Frame structure for a forklift truck with battery compartment

Abstract

Frame structure (1) for a forklift truck (3) with a battery compartment (2), wherein the battery compartment (2) in the frame structure (1) is formed with a lateral opening (12) for the removal of a traction battery (13) from the battery compartment (2) and the battery compartment (2) has at least one vertical longitudinal sheet (10) in the longitudinal direction of the vehicle and at least one vertical transverse sheet (11) in the transverse direction of the vehicle with a vertical corner edge (9) between these, characterized in that the longitudinal sheet (10) and the transverse sheet (11) are a single continuous sheet and the corner edge (9) has a rounded shape.

Description

[0001] The invention relates to a frame structure for an industrial truck with a battery compartment. In particular, the invention relates to a frame structure for an industrial truck with a battery compartment, wherein the battery compartment in the frame structure is formed with a lateral opening for removing a traction battery from the battery compartment, and the battery compartment has at least one vertical longitudinal plate in the vehicle's longitudinal direction and at least one vertical transverse plate in the vehicle's transverse direction, with a vertical corner edge between them.

[0002] For electric vehicles, especially industrial trucks with a traction battery that can be replaced for charging, a lightweight and compact design with a load-bearing frame that also has a slim main support structure is very important in order to be able to carry a relatively large and heavy traction battery in a battery compartment for the energy supply.

[0003] For traction batteries that are higher or similar in height to the frame structure, a vertical battery change was originally the only option for forklifts, a type of industrial truck. For other types of industrial trucks, such as tractors used at airports, this vertical battery change is still largely standard. A large opening is provided in the frame structure for changing the traction battery upwards, and for strength reasons, the frame structure or frame itself is designed to be closed on both sides.

[0004] In contrast, a side-loading battery swap, which is already widely used in forklifts, offers numerous advantages. This eliminates the need to lift heavy batteries, such as those weighing up to 2 tons, over the vehicle, which poses occupational safety risks. A side-loading battery swap is also faster and does not require a crane.

[0005] However, such a lateral battery change requires an opening in the side of the frame structure in order to be able to remove the traction battery. This significantly weakens the frame structure, particularly in the case of traction batteries that are higher or similar in height to the frame structure. In addition, the battery compartments may also be partially or mostly open on their bottom side to allow the traction battery in the battery compartment to be lifted using, for example, a pallet truck or forklift when changing the traction battery. Due to the height of the traction battery, or at least to alternatively allow the traction battery to be changed from above, the top of the battery compartment may also have to be left free of frame structure elements.This results in a very open structure of the vehicle frame, in which, in extreme cases, all load-bearing frame elements are concentrated to the side of the battery compartment along the vehicle's longitudinal extension. When the frame structure is subjected to loads, the transitions to these frame elements located to the side of the battery compartment are particularly exposed to increased strain and stress, as the frame structure at this transition to the battery compartment is relatively flexible and deforms significantly under heavy loads. This leads to areas with increased mechanical material stress and thus premature material fatigue.

[0006] Such areas with increased material stress are, in particular, the vertical inner corner edges of the battery compartment. The longitudinal section of the frame structure begins here, bridging the length of the battery compartment within the vehicle's length as a load-bearing structure. When the vehicle accelerates and decelerates, especially in tractors with a high towing weight, high loads arise here, which are concentrated in these vertical corner edges and are amplified by the notch effect of the corner edge.

[0007] To counteract this, the corresponding components must be designed with increased material thickness and additional stiffening elements. However, the disadvantage of this is that it results in an increased weight of the frame structure.

[0008] The problems described in designing a laterally open frame structure to accommodate a traction battery are further exacerbated by the fact that in certain industrial trucks, such as tractors, the traction battery can account for a very high proportion of the overall vehicle weight, amounting to approximately 45%. This also results in additional loads, bending, and stresses in the frame structure, which can lead to premature material fatigue.

