An apparatus for loading and unloading of an interchangeable device. TECHNICAL FIELD

The present invention relates to the field of interchangeable devices and especially to an apparatus for loading and unloading of an interchangeable device and a method to control such an apparatus.

BACKGROUND ART

An apparatus for loading and unloading of an interchangeable device can be arranged upon a trailer or directly upon a truck. The interchangeable device can be any load such as a container, a pallet or any other type of loading unit. The use of an apparatus for interchangeable devices enables the use of one vehicle for different kinds of interchangeable devices adapted to different kind of tasks. The apparatus enables an exchange of such an exchangeable device and tipping of the device loaded thereon. The working principle of an apparatus for loading and unloading of an interchangeable device is described in SE 508 727, US 4 802 81 1 and US 5 203 668 and will therefore not be treated here more than in brief.

An apparatus according to the preamble of the independent claim 1 is disclosed in DE 28 06 406 A1 .

There are several known apparatus for loading and unloading of interchangeable devices. One such apparatus is disclosed in US 5 601 393, which apparatus is suitable for loading and unloading and for tipping of the interchangeable device. The apparatus comprises a carrying frame and a loading frame with a rear and a front part. The carrying frame is fixedly arranged upon a chassis of a truck. The rear part of the loading frame can pivot about a first articulation axis relative the carrying frame. The front part of the loading frame can pivot about a second articulation axis relative the rear part of the loading frame. The rear part and the front part can be locked relative each other, disabling a pivot motion about the second articulation axis. A power arrangement in the form of a single-compartment, double acting hydraulic cylinder is arranged between the carrying frame and the front part of the loading frame. The power arrangement can thereby pivot the loading frame between its different positions: transport position, tipping positions and exchange positions. Because the power arrangement is a double acting hydraulic cylinder, it can push and pulls the loading frame into the different positions. The power arrangement in the apparatus is however to its length adapted to what is required for changing of loads, which means that when tipping, the tipping angle will be limited (about 50 degrees) with an in many cases incomplete emptying of the load as a consequence. It is not possible to increase the tipping angle by supplying the apparatus with a longer single compartment, hydraulic cylinder, because it would not fit into the vehicle.

A truck comprising a loading are that can be tipped, are commonly provided with a multi-compartment cylinder, in order to increase the tipping angle. However, because a multi-compartment cylinder only can act in one direction, these are not suitable in an exchange vehicle, because then the power arrangement must pull the exchangeable device upon the carrying frame. There is thus a need for an improved apparatus for loading and unloading an interchangeable device, which also allow a greater tipping angle of an interchangeable device loaded thereon.

SUMMARY

The object of the present invention is to provide an apparatus for loading and unloading an interchangeable device and which allows a greater tipping angle than known apparatus. A second object of the invention is to provide a method to control such an apparatus.

The apparatus of the invention is adapted for loading and unloading of interchangeable devices and is also capable of tipping a loaded interchangeable device. Said apparatus is adapted to be mounted on a vehicle, such as a trailer or a truck, i.e. an exchange trailer, a hook lift trailer, exchange truck or a hook lift truck. The nature of the vehicle is not limiting for the invention which is suitable for any kind of vehicle.

The apparatus can however be arranged in at least one transport position, a plurality of tipping positions and a plurality of exchange positions. The transport position is defined in that the loading frame is resting upon the carrying frame and a power arrangement adapted to pivot the loading frame between its different positions is unloaded.

The tipping positions are defined as any position of the loading frame between the transport position and the maximum allowable/possible tipping position, i.e. when the loading frame has pivoted from the transport position about the first articulation axis.

The exchange positions are defined as any position of the loading frame between the transport position and the maximum allowable/possible exchange position, i.e. when the front part of the loading frame has pivoted from the transport position about the second articulation axis.

