Load carrier conveying unit with compact roller arrangement

Abstract

A conveying unit (1) for conveying load carriers, comprising - an elongate frame structure (2) with a front frame portion (2A) and a rear frame portion (2B), each having a roller arrangement (5) with at least two rollers (6) which are mounted so as to be rotatable about a vertical axis of rotation (D) in relation to the frame structure (2); - a supporting element which can be brought into contact with a load carrier and can be moved by means of a lifting device in a vertical direction in relation to the frame structure (2) between a raised position and a lowered position; wherein each of the roller arrangements (5) has at least one roller (6) which can be driven by means of a roller drive (7) configured as a wheel hub drive.

Description

[0001] Load carrier conveyor unit with compact roller arrangement

[0002] The invention relates to a conveyor unit for conveying load carriers, and further to a conveyor device with several, in particular two, such conveyor units.

[0003] For the internal transport of goods, load carriers are regularly used. These can be driven under by industrial trucks, lifted together with the goods stored on them, and then set down again at the destination after transport. A well-known example of such a load carrier is the standardized and reusable "Euro pallet."

[0004] Various types of industrial trucks are known from the prior art, which are referred to below as conveyor systems. A distinction can be made between single-part and multi-part conveyor systems. In the former, as shown for example in EP 2 336075 A1, the sections of the conveyor system that travel under the load carrier are firmly connected to one another. Multi-part conveyor systems, as shown for example in DE 102007 046 868 A1, usually comprise a first and a second conveyor unit that are not physically connected to one another. Conveyor systems can also be differentiated according to their operation. On the one hand, manual or motorized operation is possible, as is the case, for example, with hand pallet trucks that are regularly used to load and unload trucks. On the other hand, autonomously operated conveyor systems are also known, see again EP 2 336 075 A1.

[0005] DE 10 2007 046 868 A1 proposes using just one electric motor to accomplish all the necessary movements of the transport system. This drive system requires a square base, which corresponds to the full width of the load carrier and has the same length. Such a design, with the associated arrangement of the rollers, also does not allow travel perpendicular to the longitudinal axis of the conveyor unit, as this would otherwise tip over. Similar conveyor systems are known, for example, from DE 102013 013 684 A1, EP 3 216 747 A2, or WO 2018 / 136987 A1. These drive systems all have two wheels that rotate around a common axis of rotation and a vertical axis. The disadvantages of these drives are their space-intensive design and the impossibility of travel perpendicular to the longitudinal axis of the conveyor unit.

[0006] In the case of autonomously operated conveyor systems which completely pass underneath the load carriers to be transported, the clearance profile provided by the corresponding load carriers, i.e. the space available for the conveyor system when moving in or out under the load carriers parked on the ground, represents a very significant limiting factor. All components required for the function and operation of the conveyor system must be accommodated within the available height, width and length, whereby certain minimum distances in height and width must also be maintained from the load carrier in order to ensure trouble-free moving in and out.

[0007] The object of the present invention is to provide a conveyor unit or a conveyor device with several such conveyor units, which has compact roller arrangements and can be moved omnidirectionally.

[0008] This object is solved by the subject matter of independent claim 1. The subclaims define preferred embodiments of the present invention.

[0009] The conveyor unit according to the invention for conveying load carriers therefore comprises

[0010] - an elongated frame structure with a front frame section and a rear frame section, each having a roller arrangement with at least two rollers mounted so as to be rotatable relative to the frame structure about a vertical axis of rotation; - a support element which can be brought into contact with a load carrier and which can be moved by means of a lifting device relative to the frame structure in the vertical direction between a raised position and a lowered position; wherein each of the roller arrangements has at least one roller which can be driven by means of a roller drive designed as a wheel hub drive.

[0011] In other words, the functional components required for moving the conveyor unit are combined in a compact unit and housed within the driven rollers of the conveyor unit. It should be noted at this point that it may be sufficient for only individual rollers of the conveyor unit to have such a drive. It is also conceivable for all rollers of a conveyor unit to have such a drive.

