Foldable structural frame for a wagon

Abstract

Foldable structural frame (1) for a trolley (40), with a front part (2) and a rear part (3) which are connected to each other via two side parts (4), wherein the side parts (4) each have a central, vertical middle strut (8) which serves as a guide rod for a sliding receiving element (9) for diagonal cross struts (10) running in the side halves (4) during the folding process, wherein the cross struts (10) are rotatably mounted on the sliding receiving element (9) and on the front part (2) and on the rear part (3), respectively, wherein the side parts (4) have an upper side strut (11) which is pivotally connected to the upper area of ​​the vertical middle strut (8) by means of a connecting element (12), characterized by that the vertical central struts (8) of the two side parts (4) are connected to each other in a U-shape and rigidly via a horizontally running connecting strut (13), that a central element (14) is firmly connected to the connecting strut (13), that each floor element (16) is hingedly connected to the front part (2) and the rear part (3) and that the central element (14) is connected to the two floor elements (16) via a pivot bearing (15) and a pivot axis.

Description

TECHNICAL AREA

[0001] The invention relates to a foldable structural frame for a cart, in particular a handcart. STATE OF THE ART

[0002] German utility model DE 20 2019 105 298 U1 discloses a foldable structural frame for a cart with a base frame, wherein the base frame is divided into a front part and a rear part, which are articulated to each other via a central joint. Furthermore, the cart has a vertical front and a vertical rear, each of which is articulated to the base plate by means of a front and rear pivot joint, respectively.The foldable frame consists of a front leg, which is articulated to the rear section via a rear pivot and to the front section via a front pivot. It also has a rear leg, which is articulated to the front section via a front pivot and to the rear section via a rear pivot. The front pivot is located at the central joint on the front section, and the rear pivot is located at the central joint on the rear section. The central joint incorporates a spring mechanism that locks the front and rear legs in place, thus stabilizing the frame when unfolded. This foldable frame is not well-suited for carrying heavy loads and is also cumbersome to handle.

[0003] US Patent 10,464,588 B1 discloses a folding stroller, which is divided into a front-wheel unit and a rear-wheel unit and has a folding mechanism comprising a left-side folding frame and a right-side folding frame, wherein each side-side folding frame has an upper front guard tube, a lower front guard tube, an upper rear guard tube, a lower rear guard tube, and a middle support frame, the middle support frame comprising an upper folding hinge, a lower folding hinge, and a vertical support bar, the vertical support bar being arranged between and connected to the upper and lower folding hinges, the upper and lower folding hinges extending forward and backward. In the unfolded state, the lower guard tubes of the side-side folding frames are held in a horizontal position by projections of the lower folding hinges.This limits the load-bearing capacity of the vehicle and also poses a risk of injury during handling.

[0004] European patent application EP 3 385 146 A1 discloses a connecting and stabilizing mechanism for a folding cart and a folding cart itself. The folding cart consists of three parts: two cart halves with a horizontal base, vertical side walls and front and back panels, as well as wheels and the connecting mechanism. The walls and base of the cart halves form a closed rectangle. The connecting mechanism comprises U-shaped rods extending between the two cart halves, connected by a handle. This handle is used to lift the U-shaped rods, thereby unlocking the upper and lower hinge blocks and allowing the cart to be folded so that the upper and lower frame rods of the cart halves fold upwards in a V-shape, thus folding the cart vertically along its length.This connection and stabilization mechanism for a foldable cart proves to be relatively complicated to assemble, not very robust, and poses a considerable risk of injury.

[0005] Document US 2022 / 0097748 A1 discloses a foldable structural frame for a cart with a front and a rear section connected by two side sections. Each side section has a central, vertical crossbar that serves as a guide for a sliding mounting element for diagonal crossbars running along the side halves during the folding process. The crossbars are rotatably mounted to the sliding mounting element and to the front and rear sections, respectively. The side sections also have an upper side crossbar that is pivotally connected to the upper portion of the vertical central crossbar by means of a connecting element. This foldable structural frame appears unsuitable for bearing heavy loads and proves to be cumbersome and complicated to handle. DESCRIPTION OF THE INVENTION

[0006] The invention is based on the objective of providing a foldable structural frame for a cart, in particular a handcart, which is improved compared to the prior art.

[0007] The problem is solved according to the invention with a foldable structural frame which has the features specified in claim 1.

[0008] Advantageous embodiments of the invention are the subject of the dependent claims.

[0009] The foldable structural frame according to the invention, which is suitable, for example, for a foldable cart, is divided into a front section and a rear section, which are connected to each other via two side sections. The front and rear sections are, for example, formed from horizontally extending upper and lower frame elements as well as vertical struts, forming an overall rectangular frame structure. The vertical struts thus form the corners of the cart in the unfolded state.

[0010] The side panels each have a centrally arranged, vertical center strut, which serves as a guide rod for a sliding mounting element for diagonal cross struts running in the side halves during the folding process, the cross struts being rotatably mounted on the sliding mounting element on one side and on the other side on the front or rear panel, for example on the lower horizontal frame elements.

[0011] The side panels have one or more upper side struts which are articulated to the upper part of the vertical central strut by means of a connecting element. The connecting element preferably forms the upper end of the vertical central strut and is rigidly connected to it.