The inventive apparatus comprises a carrying frame and a loading frame. Said carrying frame is adapted to rest on or be integrated with a chassis of said vehicle, i.e. the carrying frame could be provided with a pair of wheels. The apparatus is extending in a lengthwise direction of the vehicle, and is adapted to load the interchangeable device from it rear end. Said loading frame is divided into a rear and a front part, which are pivotally connected with each other. Said rear part is pivotally connected to the carrying frame and can pivot about a first articulation axis relative the carrying frame. The carrying frame is connected with the loading frame via a first joint coupling enabling the first articulation axis. Said first joint coupling is arranged at the rear end of the carrying and the loading frame. Said first articulation axis is provided perpendicular to the length direction of the apparatus. Said front part of the loading frame can pivot about a second articulation axis relative said rear part. The second articulation axis is provided perpendicular to the length direction of the apparatus. The loading frame is provided with a second joint coupling arranged between the front and rear part enabling the second articulation axis. The loading frame further comprises locking means, wherein the rear and the front part can be locked, by said locking means, in order to prevent a pivot motion about said second articulation shaft, i.e. the loading frame thereby becomes a rigid frame. When the locking means is in an unlocked state the rear and the front part of the loading frame a pivot motion about the second articulation axis is enabled.

The loading frame can pivot between a transport and a tipping position when said rear and front part of the loading frame is locked, i.e. when the loading frame is a rigid frame. Normally, in the transport position the loading frame is resting on the carrying frame and is parallel therewith.

When the second joint coupling is unlocked, i.e. said rear and front part of the loading frame is unlocked, said front part can be pivoted relative the rear part, about the second articulation axis, wherein the apparatus can be arranged into an exchange position for exchanging an interchangeable device.

In order to control the loading frame from its transport position to its tipping position and from its transport position to its exchange position a first hydraulic cylinder is arranged between the carrying frame and the loading frame. The first hydraulic cylinder is adapted to act upon the loading frame, such that the loading frame can pivot about said first articulation axis from its transport position to a tipping position. The first hydraulic cylinder is further adapted to act upon the front part of the loading frame, such that the loading frame can pivot about said second articulation axis from the transport position to an exchange position.

The loading frame is further provided with carrier means adapted to engage with an interchangeable device. The carrier means is a known device arranged on the front part of the loading frame. The carrier means commonly protrude essentially perpendicular from the front part of the loading frame and provided with a hook to hook into an exchange unit. The carrier means is mounted on or is integrated in the front part of the loading means. The carrier means can be able to pivot and/or extend in order to enable an easy hook in into an exchange unit. The carrier means is a known device of an exchange apparatus and the design thereof is not a scope of the invention.

The inventive apparatus is characterised in, that a second hydraulic cylinder is arranged to act upon said front part of the loading frame, wherein when said second hydraulic cylinder is positioned in an extracted position end position, said rear part and said front part of the loading frame are arranged essentially in the same plane, and when said second hydraulic cylinder is positioned in a from said end positioned retracted position, said front part is positioned with an angle to said rear part, and wherein said first and second hydraulic cylinder are multi-compartment hydraulic cylinders.

Multi-compartment cylinders have a better ratio between their retracted length and their extracted length, than a single compartment cylinder used in the prior art. It is thereby possible to achieve a greater tipping angle and still arrange the first cylinder within the carrying frame. A multi-compartment cylinder however, is just active in its extraction and must be retracted by an external force into its retracted position. Inventively is thereby a second hydraulic cylinder provided. The second hydraulic cylinder is thereby arranged on the rear side of the second articulation axis, i.e. opposite the first hydraulic cylinder, and can thereby reposition the loading frame from an exchange position to a transport position.

