The present invention relates to a pallet pull-out assembly which is easy to open and/or close. In particular, the present invention relates to a pallet pull-out assembly having an integrated mechanical arrangememt that helps or assists a user of the pallet pull-out assembly.

BACKGROUND OF THE INVENTION

Warehouses and production facilities have an extended range of products, which has to be organized in the warehouse or close to the production/assembly lines. A large proportion of product retrieval is manual, where products of various sizes are stored in different locations. The pallet pull out unit solves this issue, where palletized goods are fed directly into pallet racks, where the goods are accessed manually without the need of pallet trucks or fork lifts.

However, extending the drawer results in clashes on the bearings within the tracks. As the pallet drawer stops abruptly, there is an angular moment, which momentarily increases the load on the front beam. These dynamic effects cause vibrations within the pallet drawer unit and the pallet rack frame.

It may be seen as an object of embodiments of the present invention to provide a simple mechanical arrangement that helps or assists a user of the pallet pull-out assembly in opening and/or closing the assembly. It may be seen as a further object of embodiments of the present invention to provide an arrangement that avoid bearing/track clashes and unwanted vibrations.

DESCRIPTION OF THE INVENTION

The above-mentioned objects are complied with by providing, in a first aspect, a pallet pull- out assembly comprising

1) a stationary part being adapted to be secured to a static frame structure,

2) a moving part being adapted to be moved relative to the stationary part, the moving part being adapted to carry a load of goods, and 3) an energy storing arrangement for assisting the user of the pallet pull-out assembly in moving the moving part relative to the stationary part. Thus, the present invention relates to a drawer having a stationary and a moving part being adapted to carry loads of goods, said load of goods typically being arranged in pallets. The static frame structure to which the stationary part is secured may comprise a pallet rack or a cage construction in a goods vehicle or a container. The pallets carrying the goods may have a weight of several hundred kilos whereby the moving part of the assembly becomes difficult to handle for a single person. In particular, the initial stage of either opening or closing the assembly requires a significant heave from the user. To assist the user an energy storing arrangement is provided. This arrangement helps or assists the user of the pallet pull-out assembly in moving the moving part relative to the stationary part. The energy storing arrangement may be implemented as a pure mechanical energy storing arrangement, i.e. without the use for example electrical motors which make the arrangement more expensive and technically complicated.

The energy storing arrangement may be secured to the moving part, the stationary part and/or the static frame structure, and it may comprise one or more resilient members adapted to store energy accumulated during an opening and/or closing of the pallet pull-out assembly. In particular, during the final phase of either opening or closing of the assembly energy may be stored in the one or more resilient members. This stored energy may be released at a later stage.

In order to help or assist a user of the pallet pull-out assembly the one or more resilient members are adapted to release at least part of its stored energy upon opening and/or closing of the pallet pull-out assembly, in particular during the initial phase of either opening or closing the assembly. The one or more resilient members may be selected from various types of devices such as compression springs, leaf springs, torsion springs, constant force springs, disc springs, washer springs, tension springs, gas springs or pneumatic damping devices with an accumulator.

As previously stated the load of goods may have a weight of several hundred kilos. However, the weight of the goods may vary a lot. For that reason it might be advantageous if the energy storing arrangement is in somehow load dependent, i.e. the amount of energy stored in the arrangement depends on the weight of the load placed on the moving part of the pallet pull-out assembly. Thus, the pallet pull-out assembly of the present invention may further comprise a load determining arrangement, the said load determining arrangement being adapted to respond to the weight of the load of goods placed on the moving part.

Similar to the energy storing arrangement the load determining arrangement may be implemented as pure mechanical load determining arrangement. The load determining arrangement may comprise one or more resilient members being adapted to respond to the weight of the goods placed on the moving part. The one or more resilient members of the load determining arrangement may comprise compression springs, leaf springs, torsion springs, constant force springs, disc springs, washer springs, tension springs, gas springs or pneumatic damping devices with an accumulator.