[0012] In the structural frame according to the invention, the vertical central struts of the two side sections are rigidly connected to each other in a U-shape via a horizontally extending connecting strut. This arrangement results in increased stability of the structural frame both in the central area of ​​the base plane intended for load-bearing capacity and for the vertical central struts arranged in the central area of ​​the side sections of the folding cart.

[0013] The structural frame according to the invention also has at least one central element which is rigidly connected to the connecting strut and may, for example, be arranged to rest on the connecting strut. This central element has additional pivot bearings on which two base elements are rotatably attached. The base elements are also hinged to the lower part of the front and rear sections, for example by means of a hinge connection on the respective lower frame element.

[0014] Preferably, when unfolded, the upper side struts run approximately horizontally, i.e., at approximately right angles to the vertical central strut. The sliding mounting element, with the cross struts pivotally attached to it, is moved upwards along the central strut, which also serves as a guide rod, into an end position. This end position is defined by the sliding mounting element resting against the connecting element at the upper end of the central strut from below. This ensures that the structural frame is reliably locked in the desired position when unfolded and that a stable structure is guaranteed even when the cart is loaded with transported items.By means of a simple, for example manually operated locking mechanism (e.g. hook), the adjacent receiving elements and connecting elements on both side parts of the structural frame can be secured in their position, so that a folding process is only possible after prior unlocking.

[0015] Preferably, in the unfolded configuration, the cross braces in each side panel run diagonally between the receiving element in the upper area of ​​the central brace and the hinge mounts in the lower area of ​​the front and rear panels. This, along with the fact that the two cross braces run in opposite directions to the front and rear panels, results in exceptional stability of the side panels.

[0016] The foldable structural frame according to the invention proves to be, among other things, very easy to handle and is suitable for bearing even larger loads. When folded, a handcart with the structural frame according to the invention can still be stored in an extremely space-saving manner.

[0017] A preferred embodiment of the structural frame according to the invention is designed such that the two vertical central struts are integrally connected to the horizontally extending connecting strut. This results in a particularly stable arrangement of connecting struts and central struts, which increases the stability of the structural frame and thus of the vehicle.

[0018] A preferred embodiment of the structural frame according to the invention is designed such that at least one floor element is U-shaped with two legs, and that the central element, designed as a central plate, projects between the legs of the U-shaped floor elements. This results in a uniform, planar structure consisting of the two floor elements and the central plate, which together form the floor of the vehicle or at least a substantial part thereof. This embodiment is characterized by a very advantageous large floor area and thus by its ease of handling. The central element preferably forms a stable, central floor element that can be designed for higher load-bearing capacities.

[0019] A preferred embodiment of the structural frame according to the invention is designed such that the central plate is essentially flat and suitable, together with the base elements, to form the closed base of the foldable structural frame. This creates a very easy-to-handle base that enables the transport of delicate, especially small, objects and, in particular, also the transport of people, especially small children, without them being burdened by gaps in the base.

[0020] A preferred embodiment of the structural frame according to the invention is designed such that the central element has a substantially V-shaped structure. The V-shaped central element comprises two legs that are connected to each other centrally and exhibit an opening angle typically greater than 90°. Preferably, a pivot bearing for a base element is arranged in the region of each free end of the legs, and the fixed connection to the connecting strut is arranged centrally in the connection area of ​​the two legs. Thus, the V-shaped central element is connected to the base elements via the pivot bearings in such a way that they can pivot relative to each other, allowing the base of the foldable structural frame to be folded. This preferred embodiment of the V-shaped central element makes it possible to position the connecting strut below the axes of rotation of the pivot bearings and thereby separate them vertically.This makes it possible to position the pivot bearings at the same level as the floor elements, while the connecting strut is arranged below them, at a lower height than the floor elements with the pivot bearings. This arrangement allows the floor elements to be spatially separated from the connecting strut to a more advantageous degree, thus enabling the strut to be designed more effectively according to its specific function.

[0021] The V-shaped central element is preferably arranged approximately midway between the front part and the rear part of the structural frame, so that a symmetrical or approximately symmetrical folding of the floor is possible.

[0022] Preferably, the single V-shaped central element is arranged approximately in the middle between the side parts of the structural frame, so that the distances to the lateral end of the bottom elements are approximately equal, thus ensuring a uniform load on the rotary bearings, which increases the stability of the arrangement.

[0023] Besides the option of using a single V-shaped central element, a preferred further development of the structural frame has also proven effective: the V-shaped central element comprises at least two spaced-apart V-shaped sections, which are essentially the same shape and connected to each other. These sections are designed such that a pivot bearing for a base element is located at the free ends of each leg of the V-shaped section, and the fixed connection to the connecting strut is located centrally in the junction area of ​​the two legs. This further development of the V-shaped central element allows the load to be distributed evenly across the width of the base of the structural frame for the vehicle, thereby increasing both stability and robustness.It is even possible to arrange two of the V-shaped parts in the lateral edge area of ​​the floor elements and thus of the floor, thereby creating a way to make the axes of rotation between the V-shaped parts and the floor elements very short and therefore less susceptible to damage.

[0024] Alternatively, the pivot axes can extend across the entire width of the vehicle's structural frame to the lateral edge area, including any longitudinal beams of the floor elements located therein, thereby achieving increased stability. However, with reduced load requirements, shortened pivot axes can also be used, which, for example, only run within the recesses of the spaced-apart parts of the central element. In this embodiment, these recesses are preferably located in the lateral edge area of ​​the floor elements and, in particular, in the longitudinal beams of the floor elements potentially located there.