The first hydraulic cylinder is arranged such that when it extracts it applies a pushing force upon the loading frame such that it pivots about the first or the second articulation axis, depending upon if, the locking means is in a locking or unlocked position. If the locking means is in a locking position, the second articulation axis is not available, wherein an extraction of the first hydraulic cylinder results in that the loading frame pivots about the first articulation axis and pivots in a direction from a transport position to the tipping position. The use of multi-compartment cylinder as the first hydraulic cylinder results in that the attachment of the cylinder in the carrying frame can be made closer to the first articulation axis and thereby also achieve a greater tipping-angle, because the multi-compartment cylinder is more compact in its retracted position than a single-compartment cylinder. A further advantage of the multi- compartment cylinder is that it can apply a greater force in the beginning of the extraction of the cylinder, because it then uses a greater pressure area of the first compartments, and it is from this position the greatest force is needed, especially if the loading frame is fully loaded. At the end of the extraction of the first hydraulic cylinder the smaller areas of the outer compartments is used, whereby less power can be applied to the loading frame. This is however not a problem since lesser power is needed in the later stages of the tipping and further leads to the advantage that less hydraulic fluid is needed and the extraction (and thereby the tipping) can be made faster in the later stages of the tipping.

However because a multi-compartment cylinder is just acting in one direction a second hydraulic cylinder is arranged to act upon the front part of the loading frame in order to re position the front part of the loading frame from an exchange position to the transport position. The second hydraulic cylinder is arranged such that when it extracts it applies a load upon the front part of the loading frame, causing it to pivot about the second articulation axis in a direction from an exchange position to a transport position.

In the transport position the second hydraulic cylinder is arranged essentially parallel with the loading and the carrying frame. Also the second hydraulic cylinder is a multi-compartment cylinder, having the advantages of being compact and developing the highest force in the beginning of the extraction, when it is most needed, and a lower force in the end, wherein the extraction thereby becomes faster. The compactness of the second hydraulic cylinder allows the whole cylinder to be arranged rear of the first hydraulic cylinder in all of the transport, tipping and exchange positions.

This is achieved through controlling a control valve of the first hydraulic cylinder such that the pressure in the first hydraulic cylinder is increasing. To reposition the first hydraulic cylinder from a tipping position to a transport position, the control valve is controlled such that the first hydraulic cylinder is unpressurised, wherein the loading frame can sink back to the transport position by its own weight, i.e. the weight of the loading frame (and a possible exchange device loaded thereon) acts upon the first hydraulic cylinder such that it retracts. The first and the second cylinder cooperates during the exchange process, such that when the first hydraulic cylinder is pivoting the loading frame, about the second articulation axis, towards the maximum exchange position, the second hydraulic cylinder is passively retracted by the force applied upon the loading frame by the first hydraulic cylinder. In the opposite direction, when the loading frame is pivoting from an exchange position to a transport position, the second hydraulic cylinder is applying the force upon the loading frame, wherein the first hydraulic cylinder is passively retracted by the force applied from the second hydraulic cylinder.

The first hydraulic cylinder is arranged between the carrying frame and the front part of the loading frame. By extracting the hydraulic cylinder, the loading frame can be positioned in either an exchange position or a tipping position dependent of if the locking means is in a locking or an open position.

In an advantageous embodiment of the inventive apparatus the second hydraulic cylinder is arranged between the rear part and the front part of said loading frame. The second hydraulic cylinder would thereby be parallel with the loading frame when the rear part and the front part of the loading frame are locked by the locking means, i.e. parallel with the loading frame, in the transport position and all the tipping position. An alternative arrangement of the second hydraulic cylinder is such that the second hydraulic cylinder is arranged between the first articulation axis and the front part of the loading frame. Also in this configuration the second hydraulic cylinder would be parallel and unaffected by a tipping operation. Still another alternative arrangement of the second hydraulic cylinder is between the carrying frame and the front part of the loading frame. In this arrangement however, the length of the second hydraulic cylinder will probably be influenced by a tipping operation, wherein the second hydraulic cylinder must be controlled such that it can be extracted and retracted by external forces during a tipping operation.

The first and second hydraulic cylinder are preferably pivotally connected to said front part of said loading frame on the same distance from the second articulation axis and/or are arranged upon the same shaft upon said front part.

