Shaving table

Abstract

A scissor lift table (1) with a base (2) and a working section (3) which is height-adjustable relative to the base (2), with at least one scissor mechanism (4) arranged between the base (2) and the working section (3), which comprises two scissor arms (5, 6) pivotally connected to each other in a cross-like manner, wherein a first end region of a first scissor arm (5) is pivotably mounted on the base (2) and a first end region of a second scissor arm (6) is pivotably mounted on the working section (3) and the respective opposite end regions are guided longitudinally displaceably on the working section (3) and on the base (2), and with a lifting drive device (7), wherein the lifting drive device (7) comprises two threaded spindles (9, 10) arranged parallel to each other, on which at least one spindle nut (11) is arranged, wherein the spindles (9, 10) can be driven together by a drive, so that the spindle nuts (11) relative to the spindles (9,10) are adjustable in the axial direction, wherein the spindle nuts (11) are mounted in a bearing housing (13) in a rotationally fixed manner, and wherein at least one engagement element is provided which is force-transmittingly coupled to at least one spindle nut (11) and force-transmittingly connected to a linear drive means which has a substantially horizontal section and a section extending in the stroke direction of the working part (3) between the base (2) and the working part (3) and is supported at least at one end on the base (2) and / or on the working part (3), such that an axial adjustment of the spindle nuts (11) causes a displacement of the engagement element relative to the spindles (9, 10) and thereby a change in the shear angle and a height adjustment of the working part (3).

Description

[0001] The invention relates to a scissor lift table with a foot section, a working section that is height-adjustable relative to the foot section, and at least one scissor mechanism arranged between the foot section and the working section, as well as a lifting drive device for adjusting the height of the working section.

[0002] Such scissor lift tables are used for lifting and lowering loads and usually have a work platform on their upper side that can be adjusted in height by means of the scissor mechanism and which rests on a base frame or rack on the ground.

[0003] Scissor lift tables are known from the prior art in which the arms of the scissor mechanism are pivotally mounted at fixed bearings in a first end region on the base and working section, and are longitudinally displaceable in guides or cams at a floating bearing in an opposite end region. Height adjustment is typically achieved via linear actuators, in particular hydraulic cylinders, which are arranged between the base and working section and change the height of the lift table by altering the pivot angle of the arms relative to each other. While such lift tables have a high load-bearing capacity, they require comparatively complex, bulky, and expensive drive units.

[0004] Hydraulic drives in particular require additional components such as pumps, pressure accumulators, valves and lines, are sensitive to leaks and require increased maintenance.

[0005] Furthermore, scissor lift tables with electromechanical drives are known in which threaded spindles are arranged obliquely or alongside the scissor mechanism and act directly on a scissor arm or on a component coupled to the scissor kinematics. These solutions are also frequently arranged in the frame area in such a way that they limit the minimum installation height and restrict the usable space beneath the lift table. In addition, the drive is often designed with decentralized actuation, requiring multiple drive units or a complex power transmission system to ensure uniform, synchronized height adjustment across the width of the workpiece.

[0006] LU 102625 B1 discloses a scissor lift table with a base in the form of a frame, a working part, and two scissor mechanisms arranged between the base and the working part, in which the height adjustment is effected by a linear drive arranged on the rear of the lift table and oriented perpendicular to the plane of the base. A displacement element of the linear drive is coupled to the working part, so that the latter is directly displaced linearly relative to the base, while the scissor mechanism essentially serves to transfer the load.

[0007] Furthermore, height-adjustable worktables with lifting columns are known from WO 2021 / 013251 A1 and WO 2024 / 003139 A1. These worktables are designed for high load-bearing capacity and rigidity and are constructed from solid steel components, resulting in heavy frames that are primarily used in stationary applications and require significant manufacturing and assembly effort. In these solutions, height adjustment is achieved via ball screw drives located in the lifting columns. The drive units of these drives are coupled to each other via a drive connecting element, for example, a drive chain, and can be driven by a common drive unit.

[0008] What all known solutions have in common is that the lifting drive is either located between the base and the working section or in lifting columns, requiring a comparatively large installation space. The force flow is concentrated on a few points of application, and additional components such as hydraulic units, separate drive motors, or complex guide elements are necessary. This results in structurally complex, heavy, and expensive-to-manufacture lifting tables with limited minimum height and, in some cases, restricted suitability for uniform height adjustment under asymmetrical loads.

[0009] The invention is therefore based on the objective of providing a scissor lift table that, with a compact design and low minimum height, enables uniform, load-appropriate height adjustment with a simple, cost-effective and low-maintenance lifting drive.

[0010] The problem is solved by the features of claim 1. Advantageous embodiments are described in the dependent claims.