[0009] To compensate for these disadvantages, it is possible to provide a load-bearing door for the battery compartment. However, this requires considerable effort to connect the hinges, locks, and the door itself to the frame structure in a way that is both load-bearing and detachable. There is also the problem of compensating for manufacturing tolerances and the need for appropriate adjustments during assembly. This can also lead to functional problems, particularly jammed door locks.

[0010] From DE 10 2006 022 743 A1 a tractor with a supporting frame is known which has a receptacle for a battery compartment in a front area and a receptacle for a towing device in a rear area, wherein the frame has at least one longitudinal component for connecting the receptacle for the battery compartment to the receptacle for the towing device, wherein the longitudinal components form at least one box profile.

[0011] EP 3 048 080 B1 discloses an industrial truck with a replaceable battery block.

[0012] EP 1 362 762 B1 discloses a frame for the drive part of an industrial truck, in particular a pallet truck, which serves as a carrier for a lifting device and / or a travel drive.

[0013] DE 10 2008 008 146 A1 discloses a frame of a battery-operated industrial truck with a central frame section designed to receive a battery block, which is open at the top and which has a front transverse wall, a rear transverse wall, an open side wall provided with a lateral battery compartment opening and a closed side wall spaced therefrom in the transverse direction of the frame, wherein the central frame section has a frame base which is designed as a bending- and torsion-resistant hollow body.

[0014] DE 10 2011 011 721 A1 discloses a vehicle frame of a counterbalance forklift truck, wherein the vehicle frame has a lateral frame opening on one side of the vehicle for the horizontal removal and installation of a drive module in an aggregate compartment, wherein the vehicle frame is designed on the vehicle side opposite the lateral frame opening in the region of the aggregate compartment as a closed hollow body arranged in the vehicle longitudinal direction, which is designed as a liquid container, in particular as a liquid container for pressure medium of a working hydraulic system of the counterbalance forklift truck.

[0015] DE 10 2013 000 264 A1 discloses an anti-theft device frame for a motor vehicle.

[0016] DE 91 06 011 U1 discloses a control cabinet housing.

[0017] It is therefore an object of the present invention to provide a frame structure for an industrial truck with a battery compartment which avoids the aforementioned disadvantages and which, while being lightweight, also has high fatigue strength.

[0018] This object is achieved by a frame structure for an industrial truck having the features of independent patent claim 1. Advantageous developments of the invention are specified in the subclaims.

[0019] The object is achieved according to the invention in that in a frame structure for an industrial truck with a battery compartment, wherein the battery compartment in the frame structure is designed with a lateral opening for removing a traction battery from the battery compartment and the battery compartment has at least one vertical longitudinal sheet in the vehicle longitudinal direction and at least one vertical transverse sheet in the vehicle transverse direction with a vertical corner edge between them, the longitudinal sheet and the transverse sheet are a single continuous sheet and the corner edge has a rounded portion.

[0020] At the corner edge, there is no weld seam connecting the cross plate to the longitudinal plate; instead, a single plate is bent so that it can fulfill the function of both the cross plate and the longitudinal plate. This eliminates the notch effect caused by the weld seam and the frame structure is more robust against material fatigue. This is particularly advantageous in a frame structure that is open at the side to accommodate the battery compartment. This is particularly important if, due to the height of the traction battery, or to allow the traction battery to be removed upwards, the top of the battery compartment is also open. In addition, the floor area of ​​the battery compartment is open except for the contact points of the traction battery to enable the traction battery to be lifted by another industrial truck during replacement. Such a frame structure is subjected to severe bending stress in the corner edges of the battery compartment when subjected to shock and tensile loads in the longitudinal direction.Particularly in tractors, which are a type of industrial truck, there is a risk of material fatigue due to acceleration and braking forces, as these also brake the front wheels and, at the same time, the forces of the trailer load act in the longitudinal direction. In this case, a design of the corner edges using only a continuous sheet can be used. According to the invention, the corner edge is rounded and thus has a minimum bending radius, which significantly reduces the notch effect and thus material fatigue under a large number of alternating deformation loads. The number of individual sheets is also advantageously reduced. Even if the rounding somewhat reduces the overall rigidity, it still results in advantages in terms of durability and the elimination of otherwise required reinforcements and stiffeners.

