A mobile pallet manipulator and logistic process for handling empty pallets

BACKGROUND OF THE INVENTION

The invention relates to a mobile pallet manipulator, such as a forklift, configured to manipulate pallets.

Forklifts are well-known and used to manipulate both empty and filled pallets. Pallets and forklifts to handle them are typically found in distribution centers and storage facilities of e.g. stores or warehouses.

A packaging and transport process usually starts with empty pallets that are filled with one or more objects and transported to another location. At a specific destination, the objects are removed from the pallet after which the empty pallet can be reused. As the packaging site and the destination are usually not the same, there exists all kind of logistic processes to gather empty pallets and return them to a packaging site to be used again for transport.

Currently, these logistic processes use stacking devices to stack a plurality of empty pallets. Such a stack of pallets can then be manipulated by a forklift to be transported back to a packaging site.

A drawback of the current logistic processes is that gathering and manipulating empty pallets takes a lot of time, which problem increases drastically with increasing size of distribution centers or storage facilities and/or with increasing number of empty pallets to be handled.

SUMMARY OF THE INVENTION

In view of the above it is an object of the invention to provide a logistic process that takes less time and thus is more efficient. According to a first aspect of the invention, there is provided a mobile pallet manipulator comprising: a displacement system to move the mobile pallet manipulator through a space, a pallet holder for holding a stack of pallets, a transfer device for transferring a pallet below the pallet holder to the pallet holder to form the stack of pallets, and a lifting device with a lifting element to lift the stack of pallets from the pallet holder.

An advantage of the manipulator according to the invention is that the manipulator can easily collect empty pallets, temporarily store them in an integrated pallet holder as a stack of pallets on the manipulator, and can lift the stack of pallets for temporary storage in another location, e.g. in a storage rack. As a result, the logistic process takes less time and thus is more efficient.

In an embodiment, the mobile pallet manipulator further comprises a grabbing device to engage a pallet at a distance from the manipulator and to move said pallet to below the pallet holder. This allows to grab and thus collect pallets at locations that are not easily accessible for the manipulator itself, in particular when the pallet holder is already holding a stack of pallets. It further allows easier alignment of a to be collected pallet with the manipulator by providing the pallet at a desired location at a distance from the manipulator and thus aligning the manipulator only in one direction relative to a to be collected pallet instead of aligning the entire manipulator relative to a to be collected pallet in two directions.

In an embodiment, the lifting device is configured to be the transfer device, wherein the lifting element of the lifting device is configured to engage with a pallet below the pallet holder and to raise said pallet into the pallet holder, and wherein the lifting element of the lifting device is further configured to engage a bottom pallet of a stack of pallets in the pallet holder and to lift the stack of pallets from the pallet holder. An advantage thereof is that less components are required making the manipulator less complex. In an embodiment, the transfer device is configured to be the grabbing device. Like the lifting device can act as transfer device and/or vice versa, the transfer device may be configured to act as the grabbing device.

In an embodiment, the lifting device is configured be the grabbing device, wherein the lifting element of the lifting device is configured to engage a pallet at a distance from the manipulator and to move said pallet to below the pallet holder. Again, this has the advantage of combining multiple functions in one device.

In an embodiment, the lifting device is configured to be both the transfer device as well as the grabbing device even further combining functions in one device although this is not necessary from an invention point of view.

In an embodiment, the lifting element comprises two forks. Preferably, the lifting element is extendible. This will increase the reach of the manipulator. In one embodiment, the extendible lifting element allows to engage a pallet at a distance from the manipulator and to move said pallet to below the pallet holder by retracting the lifting element. In another embodiment, the extendible lifting element allows to move a stack of pallets away from the manipulator, i.e. to a larger distance from the manipulator, after being lifted from the pallet holder with the extendible lifting element.

In an embodiment, the transfer device comprises transfer elements separate from the lifting element to raise the pallet into the pallet holder.

In an embodiment, the grabbing device includes one or more grippers to engage with a pallet to pull the pallet to below the pallet holder.

According to a second aspect of the invention, there is provided a method for handling empty pallets, said method comprising the following steps: a. moving a mobile pallet manipulator to an empty pallet, and b. using a transfer device on the mobile pallet manipulator for transferring the empty pallet to a pallet holder on the mobile pallet manipulator to form a stack of pallets,

In an embodiment, the method further comprises the step of repeating steps a. and b. one or more times for respective empty pallets.