[0011] The invention relates to a scissor lift table with a base and a working part that is height-adjustable relative to the base, with at least one scissor mechanism arranged between the base and the working part, comprising two scissor arms pivotally connected to each other in a cross-like manner, wherein a first end region of a first scissor arm is pivotably mounted on the base and a first end region of a second scissor arm is pivotably mounted on the working part, and the respective opposing end regions are guided longitudinally displaceably on the working part and on the base, respectively, and with a lifting drive device, wherein the lifting drive device comprises two threaded spindles arranged parallel to each other, on each of which at least one spindle nut is arranged, wherein the spindles can be driven together by a drive so that the spindle nuts are adjustable in the axial direction relative to the spindles.wherein the spindle nuts are mounted in a bearing housing in a rotationally fixed manner and wherein at least one engagement element is provided which is force-transmittingly coupled to at least one spindle nut and force-transmittingly connected to a linear drive means which has a substantially horizontal section and a section extending in the stroke direction of the working part between the base part and the working part and is supported at least at one end on the base part and / or on the working part, such that an axial adjustment of the spindle nuts causes a displacement of the engagement element relative to the spindles and thereby a change in the shear angle and a height adjustment of the working part.

[0012] In the scissor lift table according to the invention, the base section forms a support structure that can be placed on a surface, while the working section provides a work or support surface that is adjustable relative to the base section. A scissor mechanism is arranged between the base section and the working section, consisting of two scissor arms connected to each other by a cross-shaped pivot. The pivotable mounting of one end of each scissor arm on the base section and the working section, respectively, and the longitudinally displaceable guidance of the opposing end sections on the other part, results in a scissor kinematic mechanism that enables defined guidance of the working section relative to the base section.

[0013] The lifting drive unit features two threaded spindles arranged parallel to each other as its central drive element. At least one spindle nut is mounted on each spindle. The spindles are rotated by a common drive, causing the spindle nuts to shift axially relative to the spindles due to their threaded connections. Since the spindle nuts are mounted in a bearing housing to prevent rotation, they cannot follow the rotation of the spindles and are instead guided and displaced longitudinally along the spindles.

[0014] The nut assembly formed by the spindle nuts includes at least one engagement element, which is coupled to at least one spindle nut for force transmission. This engagement element transmits the axial movement generated by the spindle nuts to a linear drive element. In the area of ​​the lifting drive mechanism, the linear drive element has a substantially horizontal section and extends from there in the lifting direction of the working part, so that it forms a section extending in the lifting direction between the base and the working part. In an upper region, the linear drive element is at least partially attached to or supported against the working part, so that in the respective set lifting position it acts as a load-bearing element between the base and the working part.

[0015] When the drive is activated, the spindles rotate and the spindle nuts move axially. This shifts the working element relative to the spindles and thus relative to the base, moving the linear drive mechanism and shifting it in the stroke direction of the working part. This movement of the linear drive mechanism causes a change in the height of the working part relative to the base. The scissor mechanism guides and stabilizes this movement, adjusting its scissor angle according to the stroke movement dictated by the linear drive mechanism.

[0016] The combination of features according to the invention allows a clear separation between the actual lifting force-generating assembly, consisting of spindles, spindle nuts, bearing housing, engagement element, and linear drive element, and the scissor kinematics that guide and support the working part. The arrangement of two parallel spindles and a common nut assembly with engagement element achieves a symmetrical force transmission to the linear drive element, thereby reducing tilting of the working part and supporting uniform height adjustment. The linear drive element, which extends from a horizontal section located in the area of ​​the lifting drive device and is supported in the lifting direction of the working part, performs both the transmission of the lifting forces and a significant support function for the working part in the respective lifting position.This reduces the design effort required for additional support elements. At the same time, the spindle drive enables finely adjustable, reproducible height adjustment, where the stroke and drive rotation angle are in a defined ratio to each other.

[0017] According to a preferred embodiment, the engagement element is force-transmittingly coupled to the bearing housing. In this embodiment, the engagement element is not directly coupled to the individual spindle nuts, but rather to the bearing housing that accommodates them. The bearing housing thus forms a common support and connecting element that absorbs the axial forces introduced by the spindle nuts and transmits them as a complete assembly to the engagement element. The force-transmitting coupling between the bearing housing and the engagement element can be realized, for example, via a rigid mechanical connection, such as a bolted or welded connection, or via an intermediate component, such as a bolt or a tab.It is essential that the forces generated by the axial adjustment of the spindle nuts in the bearing housing are transferred to the contact element without play and with defined stiffness, and from there to the linear drive element. Connecting only one component, namely the bearing housing, to the contact element simplifies the design compared to directly connecting multiple individual spindle nuts.