[0025] In this further development of the structural frame according to the invention with a V-shaped central element, the two bottom elements are preferably rectangular in shape and, in the erected state, form the complete bottom of the structural frame for a cart, in particular for a handcart.

[0026] A preferred embodiment of the structural frame according to the invention is designed such that at least one pivot bearing of the central element is designed as a bearing that is invisible from the outside. It has proven particularly advantageous to design the central element, in the form of a central plate, to be slightly shorter than the connecting strut, and to design the hinged base elements in a U-shape with legs that enclose the central plate in such a way that, when the carriage is unfolded, the central plate and base elements form a largely closed horizontal floor plane. This results in a very user-friendly embodiment.

[0027] A preferred embodiment of the structural frame according to the invention is designed such that at least one pivot bearing has a rod-shaped pivot shaft arranged between a base element, in particular between a leg of a U-shaped base element, and the central element. This arrangement offers the advantage that the at least one rod-shaped pivot shaft of the pivot bearing is supported in the central element or the central plate and extends into the base elements, in particular into the legs of the U-shaped base elements. The path of the pivot shafts can be designed such that they run only partially within the central element or the central plate and also partially within the legs of the base elements. This means that each pivot shaft terminates concealed within a leg of the base elements and is invisible from the outside, thus also protecting it from dust, especially in outdoor areas.This makes it possible to create a robust and user-friendly structural framework.

[0028] A preferred embodiment of the structural frame according to the invention is designed such that at least one pivot bearing has a rod-shaped pivot shaft which projects at least a few centimeters into the at least one base element, in particular into the leg of at least one U-shaped base element, and / or extends continuously through both legs of a U-shaped base element and through the central element or the central plate. Here, the rod-shaped pivot shafts are preferably guided in one piece longitudinally through the central plate and to the outer edge of the legs of the U-shaped base elements. With appropriate material selection (for example, steel) and dimensioning of the cross-section of the pivot shafts, this allows for high stability and load-bearing capacity of the unfolded carriage, especially in the central area of ​​the base plane. This makes it possible, in particular, to create a structural frame suitable even for larger loads.

[0029] A preferred embodiment of the structural frame according to the invention is designed such that the pivot bearings of the central element or the central plate for the two base elements are arranged parallel to each other and spaced at least several centimeters apart. The distance between the two parallel pivot shafts in the central element or the central plate is selected such that the U-shaped base elements, which are rotatably mounted on the legs, achieve sufficient stability in this area. This results in a robust and user-friendly structural frame.

[0030] A preferred embodiment of the invention is designed such that the rotary bearings are arranged in the front and / or rear edge region of the central element or central plate. The distance between the rotary shafts can range from a few centimeters to over a few decimeters, depending on the embodiment, and is preferably located in the edge region of the central element or central plate, resulting in a very stable construction. This makes it possible to create a robust and user-friendly structural frame that is also suitable for higher load capacities.

[0031] A preferred embodiment of the structural frame according to the invention is designed such that the central element or central plate and / or at least one base element are designed as a solid plate, particularly made of metal, wood, and / or plastic. In one exemplary embodiment, the central element or central plate and / or the supporting structure can be designed as a continuous and solid, and therefore stable, element or base element made of load-bearing material, such as a wood composite panel, metal, or rigid plastic. This embodiment is characterized by exceptional stability and load-bearing capacity.

[0032] A preferred embodiment of the structural frame according to the invention is designed such that the central element or the central plate and / or at least one base element are provided with an outer frame and with a support structure integrated therein. The central element or the central plate, or at least one base element, can be designed differently depending on the application of the folding cart. In one embodiment, the base elements have a stable outer frame, for example made of metal, into which a flat support structure is inserted. This allows the support structure to be easily removed from the outer frame and replaced in case of damage, thereby improving handling. Furthermore, the respective properties of the support structure and outer frame can be optimized through appropriate design of the components.

[0033] A preferred embodiment of the structural frame according to the invention is designed such that at least one base element is provided with an outer frame consisting of at least two longitudinal beams and with a support structure between the longitudinal beams, comprising crossbeams arranged between the longitudinal beams. This design of the base element allows the support structure to be adapted to changing needs, particularly to different objects being transported, or, if necessary, to be replaced by the user. This allows the range of applications for the cart with the structural frame according to the invention to be expanded or adapted.

[0034] A preferred embodiment of the structural frame according to the invention is designed such that the central element or the central plate and / or at least one base element comprises an outer frame with an integrated support structure, which is preferably designed as a grid and / or a honeycomb structure. The support structure is preferably designed as a grid-like honeycomb structure (for example, consisting of hexagons, triangles, squares, etc.) and is made, for example, of metal or plastic. The honeycomb structure significantly reduces the weight of the support structure and thus of the base elements while maintaining high stability, thereby improving handling.

[0035] A preferred embodiment of the structural frame according to the invention is designed such that the central plate is arranged centrally on the connecting strut. This central connection of the central plate to the connecting strut creates a very load-bearing arrangement, which greatly expands the potential application range of the foldable structural frame. The central plate, like the floor elements, can also be formed from a frame and associated supporting structure, forming the middle part of the base. However, the increased mechanical load on the central plate must be taken into account, since the central plate supports both floor elements via its integrated pivot bearings. This makes it possible to create a structural frame that is also suitable for higher load capacities.