[0012] In one embodiment, the roller drive designed as a wheel hub drive can be arranged within the rotary steering circle of the roller. This so-called rotary steering circle is defined by the running surface of the associated roller when this roller is rotated about its vertical axis of rotation. In other words, the areas of the running surface furthest away from the axis of rotation define a boundary for an area or volume when the roller rotates, which defines the maximum construction volume available for the roller drive. Conversely, in every angular position of the roller, the roller running surface is the element furthest away from the roller's axis of rotation. This can apply, for example, to a projection along the roller's axis of rotation, as well as to the three-dimensional volume defined by a complete rotation of the roller about its axis of rotation.

[0013] In a further embodiment, the roller drive can comprise an electric motor, a gear coupling the electric motor and the roller, a brake counteracting the drive torque of the electric motor, and a control unit controlling the electric motor, in particular wherein the electric motor, the gear and the brake are arranged coaxially to the rotational axis of the roller, which can extend essentially in a horizontal direction. Furthermore, the brake, like the electric motor, can be arranged on the transmission input side. The braking torque generated by the brake can thus be translated by means of the gear and, for example, act at least indirectly on the transmission input shaft. The roller arranged on the transmission output side thus experiences a braking torque converted, in particular amplified, by the gear ratio. In particular, the brake can run at the same speed as the electric motor and / or at a different speed than the roller.The conversion of the braking torque via the gearbox enables the use of a smaller-sized brake, which ultimately allows its installation in the roller unit, especially given the limited space available within the roller unit.

[0014] Furthermore, it is conceivable that the power electronics of the electric motor and / or any integrated rotary encoder sensor are also included in the roller drive and thus also located within the rotary steering circuit of the roller. Such a design allows the necessary cabling to be reduced to a minimum, which also has a positive effect on the compactness of the roller drive. Furthermore, the cabling, which, for example, ensures the data and / or power coupling of the roller unit with other components of the conveyor unit, can extend at least in sections between an interface that is fixed relative to the frame structure of the conveyor unit and an interface that rotates around its vertical axis of rotation in accordance with the rotational movement of the roller unit.To avoid stress on the cabling caused by the rotating movement of the roller unit, the cable can be laid in the form of a cable loop between the aforementioned interfaces or other fixings that secure the cable to the frame structure or the roller unit. This cable loop can encircle the vertical axis of rotation of the roller unit, in particular essentially in a horizontal plane, wherein elements of the roller unit rotating around the vertical axis of rotation, in particular the cable interface or cable fixing point, can be located in a vertical projection within the cable loop.

[0015] According to a further embodiment, the bearing for supporting the roller unit formed from the roller and the roller drive relative to the frame structure is arranged within the rotary steering circle of the roller. It is also possible for only the running surface of the roller to extend beyond the bearing plane. In particular, it is possible for the roller unit to be mounted relative to the frame structure in the functional position of the conveyor unit both above and below the rotational axis of the roller. In other words, the roller unit is supported on the frame structure above and below the roller rotational axis, in particular with only the roller running surface extending beyond the upper or lower horizontal bearing plane.

[0016] In summary, the roller, in particular its running surface, can represent a ring along whose bore all essential, in particular all functional components of the roller drive are arranged.

[0017] According to a further embodiment, the vertical axis of rotation of the roller, required for "steering" the conveyor unit, is spaced from the center plane of the roller, in particular from the center plane of the roller's running surface, and can, in particular, run parallel to it. When the roller rotates about its vertical axis of rotation, a so-called eccentric relative movement occurs between the roller's contact surface and the ground. Such an arrangement can help create additional installation space for drive components to the side of the roller.

[0018] In a further embodiment, the coordination of the rotation around the vertical axis of rotation and the drive of the rollers of a roller arrangement, in particular all rollers of the conveyor unit, is carried out by means of an electronic controller, in particular by means of the control unit and / or the power electronics. In contrast to previous drive concepts for conveyor units, the conveyor unit according to the invention therefore does not involve any mechanical coupling of individual rollers. Rather, they are coupled to one another solely by control electronics in order to execute a desired travel movement.

[0019] Furthermore, it is conceivable for the roller assemblies of the conveyor unit to be designed as modules of identical construction, which are, in particular, interchangeable. A conveyor unit according to the invention can thus have two identical roller assembly modules, between which—apart from possibly different control or programming depending on the installation position—there is no difference. In particular, it is conceivable for the modules to be designed so that they can be removed from and reinserted into the conveyor unit without the use of tools or with comparatively little use of tools. Such a design significantly reduces spare parts storage costs as well as repair costs.