[0018] According to a further embodiment, the two spindle nuts are connected to each other via a rigid bridge element. In this embodiment, the two spindle nuts are not arranged independently of each other, but are rigidly connected to each other via a component designed as a bridge element. The bridge element extends transversely to the longitudinal direction of the spindles and engages each spindle nut, so that they can only be displaced together and in an identical axial position relative to the spindles. The rigid connection of the spindle nuts via the bridge element ensures that both spindle nuts move synchronously and that no relative displacement can occur between them. In one embodiment, at least one of the engagement elements can be attached to the bridge element. The engagement element can be positively locked or materially locked to the bridge element.This ensures that the force is introduced symmetrically into the attack element and into the linear drive element connected to it in a force-transmitting manner, which reduces tilting of the working part and improves the smoothness of the lifting process.

[0019] According to a further preferred embodiment, the bridge element is designed as a dimensionally stable crossbeam that connects the two spindle nuts to each other in a force-transmitting manner. In this embodiment, the bridge element is structurally designed as a rigid crossbeam that extends transversely to the longitudinal axis of the spindles and mechanically connects the two spindle nuts or their bearing housings. The crossbeam is dimensioned with respect to its cross-section, material, and connection such that it absorbs and transmits the tensile, compressive, and bending moments occurring between the spindle nuts with minimal elastic deformation. The force-transmitting connection of the two spindle nuts via the dimensionally stable crossbeam ensures that both spindle nuts are held in a defined relative position to each other during axial adjustment.The crossbeam distributes asymmetrical loads, resulting from the lifting and supporting movement of an attack element (in an advantageous embodiment) attached to the bridge element and the linear drive connected to it, as well as optionally from the scissor kinematics, across both spindles. This results in a more even load distribution on the spindle nuts and spindles and reduces the risk of binding or jamming. Furthermore, the dimensionally stable crossbeam is suitable as a rigid support for one or more attack elements, each of which can be coupled to a linear drive.

[0020] It is preferred that a bearing housing is provided for each spindle nut and that the bearing housings are arranged in the bridge element. In this embodiment, each spindle nut is assigned its own bearing housing in which the respective spindle nut is mounted in a rotationally fixed manner. Each bearing housing has at least one bearing in which the spindle nut is radially and / or axially supported and secured against rotation with the associated spindle.

[0021] In this design, the two bearing housings are not arranged separately in the frame, but are integrated into or attached to the bridge element, so that the bridge element accommodates the bearing housings and defines their relative position to each other. The arrangement of the bearing housings within the bridge element forms a compact assembly in which the spindle nuts are guided and supported, and on which at least one attachment element for coupling to the linear drive can be mounted. Furthermore, integrating the bearing housings into the bridge element simplifies assembly, as the entire unit, consisting of the bridge element, bearing housings, and the spindle nuts housed within them, can be inserted into the scissor lift table as a pre-assembled unit.

[0022] It can be advantageous to arrange the lifting drive unit in the area of ​​the base or in the area of ​​the working part. In a first embodiment, the lifting drive unit, including the spindles, spindle nuts, bearing housing, bridge element, and linear drive element, is arranged in the base area of ​​the base, preferably within the footprint defined by the base. The drive components are thus located below any scissor mechanism that may be provided and essentially slightly above the surface on which the table is placed. This arrangement in the base area allows for a low minimum height of the scissor lift table, as no additional drive elements need to be arranged above the base. The available space above the scissor mechanism can be used entirely for the scissor mechanism and the working part.In addition, the drive components can be structurally protected in the base and encapsulated to protect against mechanical damage and contamination.

[0023] In an alternative embodiment, the lifting drive unit is arranged wholly or partially within the working section. In this case, the spindles and associated spindle nuts, along with the bridge element, bearing housing, drive element, and linear drive element, can be relocated to a drive chamber or drive compartment integrated within the working section. This is particularly advantageous for designs where the installation space is limited to or around the base, or where the scissor lift table is to be supplied and controlled from above. Furthermore, arranging the lifting drive unit within the working section simplifies the routing of power and signal cables and enables compact integration of the drive into a machine or device mounted on the working section.

[0024] It is further provided that the two spindles are arranged parallel to each other in the area of ​​the base or working section and run essentially horizontally. The spindle axes lie in a common plane and are arranged next to each other at a defined distance. In particular, it is advantageous if the components of the lifting drive unit, at least the spindles, spindle nuts, at least one attachment element, and at least one drive element, are arranged in one plane. The horizontal and parallel arrangement of the spindles enables a flat design of the lifting drive unit and contributes to a low minimum height of the scissor lift table.The parallel alignment ensures a symmetrical force transmission into the bridge element, the bearing housing, the attached lifting element, and the connected linear drive mechanism, so that the lifting forces introduced by the spindle nuts are distributed evenly across the lifting drive unit. This reduces the risk of the working part tilting or binding relative to the base.