In an embodiment, the method further comprises the following steps: c. moving the mobile pallet manipulator to a storage location, and d. moving the formed stack of pallets to the storage location by lifting the formed stack of pallets from the pallet holder.

In an embodiment, the mobile pallet manipulator is a mobile pallet manipulator according to the first aspect of the invention.

The result of the method according to the second aspect of the invention is an efficient logistic process of handling empty pallets, i.e. the collecting and temporarily storing of a stack of empty pallets.

According to a third aspect of the invention, there is provided a method for handling empty pallets, said method comprising the following steps: a. releasing an empty pallet from a pallet holder on a mobile pallet manipulator, and b. moving the released empty pallet relative to the mobile pallet manipulator to clear a space below the pallet holder.

In an embodiment, the method further comprises the step of repeating steps a. and b. one or more times for respective empty pallets.

In an embodiment, the method further comprises the following steps: moving the mobile pallet manipulator to a storage location, and lifting a stack of pallets from the storage location into the pallet holder. In an embodiment, the mobile pallet manipulator is a mobile pallet manipulator according to the first aspect of the invention.

The result of the method according to the third aspect of the invention is an efficient logistic process of handling empty pallets, i.e. the temporarily storing of and subsequent re-use of a stack of empty pallets.

According to a fourth aspect of the invention, there is provided a pallet holder for a mobile pallet manipulator, e.g. a mobile pallet manipulator according to the first aspect of the invention or a mobile pallet manipulator as used in a method according to the second and/or third aspect of the invention, said pallet holder comprising: a mounting assembly to mount the pallet holder to a mobile pallet manipulator, and a holding assembly for holding a stack of pallets and at least configured to allow the passage of an additional pallet from below to become part of the stack of pallets.

In an embodiment, the holding assembly is configured to release a lowest pallet in a stack of pallets held by the pallet holder.

In an embodiment, the pallet holder further comprises a guiding structure to limit movement of the stack of pallets in at least one direction.

According to a fifth aspect of the invention, there is provided a pallet handling system for a mobile pallet manipulator, comprising: a mounting assembly to mount the pallet handling system to a mobile pallet manipulator, a pallet holder with a holding assembly for holding a stack of pallets and at least configured to allow the passage of an additional pallet from below to become part of the stack of pallets, and a grabbing device to engage with a pallet and to move said pallet to below the pallet holder. According to a sixth aspect of the invention, there is provided a mobile pallet manipulator comprising a lifting device with a lifting element to lift a pallet, and further comprising a pallet holder according to the fourth aspect of the invention or a pallet handling system according the fifth aspect of the invention mounted to said mobile pallet manipulator.

In an embodiment, the mobile pallet manipulator is a mobile pallet manipulator according to the first aspect of the invention.

It will be apparent to the skilled person that features and/or embodiments described in relation to one aspect of the invention may also be implemented as features and/or embodiments of another aspect of the invention where applicable to avoid unduly repetition of these features and/or embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in a non-limiting way by reference to the accompanying drawings in which like parts are indicated by like reference symbols, and in which:

Fig. 1 schematically depicts a mobile pallet manipulator according to an embodiment of the invention,

Fig. 2a schematically depicts a pallet prior to being transferred to the pallet holder,

Fig. 2b schematically depicts a pallet during transfer to the pallet holder,

Fig. 2c schematically depicts a pallet after being transferred to the pallet holder,

Fig. 3 schematically depicts the manipulator of Fig. 1 with extended fork,

Fig. 4 schematically depicts the manipulator of Fig. 1 grabbing a pallet at a distance from the manipulator,

Fig. 5 schematically depicts the manipulator of Fig. 1 with the pallet of Fig. 4 being moved to below the pallet holder,

Fig. 6 schematically depicts the manipulator of Fig. 1 with the pallet of Fig. 5 being transferred to the pallet holder, and Fig. 7 schematically depicts the manipulator of Fig. 1 with a stack of pallets being lifted from the pallet holder.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 schematically depicts a mobile pallet manipulator 100 according to an embodiment of the invention. The mobile pallet manipulator 100 may be a forklift, which may alternatively be referred to as lift truck, jitney, fork truck, fork hoist or forklift truck. A forklift may be operated by a person seated or standing on the machine or by a person walking alongside, depending on the design. In its most basic form, the mobile pallet manipulator 100 may be a pallet jack, which may alternatively be referred to as a pallet truck, pallet pump, pump truck, scooter, dog, or jigger.