[0020] Furthermore, it is possible for a line connecting the contact surfaces of the rollers of a roller arrangement to run perpendicular to the longitudinal axis of the frame structure, in particular wherein the rollers of the roller arrangement assume a mirror-symmetrical position with respect to the longitudinal axis of the frame structure.

[0021] By placing the roller units side by side, the required installation volume along the longitudinal axis of the conveyor unit is minimized. The contact surfaces of a four-wheeled chassis of the conveyor unit therefore form a rectangle when viewed from above.

[0022] In an alternative embodiment, a line connecting the contact surfaces of the rollers of a roller arrangement runs obliquely with respect to the longitudinal axis of the frame structure, in particular wherein the rollers of a roller arrangement assume a rotationally symmetrical position with respect to the longitudinal axis of the frame structure.

[0023] Here, the contact surfaces of a four-wheeled chassis of the conveyor unit would form a parallelogram in a vertical view. This design can help reduce the required frame width, i.e., across the longitudinal axis of the conveyor unit.

[0024] Both of the embodiments described above allow the conveyor unit to be moved perpendicular to its longitudinal axis. Even when the rollers' rotation axes are aligned parallel to the conveyor unit's longitudinal axis, the rollers' contact surfaces are spaced apart on both sides from the conveyor unit's central longitudinal axis, so that the entire conveyor unit can be supported by these contact surfaces when traveling transversely to its longitudinal axis. Since the dissipation of heat loss becomes more important with increasing compactness of the roller units, it can be provided that individual or the essential components of the roller unit are made of materials with comparatively high thermal conductivity. Contact surfaces between such components can also be treated with materials or substances that have particularly good thermal conductivity.This can improve the dissipation of heat into the immediate surroundings or, for example, into the frame structure.

[0025] According to one embodiment, the entire roller drive is arranged within the bearing of the roller unit (or the bearing diameter) in the frame, particularly as seen in the vertical and / or horizontal direction.

[0026] Furthermore, it is conceivable that the entire roller drive, including the bearings, is located within the wheel diameter, particularly in the vertical and / or horizontal direction. Thus, the running surface of the roller can be the component of the roller unit furthest from the roller's rotation axis.

[0027] According to a further embodiment, the roller unit comprises a support structure, in particular a one-piece support element, which is supported on the frame structure via a first rolling bearing, in particular directly supported, and on which in turn the roller and / or the ring gear of the gear system designed as a planetary gear is supported via a second rolling bearing, in particular directly supported. This makes it possible to keep the force flow between the roller and the frame structure as short as possible. The forces and moments acting from the ground on the running surface of the roller can thus be introduced directly via the support structure into the frame structure, and vice versa. It is advantageous if the support structure extends as close as possible to the axis of rotation of the roller, since this minimizes moments and reduces material stress.The support structure can support any component of the roller drive, such as the electric motor, the transmission, the brake, the control unit, the power electronics, or any combination thereof, in particular directly support it or even contact it. A further aspect of the present invention relates to a conveyor device with several, in particular two, conveyor units according to one of the embodiments described above.

[0028] The present invention is described in more detail below using preferred embodiments and with reference to the accompanying figures. The invention may include all features described herein individually or in any meaningful combination.

[0029] They show:

[0030] Figure 1: a conveyor device according to the present invention, comprising two conveyor units;

[0031] Figure 2: a conveyor unit according to the invention with schematically illustrated

[0032] role arrangements;

[0033] Figure 3: a cross section through a first embodiment of a roller unit according to the invention;

[0034] Figure 4: a cross section through a further embodiment of a roller unit according to the invention

[0035] Figure 5: a plan view of a first embodiment of an inventive

[0036] roller arrangement; and

[0037] Figure 6: a plan view of a second embodiment of the inventive

[0038] Roller arrangement.

[0039] Figure 1 shows a two-part conveyor system with two conveyor units 1 that are not physically connected to each other. Such autonomously operated conveyor systems are known, for example, from DE 10 2007 046 868 A1 and DE 10 2019 001 125 A1. Figure 1 also shows how the conveyor units, when lowered, can completely pass under a load carrier (transport pallet / "Euro pallet") in order to subsequently raise the load carrier for transport.