[0025] In a further advantageous embodiment, the bearing housing is mounted in a guide so as to be movable relative to the base or working part. In this embodiment, the bearing housing is not merely freely supported, but is mounted in at least one guide so as to be movable. The guide can be designed, for example, as a linear guide, as a rail with an associated sliding or rolling carriage, or as a profiled guide track with corresponding guide surfaces on the bearing housing. The guided mounting of the bearing housing clearly defines its direction of movement relative to the base or working part and prevents lateral movements or tilting.

[0026] According to a particularly preferred embodiment, the linear drive element is designed as a rigid, multi-link chain, in particular as a push chain. The chain has a plurality of chain links arranged one behind the other, which are articulated to one another, but support each other in the loaded section, so that it acts as a substantially compression- and tension-resistant chain carrier in the longitudinal direction of the drive element. In the area of ​​a substantially horizontal section, which can be located, for example, in the foot or working section, the multi-link chain is received in a guide channel and can be retracted in a space-saving manner when unloaded. From this horizontal section extends a section in the stroke direction of the working section, which is designed as a substantially rigid chain carrier between the foot and working sections.The linear drive element is part of the lifting drive unit and is coupled to at least one spindle nut via the engagement element, transmitting force so that a displacement of the bearing housing caused by the spindle nuts results in controlled extension or retraction of the drive element. The section of the drive element running in the lifting direction not only transmits the lifting motion generated by the spindle drive, but also acts as a load-bearing component in the set position, supporting the working part against the base. In this way, the rigid, multi-link chain combines the function of a rigid lifting link with the ability to retract the unloaded chain links into a housing of the lifting drive unit, thus providing a mechanically self-supporting lifting drive with defined force transmission and support, without the need for additional separate support elements.

[0027] Furthermore, it can be provided that two linear drive elements are arranged on opposite sides of the scissor lift table. In this configuration, not just one, but two linear drive elements are provided, each arranged at a lateral distance from the other and supporting the working part from two opposite sides. In a preferred embodiment, each linear drive element is connected via its own engagement element to a spindle nut or an associated bearing housing, so that the movement generated by the axial displacement of the spindle nuts is transmitted to both drive elements. The two linear drive elements are extended together from the lifting drive unit and each supports the working part on its respective side against the base.The use of linear drive elements on both sides ensures symmetrical force application and support of the working component. Asymmetrical loads and torsional moments are better absorbed because the lifting forces are distributed across two spatially separated force paths. This reduces the risk of the working component tilting or binding relative to the base and results in a smoother, more consistent lifting action. At the same time, the stresses on the individual drive elements and the lifting drive unit are reduced, thus extending the service life of the scissor lift table.

[0028] In an alternative embodiment, two linear drive elements are also provided, but only one is primarily used for the stroke-generating force transmission, while the second mainly performs a supporting function. In this configuration, a first linear drive element is coupled via an associated engagement element to at least one spindle nut or a bearing housing associated with it, so that the movement generated by the axial displacement of the spindle nuts is directly converted into a stroke movement of the working part. In this case, the second linear drive element is also connected to the bridge element and / or a bearing housing and is moved via these components together with the first drive element, without necessarily having to participate in the stroke-generating kinematics to the same extent.The second drive element essentially serves as a supporting element to brace the working part against the base and to absorb bending and torsional moments resulting from asymmetrical loading or transverse forces. Both drive elements can be coupled to each other via the bridge element or the bearing housings, so that a joint displacement occurs and the supporting function of the second drive element is combined with the stroke-generating function of the first drive element.

[0029] Furthermore, in another embodiment, the linear drive element(s) are guided over at least one deflection element. In this configuration, the linear drive element is not stretched in a straight line between the lifting drive unit and the area where it is supported on the working part, but rather runs, at least partially, over a deflection element. The deflection element can be, for example, a deflection roller, deflection wheel, sprocket, or a fixed, profiled deflection bridge around which the drive element is deflected in a defined manner. By guiding the drive element over the deflection element, the force transmission of the drive element can be adapted to the available space in the area of ​​the lifting drive unit.In particular, a substantially horizontal section of the drive element, which may be located in the area of ​​the base or the working part, can be converted via the deflection element into a section extending in the stroke direction of the working part, and in particular a substantially vertical section. In this way, the drive element is deflected from a predominantly horizontal to a predominantly vertical direction without the need for additional rigid connecting elements.

[0030] In a further preferred embodiment, the drive comprises at least one electric motor that synchronously drives the two spindles via at least one gearbox. In this configuration, the drive is designed as an electromechanical drive with at least one electric motor. The electric motor is coupled to both spindles via at least one gearbox, so that the spindles are set into rotation together and synchronously. The gearbox can be, for example, a gear drive, chain drive, or belt drive and ensures that the rotary motion of the motor is transmitted to both spindles with a defined transmission ratio.