[0036] A preferred embodiment of the structural frame according to the invention is designed such that the central element or the central plate is laterally enclosed by legs of the U-shaped base elements. The positions of the pivot shafts in the area of ​​the legs are preferably arranged such that, in the unfolded state of the structural frame, the opposing end faces of the legs lie almost flush against each other in the horizontal end position of both base elements, thereby almost completely enclosing the central plate laterally. In addition, the U-shaped design of the base elements makes it possible to enclose the central plate completely without significant gaps. This results in a robust and user-friendly structural frame that is also suitable for higher load-bearing capacities.

[0037] A preferred embodiment of the structural frame according to the invention is designed such that one or more stop elements are provided for limiting the folding movements. The folding movement can be limited by means of specific stop elements with regard to both the unfolding and the folding movements. In particular, stop elements in the area of ​​the legs have proven effective, for example, those that either abut the adjacent leg, the central element or the central plate, the connecting strut, or the area of ​​the central strut with the sliding receiving element. This makes it possible to create a robust and user-friendly structural frame that is also suitable for higher load-bearing capacities.

[0038] A preferred embodiment of the structural frame according to the invention is designed such that the folding movement during unfolding is limited by the stop of the receiving element, which is slidable on the central strut, against the connecting element. This design of the stop proves to be a very robust embodiment that is also easy to handle during unfolding. This makes it possible to create a robust and user-friendly structural frame that is also suitable for higher load-bearing capacities.

[0039] A preferred embodiment of the structural frame according to the invention is designed such that the folding movement is limited by a stop of one or more base elements against the connecting strut and / or against the central element or the central plate. This provides increased mechanical stability and facilitates handling during the folding process.

[0040] A preferred embodiment of the structural frame according to the invention is designed such that a locking mechanism is provided which secures the unfolded or folded state of the structural frame against unintentional folding or unfolding. Such a locking mechanism simplifies the handling of the structural frame and increases safety when handling it. The locking mechanism can be implemented in various ways, for example, by a hook that, in the unfolded or folded state, engages behind another part, thereby limiting the distance between these parts and thus preventing unintentional folding or unfolding of the structural frame. Securing this state with a lock has also proven effective.

[0041] This makes it possible to create a robust and user-friendly structural framework.

[0042] Folding the structural frame can be achieved, for example, by lifting a connecting element. This simultaneously raises the vertical center struts of both side panels, as they are rigidly connected in a U-shape via the horizontal connecting strut. All side struts pivot downwards at their bearings in the respective connecting elements and upwards at their joints on the front and rear panels. This reduces the angle between the side struts and the vertical center strut during the folding process, until the side struts are approximately parallel to the vertical center strut. At the same time, the sliding mounting element moves downwards along the center strut, which serves as a guide rod, relative to the connecting element mounted above.In this process, the crossbars, which are articulated both on the sliding mounting element and in the lower area of ​​the front and rear parts, gradually shift from a diagonal position into an approximately vertical direction.

[0043] During the folding process, the base elements are lifted via the pivot bearings on the central element or plate and fold upwards from their horizontal position around their hinge points at the front and rear sections, respectively, until they reach an approximately vertical final position. In its folded state, the structural frame is therefore very compact and can be set up in a space-saving manner.

[0044] In another embodiment, the foldable structural frame is equipped with upwardly extendable poles in the area of ​​the vertical struts of the front and rear sections. These poles have connecting elements at their ends for two additional support poles. Clamping devices are provided on the vertical struts to fix the extendable poles in any desired position, allowing the connecting elements to be positioned at different heights. The two support poles are intended, for example, for holding a tarpaulin or similar item, thus protecting transported goods from rain, sunlight, dust, etc.The support bars span the entire loading area by running diagonally from the front left vertical strut of the front section to the rear right vertical strut of the rear section, or from the front right vertical strut of the front section to the rear left vertical strut of the rear section, where their ends are detachably fixed in the connecting elements. This creates a roof structure that is variably adjustable in height.

[0045] The invention is explained below by way of example with reference to preferred embodiments and the illustrations. The invention is not limited to these preferred embodiments. Fig. Figure 1 shows a schematic representation of an exemplary, inventive foldable structural frame for a handcart with, in the unfolded state, Fig. Figure 1a shows a schematic representation of the exemplary structural framework for a handcart made of Fig. 1. When unfolded, viewed from the side, Fig. Figure 2 shows a schematic representation of the exemplary structural framework for a handcart made of Fig. 1 in the unfolded state from above, Fig. Figure 2a shows a schematic representation of the exemplary structural framework for a handcart made of Fig. 1 in the unfolded state from below, Fig. Figure 3 shows a schematic representation of the exemplary structural framework for a handcart made of Fig. 1 in the unfolded state as a front view, Fig. Figure 3a shows a schematic representation of the exemplary structural framework for a handcart made of Fig. 1 in the unfolded state as a rear view, Fig. Figure 4 shows a schematic oblique view of the exemplary structural frame for a handcart made of Fig. 1 in a partially folded state, Fig. Figure 4a shows a schematic representation of a side view of the exemplary structural frame for a handcart made of Fig. 1 in a partially folded state, Fig. Figure 5 shows a schematic oblique view of the exemplary handcart made of Fig. 1 in its fully folded state, Fig. Figure 5a shows a schematic side view of the exemplary handcart made of Fig. 1 in its fully folded state, Fig. Figure 6 shows a schematic representation of a side view of another exemplary structural frame in its fully unfolded state, with the central element designed as a V-shaped structure. Fig. Figure 6a shows a schematic top view of the exemplary handcart. Fig. 6.