By connecting the first and the second hydraulic cylinder at the same distance, i.e. in the same point/axis, the operating angles of the apparatus is kept as great as possible, without any interference between the two hydraulic cylinders during the pivot motions. This together with the compactness of the multi compartment cylinders enables the construction with only two hydraulic cylinders. Further, the centred position of the hydraulic cylinders eliminates any unbalances in the device, caused by two parallel cylinders, which are unevenly loaded with working fluid.

A preferred solution to attaching the two hydraulic cylinders on the same shaft in the front part of the loading frame is to provide them with a with a fork coupling. A fork coupling enables that both cylinders can apply their load centrally upon the same shaft, which is advantageous for the force distribution. The fork coupling enables that both hydraulic cylinders can apply there loading force in the same point, due to the mutual centred arrangement. To control the inventive apparatus an inventive method is suggested. The hydraulic cylinders are provided with a respective control valve, which enables an individual control of the first and the second hydraulic cylinder. The control valves can control the first and the second hydraulic cylinder such that they can be extracted, be unpressurised, such that the hydraulic cylinder can be retracted from external forces. Optionally the control valves can also control the hydraulic cylinders such that they are fixed in their position.

The inventive method thereby controls the hydraulic cylinder such that to move said loading frame in a direction from said transport position to said maximum tipping position, said first cylinder is controlled to be extracted and said second cylinder is controlled to be unpressurised.

To move said loading frame from a transport position to an exchange position said first cylinder is controlled to be extracted and said second cylinder is controlled to be unpressurised. To move said loading frame from an exchange position to a transport position said second cylinder is controlled to be extracted and said first cylinder is controlled to be unpressurised. When the vehicle is used and the apparatus is in the transport position, the apparatus can either be locked with mechanical locking means, such that it cannot pivot about either its first or second articulation axis. It also possible to provide the hydraulic cylinders with control valves enabling to lock the cylinders in a specific position, then the hydraulic cylinders could be locked in their respective positions when the apparatus is in its transport position. The second hydraulic cylinder could also be lock in its extracted end position during tipping, given that the length of the second hydraulic cylinder is not influenced by a tipping operation. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in detail with reference to the figures, wherein: shows an embodiment of the inventive apparatus in its transport position,

shows an embodiment of the inventive apparatus in a tipping position,

shows an embodiment of the inventive apparatus in an exchange position, and

shows an embodiment of the inventive apparatus in its maximum tipping position.

DETAILED DESCRIPTION

In the following only one embodiment of the invention is shown and described, simply by way of illustration of one mode of carrying out the invention. Now the inventive apparatus 10 is described in conjunction with the figures 1 - 4. The inventive apparatus 10 comprises a carrying frame 1 1 and a loading frame 12. In the embodiment shown, the inventive apparatus 1 is disclosed as an exchange trailer 4, this is however not limiting for the invention. The inventive apparatus 10 could just as likely be arranged upon a truck. In the four figures the loading frame 12 is arranged in four different positions; figure 1 , transport position; figure 2, tipping position; figure 3, middle exchange position and figure 4, max exchange position. The inventive apparatus 1 can however be position in intermediate positions between these positions.

The inventive apparatus 1 comprises a carrying frame 1 1 and a loading frame 12. The carrying frame 1 1 is provided as an integral part of the chassis of the trailer 3. The apparatus 10 has a front and a rear end, which are correspondently arranged in the front and the rear of the vehicle respectively. The carrying frame 1 1 is rigid and does not perform any movement in relation to the vehicle 3 in order to change position of the loading frame 12.

The general functioning of an exchange trailer is known and will therefore not be described in further detail

The loading frame 12 is pivotally connected to the carrying frame 1 1 in a first joint coupling 20 at the rear end of the apparatus 10. The loading frame 12 can thereby pivot about the first articulation axis ax1 .