[0031] In an alternative embodiment, instead of a single electric motor, two electric motors can be provided, each assigned to a spindle and coupled to it in a rotationally fixed manner. The two electric motors are electrically controlled so that they essentially operate at the same speed and drive the spindles synchronously. Synchronization can be ensured by electronic control, for example, via a shared power electronics unit or speed sensors on the spindles.

[0032] In both versions, the synchronous drive of both spindles ensures that the spindle nuts, and thus the bearing housing, move at the same stroke speed on both spindles. This allows the forces transmitted to the striking element to be introduced symmetrically into at least one linear drive element, so that this supports and moves the working part evenly relative to the base.

[0033] The use of one or more electric motors also enables convenient, electrically controlled operation of the scissor lift table. The lifting speed can be adjusted via motor speed control, and defined lifting positions can be reached reproducibly. This improves usability and allows the scissor lift table to be integrated into automated processes or higher-level control systems.

[0034] It can advantageously be provided that the drive comprises at least two gear units, each rotationally fixed to one of the spindles and each having a connection device for the detachable connection of an external drive, in particular a handheld cordless screwdriver. In this embodiment, each of the two spindles has its own gear unit, which is rotationally fixed to the corresponding spindle. Each gear unit has a connection device designed for the detachable connection of an external drive. The connection device can, for example, be designed as a hexagonal socket, a square socket, or a profiled tool holder into which the drive square or hexagon of a handheld cordless screwdriver or a comparable external drive engages.

[0035] This design allows the scissor lift table to be operated without a permanently attached electric motor. Instead, an external drive, in particular a standard cordless screwdriver, is attached to the respective gearbox unit as needed to drive the corresponding spindle. This enables simple, cost-effective, and robust operation, especially in environments where no permanent electrical infrastructure is available or where an integrated motor is to be avoided for cost reasons.

[0036] The use of two gear units allows both spindles to be driven either sequentially or simultaneously with a suitable auxiliary adapter. Appropriate gear ratio design ensures that both spindles operate at the same speed and thus with identical stroke rates, resulting in symmetrical movement of the spindle nuts, the actuating element, and the linear drive mechanism. This guarantees uniform adjustment of the stroke drive and largely symmetrical height adjustment of the working part relative to the base.

[0037] In a further advantageous embodiment, the at least one electric motor is designed as a detachable drive unit from the scissor lift table and can be coupled to the lifting drive unit. In this embodiment, the electric motor is not permanently integrated into the frame of the scissor lift table, but rather designed as a separate drive unit that can be detachably connected to the lifting drive unit. For this purpose, the drive unit can, for example, have a housing with an integrated motor-gearbox combination and a coupling or plug connection that interacts with a corresponding coupling or receptacle on the spindles or on an intermediate shaft of the lifting drive unit.

[0038] The detachable design of the drive unit allows the scissor lift table to be operated with or without a permanently attached motor, as needed. This means the same motor can be used successively on different lift tables, or the motor can be removed and stored separately for transport, maintenance, or in safety-critical areas. When the drive unit is coupled to the lifting drive mechanism, it synchronously drives the spindles as described above, causing the spindle nuts, the actuating element, and the linear drive mechanism to move in a defined manner and adjust the height of the working part relative to the base.

[0039] In a further advantageous embodiment, the spindles are provided with self-locking threads. In this design, the spindles are configured such that the thread acting between the spindle and the spindle nut is self-locking. Self-locking means that when a load is applied to the working part, and thus to the linear drive element supporting it, as well as to the spindle nuts, the forces acting on the spindle nuts prevent the spindles from rotating backwards as long as the drive is not actively operated. Typical self-locking threads are, for example, trapezoidal threads with a suitable pitch and surface finish. The self-locking mechanism ensures that the scissor lift table can be held in a set lifting position without additional mechanical brakes or locking elements.In particular, it is not necessary to provide separate backstops or locking brakes to prevent the working part from unintentionally lowering under load, as the spindles absorb the forces acting on the linear drive and the working part via the self-locking thread and prevent the drive from running back automatically.

[0040] It can be advantageous to provide that feet and / or rollers are arranged on the base and / or the working section. In this configuration, the scissor lift table has additional features for setup and / or movement. In particular, height-adjustable feet can be provided on the base, allowing the lift table to be leveled on the surface and secured against unintentional movement. The feet can be designed as rubber feet, spindle feet, or similar support elements that ensure defined, slip-resistant support.

[0041] Alternatively or additionally, casters, in particular swivel or fixed casters, can be provided on the base to allow the lifting table to be moved whether unloaded or loaded. Preferably, such casters have locking or braking devices that allow the lifting table to be locked in the desired position.

