The present invention relates to an arrangement that makes possible the automatic coupling of a removable tool to a tool attachment of a work machine as described in the introduction to claim 1.

Arrangements for the automatic coupling of the tool attachment of a work machine with a tool in the form of, for example, a digger are previously known in several designs, as are such coupϋng arrangements for the coupling of a tool with a machine, These coupling arrangements comprise automatic hose couplings for the hydraulic coupling of the tool to the hydraulic system of the work machine such that functions that are part of the tool and that are driven by hydraulic means can be operated directly from the control cabin of the work machine. This latter type of automatic coupling is furthermore so designed that it is to be possible to couple a tool with a work machine without the driver needing to leave the control cabin and without the help of an external assistant. Despite this, it has proved to be the case despite this that the known coupling arrangements of this type do not satisfy the said conditions, and they are also associated with the problematical disadvantage that release of hydraulic oil to the ground always takes place both during coupling and during disconnection of the hydraulic hoses, something that attempts have been made to avoid without, however, success to any significant degree.

Furthermore, it has proved to be the case that the automatic hose couplings in their disconnected state are fully unprotected, and thus exposed to dust, sand, gravel and similar substances that, due to the oil that is present on the disconnected rapid-coupling units readily sticks to these and can in this way totally destroy the hose couplings. It has also for this reason proved to be the case that achieving a well-functioning coupling arrangement for a tool that requires for its function, or for the function of arrangements arranged on the tool, access also to a source of energy on the work machine is associated with major problems. As examples of this, tools that have moving parts that require a driving force may be mentioned, such as, for example, a fork framework provided with moving lifting forks that are suspended from the fork framework in a manner that allows displacement, where the lifting forks are displaced away from and back into a side position with the aid of a motor. Other examples are tools with sensor arrangements, vibrating arrangements and similar that are in any way driven, controlled, regulated, activated, influenced, or for any reason require the supply of energy. One aim of the present invention is to achieve an arrangement that makes possible the automatic coupling of a tool to the tool attachment of a work machine such that at least

one of parts of the tool and arrangements arranged on the tool is coupled with a source of power on the work machine in a safe way without the loss of energy.

This aim is achieved through an arrangement with the technical characteristics that are made clear by the characterising sections of claim 1.

An embodiment of the invention will be described below as an example, with reference to the drawings.

Figure 1 shows an arrangement according to the invention in a perspective view in a condition just before the coupling of the tool to the tool attachment of a work machine, which tool attachment is mounted on an arm.

Figure 2 shows a detail of the arrangement according to the invention at an enlarged scale.

Figure 3 shows an arrangement according to the invention comprising a contact construction in two parts that has one of its parts arranged on the tool attachment and its second part arranged on the tool in such a manner that the two parts are automatically brought into contact with each other for the supply of power to at least one of the tool and arrangements arranged on the tool from the work machine when the tool is coupled with the tool attachment of the machine.

A tool attachment 1 is shown in the drawings supported at the end of the operational and tool arm (not shown in the drawings) of a work machine, with a tool 2 in the form of a fork framework 4 that is equipped with lifting forks 3. The fork framework 4 is provided with attachment means adapted for the tool attachment 1 , in the form of attachment hooks 5 and two attachment lugs 6 provided with holes. The tool attachment 1 can be operated from within the control cabin of the machine and comprises a transverse support rod 7, preferably with round cross-section, attached at the side pieces 8 of the attachment, each of which comprises two separated plates 9 with a distance between them that is greater than the thickness of the attachment hooks 5 of the tool. Each one of the side pieces 8 of the tool attachment is provided at its lower part with a locking hole 10 for locking pins 11 that can be operated either by hydraulic means or by mechanical means, for locking of the attachment lugs 6 of the fork framework to the tool attachment and fixing them in position there.

During coupling of the tool 2 to the tool attachment 1 of the machine, the rod 7 of the manoeuvrable tool attachment is introduced in a known manner from below into the attachment hooks 5 of the tool, after which the tool attachment 1 is rotated around its rod 7, on which it is now the case that the tool is suspended with the aid of its hooks 5, in towards the attachment lugs 5 and, with these lugs in line with the locking holes 10 of the tool attachment, the displaceable locking pins 11 are operated to achieve locking of the

attachment lugs 6 to the too! attachment 1, after which the tool is held suspended in an immobile manner from the tool attachment 1 of the machine.

The present fork framework 4 comprises a pair of lifting forks 3 that are suspended in a known manner with the aid of sliding hooks 12 in a manner that allows displacement on a transverse sliding beam 13 in the fork framework 4, against the side 14 of which the lifting forks 3 are placed in contact and supported in a manner that allows sliding also against the lower transverse sliding beam 15 of the fork framework.