[0040] The conveyor unit 1 shown in Figure 2 comprises, in addition to a support element (not shown) for lifting a load carrier, a frame structure which, in the example shown in Figure 2, is divided into a front frame section 2A and a rear frame section 2B. A predefined construction volume is provided in both the front frame section 2A and the rear frame section 2B, which serves to accommodate a roller arrangement 5, each with two rollers. All components of the roller arrangements 5 must therefore be accommodated in the available construction volume, which in turn is limited in height h and width b by the clearance profile provided by the load carrier.Only the length I of the available construction volume for the roller assembly 5 can be varied to a certain extent, however, at the expense of other devices necessary for the function of the conveyor unit, such as a lifting device for the support element (not shown), an energy storage device, or a sensor system required for autonomous operation. Since in the example shown, a roller assembly 5 has two identical roller units 8, only half the construction volume is available for the latter.

[0041] With the aim of achieving the smallest possible installation volume for the roller unit 8, as can be seen in Figure 3, the entire roller drive 7 required to drive a roller 6 is housed within a rotary steering circuit 9. The rotary steering circuit 9 shown in Figure 3 is defined by rotating the roller 6 by 90° about its axis of rotation D. All components of the roller drive 7, as well as the bearing 16 of the roller unit 8 relative to the frame structure 2 and about the vertical axis of rotation D, are arranged within this rotary steering circuit 9.

[0042] Figure 3 further shows that the electric motor 11, as well as the single-stage planetary gear 12 and the brake 13, are arranged both coaxially to one another and opposite the rotational axis R of the roller 6. The space still available to the right of the brake 13 is occupied by the control unit 14 and the power electronics 15 for the electric motor 11. The running surface 10 of the roller 6 is directly connected to the ring gear (not shown) of the planetary gear 12 and forms the only component that extends beyond the upper and lower horizontal bearing planes defined by the pivot bearings 16.

[0043] Figure 4 shows a roller unit 8 according to the invention in a further embodiment, which comprises a support structure 17 designed as a one-piece element. The support element 17 is supported directly on the frame structure 2 above and below the roller rotation axis R via a rolling bearing 16 each and can rotate about the vertical axis of rotation D. The ring gear 18 of the planetary gear is supported directly on the support element 17 via two further rolling bearings 19 above and below the roller rotation axis R and can rotate about the horizontal axis of rotation R. By directly mounting the support element 17 on the frame structure 2 on the one hand and the ring gear 18 or the roller 6 on the support element 17, forces are transmitted directly between the frame structure 2 and the roller 6, which increases the stability of the roller unit 8 according to the invention.It can also be seen that the support element 17 extends vertically close to the vertical axis of rotation D, which also leads to a low moment load on the roller unit 8. At the same time, space is created for the electric motor 11 and the brake 12, which are directly supported by the support element 17. In the embodiment shown, the bearing 16 is not entirely within the rotary steering circle 9, but is within the diameter of the roller 6 or the running surface 10, both in the horizontal and vertical directions. The bearing 16 therefore has a smaller diameter than the roller 6 or the running surface 10.

[0044] Figure 5 shows a first embodiment of a roller assembly 5 according to the invention with exactly two roller units 8 arranged "side by side," as shown in more detail in Figure 3. The vertical rotation of the respective rollers is accomplished by two independent actuators, which are schematically shown as circles in Figure 4. A mechanical connection to the respective roller units 8 can be established, for example, via a belt drive (not shown), although any other connection design, such as chain drives or gear transmissions, is also conceivable. The independent actuators, which can be configured as electric motors or servomotors, allow the rollers to be rotated independently of one another about their respective vertical rotation axes.Since the steering movement of the individual rollers is carried out by the actuators assigned to them, the steering of the conveyor unit according to the invention is also completely independent of the drive of the individual rollers by the electric motors 11 assigned to them. Furthermore, Figure 5 shows, by way of example, a cable for the signal and energy supply of the roller unit 8 arranged on the left in Figure 5. The cable extends between a frame-side interface and a roller-unit-side interface and forms a cable loop between these interfaces, which loops around the vertical axis of rotation of the roller unit 8. Corresponding to the "excess" cable length between the interfaces, this allows a certain number of rotations of the roller unit 8 without any significant stress on the cable occurring.Alternatively, the points shown in Figure 5 at both ends of the cable loop can also represent fixed points at which the cable is fixed in position relative to the frame structure or the roller unit 8.