[0046] Fig. Figure 1 shows a schematic oblique view of an exemplary handcart 40, which includes a foldable frame 1 as a key component. The figure shows the fully unfolded state for use of the handcart 40. The foldable frame 1 has a front section 2 and a rear section 3, which in this embodiment are each formed as a rectangular frame structure by upper and lower horizontal frame elements 5, 6 and vertical struts 7. Attached to this are handling aids, such as handles 27, 28 at different heights or, as shown in the figure, a pull bar 26 with a handle 25.

[0047] The front section 2 and the rear section 3 are connected to each other via two side sections 4. The loadable floor of the cart is a rectangular plane formed from two floor elements 16, which in this embodiment enclose a central element 14 designed as a central plate. For attaching a tarpaulin or film to protect against dust or rain, poles 21 are provided in the corners of the cart. These poles are, for example, recessed into the vertical struts 7 as extendable elements and can be fixed at the desired height by means of manually operated clamping devices 24. The poles 21 hold, via connecting elements 22, two diagonally crossed support bars 23 to which, for example, a tarpaulin can be attached as a cover.

[0048] In Fig. Figure 1a is a schematic top view of a side panel 4 of the handcart 40. As in Fig. Figure 1 shows the fully unfolded state of the structural frame 1. In this embodiment, the side panel 4 has a symmetrical arrangement of various elements: A vertical central strut 8 is arranged in the center, at the upper end of which a connecting element 12 is fixed, serving as a pivot point for two side struts 11. When the wagon 40 is fully unfolded, the side struts 11 run horizontally to the front panel 2 and rear panel 3, respectively, and are also pivotally attached there, for example, to the vertical struts 7. A receiving element 9 is attached to the central strut 8, which pivotally accommodates two diagonally extending cross struts 10. The cross struts 10 are also pivotally connected to the lower area of ​​the front panel 2 and rear panel 3, respectively, for example, to the vertical struts 7 located there.In the base of the handcart 40 are two symmetrically arranged base elements 16, which are connected on one side to a central plate 14 by means of pivot axes 15, and on the other side are rotatably mounted in the lower part of the front section 2 and the rear section 3, respectively. In the fully unfolded operating state of the handcart 40 shown, the base elements 16 together with the central plate 14 form a largely closed horizontal surface, except for the inevitably remaining narrow gaps.

[0049] The central strut 8 and the receiving element 9 are designed such that the receiving element 9 is vertically displaceable along the central strut 8. When the structural frame 1 is folded, the receiving element 9 moves downwards along the central strut 8 relative to the upper connecting element 12. Conversely, when the structural frame 1 is unfolded, the receiving element 9 moves in the opposite direction along the central strut 8 towards the connecting element 12. In the fully unfolded state of the structural frame 1 shown, the displaceable receiving element 9 rests flush against the bottom of the connecting element 12 in its uppermost position and is thus prevented from moving upwards further.This defines, on the one hand, the desired final state when the structural frame 1 is unfolded and, on the other hand, stabilizes the structural frame 1 when carrying heavier loads: Weight in the central area of ​​the support floor acts via the floor elements 16 and the central plate 14, which is articulated to them, as pressure on the connecting strut 13 and thus as a downward pull on the central struts 8 on both sides, so that the connecting element 12 exerts a corresponding downward pressure on the adjacent receiving element 9. The resulting forces are transferred from the receiving element 9 to the diagonally extending cross struts 10, which are rotatably attached to it, and from these, via their articulated connections to the vertical struts 7 of the front and rear sections 2 and 3, respectively, into the outer area of ​​the structural frame 1.

[0050] Fig. Figure 2 shows the fully unfolded handcart 40 of the Fig. Figure 1 from above. The base plane in the preferred embodiment is shown, formed from a centrally arranged central plate 14 and the base elements 16 pivotally attached to it. The base elements 16 encompass the central plate, which is slightly shortened compared to the width of the base plane, via legs 17 of the U-shaped base elements 16. This forms an almost continuous rectangular base plane. These legs 17 serve as pivot bearings 15 for the folding process, and in this exemplary embodiment, they are designed as pivot shafts that extend completely through the central plate 14 and the legs 17 of the U-shaped base elements 16.

[0051] The base elements 16 are shown here as an example consisting of a surrounding outer frame 18 and a supporting structure 19 embedded within it, which is designed here as a honeycomb-shaped grid structure. Other grid structures with different mesh shapes, such as triangles, squares, etc., are equally suitable. The advantage of such a design lies in a significant weight saving while maintaining a relatively high load-bearing capacity. For a design of the handcart for higher weight loads due to correspondingly heavy transport objects, the base elements 16 can alternatively be designed as solid panels made of a stable material, for example, metal, or as a grid-shaped supporting structure in which crossbeams are embedded in the frame structure 18.In the illustrated embodiment, the central plate 14 has a narrow frame 20 and is not equipped with a grid-shaped support structure 19, but is formed over a full surface.