[0042] Alternatively, or in addition, rollers can be provided on the working section, for example, in the form of transport rollers or roller strips, which facilitate the transport of goods placed on it. With this design, feet or rollers on the base are unnecessary. The rollers or feet provided on the working section only come into contact with the floor when the working section is positioned close to the surface being installed or rests on the base. Equipped with feet and / or rollers, the scissor lift table can be used both stationary and mobile, with the lifting drive and the linear drive operating independently of the chosen installation or travel configuration.

[0043] In a further embodiment, the scissor lift table has an electrical or electronic control unit for controlling the lifting drive. The control unit can be housed in a control cabinet located at the base or in an operating housing attached to the working section and is connected to the lifting drive, in particular to the at least one electric motor and optionally to sensors and switching elements. For operation, a control unit can be provided, which has at least one push button for raising and one push button for lowering the working section. The push buttons can be designed as dead man's switches, so that the lift table only moves as long as the respective button is pressed. Alternatively or additionally, a foot switch unit can be provided, which is connected to the control unit via a cable and enables hands-free operation of the lift table.

[0044] The control unit can be connected to limit switches or position sensors that detect the lower and / or upper end position of the working part. When an end position is reached, the drive is automatically switched off, thus preventing the mechanical stroke limits from being exceeded. Additionally, overload monitoring can be provided, which switches off the drive or reduces the stroke speed if a permissible motor current or load is exceeded.

[0045] Furthermore, the control unit can be designed so that predefined target positions of the working part can be approached. For this purpose, the lifting movement can be detected via a displacement sensor or by counting the spindle angle or revolutions and compared with stored setpoint values. In this way, repeatable working positions can be set, which facilitates the ergonomic and process-reliable use of the scissor lift table. An emergency stop switch can be provided, which allows the drive to be switched off immediately at any time, regardless of the current operating status.

[0046] In a further embodiment, the base and / or the working part may be designed as a welded or bolted steel structure, in particular made of structural steel or high-strength steel. The scissor arms of the scissor mechanism may also consist of steel profiles or laser-cut and formed steel sheets to ensure high bending and compressive stiffness with a comparatively slim design. The spindles of the lifting drive unit may be made of tempered or surface-hardened steel to achieve high wear resistance of the thread flanks. The spindle nuts may be made of steel, ductile iron, or a wear-resistant sliding material, for example, a bronze alloy or a plastic sliding bearing material.The bridge element and the bearing housings can be manufactured as steel castings, as welded steel assemblies or as precision castings, depending on the required stiffness and manufacturing effort.

[0047] The linear drive element, in the form of a rigid, multi-link chain, can consist of hardened steel chain links guided in a low-wear guide channel. Deflection elements such as sprockets or pulleys can be made of steel or cast iron with hardened teeth or running surfaces. Feet can have rubber pads or elastomer inserts for vibration and noise damping, while roller assemblies can have plastic or elastomer running surfaces to protect the floor covering. Covers, panels, and control element housings can be made of sheet steel, aluminum, or impact-resistant plastic.

[0048] In a further embodiment, the drive may include a distribution shaft coupled via a gearbox to a connection device for the detachable connection of an external drive element, in particular a handheld cordless screwdriver, and connected to the two spindles in a rotationally fixed manner via at least two further gearbox units. In this configuration, the external drive element initially engages a single gearbox unit, which transmits the torque to the distribution shaft. From this distribution shaft, the torque is distributed to the two spindles via two separate gearbox units, so that both spindles are driven mechanically synchronously.By dividing the drive path into several gear stages, the transmission ratio can be precisely adjusted to provide sufficient torque for lifting heavy loads while simultaneously enabling an ergonomically favorable speed for the external drive mechanism. At the same time, the common distribution shaft ensures defined synchronization of the two spindles without the need for complex electronic control, resulting in uniform displacement of the spindle nuts, the attached lifting element, and the linear drive mechanism, as well as largely symmetrical height adjustment of the working part.

[0049] According to a further advantageous embodiment, the attack element is positively coupled to at least one drive element arranged on the drive means. For this purpose, the attack element has at least one receptacle in which the drive element is positively held. The drive element can, in particular, be designed as a connecting bolt of a push chain, connecting adjacent chain links; however, it can also be designed as a separate drive element attached to a chain link, a chain carrier, or another section of the drive means. Crucially, the drive element engages in the receptacle of the attack element and serves as a positive-locking coupling element between the attack element and the drive means. The attack element does not engage in the gaps between the chain links.

