Lifting mechanism for an autonomous under-carrier industrial truck

Abstract

The present invention relates, inter alia, to a lifting mechanism (100) for an autonomous under-carrier industrial truck having a vehicle body (12) that defines a length direction (L) and a width direction (B) and having a load-bearing platform (14) that is height-adjustable with respect to the vehicle body (12), comprising at least one length-variable drive unit (102), which is designed to be drivable for selective lifting and lowering of the load-bearing platform (14) in a vertical direction (H). According to the invention, the lifting mechanism (100) further comprises a passive stabilisation system (116), in turn having: an upper plate element (112) that is assigned to or forms the load-bearing platform (14); at least one hinge arrangement with at least two points of attachment on the vehicle body (12) and at least two points of attachment on the upper plate element, which hinge arrangement height-adjustably couples the upper plate element (112) to the vehicle body (12) and thereby provides a spatial axis for parallelism between the vehicle body (12) and the upper plate element; at least one unit for transmitting lateral forces between the vehicle body (12) and the upper plate element (112); and at least one unit for transmitting longitudinal forces between the vehicle body (12) and the upper plate element (112).

Description

[0001] Lifting mechanism for an autonomous under-floor industrial truck

[0002] Description

[0003] The present invention relates to a lifting mechanism for an autonomous under-floor industrial truck having a vehicle body defining a longitudinal direction and a width direction and a load-bearing platform that is height-adjustable relative to the vehicle body, comprising at least one variable-length drive unit that is configured to be drivable for selectively raising and lowering the load-bearing platform along a vertical direction. Furthermore, the present invention relates to an under-floor industrial truck comprising such a lifting mechanism.

[0004] With the increasing automation of logistics facilities, so-called under-ride industrial trucks or under-ride shuttles have recently gained increasing importance. These can transport loads, such as various types of pallets with goods carried on them, autonomously or semi-autonomously on their top surfaces. To pick up such loads, such an under-ride industrial truck passes underneath them at a transfer station, and the corresponding load-carrying platform or loading area on top of the under-ride industrial truck is raised vertically until the load is lifted from the transfer station, carried on the under-ride industrial truck, and then transported to a designated location, where it can be transferred to another station.

[0005] In the following description of such under-floor industrial trucks, a horizontal main direction of travel is referred to as the longitudinal direction, a horizontal direction perpendicular to the longitudinal direction is referred to as the width direction, and a vertical direction is referred to as the height direction. Furthermore, in analogy to corresponding designations in aircraft, for example, a central longitudinal axis is referred to as the roll axis, a central width axis is referred to as the pitch axis, and a central vertical axis is referred to as the yaw axis.

[0006] To enable the height adjustment of the load-carrying platform, such under-floor industrial trucks must be equipped with a suitable lifting mechanism that, on the one hand, can exert sufficient forces to safely lift even heavy loads, and, on the other hand, is sufficiently robust with regard to longitudinal and lateral accelerations in the horizontal plane as well as bending moments around all axes of the industrial truck to ensure safe operation of the industrial truck under all conceivable operating conditions. Such forces and moments can occur, for example, when the respective truck accelerates or decelerates, negotiates a curve, or carries a load that is asymmetrical with respect to one of the vehicle's axles.With regard to such forces and moments, it should be noted that variable-length drive devices commonly used in similar applications, and in particular the frequently used spindle drives or hydraulic cylinders, are very sensitive to forces that do not act strictly along the stroke direction, which in the example mentioned corresponds to the direction of extension of the corresponding threaded spindle or cylinder.

[0007] In this context, for example, EP 3 845 482 A1 proposes, in addition to the threaded spindle drive responsible for the actual vertical displacement of the load-bearing platform, to further provide at least one linear guide device comprising a guide rod guided in a sliding guide. In particular, EP 3 845 482 A1 uses two independent linear guides for this purpose, the first of which comprises a guide rod with a circular cross-section and the other of which comprises a guide rod with an angular cross-sectional profile, in order to be able to absorb, for example, yaw moments about a vertical axis of the corresponding industrial truck.In fact, the threaded spindle drives that can be used for this purpose, as well as other conceivable types of length-adjustable drive units, such as hydraulic or pneumatic cylinders, are sensitive to force introductions that do not run strictly along the direction of extension of the threaded spindle or the direction of its length change, which in the present case is oriented in the vertical direction.

[0008] However, it becomes apparent that the arrangement known from EP 3 845482 A1, with its two linear guides, cannot provide sufficient mechanical reinforcement of the corresponding lifting mechanism, for example, in the case of a moment acting around a longitudinal axis of the industrial truck, which corresponds to a moment about a roll axis of the industrial truck. Such loads acting around a roll axis of the vehicle can occur, among other things, when the load rests asymmetrically on the load-bearing platform or, more generally, exhibits an asymmetric weight distribution.