[0052] Fig. 2a shows the ready-to-use handcart 40 of the Fig. 1 from below. In the center of the base plane, a horizontal connecting strut 13 runs between the side parts 4. This connecting strut 13 fixes the central plate 14 and is rigidly connected to it, thus also absorbing the mechanical loads on the central plate 14 caused by the rotatably attached base elements 16. In the illustrated embodiment, the pivot bearings for the attached base elements 16 are designed as axes of rotation 15, which run parallel to each other at a distance A through the central plate 14 and the legs 17 of the U-shaped base elements 16. Here, the distance A is chosen such that the axes of rotation 15 each run in the edge region of the central plate 14.Preferably, the pivot axes 15 are designed to be so stable by the choice of material (for example, steel) and cross-sectional profile that the edge areas of the central plate 14 and also the floor elements 16 with their legs 17 are stabilized against a higher load that may be placed there.

[0053] The connecting strut 13 is additionally firmly connected at both ends to the vertical central struts 8 of the side parts 4 (in the perspective shown). Fig. 2a not visible) and forms a rigid U-shaped profile with these, which in a preferred embodiment can also be manufactured from a single piece. This stabilizes both side parts 4 in their center via the central struts 8 as part of the U-profile. Furthermore, the side parts 4 are also stabilized by the frame elements 5, 6 and vertical struts 7 of the front part 2 and the rear part 3, respectively. This ensures that even when transporting larger objects, which may press against the upper side struts 11 of the side parts 4 and exert lateral pressure there, particularly when cornering, the structural frame 1 does not deform significantly.

[0054] Fig. Figure 3 shows a front view of the erected handcart 40 in the embodiment according to Fig. 1. The stable basic structure of the front part 2 is formed by the two outer vertical struts 7, which are connected to form a rectangular frame structure via an upper frame element 5 and a lower frame element 6. A fold-out pull rod 26 with an upper handle 25 is attached to this frame structure. In this embodiment, the outer vertical struts 7 serve as a receptacle for upwardly extendable rods 21. To fix these rods 21 in a desired extended position, clamping devices 24 are provided at the upper ends of the vertical struts 7. These clamping devices can, for example, be designed as conical plastic elements through which a rod 21 is guided centrally. The rod 21 can then be easily fixed or released manually by turning the plastic element, for example, using a screw thread.Two support rods 23 are detachably fixed diagonally across each other via connecting elements 22 at the upper ends of the rods 21 and serve, for example, as a support or holder for covers, such as cloths or tarpaulins.

[0055] Fig. Figure 3a shows the rear view of the erected handcart 40. The basic structure of the rear section 3 is identical to that of the front section 2. The two lateral vertical struts 7, together with the upper and lower frame elements 5, 6, form a stable rectangular frame structure. Attached to this, in this embodiment, are a first upper bracket 27 and a further, slightly downward-positioned lower bracket 28 for ergonomic handling of the handcart 40. Extendable poles 21, as well as connecting elements 22 and support bars 23 for a cover of the handcart 40, are implemented here in the same way as in the front section 2.

[0056] Fig. Figure 4 shows an oblique view of the partially folded handcart 40 in the embodiment according to Fig. 1. This handcart 40 shows a partially folded structural frame 1.

[0057] The two opposing connecting elements 12 are raised upwards by approximately the same distance. As a result, the upper side struts 11, which are rotatably attached to the connecting elements 12 on one side and to the vertical struts 7 on the other, are tilted from their previously horizontal position.

[0058] By lifting the connecting elements 12, the rigidly connected vertical center struts 8 are also lifted simultaneously, and thus the entire U-profile, which runs transversely in the middle of the wagon and is formed by the two vertical center struts 8 and the horizontal connecting strut 13 running in the base area, is also lifted. The central plate 14, fixed to the horizontal connecting strut 13, is thus also lifted and, via the pivot axes 15, takes the legs 17 of the U-shaped base elements 16 with it, so that the base elements 16 rise from the horizontal position at their joints at the lower area of ​​the outer vertical struts 7.

[0059] During this folding process, the front section 2 and the rear section 3 are guided towards each other, a movement facilitated by the base rollers 30. This movement causes the crossbars 10 to pivot from their diagonal position into a more upright position, thereby inevitably pushing the receiving element 9, which is slidable on the central strut 8, upwards via their rotatable bearings. However, the upward movement of the receiving element 9 is slower than the simultaneous lifting of the connecting element 12 and the associated central strut 8. This is due to the different starting angles at the beginning of the folding process: the upper side struts 11, which are articulated to the connecting element 12, are initially in a horizontal position, while the crossbars 10, which are articulated to the receiving element 9, are initially in a diagonal position.In the interplay of both upward movements, the central strut 8 is pulled upwards faster via the connecting element 12 than the upward movement of the receiving element 9, so that the distance between the movable receiving element 9 increases with respect to the position of the upper connecting element 12 on the central strut 8.

[0060] Fig. 4a shows a schematic side view, which illustrates the Fig. Figure 4 shows a handcart 40 with a partially folded structural frame 1. The connecting element 12, the rigidly connected central strut 8, the horizontal connecting strut 13 (not visible in this perspective), and the central element 14, for example, the central plate, which rests on and is firmly connected to it, are all raised vertically by the same amount. The receiving element 9 has also moved upwards due to the erection of the cross struts 10, but by a smaller amount than the aforementioned elements. Thus, the receiving element 9, which previously rested flush against the connecting element 12 from below in the fully unfolded operating state, has been moved slightly away from it along the vertical central strut 8.