[0021] Advantageously, the longitudinal sheet and two transverse sheets run as a single continuous sheet over three sides of the battery compartment with two rounded corner edges.

[0022] The transverse front wall, the longitudinal side wall of the battery compartment in the form of the longitudinal sheet, and the transverse rear wall of the battery compartment as a second transverse sheet consist of a single continuous sheet. The use of such a continuous sheet without rounding the corner edges is conceivable and advantageous. However, particular advantages arise when both the front corner edge and the rear corner edge (relative to the truck's longitudinal direction) are rounded. It is precisely at these two points that the greatest deformations due to impact loads occur.

[0023] In a favorable embodiment, the fillet on one side of the corner edge can have an opposite fillet, so that the continuous sheet runs outside the cutting edge of the longitudinal sheet with the transverse sheet.

[0024] As a result, the respective sheet metal is first bent away from the battery compartment in front of the corner edge and then runs in a rounded shape up to 90° to the original direction to form the corner edge. The rounded shape therefore does not protrude into the interior of the battery compartment at any point beyond the lines extended to the cutting edge of the two sheets which abut each other at the corner edge. In contrast to a design of the battery compartment with non-rounded corner edges, a cuboid-shaped traction battery of the same size can be inserted into the battery compartment. The opposite rounding can be made in the longitudinal sheet metal so that the entire rounding is located in the space to the side of the battery compartment. Alternatively, the opposite rounding with the actual rounding can also be arranged alone on the transverse sheet metal so that the additional installation space required extends to the space in front of or behind the battery compartment.

[0025] Opposite curves may be present on both sides of the corner edge.

[0026] If the fillet is distributed with a counter fillet on both sides of the corner edge, a more compact arrangement can be achieved overall.

[0027] In a further development of the frame structure, the upper side of the longitudinal sheet and / or transverse sheet has a rounded portion and connections, in particular a weld seam, are arranged adjacent to the rounded portion.

[0028] This advantageously means that any welding seams required on the top side of the battery compartment are relocated away from the corner joint area and the welding seam is located in an area subject to less stress.

[0029] The frame structure may have an outer sheet parallel to the longitudinal sheet on the side facing away from the opening of the battery compartment.

[0030] Together with the longitudinal sheet and possibly stiffening elements arranged between them, such as a lower or upper end sheet or diagonally arranged sheets, a torsion box can thus be formed, which forms a main supporting structure of the frame or frame structure over the length of the battery compartment.

[0031] In a further development, further frame elements of the frame structure, which are arranged transversely in front of and behind the battery compartment, in particular sheets, are passed through to the outer sheet and connected to the outer sheet with a weld seam which is arranged at an angle to the vertical.

[0032] For example, transverse torsion boxes can be formed by additional sheets connected to a front or rear cross member. If such an additional sheet is extended to the outer sheet for stiffening reasons, and the connecting weld seam is positioned as far as possible away from the extension of the cross member and / or at an angle to the vertical, these weld seams are not located in the same area where the frame structure transitions to the battery compartment, and if positioned at an angle, they are not subjected to bending stress along their longitudinal extent. This reduces the impact of the notch effect, which is always present in a weld seam, on material fatigue life.

[0033] The battery compartment may be open at the top.

[0034] If, for reasons of space and room alone, no elements of the frame structure can be arranged above the traction battery and this area must therefore remain open, such a design also provides the alternative option of carrying out a battery change by lifting the traction battery upwards.

[0035] Advantageously, the battery compartment is open downwards at least to the extent that a traction battery located in the battery compartment can be lifted using lifting equipment, in particular a second industrial truck.