As stated above the load determining arrangement may be configured to adjust the energy storing arrangement. By adjusting, it is meant, that for example a loading of a resilient member of the energy storing arrangement may be altered by the load determining arrangement. The load determining arrangement may comprise a plurality of leaf springs being hinged together in a longitudinal direction. Each leaf spring may be a curved structure, such as a U- shaped structure turned upside down. The U-shaped leaf springs may be mutually connected via respective hinges thereby forming an elongated structure having two ends. The plurality of leaf springs being hinged together may be attached to the moving part at one of its ends, whereas the other end of the plurality leaf springs is free to move in response to the weight of the goods placed on the moving part. This free end is arranged to perform an essential linear movement in response to the weight of the goods placed on the moving part. This essential linear movement of the free end of the plurality of leaf springs being hinged together may be performed in a plane being essentially perpendicular to the load-related forces acting on the load determining arrangement. Thus, if the load-related forces are acting in the vertical direction, which they normally are, the essential linear movement of the free end is perform in an essentially horizontal direction.

The free end of the plurality of leaf springs being hinged together may be mechanically coupled to an energy storing arrangement comprising a front and a rear spring member. The front and the rear spring member may comprise compression springs, a multitude of disc springs or spring washers. The front and rear spring members may be partially preloaded when no load of goods are placed on the moving part of the pallet pull-out assembly, i.e. when no load-related forces are acting on the moving part of the assembly. The preloaded front spring member may be arranged to be at least partly unloaded when a load of goods is placed on the moveable part, i.e. the preloaded front spring may be at least partly released when load-related forces are acting on the moving part.

The pallet pull-out assembly of the present invention may further comprising a locking mechanism adapted to hold the moving part of the pallet pull-out assembly in a closed or open position in order to prevent the energy storing arrangement from oscillating. The locking mechanism may involve a catch mechanism that engages, when the pallet pull- out assembly is extended. As the kinetic energy is stored in the energy storing arrangement, this locking mechanism engages to prevent the moving part recoiling. The locking mechanism may be attached to the pull handle of the moving part. When the moving part is closed, the return momentum is stored in the energy storing arrangement, and to prevent recoil the locking mechanism engages. The locking mechanism may be automatically disengaged by pulling the handle in a given direction.

In static frame structures, where it is pertinent, these locking mechanisms may be attached to other pallet pull-out assemblies such that multiple extensions in a pallet rack may be avoided. This prevents excessive loading and tipping of the static frame structure.

The locking mechanism may be linked by rotating axles that block extension of other pallet pull-out assemblies horizontally. Extension of one pallet pull-out assembly may tip a paddle, which rotates an axle which is linked to the horizontal adjacent pallet pull-out assemblies. Rotating the axel tips the locking flap on the other pallet pull-out assemblies. This prevents the adjacent pull-out assemblies from opening. The locking mechanism axle may be attached to the axles of the vertically adjacent pallet pull-out assemblies via a linkage. As one axle rotates, this rotates the axles of the vertically adjacent pallet pull-out assemblies, which in turns tips the locking flaps of all of the horizontally adjacent pallet pull-out assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in further details, with reference to the accompanying figures, wherein

Fig. 1 shows a first embodiment of the present invention using a single compression spring,

Fig. 2 shows the first embodiment of the present invention using two compression springs,

Fig. 3 shows other embodiments of the present invention, Fig. 4 shows a preferred embodiment of the present invention,

Fig. 5 shows a close-up of the leaf springs of the preferred embodiment of the present invention, and Fig. 6 shows the mechanical coupling between the load responding arrangement and the mechanical energy storing arrangement that assists the user of the pallet pull-out assembly.

While the invention is susceptible to various modifications and alternative forms, specific embodiments and adaptations have been shown by way of examples in the drawings and will be described in details herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed as certain modifications may be easier to implement. Rather, the invention is to cover all modifications, equivalents, and

alternatives falling within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION

In its most general aspect, the present invention relates to a simple mechanical arrangement that helps or assists a user of the pallet pull-out assembly to open and/or close the assembly. The general principle underlying the present invention, is concerned with accumulation and storage of energy when opening and/or closing the pallet pull-out assembly. The energy is stored in a simple mechanical arrangement and subsequently released when a user of the pallet pull-out assembly either initiates closing or opening of the assembly. Thus, the released energy helps or assists the user of the assembly to help bring a moving part of the pallet pull-out assemply from still stand into a movement.