[0009] On the other hand, it is also evident that the linear guides known from the state of the art always exhibit a certain amount of play. Likewise, the forces occurring during operation inevitably lead to deformations of the industrial truck's vehicle body, which in turn influence the parallelism and distance between the threaded spindle drive and the linear guide. Therefore, even when using such linear guides to absorb transverse forces, a certain proportion of these transverse forces can always act on the corresponding spindle drive if it is firmly installed in the vehicle with little play, thereby reducing the intended effectiveness of the linear guides.

[0010] It is therefore the object of the present invention to provide an improved lifting mechanism for an autonomous under-floor industrial truck, in which an optimal absorption of forces and moments that do not act strictly in the vertical direction is guaranteed and which is thus able to relieve the corresponding length-adjustable drive unit acting as the actual lifting device with regard to such forces and moments in every conceivable operating state of the industrial truck.To achieve this object, according to a first aspect of the present invention, a generic lifting mechanism of the type described above is proposed which, in addition to the length-adjustable drive unit, further comprises a passive stabilization system which in turn comprises an upper plate element assigned to or forming the load-bearing platform, at least one joint arrangement with at least two attachment points on the vehicle body and at least two attachment points on the upper plate element, which couples the upper plate element to the vehicle body in a height-adjustable manner and in doing so ensures parallelism between the vehicle body and the upper plate element with respect to a spatial axis, at least one unit for transmitting transverse forces between the vehicle body and the upper plate element and at least one unit for transmitting longitudinal forces between the vehicle body and the upper plate element.

[0011] In this way, the passive stabilization system creates a structure capable of absorbing and decoupling forces and moments from the variable-length drive unit, forces that could not be handled by a linear guide unit alone because they act in directions perpendicular to it. Furthermore, it should be noted at this point that the width and length directions mentioned here are essentially interchangeable, and in principle, designs are also conceivable in which the directions of the two units can be rotated by any angle around a vertical axis to transmit forces, as long as forces can be transmitted with respect to three mutually perpendicular axes by the lifting mechanism according to the invention.Furthermore, it should be noted that the parallelism to be achieved according to the invention between the vehicle body and the upper plate element is to be understood in such a way that, when the upper plate element is displaced in height, these two components are always in the same alignment with respect to one another with respect to the plane perpendicular to the height direction and do not tilt against one another. In this case, the two parallel planes are each also horizontal when the vehicle is standing up on a flat, horizontal surface. Furthermore, the lifting mechanism according to the invention can comprise at least one linear guide unit extending in the vertical direction with a sliding guide and a guide rod guided therein, wherein one of the sliding guide and the guide rod is assigned to the vehicle body and the other is assigned to the load-bearing platform.In particular, it should be noted that in embodiments in which a plurality of linear guide units are provided, these could already act as one of the units for transmitting transverse forces or longitudinal forces. Similarly, it should be noted that the above-described functionalities of the joint arrangement and the units for transmitting transverse and longitudinal forces can be performed by the same or related components in certain embodiments of lifting mechanisms according to the invention.

[0012] For example, according to the invention, at least one of the units for transmitting transverse forces and / or at least one of the units for transmitting longitudinal forces can comprise a joint arrangement in which a coupling element running in the corresponding direction, for example a coupling rod, extends between two spaced-apart attachment points and is arranged in an articulated manner at the attachment points. In addition to a coupling rod, the coupling element can also be a coupling shaft, for example. However, hinge or plate elements are also conceivable, the attachment points of which can form a corresponding line or surface. The coupling element is suitable for absorbing a force acting on the load-bearing platform or the upper plate element forming it via one of the attachment points and transmitting it to another attachment point.This ensures that forces acting asymmetrically on the platform, for example, caused by unevenly distributed loads or forces occurring during (lateral) acceleration, are absorbed by the joint arrangement. The jointed connection can, in particular, comprise three joint elements to allow purely vertical movement between the vehicle body and the plate element or platform. At least one attachment point is provided for the connection to the vehicle body.

[0013] Some examples of possible combinations of numbers of units for transmitting forces with respective length-adjustable drive units and linear guide units in the lifting direction, which as such can form a passive stabilization system of a lifting mechanism according to the invention, are summarized in the following non-exhaustive table:

[0014] In the cases marked with (*a), the joint arrangements used in the transverse direction must also be able to transmit transverse forces, while the joint arrangements used in the longitudinal direction marked with (*b) must also be able to transmit longitudinal forces. In other words, in these cases the corresponding joint arrangement is designed to be so rigid and low-play that forces in the direction of extension of the coupling element can be absorbed. In this way, the number of joint arrangements and / or linear guides can be reduced. In the cases marked with (*c), the length-adjustable drive units must be spaced apart in the longitudinal direction and synchronized in their direction of extension. In this way, pitching movements of the load-bearing platform are prevented and the number of joint arrangements with coupling elements in the longitudinal direction can be reduced.The transverse (width) and longitudinal directions are interchangeable as described above and can be rotated around a vertical direction. It is also conceivable to use the passive stabilization system in an identical manner but tilted laterally in situations where the external dimensions of the robot system need to change in the longitudinal or width direction, e.g., to clamp it to a base as a work platform, to adjust it locally using appropriate centering projections, to drive external mechanisms, or to generate lateral compressive forces for other purposes.

