6 of said heavy object 4 to a quick release of said heavy object is facilitated by the shaping of said suspension surface 6 and said rolls 50 of said holding arms 8. In the illus- trated embodiment said suspension surface 6 is part of an annular recess with a curvature suited to said rolls 50 in a way that the radius of said rolls 50 is slightly less than the corresponding curvature of the annular recess whereby the release is observed to be quick and easy compared to prior art techniques. Almost no friction is involved when releasing the heavy object 4 due to the described construction. Obviously the same effect may be obtained when said suspension surface 6 is not part of an annular recess. Therefore in an advantageous embodiment of the invention, said rollers 50 have a radius smaller than an approximated radius of curvature of the suspension surface 6, whereby the gripping and releasing of the locking member 5 is facilitated through an easier engaging process between the rollers 50 and the suspension surface 6.

As soon as the locking member 5 has been released, as seen in fig. 4, the locking arrangement 2 may be lowered/released, whereby the spring 17 will bring back the toggle joint 75 to the locked position and thereby also bring back the locking links 85 and the link liftings 80 to the initial position and further the springs 70 will bring back the holding arms 8 to the initial position of these.

The lowering of the locking arrangement 2 may be carried out at various velocities; however to save time a fast lowering is advantageous to obtain as many strokes as possible per minute. Therefore in a preferred embodiment of the invention a substan- tially free fall driven by gravity is used.

Having explained the principle of the releasable coupling with respect to an example comprising a toggle joint and a heavy object, it is evident that this inventive system and construction may be used for other purposes without departing from the scope of protection as afforded by the appended claims. In particular hydraulic, pneumatic, mechanical or electrical means may replace all or part of the inventive means and moreover the invention, with or without amendments to the invention as described herein, may be applied within other technical fields where a skilled person may recognise the advantages of the present invention.

Although a specific example has been described above, it is also contemplated within the scope of the present invention that active means may be provided in order to force the locking member 5 and the locking arrangement 2 together or apart regardless of the orientation of the coupling.

Claims

1. Releasable coupling between a heavy object and a locking arrangement (2), said heavy object being provided with a locking member (5) comprising at least one sus- pension surface (6), and said locking arrangement (2) comprising at least one holding arm (8) displaceably arranged on said locking arrangement (2) and release means (88, 90) for releasing said coupling, characterized in that said locking arrangement (2) comprises a toggle joint (75) which in a locked position thereof holds the locking arrangement (2) in locking engagement with the locking member (5) when the two are coupled together, and said release means (88, 90) comprises means for shifting the toggle joint (75) to an unlocked position thereof.

2. Releasable coupling according to claim 1, wherein said at least one holding arm (8) is pivotably arranged on said locking arrangement (2).

3. Releasable coupling according to claim 1 or 2, wherein said releasable coupling comprises at least two holding arms (8) displaceably arranged on said locking arrangement (2).

4. Releasable coupling according to any of the claims 1-3, wherein said locking arrangement (2) comprises at least one locking link (85).

5. Releasable coupling according to any of the claims 1-4, wherein said locking ar- rangement (2) comprises at least one link lifting (80).

6. Releasable coupling according to claim 4 or 5, wherein said at least one toggle joint (75) connects at least two locking links (85).

7. Releasable coupling according to claim 5 or 6, wherein said locking arrangement (2) comprises at least one link lifting (80) to connect one locking link (85) to one holding arm (8).

8, Releasable coupling according to any of the claims 5-7, wherein said releasable coupling comprises at least one double pivot joint comprising the pivotable holding arms (8) and the pivotable link liftings (80).

9. Releasable coupling according to any of the claims 1-8, wherein a lifting force is provided through wires (13) and at least one pulley (14) when lifting said locking arrangement (2).

10. Releasable coupling according to any of the claims 1-9, wherein said locking ar- rangement (2) comprises a bridge (25) for supporting the element of said releasable coupling.

11. Releasable coupling according to any of the claims 1-10, wherein said releasable coupling is adapted for use with excavators, e.g. in combination with a pile driver, a crusher, a demolition hammer, a stone or aggregate crusher

12. Releasable coupling according to any of the claims 1-11, wherein said at least one suspension surface (6) is part of a protrusion, an indentation, a recess or a conical shaping.

13. Releasable coupling according to any of the claims 1-12, wherein said at least one suspension surface (6) is essentially rotational-symmetrical.

14. Releasable coupling according to any of the claims 1-13, wherein the engaging surfaces of the at least one holding arm (8) and the locking member (5) are designed so that the action of gravity on the heavy object will affect the at least one holding arm (8) from the locking engagement with the locking member (5) and thereby aid to release said coupling when said generated radial locking force is released by relieving said toggle joint (75).

15. Releasable coupling according to any of the claims 1-14, wherein said release means (88, 90) are adapted for automatically relieving the toggle joint (75) when said locking arrangement (2) has reached maximum height.

16. Releasable coupling according to any of the claims 1-15, wherein at least one of the engaging surfaces of the at least one holding arm (8) and the locking member (5) comprises at least one roller (50) so as to facilitate the release of the coupling.

17. Releasable coupling according to claim 16, wherein said one or more rollers (50) are provided on the at least one holding arm (8).

18. Releasable coupling according to claim 16 or 17, wherein the radius of said at least one roller (50) is slightly smaller than an approximated radius of curvature of said at least one suspension surface (6) of said locking member (5).

19. Releasable coupling according to any of the claims 4-18, wherein said link liftings (80), locking links (85) and holding arms (8) following release of said releasable cou- pling through relief of said toggle joint (75) are brought back to initial position by a holding arm return means (70) and a toggle joint return means (17).

20. Releasable coupling according to claim 19, wherein said holding arms (8) are brought in below said at least one suspension surface (6) by said holding arm return means (70) during coupling of said locking arrangement (2) with said locking member (5).

21. Releasable coupling according to claim 19 or 20, wherein at least one of said holding arm return means (70) and said toggle joint return means (17) are springs.

22. Releasable coupling according to any of the claims 1-21, wherein said releasable coupling is adapted for handling a heavy object with a weight above 1 tonne, preferably above 2 tonne.

23. Releasable coupling according to any of the claims 1-22, wherein a dampener (20) is provided on the locking arrangement (2) to decelerate the relative movement between the locking arrangement (2) and the locking member (5).

24. Releasable coupling according to any of the claims 1-23, wherein said locking member (5) comprises a tapering end (7).

25. Apparatus comprising one or more couplings according to any of claims 1-24, where the apparatus is a pile driver, crusher, demolition hammer, stone or aggregate crusher.

26. Method of engaging and disengaging a heavy object by means of a release coupling according to any of the claims 1-24.

27. Method according to claim 26, whereby the engaging comprises the step of coupling together said locking arrangement (2) with said locking member (5), after which said locking member (5) is lifted with said locking arrangement (2).

28. Method according to claim 26, whereby the disengaging comprises the step of lifting said locking member (5) with said locking arrangement (2) until a desired height where the locking member (5) is released from said locking arrangement (2).

29. Use of one or more couplings according to any of claims 1-24 in a pile driver, crusher, demolition hammer, stone or aggregate crusher wherein the weight of said heavy object is above 1 ton.