Referring now to Fig. 1 a flange 103 is welded onto the rear cross member 101 on the upper drawer mechanism of the assembly, i.e. the moving part of the pull-out assembly. A rod 105 is welded onto this flange, onto which a compression spring 104 is threaded. The

compression spring 104 extends past the end of the rod 105. A rubber cap can be placed over the compression spring 104 to aid in cushioning. When the pallet pull-out assembly is opened, the extension moves the rear cross member 101 of the upper pallet drawer towards the lower cross member 102 of the lower pallet drawer which has a tube welding (not shown) onto it. The lower pallet drawer forms part of the stationary part of the pallet pull-out assembly. The compression spring 104 then aligns inside the tube and compresses. The tube prevents any bucking of the compression spring 104. The tolerances on the diameter of the compression spring have to be large, as different mass loads on the pallet pull-out assembly will result in different deflections of the extended cantilever pallet drawer. In turn this results in different angular deflections, where the cross members 101, 102 are slightly out of alignment. It is conceivable that the compression spring 104 may be replaced with disc/Belleville/Waverly springs. Disc springs can be stacked to give a progressive spring characteristic that alleviates some of the problems mentioned with regard to compression springs. The assembly depicted in Fig. 1 only requires a simple flange welded onto the cross member 101. However, the guide tube for the spring needs to be placed precisely. The mechanism is simple and can be easily maintained, though the components are open. The spring displacement need only be minimal, as initial start or finish forces are needed to accelerate the load up to a speed where manual force takes over. The springs will also regulate the manual force at the start and finish of the cycle, so that clashing of the pallet drawer is significantly reduced. This assembly can be repeated on the opposite side of the rear upper pallet drawer cross member, where a small compression spring is placed to absorb the closing force. Effectively different spring types could be used; gas, variable, compression or constant force springs.

The embodiment shown in Fig. 1 has a basic though exposed design, which has various safety issues that need to be addressed. Effectively all the components would be placed in a tube, so that it looks like a regular gas spring with an impact plate. Barring the flange plates, all components could be mounted by the customer after shipping. Repairing and maintenance is simple, though replacement of springs is costly. The springs can be dimensioned after the relevant euro code standards, though taking load variation into account may prove difficult. The spring can be adjusted by applying torsion, or preloading it according to the actual load. This would however require that the warehouse know the weight that it is on the pallet, load sensors and a display could be placed on the pallet pull out assembly. Fig. 2 shows an arrangement 200 where the spring system 206, 207, 208 is mounted on a member 204 connecting middle 202 and rear 203 square tubing stiffeners of the upper frame of the pallet pull-out assembly. The spring system 206, 207, 208 absorbs the impact when the drawer, i.e. the moving part of the pallet pull-out assembly, is opened and closed. The springs 207, 208 float on a guide rod (not shown) that is supported by brackets 206. In another embodiment 300, cf. Fig. 3a, a stop plate 302 is welded onto the run of the upper pallet drawer, much like the axle 305 of the rear wheel 304. As the pallet drawer extends, this compresses against a spring 303 that is placed on a rod (not shown), which is welded inside the C profile 301. Again a guide tube (not shown) may be needed for the spring 303 in order to avoid bucking. In an alternative embodiment a constant spring 308, 311 could be curled into a circle and attach this to a rear and front stop plate. This would also cushion the wheels 308, 310 of the pallet drawer but also load the spring, to allow a soft open. The spring displacement is relatively small. However, tests have revealed that only a short burst of force is needed to accelerate the load to a velocity, after which a manual force is sufficient.

Referring now to Fig. 3b an arrangement where the spring both stores energy but also provides a dampening effect over a short distance is depicted. One or more constant springs 316 are used where they splays against a member 317 having an angled or curved surface. The one or more constant springs are secured to a rod 315 which is secured to a flange 314 which is welded to the upper cross member 312. As the upper 312 and lower 313 cross members approach each other the spring is forced along the slope or curvature of the member 317. The spring constant of the setup is not linear and can be tweaked by altering the angle or curvature of the slope. Thus, varying amounts of energy can be stored or dissipated depending on the load. There might be a slight loss in extension. The spring displacement however is small. Additionally this embodiment could be placed within the guide rails, one on either side. The spring displacement is small, though the force is applied or dissipated quickly.

Still referring to Fig. 3b the system consists of a flange 314 that is welded onto the upper cross member 312, on this a rod 315 is welded on which has a head with four constant springs that are slightly furled outwards. A pyramid having an angled or curved surface is welded onto the lower cross member 313. The advantage of this system is that it is cheap and relatively easy to assemble and adjust. Also there is no risk the spring will buckle, or will the rod if the distance is dimensioned accurately. This can easily be adjusted for different pallet drawers, by swapping the head which has the four constant springs attached.