The manipulator 100 of Fig. 1 is of the type in which a person P can operate the manipulator 100 while standing on a platform 101. Operating the manipulator 100 is carried out using a steering arm 102 including multiple input devices at a free end of the steering arm 102 to be manipulated by the person P and allowing the person P to control the working of the manipulator 100.

The steering arm 102 is arranged pivotably to a body 103 of the manipulator 100 to pivot about a substantially horizontal pivot axis between an upright position as shown in Fig. 1 and a walking position in which the steering arm 102 is inclined or substantially horizontal. The upright position of the steering arm 102 shown in Fig. 1 allows the person P to operate the manipulator 100 while standing on the platform 101. The walking position of the steering arm 102 allows the person P to operate the manipulator 100 while standing next to the platform 101 as the distance to the body 103 may be larger.

The body 103 includes in this example a main portion 104 and extending from the main portion 104 two beams 105 that together define a U-shaped space to receive pallets. In Fig. 1, one pallet 106a is shown.

A pallet, e.g. pallet 106a, alternatively referred to as a skid, is a flat transport structure typically made from wood, plastic, metal, paper and/or recycled materials. A pallet may include three or four stringers that support several deckboards. A pallet may be of the two-way type allowing to manipulate the pallet from two opposite sides. Two-way pallets are typically designed to be lifted by the deckboards. A pallet may also be of the four-way type allowing to manipulate the pallet from four sides. Four-way pallets or pallets for heavy loads, or general-purpose systems that might have heavy loads, may be designed to be lifted by their more rigid stringers.

The manipulator 100 may be suitable to handle pallets of different sizes. However, it is preferred that the manipulator is at least suitable for one pallet size sanctioned by the International Organization for Standardization (ISO) detailed in ISO standard 6780:2003 Flat pallets for intercontinental materials handling - Principal dimensions and tolerances, which was reviewed and confirmed in 2020 at the time of filing of this application or any successor of this ISO standard.

The manipulator 100 of Fig. 1 is moveable through a space, e.g. a distribution center or storage facility using a displacement system. The displacement system in this embodiment includes three wheels to support the manipulator 100 from the ground. Two of the three wheels are arranged in the beams 105, one wheel 107 per beam 105, of which only one wheel 107 is visible in Fig. 1. The remaining wheel of the three wheels is arranged below main portion 104. This wheel, referred to as main wheel, is typically larger than the other two wheels 107 and is preferably steerable. The displacement system may include a drive arranged in the main portion 104 to drive one or more wheels and/or steer one or more wheels of the displacement system. The main wheel may include two or more wheels arranged to a support element to rotate about a single vertical steering rotation axis. In such a situation, the two or more wheels act as a single wheel with several different wheel portions. However, it is also envisaged that the main wheel is replaced by two or more wheels having a separate vertical steering rotation axis.

The steering arm 102 may include input devices to set a steering angle of the main wheel. Alternatively, or additionally, the steering arm 102 may be pivotable about a substantially vertical pivot axis. This allows the steering arm 102 to extend in different directions from the body 103 allowing a person to stand at different positions relative to the manipulator 100 and still be able to operate the manipulator 100. In an embodiment, the angular orientation of the steering arm 102 about said vertical pivot axis is used to set a steering angle of the main wheel.

The drive of the displacement system of the manipulator 100 may include electrical or fuel-based motors to move the manipulator 100 using the main wheel. Hence, the body 103 may also accommodate batteries and/or a fuel tank to power the drive as is known in the art. Said drive for moving the manipulator or a separate drive may be used to drive other devices of the manipulator, which will be explained below in more detail, as well. Hence, the body 103 may also accommodate batteries and/or hydraulic system components for this purpose as is known in the art.