[0045] In the arrangement shown in Figure 5, a connecting line V runs between the contact surfaces of the respective rollers 6 perpendicular to the longitudinal axis of the conveyor unit 1. The illustrated arrangement of the two roller units 8 enables a roller arrangement 5 with a very short length I. The minimum width b is determined by the diameter of the rollers 6 or the diameter of the rotary steering circles 9.

[0046] An embodiment with a more compact width b is shown in Figure 6. Here, the roller units 8 are arranged offset from one another so that their respective contact surfaces can be connected via a connecting line V, which runs obliquely to the longitudinal axis L of the conveyor unit 1.

[0047] Although the embodiment shown in Figure 6 is slightly longer in length I, the diameter of the rollers 6 or the rotary steering circuits 9 and thus the entire construction volume available for the roller drives 7 and the bearing 16 for a given width b can be dimensioned larger, which results, for example, in a lower surface pressure on the contact surfaces of the rollers 6, whereby travel perpendicular to the longitudinal axis L of the conveyor unit 1 is still possible.

Claims

Patent claims 1. Conveyor unit (1) for conveying load carriers, comprising - an elongated frame structure (2) with a front frame section (2A) and a rear frame section (2B), each having a roller arrangement (5) with at least two rollers (6) mounted rotatably relative to the frame structure (2) about a vertical axis of rotation (D); - a support element which can be brought into contact with a load carrier and which can be moved vertically between a raised position and a lowered position relative to the frame structure (2) by means of a lifting device; characterized in that each of the roller arrangements (5) has at least one roller (6) which can be driven by means of a roller drive (7) designed as a wheel hub drive.

2. Conveyor unit according to claim 1, wherein the roller drive (7) is arranged within the rotary steering circle (9) of the roller (6), which is swept over by the running surface (10) of the roller (6) when the roller (6) rotates about the vertical axis of rotation (D).

3. Conveyor unit according to one of claims 1 or 2, wherein the roller drive (7) comprises an electric motor (11), a gear coupling the electric motor (11) and the roller (6) (12), a brake counteracting the drive torque of the electric motor (11) (13) and a control unit (14) controlling the electric motor (11), in particular wherein the electric motor (11), the gear (12) and the brake (13) are arranged coaxially to the rotation axis (R) of the roller (6).

4. Conveyor unit according to claim 3, wherein the roller drive (7) further comprises the power electronics (15) of the electric motor (11).

5. Conveyor unit according to one of claims 1 to 4, wherein the bearing (16) for supporting the roller unit formed from the roller (6) and the roller drive (7) (8) is arranged relative to the frame structure (2) within the rotary steering circle (9) of the roller (6), which is swept over by the running surface (10) of the roller (6) when the roller (6) rotates about the vertical axis of rotation (D), in particular wherein the roller unit (8) is mounted relative to the frame structure (2) both above and below the axis of rotation (R) of the roller (6).

6. Conveyor unit according to one of claims 1 to 5, wherein the vertical axis of rotation (D) of the roller (6) is spaced from the center plane (M) of the roller (6), in particular from the center plane (M) of the roller running surface (10), in particular runs parallel thereto.

7. Conveyor unit according to one of claims 1 to 6, wherein the coordination of the rotation about the vertical axis of rotation (D) and the drive of the rollers (6) of a roller arrangement (5), in particular all rollers (6) of the conveyor unit (1), is carried out by means of an electronic control, in particular by means of the control unit (14) and / or the power electronics (15).

8. Conveyor unit according to one of claims 1 to 7, wherein the roller arrangements (5) of the conveyor unit (1) are designed as modules of identical construction, which are in particular interchangeable with one another.

9. Conveyor unit according to one of claims 1 to 8, wherein a line (V) connecting the contact surfaces (17) of the rollers (6) of a roller arrangement (5) runs perpendicular to the longitudinal axis (L) of the frame structure (2), in particular wherein the rollers (6) of the roller arrangement (5) assume a mirror-symmetrical position with respect to the longitudinal axis (L) of the frame structure (2).

10. Conveyor unit according to one of claims 1 to 8, wherein a line (V) connecting the contact surfaces (17) of the rollers (6) of a roller arrangement (5) runs obliquely with respect to the longitudinal axis (L) of the frame structure (2), in particular wherein the rollers (6) of a roller arrangement (5) assume a rotationally symmetrical position with respect to the longitudinal axis (L) of the frame structure (2).

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