[0015] Furthermore, further variants are conceivable in which, when using length-adjustable drive units which are designed in such a way that they can absorb the forces occurring in the longitudinal or width direction, the joint arrangement in the corresponding direction can be dispensed with.

[0016] In certain embodiments of the passive stabilization system, yaw moments and roll moments about a respective vertical axis or longitudinal axis of the corresponding underride industrial truck can also be absorbed by means of the joint arrangements each forming part of the stabilization system and can be introduced directly into the vehicle body via the attachment points in order to relieve the at least one length-adjustable drive unit in this respect.

[0017] In a possible specific embodiment of a lifting mechanism of the type just described, the at least one joint arrangement can comprise at least two mounting blocks coupled to the vehicle body and acting as attachment points, and at least two joint units each coupled to one of the mounting blocks and the upper plate element, with a first arm which is pivotally connected to one of the mounting blocks by means of a first pivot axis, and a second arm which is pivotally coupled to both the corresponding first arm and the upper plate element, wherein furthermore at least one of the first or second arms of the first joint unit is angularly coupled to the corresponding first or second arm of the second joint unit by a coupling element extending between the pair of joint units, in particular a crossbar acting as a coupling element,Preferably, at least two such joint arrangements are included in the lifting mechanism. The term "angular coupling" is to be understood as meaning that the angular position of the correspondingly coupled arms relative to the vehicle body is always at least approximately the same, or the angular position of the arms around the respective pivot axis is at least approximately the same.

[0018] In this context, the at least one coupling element, in particular the at least one corresponding crossbar, can be aligned along the width direction of the under-floor industrial truck, so that its direction of extension runs perpendicular to that of the at least one linear guide unit.

[0019] In a variant of the design just described, however, it would also be conceivable, for example, to use hinge units acting as corresponding joint assemblies instead of the joint units with individual mounting blocks, which are connected to the vehicle body and the upper plate element at several points along their extension or even continuously. For example, such a hinge unit could extend across essentially the entire width of the respective vehicle. In this embodiment, too, these units can, depending on the equipment, act to transmit transverse or longitudinal forces in addition to the force redirection and parallel-holding functions.

[0020] Furthermore, in an embodiment of the type described above, it is conceivable that the guide rod of the at least one linear guide unit is attached to the upper plate element of the passive stabilization system by means of a rod mounting block, in order to achieve a simplified connection thereof and an optimal force distribution between the relevant components of the stabilization system. Although it would also be conceivable in principle to design the length-adjustable drive unit, for example, as a hydraulic cylinder or a plurality of synchronized hydraulic cylinders and still be able to achieve the aforementioned advantages of the present invention with regard to relieving the corresponding hydraulic drive, the at least one length-adjustable drive unit in the lifting mechanism according to the invention can be formed, in particular, by a spindle drive.which comprises a threaded spindle coupled to the vehicle body and driven in rotation, a spindle nut seated on the threaded spindle, and a connecting unit coupled on the one hand to the spindle nut and on the other hand to the load-bearing platform, or a spindle nut coupled to the vehicle body and driven in rotation, a threaded spindle carrying the spindle nut, and a connecting unit coupled on the one hand to the threaded spindle and on the other hand to the load-bearing platform.

[0021] Such spindle drives are characterized by their excellent controllability using suitable electric motors and their exceptional robustness with respect to the weight forces acting on them along their extension. Furthermore, such drives allow monitoring of their electrical power consumption and, through this, the recording of derived operating parameters, such as the load absorbed or wear on electrical or mechanical components.Furthermore, by providing such electrically operated spindle drives, it may be possible under certain circumstances to completely dispense with the provision of a hydraulic system in the corresponding under-floor industrial truck, which can mean significantly reduced design effort for the integration of the individual vehicle components and, in particular by completely dispensing with hydraulic oil in the vehicle, can rule out numerous potential malfunction or accident scenarios from the outset, for example with regard to escaping slippery or flammable oil. According to a second aspect, which is intended to be claimed here both on its own and in combination with the first aspect described above, the present invention proposes a generic lifting mechanism with a spindle drive of the type just described, in which the coupling of the vehicle body with the threaded spindle orthe spindle nut is designed such that a relative pivoting movement of the threaded spindle or the spindle nut with respect to the vehicle body about a first pivot axis is enabled, the coupling of the spindle nut or the threaded spindle and the connecting unit is designed such that a relative pivoting movement of the connecting unit with respect to the spindle nut or the threaded spindle about a second pivot axis is enabled, and the first pivot axis and the second pivot axis extend parallel to one another in a horizontal direction.