The manipulator 100 of Fig. 1 further comprises a pallet holder in this embodiment formed by two sidewalls 108, 109 extending from the respective beams 105. Each sidewall 108, 109 includes two moveable cams 110 configured to hold a pallet. The pallet 106a is shown in a position in which it is held by the cams 110. The pallet holder is configured to hold a stack of pallets, in this embodiment by holding only a bottom pallet of the stack of pallets. It is also envisaged that the pallet holder holds a stack of pallets by engaging each pallet in the stack of pallets. As the pallet holder of Fig. 1 only holds the bottom pallet, there may be a risk of the pallets above moving relative to each other while moving the manipulator 100. To this end, guiding structures 111 as shown in Fig. 1 may extend from the sidewalls 108, 109 to limit movement of the pallets in the stack of pallets. The guiding structures 111 may include a stop 112 allowing to engage with a head of a pallet to aid in aligning the pallets in the stack of pallets. The stop 112 may extend over a specific height thereby also acting as a guiding for the stack of pallets like the guiding structures 111 but in a different direction. Guiding structures 111 guide the stack of pallets in a sideways direction (Y-direction) while the stops 112 guide the stack of pallets in a back-and-forth direction (X-direction).

The working principle of the pallet holder shown in Fig. 1 is schematically depicted by reference to Figs. 2a, 2b and 2c. Fig. 2a schematically depicts a pallet 106b prior to being transferred to the pallet holder, Fig. 2b schematically depicts the pallet 106b during transfer to the pallet holder, and Fig. 2c schematically depicts the pallet 106b after being transferred to the pallet holder. Only a part of the pallet 106b is visible in the Figs. 2a-2c, in this case a bottom deckboard 106bl, a block 106b2, a stringer board 106b3 and a top deckboard 106b4, see Fig. 2a.

The pallet holder is also depicted partially in Figs. 2a-2c. Shown is the sidewall 109 with a cam 110 in its equilibrium position. The cam 110 is pivotable about a pivot axis 110a against a compression spring 113. The pallet 106b is shown in a position below the cam 110 in Fig. 2a. in Fig. 2b, the pallet 106b is raised relative to the cam 110 thereby pivoting the cam 110 into the sidewall 109 allowing the pallet 106b to pass the cam 110. In Fig. 2c, the pallet 106b has passed the cam 110 allowing the cam 110 to return to its equilibrium position. In the equilibrium position, the cam 110 is able to support the pallet 106b thereby holding the pallet 106b and any pallet on top of pallet 106b.

The manipulator 100 of Fig. 1 is configured to raise the pallet 106b relative to a stationary pallet holder formed amongst others by sidewall 109 and cam 110 using a transfer device to be discussed below. However, the transfer device may alternatively be configured to lower the pallet holder (or a part thereof) relative to a stationary pallet 106b and return back to its rest position to pick up pallet 106b, i.e. to transfer the pallet 106b to the pallet holder. A combination in which both the pallet 106b and the pallet holder (or a part thereof) are movable is also envisaged.

The manipulator 100 of Fig. 1 further includes a lifting device with a lifting element to lift a stack of pallets from the pallet holder. In this embodiment, the lifting element comprises two forks 114 that can for instance be received in the two openings between the three stringers of a pallet. By subsequent lifting of the forks 114 along a lifting frame 115, the pallet is lifted from the ground or from the pallet holder and can be moved around by the manipulator 100. Hence, in this embodiment, the lifting device is able to lift a pallet and to introduce, i.e. transfer, the pallet to the pallet holder as described by reference to Figs. 2a-2c. The lifting device is thus configured to be the transfer device of the manipulator 100 as well. A transfer device separate from the lifting device is also envisaged. The sidewalls 108, 109 may for instance be provided with separate transfer elements raising the pallet into the pallet holder.

The lifting element, i.e. the forks 114, of the lifting device of manipulator 100 are extendible as can be seen in Fig. 3. Fig. 3 depicts the manipulator 100 of Fig. 1 with the forks 114 fully extended. This functionality can be used to engage a pallet at a distance from the manipulator and to move said pallet to below the pallet holder as depicted in Figs. 4 and 5.

In Fig. 4, an empty pallet 106b is lying on the ground. A pallet 106a is held by the pallet holder of the manipulator 100. In an embodiment, the forks 114 may be lowered such that the manipulator 100 is able to move the manipulator 100 such that the pallet 106a in the pallet holder is above the pallet 106b so that subsequent lifting of the forks 114 allows to transfer the pallet 106b into the pallet holder. In such a case, the forks 114 do not necessarily need to be extended, but the manipulator 100 can be positioned with the pallet 106b below the pallet 106a.