[0050] The engagement element can be designed, for example, as a one- or multi-part drive plate attached to the bridge element or the bearing housing, featuring at least one downwardly or laterally projecting lug with a U-shaped or fork-shaped receptacle in cross-section. Alternatively or additionally, several such lugs, each with its own receptacle, can be provided, interacting with multiple drive elements of the drive system to enable redundant or load-distributing power transmission. The receptacles can be designed as open fork contours, closed bores, or profiled pockets into which the drive element engages positively. The positive-locking coupling between the engagement element and the drive element achieves a defined, largely backlash-free power transmission without requiring a gear or pinion engagement on the push chain.This reduces wear on the contact surfaces, simplifies the design of the lifting drive unit and enables smooth, jerk-free operation of the drive unit during lifting movement.

[0051] Further advantageous embodiments are explained in more detail with reference to exemplary embodiments shown in the drawing.

[0052] They show: Fig. 1. A design of a scissor lift table in perspective view from its narrow side and , Fig. 2. A design of a scissor lift table in perspective view from its long side.

[0053] Fig. 1 and Fig. Figure 2 shows a scissor lift table 1 with a base 2 and a work section 3 that is vertically adjustable relative to the base. A scissor mechanism 4 is arranged between the base 2 and the work section 3, comprising two scissor arms 5 and 6 that are articulated in a cross shape. In the Fig. In the perspective view shown in Figure 1 from the narrow side, the lateral contour of the foot section 2, the working section 3 and the scissor mechanism 4 arranged between them is particularly recognizable, while Fig. Figure 2 shows a perspective view from the long side, illustrating the longitudinal extent of the scissor lift table 1 and the arrangement of the drive components in the base 2.

[0054] A lifting drive unit 7 is arranged in the base area of ​​the foot section 2. The lifting drive unit 7 comprises an electric motor 8, which drives two spindles 9 and 10 arranged parallel to each other. The spindles 9 and 10 extend essentially in the longitudinal direction of the foot section 2. At least one spindle nut 11 is arranged on each spindle 9 and 10, engaging with the thread of the respective spindle. The spindle nuts 11 are received in a common bridge element 12, which is designed as a crossbeam and extends transversely to the longitudinal direction of the spindles 9 and 10. A bearing housing 13 is formed or arranged in the bridge element 12, in which the spindle nuts 11 are mounted in a rotationally fixed manner, so that they do not follow a rotational movement of the spindles 9 and 10, but are moved axially along the spindles.

[0055] When the scissor lift table 1 is actuated, the electric motor 8 is set in rotation by a control unit and drives the two spindles 9 and 10 synchronously via a gearbox. Due to the rotationally fixed mounting of the spindle nuts 11 in the bearing housing 13, the spindle nuts 11 are axially displaced along the spindles 9 and 10 and move the bridge element 12 relative to the base 2. The movement generated by this displacement is transmitted to an actuation element of the scissor mechanism 4 (not shown). This adjusts the scissor mechanism 4, changes the scissor angle, and raises or lowers the working part 3 relative to the base 2. A linear drive element (also not shown) can additionally function as a force-transmitting element for generating the lifting movement and as a load-bearing support between the base 2 and the working part 3 in the set lifting position.

[0056] The Fig. Figures 3 to 5 show the lifting drive unit 7 in the area of ​​the foot section 2 from different perspectives. Fig. Figure 3 shows a perspective view of the base 2 with the lifting drive unit 7 arranged therein. The first spindle 9 and the second spindle 10 are arranged parallel to each other, each with a spindle nut mounted on it. The spindle nuts are each mounted in a bearing housing 13 to prevent rotation. The two bearing housings 13 are rigidly connected to each other via the bridge element 12, forming a common nut assembly that is axially movable along the spindles 9 and 10. The drive element 14 extends downwards from a substantially central region of the bridge element 12 towards a channel formed in the base 2. The drive element 15, in the form of a multi-link push chain, is guided in this channel and is operatively connected to the drive element 14 to transmit force.

[0057] Fig. Figure 4 shows a top view of the base 2 with the lifting drive unit 7 arranged therein. In this view, the parallel spindles 9, 10 and the bridge element 12 spanning them transversely, in which the bearing housings 13 with the spindle nuts are arranged, can be seen. The engagement element is attached centrally to the bridge element 12 and projects into the channel below containing the drive element 15. The channel and the drive element 15 running within it extend essentially in the longitudinal direction of the base 2.