The loading frame 12 is further divided into a rear and a front part 13, 14, which are pivotally connected in a second joint coupling 21 . The front part 14 can thereby pivot about the second articulation axis ax2. The locking means 15 can be of any suitable type. The second joint coupling 21 is provided with a locking mechanism 15, which in its locking state locks the rear and the front part 13, 14 together such that the front part 14 cannot pivot about the second articulation axis ax2. The inventive apparatus 1 is provided with a first and a second hydraulic cylinder 16, 17. Both the first and the second hydraulic cylinder 16, 17 are multi-compartment cylinders. The advantages with multi-compartment cylinders are that they are more compact in their retracted state relative a single-compartment cylinder. The first hydraulic cylinder 16 is arranged between the carrying frame 1 1 and the front part 14 of the loading frame 12. The second hydraulic cylinder 17 is arranged between the rear part 13 and the front part 14 of the loading frame 12.

The first hydraulic cylinder 16 has two objects, first to pivot the loading frame 12 from a transport position to a tipping position. This is done with the locking mechanism 15 in a locked position, whereby the loading frame 12 only can pivot about the first articulation axis ax1 . Because the first hydraulic cylinder 16 is a multi-compartment cylinder, it cannot be retracted actively, the reversed motion to get the loading frame 12 from the tipping position (figure 2) to the transport position (figure 1 ) is done due to the gravity of the loading frame 12 and a device 2 loaded thereon. During a tipping operation the second hydraulic cylinder 17 is passive. The second hydraulic cylinders 17 length is not influenced by the tipping motion, due to its arrangement between the rear and the front part 13, 14 of the loading frame. In figure 2 the maximum tipping position is shown. The apparatus can obviously be arranged in any suitable tipping position between the transport position and the maximum tipping position.

The second object of the hydraulic cylinder is to pivot the front part 14 of the loading frame 12 in the direction from a transport position (figure 1 ) towards an exchange position (figure 3 and 4). This is done with the locking mechanism 15 in an unlocked position, whereby the front part 14 of the loading frame 12 can pivot about the second articulation axis ax2. As before, the first cylinder can just be actively extracted and thereby just pivot the front part 14 of the loading frame 12 in one direction i.e. from a transport position (figure 1 ) in direction towards the maximum exchange position (figure 4). To pivot the front part 14 of the loading frame back from an exchange position (figure 3 and 4) towards the transport position (figure 1 ), the second hydraulic cylinder 17 is activated. The object of the second hydraulic cylinder 17 is thereby to pivot the front part 14 of the loading frame 12 in direction towards the transport position (figure 1 ) from an exchange position. The apparatus can obviously be arranged in any suitable exchange position between the maximum and the middle exchange position (figure 4, figure 3) and between the middle exchange position (figure 3) and the transport position (figure 1 ).

In the exchange positions (figure 3 and 4) the rear part 13 of the loading frame 12 is resting upon the carrying frame 1 1 . The movement between the transport position (figure 1 ) and any of the exchange positions (figure 3 and 4) does not result in any pivot motion about the first articulation axis ax1 .

The front part 14 of the loading frame 12 is provided with carrier means 30, which is adjustable in order to easier position a hook 32 of the exchange apparatus 10 into a suitable position to hook into an exchange device 2. A power arrangement in the form of a hydraulic cylinder 31 is arranged to adjust the position of the carrier means 30. The carrier means 30 is known and can be varied without influence the scope of the invention.

The inventive apparatus 10 provides an exchange trailer/truck which enables fast exchange and tipping operations due to the two compact hydraulic cylinders 16, 17 provided therefore. Reference signs mentioned in the claims should not be seen as limiting the extent of the matter protected by the claims, and their sole function is to make claims easier to understand. As will be realised, the invention is capable of modification in various obvious respects, all without departing from the scope of the appended claims. Accordingly, the drawings and the description thereto are to be regarded as illustrative in nature, and not restrictive.