However, the pallet 106b may be in a position, e.g. in a storage rack, which is not accessible by the manipulator 100. When the manipulator 100 is able to be positioned in front of the pallet 106b as shown in Fig. 4, the extension of the forks 114 allows to extend the forks 114 below the pallet 106b and to lift the pallet 106b at least partially from the ground. Subsequent retracting of the forks 114 will position the pallet 106b below the pallet 106a in the pallet holder, i.e. below the pallet holder, as shown in Fig. 5.

The lifting device may thus function as a grabbing device to engage a pallet at a distance from the manipulator and to move said pallet to below the pallet holder. However, a separate grabbing device is also envisaged. The beams 105 or sidewalls 108, 109 may be provided with a gripper to grip one end of the pallet 106b and pull the pallet 106b into the space between the beams 105 below the pallet holder.

Fig. 6 depicts the manipulator 100 with the pallet 106b being transferred from the position in Fig. 5 into the pallet holder. Hence, the cams 110 now support the pallet 106b, which in turn supports the pallet 106a, so that the pallet holder is now supporting a stack of two pallets.

Fig. 7 depicts the manipulator 100 with the stack of two pallets of Fig. 6 being lifted from the pallet holder by the lifting device. The forks 114 are used to engage with the bottom pallet 106b and are able to lift the stack of pallet to a height defined by the lifting frame 115. The lifting frame 115 may be extendible as well, e.g. telescopically, allowing to reach an even higher level with the stack of pallets. In the lifted position, the forks 114 may be extendible as well, allowing the stack of pallets to be easily positioned on a second level of a storage rack without having to move the manipulator into the storage rack, which may be advantageous as it saves time and/or may be advantageous when the storage rack is not be accessible for the manipulator 100.

The above description of forming a stack of pallets by introducing an empty pallet into the pallet holder corresponds to a method according to the second aspect of the invention, in which the mobile pallet manipulator 100 is moved to an empty pallet 106b and subsequently a transfer device, in this case embodied as the lifting device, is used to transfer the pallet to the pallet holder.

However, the mobile pallet manipulator 100 can also be used to carry out a method according to the third aspect of the invention by releasing an empty pallet from the pallet holder and moving the released empty pallet relative to the mobile pallet manipulator to clear a space below the pallet holder. This may include the use of the transfer device or lifting device. The lifting device as described above to introduce the pallet 106b into the pallet holder may also be used to lower the pallet 106b. This may require the cams 110 to be moved inwards to allow the passage of the pallet in downward direction. This can be done actively, but also passively using other elements pushing the cams inwards, e.g. the transfer device, the lifting device, or manually.

The method according to the third aspect allows a stack of pallets to be transformed in individual empty pallets that can be re-used for transporting objects. The manipulator 100 may be a manipulator according to the first aspect of the invention or a manipulator according to the sixth aspect of the invention. The manipulator 100 may be a mobile pallet manipulator specifically designed for forming stacks of pallets on the manipulator itself. The pallet holder may for instance be integrally formed with other components of the manipulator 100.

However, manipulator 100 may alternatively be designed as a conventional mobile pallet manipulator, e.g. only having the lifting device, and without the pallet holder to form a stack of pallets. The manipulator 100 may then be transformed into a manipulator according to the sixth aspect of the invention by mounting a pallet holder, e.g. a pallet holder according to the fourth aspect of the invention, or a pallet handling system, e.g. a pallet handling system according to the fifth aspect of the invention, to the conventional manipulator.

In case of a pallet holder, the pallet holder to be mounted to the manipulator at least includes: a mounting assembly to mount the pallet holder to the mobile pallet manipulator, and a holding assembly for holding a stack of pallets and at least configured to allow the passage of an additional pallet from below to become part of the stack of pallets, e.g. the cams 110 and their functioning as described in relation to Figs. 2a to 2c.

In case of a pallet handling system, the pallet handling system to be mounted to the manipulator at least includes: a mounting assembly to mount the pallet handling system to a mobile pallet manipulator, a pallet holder with a holding assembly for holding a stack of pallets and at least configured to allow the passage of an additional pallet from below to become part of the stack of pallets, e.g. the cams 110 and their functioning as described in relation to Figs. 2a to 2c, and a grabbing device to engage with a pallet and to move said pallet to below the pallet holder, e.g. the aforementioned grippers as alternative for the extendible lifting element.