[0022] In this way, a double-pivoting arrangement of the threaded spindle and the spindle nut enables the threaded spindle to pivot with respect to both the vehicle body and the load-bearing platform between the two axes mentioned, which makes it possible, even in cases in which the at least one linear guide unit or the joint arrangements transmitting longitudinal / transverse forces have a certain tolerance in a direction perpendicular to the two pivot axes, not to allow the resulting forces to act on the spindle drive, but to equip the threaded spindle with a larger pivoting range in any case.This reliably prevents transverse forces or bending moments from acting on the spindle drive in the respective affected direction, since in the area of ​​play, due to the pivoting bearing of the threaded spindle, the spindle can always perform a corresponding compensating movement without the transverse forces or bending moments leading to structural stress or even deformation and damage to the spindle.

[0023] In this case, the first pivot axis and the second pivot axis can be aligned, in particular, along the width direction of the underride industrial truck, enabling pivoting of the at least one threaded spindle when a force is applied along the longitudinal direction of the industrial truck. This corresponds precisely to a primarily expected direction of force during acceleration and deceleration of the corresponding vehicle, so that the highest loads on the lifting mechanism are to be expected in this direction due to the inertia of the vehicle and the load. Thus, the corresponding measure according to the second aspect of the present invention can also minimize the effect of a force occurring during operation of the vehicle and directed in this way on the length-adjustable drive unit.

[0024] Alternatively, however, it would also be conceivable to provide at least one elastic damping element for this purpose, for example, a flexible rubber mat arranged between the vehicle body and the length-adjustable drive unit, in order to achieve a certain degree of mechanical decoupling in one spatial plane. In such a case, the corresponding counterpart would also have to be mounted in such a way that decoupling on both sides is achieved.

[0025] As an alternative to tilting bearings in one or more directions, it is conceivable to provide a horizontally movable sliding bearing (for example realized by PTFE or POM plates), which is arranged between the vehicle body and the length-adjustable drive unit and / or between the load-bearing platform and the length-adjustable drive unit and can thus achieve a decoupling that leads to compliance with the permitted operating parameters of the length-adjustable drive unit.

[0026] Furthermore, in lifting mechanisms according to the first and / or second aspect of the invention, at least two spindle drives can be provided, which can be driven by a single motor coupled to the spindle drives via respective drive shafts and gears and / or which are configured for coordinated operation by means of a plurality of motors. In this way, several spatially distributed spindle drives can be driven jointly or, for example, in a coordinated manner by a common control unit. This, for example, with a suitable arrangement, can lead to the adequate management of pitching moments with a corresponding elimination of the need for additional assemblies or to the management of larger loads.While the provision of a single motor with corresponding mechanical coupling eliminates the necessary synchronization of multiple drive motors, the provision of multiple motors can save installation space in a central area of ​​the vehicle. In the case of a single motor, suitable cardan shafts and reduction gears can be used as drive shafts and gearboxes. These can, for example, also enable the corresponding axis of rotation to be converted from a horizontal to a vertical direction and can ensure that the drive system tolerates deformations of the vehicle body and tilting of the length-adjustable drive units without damage. The use of cardan shafts, which support increased length compensation, simplifies the installation of the system in the vehicle body.

[0027] Furthermore, the lifting mechanism according to the invention can comprise two linear guide units that are spaced apart from one another in the longitudinal direction of the underride industrial truck. Such a spaced arrangement of two linear guide units also contributes to the improved absorption of forces and moments in certain directions and the coupling of these into the vehicle body, thus keeping them away from the variable-length drive unit, for example, yaw moments and forces acting in the longitudinal direction of the industrial truck. In particular, in design variants, this arrangement can result in no additional components being required to absorb yaw moments as well as longitudinal and transverse forces of the load-bearing platform.

[0028] For process-reliable operation, the lifting mechanism according to the invention can, according to both aspects mentioned, further comprise a photoelectric sensor and / or a motion encoder for determining the current height position of the load-bearing platform, in order to ensure that the load-bearing platform is always located within a specified and operationally reliable height range. The corresponding output data of the photoelectric sensor are used to calibrate the motion sensor, which can be an absolute encoder, for example. Similarly, an angle sensor could be used on the rapidly rotating motor axis or any axis in the power flow, for example in a reduction gear. The calibration mentioned here refers to zeroing to a specific, known height position, from which integration can then be carried out using a detected angular change of a suitable axis.Another alternative could be to evaluate internal information from a corresponding controller (motor inverter) when using synchronous motors, from which corresponding values ​​can also be derived. The determined values ​​can in any case be sent to a central control unit of the under-floor industrial truck, which enables control of the lifting mechanism in autonomous normal operation as well as targeted control of any desired height within the travel range.

[0029] As a safety measure during operation, the threaded spindle of the at least one spindle drive can be provided with at least one stop that limits the movement of the spindle nut on the threaded spindle. Such a mechanical stop for the spindle nut can be advantageous, for example, in scenarios in which, in the event of a malfunction of the lifting mechanism, a human operator manually raises or lowers the load-bearing platform by rotating the spindle drive using a corresponding manual actuation unit. This movement could be achieved, for example, by a correspondingly prescribed torque-limiting tool.