[0061] The base elements 16 are lifted by the central element 14 via the pivot bearings 15 during the folding process and thus fold upwards at their joints on the lower area of ​​the outer vertical struts 7. On the front part 2, shown schematically on the left side of the Fig. 4a, a pull rod 26 with handle 25, attached in this embodiment, is already positioned in the space-saving, vertical position. At the rear section 3 (right in Fig. 4a) shows an upper bracket 27 attached there, for example, which is still extended, but can preferably also be brought into a space-saving vertical position by means of folding joints 29.

[0062] By lifting the upper connecting elements 12, the transverse U-shaped central profile, formed from the opposing vertical central struts 8 and the horizontal connecting strut 13 with the central plate 14 rigidly connected to it, is raised in its entirety. This causes the hinged elements of the side sections 4 (upper side struts 11, cross struts 10, and base elements 16) to gradually rise from their horizontal or diagonal positions in the unfolded operating state of the handcart 40 towards a vertical position.

[0063] Fig. Figure 5 shows an oblique view of the fully folded handcart 40 in the embodiment according to Fig. 1, Fig. Figure 5a shows a corresponding side view. The connecting elements 12 are in their uppermost mechanically possible position. This is defined by the length of the upper side struts 11, which, due to their articulated attachment to the front part 2 and rear part 3, prevent further lifting in a nearly vertical end position.

[0064] The base elements 16 are also folded into a nearly vertical end position via their pivot connection on the central plate 14. The connection of the base elements 16 to the lower part of the front and rear sections 2 and 3 prevents further lifting of the central plate 14 and thus of the connecting elements 12, which are rigidly connected via the U-profile of the connecting strut 13 and the vertical center struts 8. Manual folding of the wagon 40 is therefore so simplified that the optimal final position of the wagon 40, requiring minimal space, is inevitably achieved simply by lifting the connecting elements 12 to their upper end position.

[0065] In the illustrated preferred embodiment, the bracket 27 located on the rear section 3 is attached to the rear section 3 in a space-saving manner by means of a folding hinge 29. Furthermore, the base wheels 30 on the front section 2 and the rear section 3 have different wheel spacing and, as shown, can optionally be of different sizes. This allows the base wheels to be guided at least partially side by side in the folded position of the wagon, further reducing the space required.

[0066] Fig. Figure 6 shows a schematic representation of a side view of the exemplary structural frame 1 in its fully unfolded state, with the central element 14 showing a V-shaped structure.

[0067] The V-shaped central element 14 has two legs connected centrally, forming an opening angle of approximately 140°. A pivot bearing 15 for a base element 16 is arranged at the free ends of each leg, and the fixed connection to the connecting strut 13 is located centrally in the junction area of ​​the two legs. The pivot bearing 15 is formed by a recess at the free end of the legs and by a rod-shaped pivot shaft extending across the entire width of the base. The rod-shaped pivot shaft is rotatably inserted centrally into the aforementioned recess in the V-shaped central element 14 and is rotatably mounted at its ends in recesses in the outer frame 18 of the base elements 16. Each base element 16 consists of an outer frame 18 into which spaced-apart crossbars are inserted, together forming a kind of lattice frame.

[0068] The V-shaped central element 14 is connected to the base elements 16 via the pivot bearings 15 in such a way that they can pivot relative to each other, allowing the base of the foldable structural frame 1 to be folded. This preferred design of the V-shaped central element 14 makes it possible to position the connecting strut 13 below the pivot axes of the pivot bearings 15, thereby separating them vertically. This allows the pivot bearings 15 to be positioned at the same height as the base elements 16, while the connecting strut 13 is located below them and thus at a lower height than the base elements 16 with the pivot bearings 15. This arrangement allows the base elements 16 to be spatially separated from the connecting strut 13 in an advantageous way, enabling the strut to be designed to suit its specific functions.

[0069] Furthermore, the V-shaped central element 14 is arranged centrally between the front part 2 and the rear part 3 of the structural frame 1, so that a symmetrical folding of the structural frame 1 is possible.

[0070] In addition, the V-shaped central element 14 is arranged centrally between the side parts 4 of the structural frame 1, so that the distances to the lateral end of the bottom elements 16 are approximately equal and thus a uniform load on the pivot bearings 15 is given, which increases the stability of the structural frame 1.

[0071] In Fig.Figure 6a schematically shows a corresponding vertical plan view. It can be seen that the two base elements 16 have an outer frame 18, which is connected to each other in a grid-like fashion via cross braces of the base elements 16. The cross braces of the two base elements 16, which are arranged in the area of ​​the connecting strut 13 and define the longitudinal boundaries of the base element 16, are located above the area of ​​the V-shaped central element 14, which accommodates the connecting strut 13 and represents the center or connection point of the two legs of the V-shaped central element 14. The height of the two limiting cross braces of the base elements 16 corresponds approximately to the height of the two stacked pivot shafts of the rotary bearings 15. This is made possible by the V-shaped structure of the central element 14.Furthermore, this structure also allows the limiting crossbars of the floor elements 16 to lie close together, forming a virtually closed floor surface and thus creating a possibility to transport even heavy objects or goods. Reference symbol list 1 Foldable structural frame 2 Front part 3 Rear section 4 side panels 5 Upper frame element 6 Lower frame element 7 Outer vertical struts 8 Center brace 9. Sliding mounting element 10 cross braces 11 Upper side struts 12 Connecting element 13 Horizontal connecting strut 14 Central element, central plate 15 swivel bearings 16 floor elements 17 thighs 18 outer frames 19 Supporting structure 20 frame central plate 21 poles 22 Connecting element 23 Support bar 24 clamping device 25 handle 26 pull rod 27 top hangers 28 bottom hangers 29 Folding joint 30 floor casters 40 Folding Wagon A distance between the pivot bearings of the central plate QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2019 105 298 U1