[0036] For example, the floor can be cut out except for a surrounding edge area on which the traction battery rests, so that it is possible to drive a pallet truck under the traction battery and lift it when changing the battery.

[0037] In an inexpensive version, the industrial truck is a tractor.

[0038] The frame structure described above offers particular advantages, particularly for tractors that can tow or pull loads several times their own weight. Firstly, a powerful and large traction battery is possible, which can still be swapped sideways. At the same time, the impact of the towed weight on a tractor results in particular bending loads of the type described above at the corner edges of the battery compartment. This arises, for example, from the fact that even with only one driven rear axle, the front axle can also be braked, resulting in torsion of the entire frame structure due to the thrust of the approaching trailers during braking.

[0039] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments shown in the schematic figures. Fig. 1 schematically from the side the frame structure of an industrial truck with a battery compartment, Fig. 2 the framework structure of the Fig. 1 under supervision, Fig. 3 the frame structure in a perspective view with a traction battery, Fig. 4 the frame structure in another perspective view, Fig. 5 the corner area of ​​the battery compartment in a sectional view, Fig. 6 the corner area in a further embodiment and, Fig. 7 the corner area in a third embodiment.

[0040] The Fig. 1 shows schematically from the side the frame structure 1 of an industrial truck 3, which is not shown in more detail and only in parts, in the present example a tractor 4, with a battery compartment 2 and a front axle 5 as well as a rear axle 6 between which the battery compartment 2 is arranged.

[0041] The Fig. 2 shows the frame structure 1 of the Fig. 1 in plan view. The battery compartment 2 has a base plate 7, which is cut out except for a circumferential edge 8 and is open at the bottom, so that a traction battery (not shown) can be lifted with suitable lifting equipment and removed through the side opening 12 for replacement. The inner corner edges 9 between a longitudinal plate 10 and two transverse plates 11, which form the walls of the battery compartment 2, are rounded. The transverse plates 11 and the longitudinal plate 10 are formed from a single continuous sheet, which is appropriately bent and rounded at the corner edges 9.

[0042] The Fig. Figure 3 shows the frame structure 1 in a perspective view with a traction battery 13, which can be removed from the battery compartment 2 upwards or to the side, as indicated by the arrows. The traction battery 13 stands on the base plate 7 of the battery compartment 2, which is designed as a circumferential edge 8. The corner edges 9 of the battery compartment 2 are rounded.

[0043] The Fig. 4 shows the frame structure 1 in a further perspective view, in which the traction battery 13 has been removed and hidden sheets are shown by dashed lines. The battery compartment 2 is formed by the base plate 7, designed as a circumferential edge 8 for supporting the traction battery 13, to which the longitudinal sheet 10 and two transverse sheets 11, which are designed as a single circumferential sheet, adjoin as walls. The corner edges 9 are rounded. On the side of the outer wall facing away from the lateral opening 12 of the battery compartment 2, an outer sheet 14 is arranged parallel to the longitudinal sheet 10. Together with a base plate 15 and a cover plate 16, this outer sheet forms a lateral torsion box 17, which forms the essential supporting structure of the frame structure over the length of the battery compartment 2.Additional stiffening is provided solely by the base plate 7 of the battery compartment, which, however, is heavily cut out and only designed as a circumferential edge 8.

[0044] In front of and behind the cross plates 11, additional plates 19 are welded at an angle as further frame elements 18. These plates form triangular torsion elements 20 with the cross plates 11 and extend to the outer plate 14. The additional plates 19 are each connected to the outer plate 14 by an oblique weld seam 21, which is therefore not subjected to bending stress in its longitudinal extension when the frame structure 1 is subjected to longitudinal loading. Compared to an arrangement of the weld seam 21 precisely at the bending edge, the risk of fractures and material fatigue due to the notch effect in the weld seam 21 is significantly reduced.