[0030] Furthermore, a breaking or shifting element can be provided, which indicates a single departure from the permitted range of movement of the spindle nut of at least one spindle drive. For example, it would be conceivable to design one or both of the aforementioned stops in such a way that a single departure from the permitted range is indicated by a breakage of the same. In any case, any possible incorrect operation of the manual emergency operation can be verified in this way, since the unrestricted functionality of the lifting system may need to be checked.

[0031] As a further safety measure, an inductive sensor can be provided to detect the lower position of the load-carrying platform, ensuring that the lifting mechanism is at bottom dead center. This enables, for example, higher driving dynamics of the industrial truck, as the lifting mechanism and its components are in a position that can withstand higher lateral and longitudinal forces and moments.

[0032] As a further safety measure, at least one roller switch can be provided, which is designed to safely prevent the load-carrying platform from exceeding a permissible maximum lifting height. This prevents the spindle balls from falling out of the spindle nut if the permissible maximum stroke length is exceeded, which would render the lifting mechanism unusable and could pose a danger to people and machines. It also prevents spring energy from being stored in the lifting mechanism in the event of a one-sided fault, which could also lead to danger. Triggering the roller switch interrupts the power supply to the lifting mechanism, thus initiating a safe stop before irreversible damage can occur.

[0033] According to a third aspect, the present invention relates to an autonomous under-ride industrial truck with a vehicle body defining a longitudinal direction and a width direction and a load-bearing platform that is height-adjustable relative to the vehicle body and comprises a lifting mechanism of the type described above according to the first and / or second aspect of the present invention. Such an under-ride industrial truck can further comprise other components known per se, for example control, sensor, and communication units, which are configured to enable the intended autonomous operation of the vehicle. Furthermore, such an industrial truck can be characterized by a flat design, which on the one hand allows loads to be picked up to be driven underneath, but on the other hand results in the rigidity of both the vehicle body and the load-bearing platform being limited.This can lead, particularly on uneven driving surfaces and thus in cases where individual wheels would not be in contact with the ground, to bending moments acting on the vehicle body (or the vehicle body actually deforming elastically), which can be tolerated in a suitable manner by the lifting mechanism described above without functional restriction or increased wear.

[0034] With regard to movement on the intended travel surface, the underride industrial truck according to the invention can further comprise two drive wheels opposite one another in the width direction and arranged in a central region of the vehicle body with respect to the longitudinal direction and individually drivable, as well as four freely pivoting support wheels assigned to the respective corners of the vehicle body. Of course, other concepts for the arrangement of driven and non-driven wheels are also conceivable, for example, steered driven wheels that control the movement of the vehicle not via differential rotational drive speeds, but rather through a desired orientation of at least one corresponding steerable wheel.

[0035] Further features and advantages of the present invention will become more apparent from the following description of an embodiment thereof, when considered together with the accompanying figures. These show in detail:

[0036] Fig. 1 is an isometric view of an under-floor industrial truck according to the invention; Fig. 2 is an isometric view of the lifting mechanism of the vehicle from Fig. 1;

[0037] Fig. 3 is an isometric view of the drive train of the lifting mechanism of Fig. 2;

[0038] Fig. 4a and 4b are an enlarged isometric view and a detailed sectional view of one of the spindle drives of the lifting mechanism of Fig. 2; and

[0039] Fig. 5A and 5B two schematic views of the spindle drive from Fig. 4a from mutually perpendicular viewing directions.

[0040] In Fig. 1, a concrete embodiment of an under-ride industrial truck according to the invention is shown in an isometric view and is generally designated by the reference numeral 10. The under-ride vehicle 10 comprises, in a manner known per se, a vehicle body 12 with a load-bearing platform 14 provided on its upper side so as to be height-adjustable, wherein the vehicle body 12 defines a longitudinal direction L, a width direction B and a vertical or height direction H. Furthermore, the under-ride industrial truck 10 comprises a largely concealed propulsion system which enables omnidirectional propulsion by means of two individually drivable drive wheels 16 which are opposite one another in the width direction B and arranged in a central region of the vehicle body 12 with respect to the longitudinal direction L. Furthermore, in the respective corners of the vehicle body 12 on its underside in Fig.1 freely pivoting support wheels are provided which cannot be seen.

[0041] Furthermore, laser scanners 18 are arranged in opposite corners of the vehicle 10. These enable detection of the surroundings of the vehicle 10 and can thus serve as both a navigation and a safety device. Furthermore, centering projections 20 can be seen on the top of the load-carrying platform 14. These serve to center a load carrier received on the load-carrying platform in a predetermined manner to ensure its correct alignment with respect to the load-carrying platform.

[0042] The under-floor industrial truck 10 is designed for autonomous or semi-autonomous operation and for this purpose comprises additional components, such as in particular a central control unit, various sensor units and a communication unit, via which work and operating instructions can be transmitted from a higher-level system to the vehicle 10.