In addition to the embodiments depicted in Figs. 1-3 various arrangement including tension springs, gas springs, buckled tension springs in combination with other sliding mechanisms as well as pneumatic systems may be applicable as well.

In a preferred embodiment, the arrangement that helps or assists the user of the pallet pull- out assembly can be adjusted according to the load placed on the pallet pull-out. This requires transfer of at least part of the vertical load, to adjust a horizontally arranged spring so that the spring displacement length is adjusted according to load. The initial condition without a vertical load, is a compressed preloaded spring. A preferred embodiment 400, 500, 600 of the present invention is depicted in Figs. 4-6.

Referring now to Fig. 4 a load placed on the moving pallet part 403, 404, 405 pushes the leaf springs 407 downwards. The leaf springs 407, which as placed in a channel track 408, are connected in series via a number of hinges, cf. Fig. 5b. The vertical displacement of the leaf springs 407, results in a horizontal displacement that regulates the length of the horizontal springs, cf. Fig. 6b, which absorb the impact of the pallet pull-out on the stop plates. The kinetic soft close/open mechanism is slung between the cross beams 404, 405 of the upper pallet pull out unit. A handle 406 is provided easy opening of the moving part of the assembly which is support by stationary cross beams 401, 402. Depending on the maximum load of the pallet pull-out assembly, the number of leaf springs 407 can be adjusted. Thus, the number of leaf springs may differ from the three depicted in Figs. 4-6. The leaf springs 407 are mounted in a channel, cf. Fig. 5, that is slung between the middle 404 and rear 405 square tubing stiffeners of the upper pallet frame. Referring now to Fig. 5a a total of three leaf springs 501, 502, 503 are hinged together via hinges 505, 506. The end hinge 507 is adapted to be hinged to a fixed end position within the channel being defined by side walls 513, 514, cf. Fig. 5b, whereas the opposite end of the connected leaf springs is free to move in the horizontal direction, i.e. in the longitudinal direction of the channel. A through going opening adapted to receive a rod is provided in connection with end hinge 504. Referring now to Fig. 5b the leaf springs 510, 511, 512 are positioned in the channel being defined by side walls 513, 514. The channel is configured to be positioned between cross beams 404, 405, cf. Fig. 4, via fastening arrangements 508, 509.

Referring now to Fig. 6a when a pallet is placed on the pallet pull-out assembly, the load compresses the leaf springs 601, 602, 603 in the overall arrangement 600. The leaf springs 601, 602, 603 are mounted in a channel 604, such that the vertical compression results in horizontal elongation of the leaf springs 601, 602, 603. The leaf springs 601, 602, 603 are hinged and attached to a leaf spring hinge plate/guide 610 that guides the compression spring guide pin 609 and regulates the extension of the front compression spring 607. The compression spring guide pin 609 rests in the leaf spring hinge plate 610 and a bracket 611. The bracket 611 limits the extension of the rear spring 608 over a given interval. The front and rear springs 607, 608 are hold in position by pins 612, 613. The channel 604 is secured to the moving part of the pallet pull-out assembly via fixation means 605, 606.

With reference to Fig. 6b as the leaf springs 614 are loaded vertically (indicated by the vertical arrows), the leaf springs elongate along a horizontal plane adjusting the position of the leaf spring hinge along the spring guide pin as indicated by the horizontal arrow. This unloads the pre-loaded front spring 615, such that as the load is increased the front spring length increases. When the pallet pull-out assembly is extended, the front rubber bumper 617 contacts with the cross member beam of the pallet rack. The front spring 615 cushions the impact and stores some of the impact energy, which aids in the retraction of the pallet pull-out. The heavier the load, the greater the length of the front spring 615, which can then decelerate the heavier load over a longer spring displacement. When the load is low, the front spring 615 is already slightly compressed and only needs to store a small amount of energy for the retraction of the pallet pull out. The spring system is designed such that the maximum load length is not reached as the rubber bumper 617 contacts with the front cross member beam of the pallet rack. When the drawer is retracted, the rear spring 616 cushions the impact of the pallet pull-out via the rear rubber bumper 618 as it is returned to the closed position. As extension is relatively easy this only needs to cushion the impact and store enough energy to overcome the rolling resistance/static friction when the unit is stationary.