[0045] The Fig. Figure 5 schematically shows the corner area with the corner edge 9 of the battery compartment 2 in a sectional view, in which the longitudinal sheet 10 merges into the transverse sheet 11. The outer sheet 14 is arranged next to the longitudinal sheet 10. The rounded corner edge 9 is recessed by an opposing curve 22 in such a way that it does not protrude at any point inward toward the battery compartment 2 beyond the lines of the longitudinal sheet 10 and the transverse sheet 11, which extend to a cutting edge 23. As a result, the same cuboid-shaped interior of the battery compartment 2 is available despite the rounding of the corner edge 9.

[0046] The Fig. 6 schematically shows the corner region with the corner edge 9 in a further embodiment, wherein the same reference numerals are used for the same elements. In the corner region, the longitudinal sheet 10 merges into the transverse sheet 11, and the outer sheet 14 is arranged next to the longitudinal sheet 10. By an opposing rounding 22, the rounded corner edge 9 is set back towards the outer sheet 14 such that at no point does it protrude inward toward the battery compartment 2 beyond the extended line of the longitudinal sheet 10. The additional installation space required by the rounding is thus relocated to the torsion box 17.

[0047] The Fig.Figure 7 schematically shows the corner area with the corner edge 9 in yet another embodiment with the outer sheet 14 and the transverse sheet 11, which merges into the longitudinal sheet 10. By means of an opposing rounding 22, the rounded corner edge 9 is set back behind the transverse sheet 11 relative to the battery compartment 2 in such a way that it does not protrude beyond the extended line of the transverse sheet 10 at any point toward the inside of the battery compartment 2. The additional installation space required by the rounding is thus relocated to the installation space in front of or behind the battery compartment 2 relative to the battery compartment 2.

Claims

[1] Frame structure (1) for an industrial truck (3) with a battery compartment (2), wherein the battery compartment (2) in the frame structure (1) is formed with a lateral opening (12) for the removal of a traction battery (13) from the battery compartment (2) and the battery compartment (2) has at least in the vehicle longitudinal direction a vertical longitudinal plate (10) and in the vehicle transverse direction at least one vertical transverse plate (11) with a vertical corner edge (9) between them, characterized by that the longitudinal sheet (10) and the transverse sheet (11) are a single continuous sheet and the corner edge (9) has a rounded portion. [2] Frame structure (1) according to claim 1, characterized by that the longitudinal sheet (10) and two transverse sheets (11) run as a single continuous sheet over three sides of the battery compartment (2) with two rounded corner edges (9). [3] Frame structure (1) according to claim 1 or 2, characterized bythat the fillet on one side of the corner edge (9) has an opposite fillet (22), so that the continuous sheet runs outside the cutting edge (23) of the longitudinal sheet (10) with the transverse sheet (11). [4] Frame structure (1) according to claim 3, characterized by that opposite curves (22) are present on both sides of the corner edge (9). [5] Frame structure (1) according to one of claims 1 to 4, characterized by that the upper side of the longitudinal sheet (10) and / or transverse sheet (11) has a rounded portion and connections, in particular a weld seam, are arranged adjacent to the rounded portion. [6] Frame structure (1) according to one of claims 1 to 5, characterized by that the frame structure (1) has an outer sheet (14) parallel to the longitudinal sheet (10) on the side facing away from the opening (12) of the battery compartment (2). [7] Frame structure (1) according to claim 6, characterized bythat further frame elements (18) of the frame structure (1), which are arranged transversely in front of and behind the battery compartment (2), in particular sheets (19), are passed through to the outer sheet (14) and are connected to the outer sheet (14) by a weld seam (21) which is arranged at an angle to the vertical. [8] Frame structure (1) according to one of claims 1 to 7, characterized by that the battery compartment (2) is open at the top. [9] Frame structure (1) according to one of claims 1 to 8, characterized by that the battery compartment (2) is open downwards at least far enough that a traction battery (13) located in the battery compartment (2) can be lifted by means of lifting means, in particular a second industrial truck. [10] Frame structure (1) according to one of claims 1 to 9, characterized by that the industrial truck (3) is a tractor (4).

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