[0043] Fig. 2 now also shows, in an isometric view, the lifting mechanism 100 of the under-floor industrial truck 10 from Fig. 1. This lifting mechanism 100 comprises two vertically arranged, length-adjustable drive units 102 designed as spindle drives with a rotatable threaded spindle 102a and a spindle nut 102b sitting thereon, wherein the two spindle drives 102 are spaced apart with respect to the longitudinal direction L of the vehicle body 12 and arranged in a central area with respect to the width direction B. The two spindle drives 102 serve to selectively raise and lower the load-bearing platform 14 of the vehicle 10 in a consistently horizontal alignment therefrom and to derive pitching moments and are explained in more detail below with reference to Fig. 3 with regard to their operation.

[0044] Arranged in the width direction B next to the two spindle drives 102, the lifting mechanism 100 comprises two linear guide units 104, which also extend in the vertical direction H. In each of these linear guide units, a guide rod 106 is guided in a sliding guide 108 in order to be able to absorb forces acting, for example, in the longitudinal direction L and the width direction B and to be able to relieve the spindle drives 102 of such forces. The respective sliding guides 108 are assigned to the vehicle body 12 of the vehicle 10, while the guide rods 106 are connected to an upper plate element 112 via rod mounting blocks 110. In the embodiment shown here, this upper plate element 112 is in turn firmly coupled to the load-bearing platform 14 of the vehicle 10, but in alternative embodiments it could also be formed directly by the load-bearing platform 14 in an integrated manner.Accordingly, the two linear guide units spaced apart from each other in the longitudinal direction L act as a unit for transmitting longitudinal forces and yaw moments in the sense of the present invention.

[0045] It can also be seen from Fig. 2 that, in the embodiment shown here, the spindle drives 102 are connected to the upper plate element 112 in such a way that the spindle nut 102b is coupled to a connecting unit 114, which is firmly connected to the upper plate element 112 and, for this purpose, comprises two wall elements 114a opposite one another in the width direction B. This coupling of the two spindle nuts 102b via the connecting units 114 to the upper plate element 112 ensures, among other things, that the spindle nuts 102b are rotationally fixed with respect to both the load-bearing platform 14 and the vehicle body 12 of the vehicle 10, thereby ensuring the intended lifting operation of the spindle drives 102 upon rotation of the threaded rods 102a.

[0046] Furthermore, it can be seen in Fig. 2 that the lifting mechanism 100 further comprises a passive stabilization system 116, which, in addition to the already mentioned upper plate element 112, further comprises four mounting blocks 118 connected to the vehicle body 12 and four joint units 120, each connected to one of the mounting blocks 118 and the upper plate element 112. These joint units 120 each consist of a first arm 120a and a second arm 120b, wherein the first arm 120a is pivotally connected to the respective mounting block 118 by means of a first pivot axis 122a, the two arms 120a and 120b are connected to one another by means of a second pivot axis 122b, and the second arm 120b is pivotally connected to the upper plate element 112 by means of a third pivot axis 122c. In this way, the relative pivoting of the arms 120a and 120b enables a height displacement of the upper plate element 112.In addition, the stabilization system 116 comprises two crossbars 124, each acting as a coupling element, which extend between mounting blocks 118 opposite one another in the width direction B and, in pairs, form the first pivot axes 122a of the four joint units 120. Due to this arrangement of the crossbars 124 between respective pairs of mounting blocks 118, they are capable of absorbing rolling moments occurring during operation of the vehicle 10 and transmitting them to the vehicle body 12 via the mounting blocks 118. Accordingly, the joint units 120 jointly act as units for transmitting transverse forces within the meaning of the present invention, while the crossbars 124 ensure parallelism between the vehicle body 12 and the upper plate element 112. Thus, the spindle drives 102 are not overloaded even in corresponding operating situations of the vehicle 10 in which such moments may occur.

[0047] Accordingly, in the under-floor industrial truck 10 shown here, two joint arrangements are formed, each comprising two of the mounting blocks 118 and a pair of joint units 120, wherein one of the arms 120a, 120b of one joint unit 120 is angularly coupled to the corresponding arm 120a, 120b of the other joint unit 120 by the crossbar 124 such that the angular position of the coupled arms 120a and 120b relative to the vehicle body 12 is always at least approximately the same.

[0048] Next, with reference to Fig. 3, the drive train 126 of the two spindle drives 102, which can already be seen in Fig. 2, will be explained. It should be noted here that the arrangement of this drive train 126 in a central area with respect to the width direction B, as well as the design and arrangement of the mounting blocks 118 in the four corners of the vehicle body 12, as can be seen in Fig. 2, creates sufficient installation space to accommodate the drive wheels 18 and corresponding motors in the longitudinal direction L between the two mounting blocks 18 and in the width direction B outside the drive train 126. The core of the drive train 126 is a single electric motor 128, which can be precisely controlled by the central control unit of the vehicle 10 to rotate an output shaft, which in turn is directly converted in a downstream transmission 130 into a respective rotation of two cardanic drive shafts 130a and 130b.These drive shafts 130a and 130b in turn act on respective spindle drive gears 132a and 132b, which in turn synchronously rotate the threaded spindles 102a of the two spindle drives 102 and can thus cause a vertical movement of the spindle nuts 102b and thus, via the connecting units 114, of the upper plate element 112. It should be noted at this point that the drive train 126 also offers the possibility of allowing an operator, for example in the event of a malfunction, to manually change the height position of the load-bearing platform 14 of the vehicle 10. For this purpose, an axle stub 134 is provided in the area of ​​the spindle drive gear 132a, onto which a force for driving the spindle drives 102 can be applied directly using a suitable tool.