Furthermore, the lifting fork 3 is, or in the example shown both lifting forks 3 are, in accordance with the present invention, connected to a device 16 such that they can be moved, displaced, in the transverse direction and in this way set at a suitable distance from each other with respect to the size of the object or objects that are to be handled. The means 16 of such motion is shown in the drawing in the form of an endless chain that passes over chain wheels 19 arranged at the sides of the fork framework, at least one of which wheels is to be driven, while the other in this case is arranged to freewheel. The endless means 16 of motion or chain is attached at its upper part 20 with one of the lifting forks 3 and it is attached at its lower part 21 with the second lifting fork 3. and in this way the two lifting forks 3 will, when the means 16 of motion is driven in the direction that is shown by arrows 22, be driven towards each other, while for the opposite direction of motion of the means 16 of motion the lifting forks 3 will move away from each other. The connection between the chain and the fork can either be a fixed connection, constituted by, for example, a bolt, or it can be removable, constituted by, for example, an electromagnet, whereby one or the other of the forks 3 can be displaced independently of the other fork.

An electric motor 23 is arranged for driving the means 16 of motion in the embodiment of the invention shown solely as an example in the drawing. This motor 23 supports the driven chained wheel 19 on its output drive shaft.

The electric motor 23 receives its power supply via a contact construction that connects the motor 23 to a source of power (not shown in the drawings). The contact construction is in two pieces, one piece 25 of which is connected with the tool attachment 1 while the second piece 26 is connected with the tool, the fork framework 4. These two contact pieces 25 and 26 are so arranged relative to each other that they are automatically brought into contact with each other when the fork framework 4 is applied to the tool attachment 1.

The contact pieces 25 and 26 comprise a contact plate 27 and 28, one plate on each contact piece. The contact plates 27 and 28 are arranged such that they come into contact with each other when the fork framework 4 is applied to the tool attachment 1. There are two contact plates 27 and 28 at each contact piece 25 and 26. At least two of these contact plates 27 and 28 that make contact with each other, one plate at each contact piece,

are so designed that they make contact in a manner that is a consequence of their shape, they have outer forms that make it possible for them to be in contact with each other in a manner that ensures contact and that centres the plates relative to each other.

Each one of the two plates 27 and 28 that lie in contact with each other has a three- dimension form where the extent of the plate 27 or 28 has its greatest dimension in a plane that is essentially parallel with the front surface of the body 25a and 26a of the contact piece. One of the contact plates 27 has a lesser extent than the second plate 28. One of the plates 27 has a form that bulges outwards in a direction away from the body 25a of the contact piece, while the second plate 28 has a form that bulges inwards towards the body 26a of the contact piece. This complementarity of shape that extends over an area ensures that the plates 27 and 28 are centred relative to each other when the lifting frame 4 is applied to the tool attachment, without it needing as a result of this any high precision at the actual instant of coupling. The plates 27 and 28 will come into close contact with each other whereby good electrical contact and transfer of current will be obtained. In the embodiment shown in the drawings, one of the plates 27 has a convex form while the second plate 28 has a concave form. It is appropriate that the plates 27 and 28 have low curvature for their convex and concave forms, that they follow a partial surface of a sphere with a large radius of curvature.

It is also possible that the plates 27 and 28 may have the form of cones while still offering the same function and advantages since guidance towards centred contact takes place also with this form when the two plates are brought towards each other. The plates 27 and 28 may also have a somewhat edged shape, for example the form of a somewhat edged polygonal cone.

Two contact plates of the same type 27 or 28 are arranged at the same contact piece 25 or 26. It is, of course, possible to have two different types of contact plate on one contact piece without deviating from the innovative concept of the invention. The contact plate 27 is shown in the drawings located on the tool attachment of the machine while the contact plate 28 is shown on the tool. The two different types of contact plate 27 and 28 may be mounted in the opposite sense without deviating from the innovative concept of the invention.

One of the plates 27, the convex plate, of the two contact plates 27 and 28 is spring-mounted in the body 25a of the contact piece with the aid of a spiral spring 29 arranged between the plate 27 and the body 25a of the contact piece, see Figure 2. This design provides the contact force between the two plates 27 and 28 that are in contact, and it

locked to each other during the coupling of the too! to the tool attachment of the machine, whereby also the contact pieces 25 and 26 will take up their locked positions relative to each other,

The contact plates 27 and 28 are easy to clean by wiping a cloth over them if either the tool or the machine, or both, has been in an environment in which dirt accumulates, due to their relatively flat design. Since an electric motor is used, the same collection of dirt will not take place around this contact as is otherwise the case with hydraulic couplings, and this further facilitates the contact of the contact plates 27 and 28 against each other. The means 16 of motion can be constituted by a V-belt, a wire, a cogged belt or its equivalent, since no major forces are required to displace the two lifting forks towards and away from each other.

Parts of the tool that require energy or parts arranged on the tool that require energy can, as has been described in the introduction to the description, be of different types than the forks that have been described here. The present invention is not limited to what has been described above and shown in the drawings: it can be changed, modified and supplemented in many different ways within the framework of the innovative concept defined in the attached patent claims. There may, for example, be one motor and one means of motion arranged for each lifting fork. The electric motor may be used for several functions and for the control of other types of parts or arrangements that require energy in the vicinity of the tool attachment 1 and at the end of the arm construction of the work machine. The contact construction can be adapted to be appropriate for these without deviating from the innovative concept of the invention.