[0002] US 10,464,588 B1

[0003] EP 3 385 146 A1

[0004] US 2022 / 0097748 A1

[0005]

Claims

[1] Foldable structural frame (1) for a trolley (40), with a front part (2) and a rear part (3) which are connected to each other via two side parts (4), wherein the side parts (4) each have a central, vertical middle strut (8) which serves as a guide rod for a sliding receiving element (9) for diagonal cross struts (10) running in the side halves (4) during the folding process, wherein the cross struts (10) are rotatably mounted on the sliding receiving element (9) and on the front part (2) and on the rear part (3), respectively, wherein the side parts (4) have an upper side strut (11) which is pivotally connected to the upper area of ​​the vertical middle strut (8) by means of a connecting element (12), characterized by , that the vertical central struts (8) of the two side parts (4) are connected to each other in a U-shape and rigidly via a horizontally running connecting strut (13), that a central element (14) is firmly connected to the connecting strut (13), that each floor element (16) is hinged to the front part (2) and the rear part (3) and that the central element (14) is connected to the two floor elements (16) via a pivot bearing (15) and a pivot axis. [2] Foldable structural frame (1) for a carriage (40) according to claim 1, wherein the two vertical central struts (8) are integrally connected to the horizontal connecting strut (13). [3] Foldable structural frame (1) for a carriage (40) according to claim 1 or 2, wherein at least one base element (16) is U-shaped with two legs (17) and the central element (14) is substantially planar and is arranged in the form of a central plate between the legs (17). [4] Foldable structural frame (1) for a carriage (40) according to claim 3, wherein the central plate (14) is suitable to form the base of the foldable structural frame (1) together with the base elements (16). [5] Foldable structural frame (1) for a carriage (40) according to claim 1 or 2, wherein the central element (14) has a substantially V-shaped structure. [6] Foldable structural frame (1) for a carriage (40) according to claim 5, wherein the central element (14) comprises at least two spaced-apart parts which have the same substantially V-shaped structure and which are firmly connected to each other. [7] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 6, wherein at least one pivot bearing (15) is designed as a bearing that is invisible from at least one side. [8] Foldable structural frame (1) for a carriage (40) according to any one of claims 1 to 7, wherein at least one pivot bearing (15) has a rod-shaped pivot shaft extending between a base element (16) and the central element (14), in particular between a leg (17) of a U-shaped base element (16) and the central element (14) or the central plate (14). [9] Foldable structural frame (1) for a carriage (40) according to claim 8, wherein at least one pivot bearing (15) has a rod-shaped pivot shaft which projects at least a few centimeters into the base element (16), in particular into at least one leg (17) of the base element (16), or extends continuously through the two legs (17) of a U-shaped base element (16) and through the central plate (14). [10] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 9, wherein the axes of rotation of the pivot bearings (15) are arranged between the central element (14) or the central plate (14) and the two bottom elements (16) at a distance of at least several centimeters from each other and running parallel to each other. [11] Foldable structural frame (1) for a carriage (40) according to claim 10, wherein the pivot bearings (15) are arranged in the front and / or rear edge region of the central element (14) or the central plate (14) and / or the floor elements (16). [12] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 11, wherein the central plate (14) and / or at least one base element (16) are designed as a solid plate, in particular made of metal, wood and / or plastic. [13] Foldable structural frame (1) for a wagon (40) according to one of claims 1 to 12, wherein at least one floor element (16) is provided with an outer frame (18) made of at least two longitudinal beams and with a support structure (19) made of crossbeams arranged between the longitudinal beams and inserted therein between the longitudinal beams. [14] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 12, wherein the central plate (14) and / or at least one base element (16) is provided with an outer frame (18) and with a supporting structure (19) incorporated therein, which is designed as a grid and / or as a honeycomb structure. [15] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 14, wherein the central element (14) is arranged centrally on the connecting strut (13). [16] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 15, wherein the central element (14) is enclosed laterally by the floor elements (16), in particular the central plate (14), by the legs (17) of the U-shaped floor elements (16). [17] Foldable structural frame (1) for a carriage (40) according to one of claims 1 to 16, wherein one or more stop elements are provided for limiting the folding movements. [18] Foldable structural frame (1) for a carriage (40) according to claim 17, wherein the folding movement is limited by a stop of the receiving element (9) which is slidable on the central strut (8) against the connecting element (12). [19] Structural frame (1) for a carriage (40) according to claim 17 or 18, wherein the folding movement is limited by a stop of one or more bottom elements against the connecting strut (13) and / or against the central element (14). [20] Foldable structural frame (1) for a carriage (40) according to any one of claims 1 to 19, wherein a locking mechanism is provided which secures the unfolded and / or folded state of the structural frame (1) against unintentional folding and / or unfolding.

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