[0049] With reference to Figs. 4a and 4b, various safety features in connection with the spindle drives 102 and linear guide units 104 can now be understood, wherein Fig. 4a shows an enlarged isometric view and Fig. 4b shows a detailed sectional view of one of the spindle drives 102 of the lifting mechanism 100 from Fig. 2. In particular, it can be seen here that the threaded spindle 102a is provided with an upper stop 136, which limits an upward movement of the spindle nut 102b on the threaded spindle 102a. Such a mechanical stop for the spindle nut 102b is particularly advantageous in the aforementioned malfunction case, in which a human operator manually drives the load-carrying platform 14 upwards, while in autonomous normal operation the lifting mechanism 100 can be controlled from the outset by the control unit of the vehicle 10 in such a way that exceeding a maximum lifting height should be excluded.

[0050] In this context, the roller switch 138 shown in Fig. 4b also functionally contributes to preventing the maximum permissible lifting height from being exceeded. This switch is always in contact with the threaded spindle 102a during regular operation. However, if the system is moved too far upwards, the roller switch 138 loses its contact, and the power supply to the electric motor 128 can be immediately interrupted. As a safety measure with regard to ensuring that the maximum lowered position is not exceeded, an inductive sensor 140a is also attached to the sliding guide 108. This sensor can emit a corresponding signal when the load-bearing platform 14 or the upper plate element 112 approaches from above. This signal, in turn, can also be further processed into a corresponding control signal for shutting down or reversing the electric motor 128.Furthermore, a photoelectric sensor 140b is provided, which can generally detect the current stroke position of the spindle nut 102b and supply corresponding data to the central control unit of the vehicle 10.

[0051] Finally, with reference to Figs. 5A and 5B, a further mechanism will now be explained which also prevents the action of longitudinal forces on the spindle drives 102, wherein for this purpose a corresponding spindle drive 102 is shown in the figures in a schematic sectional view along the longitudinal direction L and in a schematic side view along the width direction B.

[0052] It can be seen here that both the coupling of the threaded spindle 102a to the vehicle body 12 and the coupling of the spindle nut 102b to the connecting unit 114 are designed such that a respective rotation about first and second pivot axes 142a and 142b extending along the width direction B of the vehicle 10 is permitted. In this way, it is possible for the assembly formed from the threaded spindle 102a and the spindle nut 102b to be pivotable with respect to both the vehicle body 12 and the load-bearing platform 14 in the manner indicated in Fig. 5B, while the relative orientation of the vehicle body 12 and the load-bearing platform 14 remains essentially unchanged due to the action of the remaining components of the lifting mechanism 100.Thus, the pivoting of the threaded spindle 102a relative to the vehicle body 12 shown here prevents the introduction of forces acting along the longitudinal direction L, even in cases where the linear guide units 104 exhibit a certain amount of play in this direction, or in cases where the vehicle body deforms. At the same time, however, the cardanic connection of the spindle drives 102 within the

[0053] Drive train 126, correct operation thereof is also possible in the pivoted state according to Fig. 5B.

Claims

Claims 1 . Lifting mechanism (100) for an autonomous under-floor industrial truck (10) with a vehicle body (12) defining a longitudinal direction (L) and a width direction (B) and a load-carrying platform (14) whose height can be adjusted relative to the vehicle body (12), comprising: - at least one variable-length drive unit (102) which is adapted to be driven to selectively raise and lower the load-bearing platform (14) along a vertical direction (H); and characterized in that it further comprises a passive stabilization system (116), again comprising: - an upper plate element (112) associated with or forming the load-bearing platform (14); - at least one joint arrangement with at least two attachment points on the vehicle body (12) and at least two attachment points on the upper plate element (112), each of which couples the upper plate element (112) to the vehicle body (12) in a height-adjustable manner and in doing so ensures parallelism between the vehicle body (12) and the upper plate element (112) with respect to a spatial axis; - at least one unit for transmitting transverse forces between the vehicle body (12) and the upper plate element (112); and - at least one unit for transmitting longitudinal forces between the vehicle body (12) and the upper plate element (112).

2. Lifting mechanism according to claim 1, comprising at least one linear guide unit (104) extending in the vertical direction (H) with a sliding guide (108) and a guide rod (106) guided therein, wherein one of the sliding guide (108) and the guide rod (106) is assigned to the vehicle body (12) and the other is assigned to the load-bearing platform (14).

3. Lifting mechanism according to claim 1 or 2, wherein at least one of the units for transmitting transverse forces and / or at least one of the units for transmitting longitudinal forces comprises a joint arrangement in which a coupling element running in the corresponding direction, for example a coupling rod, extends between two spaced-apart attachment points.

4. Lifting mechanism according to claim 3, wherein the at least one joint arrangement comprises: - at least two mounting blocks (118) coupled to the vehicle body (12) and acting as attachment points; and - at least two joint units (120), each coupled to one of the mounting blocks (118) and the upper plate element (112), comprising a first arm (120a) pivotally connected to one of the mounting blocks (118) by means of a first pivot axis (122a), and a second arm (120b) pivotally coupled to both the corresponding first arm (120a) and the upper plate element (112), wherein at least one of the first and second arms (120a, 120b) of the first joint unit is angularly coupled to the corresponding first or second arm of the second joint unit by a coupling element extending between the pair of joint units, in particular a crossbar (124) acting as a coupling element, wherein preferably at least two such joint arrangements are included in the lifting mechanism.

5. Lifting mechanism (100) according to claim 4, characterized in that the at least one coupling element is aligned along the width direction (B) of the under-ride industrial truck (10).

6. Lifting mechanism (100) according to one of claims 2 to 5, characterized in that the at least one guide rod (106) is attached to the upper plate element (112) by means of a rod mounting block (110).

7. Lifting mechanism (100) according to one of the preceding claims, characterized in that the at least one length-adjustable drive unit (102) is formed by a spindle drive (102) which comprises: - a threaded spindle (102a) coupled to the vehicle body (12) and driven in rotation, a spindle nut (102b) seated on the threaded spindle (102a), and a connecting unit (114) coupled on the one hand to the spindle nut (102b) and on the other hand to the load-bearing platform (14); or - a spindle nut coupled to the vehicle body (12) and drivable in rotation, a threaded spindle carrying the spindle nut and a connecting unit coupled on the one hand to the threaded spindle and on the other hand to the load-bearing platform.

8. Lifting mechanism (100) according to the preamble and optionally also the characterizing part of claim 1 and claim 7, characterized in that the coupling of the vehicle body (12) to the at least one threaded spindle (102a) or the spindle nut is designed such that a relative pivoting movement of the threaded spindle (102a) or the spindle nut with respect to the vehicle body (12) about a first pivot axis (142a) is enabled, the coupling of the spindle nut (102b) or the threaded spindle with the connecting unit (114) is designed such that a relative pivoting movement of the connecting unit (114) with respect to the spindle nut (102b) or the threaded spindle about a second pivot axis (142b) is enabled, and the first pivot axis (142a) and the second pivot axis (142b) extend parallel to one another in a horizontal direction.

9. Lifting mechanism (100) according to claim 8, characterized in that the first pivot axis (142a) and the second pivot axis (142b) are aligned along the width direction (B) of the undercarriage industrial truck (10).

10. Lifting mechanism (100) according to one of claims 7 to 9, characterized in that at least two spindle drives (102) are provided, which can be driven by means of a single motor (128) which is coupled to the spindle drives (102) via drive shafts (130a, 130b) and gears (132a, 132b), and / or which are set up for coordinated operation by means of a plurality of motors.

11. Lifting mechanism (100) according to one of claims 7 to 10, characterized in that the threaded spindle (102a) of the at least one spindle drive (102) is provided with at least one stop (136) which limits a movement of the spindle nut (102b).

12. Lifting mechanism (100) according to one of claims 7 to 11, characterized in that a breaking or shifting element is provided, by means of which a one-time departure from a permitted range of movement of the spindle nut (102b) of the at least one spindle drive (102) is indicated.

13. Lifting mechanism (100) according to one of the preceding claims, characterized in that it comprises two linear guide units (104) which are spaced apart from one another in the longitudinal direction (L) of the undercarriage industrial truck (10).

14. Lifting mechanism (100) according to one of the preceding claims, characterized in that it further comprises a photoelectric sensor (140b) and / or a motion encoder for determining the current height position of the load-bearing platform (14).

15. Lifting mechanism (100) according to one of the preceding claims, characterized in that it further comprises an inductive sensor (140a) for detecting a lower position of the load-bearing platform (14).

16. Lifting mechanism (100) according to one of the preceding claims, characterized in that it further comprises a roller switch (138) which is designed to safely prevent exceeding a permissible maximum lifting height of the load-bearing platform (14).

17. Autonomous underride industrial truck (10) with a vehicle body (12) defining a longitudinal direction (L) and a width direction (B) and a load-carrying platform (14) whose height can be adjusted relative to the vehicle body (12), comprising a lifting mechanism (100) according to one of the preceding claims for adjusting the height of the load-carrying platform (14).

18. Underride industrial truck (10) according to claim 17, further comprising two drive wheels (16) which are opposite one another in the width direction (B) and arranged in a central region of the vehicle body (12) with respect to the longitudinal direction (L) and which can be driven individually, as well as four freely pivoting support wheels assigned to the respective corners of the vehicle body (12).

Images