[0058] Fig.Figure 5 shows a longitudinal section through the base section 2 in the area of ​​the channel for the drive element 15. In this sectional view, the push chain is guided in the channel as the drive element 15, with several chain links arranged one behind the other in the longitudinal direction. The engagement element 14 can be multi-part and attached to the bridge element 12 via screw connections and has at least one lug with a receptacle that positively engages a drive element 16 of the drive element 15. The receptacle can completely enclose the drive element 16, at least in its circumferential direction. The drive element 16 is designed, in particular, as a connecting bolt of the push chain, which connects adjacent chain links and serves as a driving and coupling element for the drive element 15. In the area of ​​the engagement element 14, the drive element 16 positively engages in the receptacle of the engagement element 14.If the bridge element 12 is displaced axially along the spindles 9, 10 by an axial displacement of the spindle nuts, the attack element 14 follows this movement and engages the drive element 15 via the drive element 16. This causes the drive element 15 to be moved axially in a controlled manner in the longitudinal direction of the spindles 9, 10, so that the section of the drive element 15 extending in the stroke direction is lengthened or shortened accordingly, and the working part is supported against the base 2 and its height is adjusted. Reference symbol list 1 scissor lift table 2 foot section 3. Work section 4 Scissor mechanism 5 first scissor arm 6 second scissor arm 7 Lifting drive unit 8 Electric motor 9 first spindle 10 second spindle 11 Spindle nut 12 bridge elements 13 bearing housings 14 Propulsion devices 15 attack element 16 Drive element 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] WO 2021 / 013251 A1

[0007] WO 2024 / 003139 A1

[0007]

Claims

[1] Scissor lift table (1) with a base (2) and a working part (3) which is height-adjustable relative to the base (2), with at least one scissor mechanism (4) arranged between the base (2) and the working part (3), which comprises two scissor arms (5, 6) hinged crosswise to each other, wherein a first end region of a first scissor arm (5) is pivotably mounted on the base (2) and a first end region of a second scissor arm (6) is pivotably mounted on the working part (3) and the respective opposite end regions are guided longitudinally displaceably on the working part (3) and on the base (2), and with a lifting drive device (7), wherein the lifting drive device (7) comprises two threaded spindles (9, 10) arranged parallel to each other, on each of which at least one spindle nut (11) is arranged, wherein the spindles (9, 10) can be driven together by a drive, so that the spindle nuts (11) relative to the spindles (9,10) are adjustable in the axial direction, wherein the spindle nuts (11) are mounted in a bearing housing (13) in a rotationally fixed manner, and wherein at least one engagement element is provided which is coupled to at least one spindle nut (11) in a force-transmitting manner and is connected to a linear drive means in a force-transmitting manner, which has a substantially horizontal section and a section extending in the stroke direction of the working part (3) between the base part (2) and the working part (3) and is supported at least at one end on the base part (2) and / or on the working part (3), such that an axial adjustment of the spindle nuts (11) causes a displacement of the engagement element relative to the spindles (9, 10) and thereby a change in the shear angle and a height adjustment of the working part (3). [2] Scissor lift table according to claim 1, characterized by , that the attack element is coupled to the bearing housing (13) in a force-transmitting manner. [3] Scissor lift table according to one of the preceding claims, characterized by , that the two spindle nuts (11) are connected to each other via a rigid bridge element (12). [4] Scissor lift table according to claim 3, characterized by , that the bridge element (12) is designed as a dimensionally stable crossbeam which connects the two spindle nuts (11) to each other in a force-transmitting manner. [5] Scissor lift table according to one of claims 3 or 4, characterized by , that a bearing housing (13) is provided for each spindle nut (11) and that the bearing housings (13) are arranged in the bridge element (12). [6] Scissor lift table according to one of the preceding claims, characterized by , that the lifting drive device (7) is arranged in the bottom area of ​​the foot part (2). [7] Scissor lift table according to any one of the preceding claims 1 to 5, characterized by , that the lifting drive device (7) is arranged in the working part (3). [8] Scissor lift table according to one of the preceding claims, characterized by that the two spindles (9, 10) are arranged parallel to each other in the area of ​​the foot part (2) or the working part (3) and run essentially horizontally. [9] Scissor lift table according to any of the preceding claims, characterized by , that the bearing housing (13) is mounted in a guide so as to be movable relative to the foot part (2) or the working part (3). [10] Scissor lift table according to one of the preceding claims, characterized by that the linear drive element is designed as a rigid, multi-linked chain. [11] Scissor lift table according to one of the preceding claims, characterized by , that two linear drive means are provided, each running on opposite sides of the scissor lift table (1) and each coupled to its own attack element, which is connected to one of the spindle nuts (11) in a force-transmitting manner. [12] Scissor lift table according to one of the preceding claims, characterized by , that the drive includes at least one electric motor (8) which drives the two spindles (9, 10) synchronously via at least one gearbox. [13] Scissor lift table according to one of the preceding claims, characterized by , that the drive comprises at least two gear units, each of which is non-rotatably coupled to one of the spindles (9, 10) and each has a connection device for the detachable connection of an external drive means, in particular a handheld cordless screwdriver. [14] Scissor lift table according to one of the preceding claims, characterized by , that at least one electric motor (8) is designed as a drive unit that can be detached from the scissor lift table (1) and coupled to the lifting drive device (7). [15] Scissor lift table according to one of the preceding claims, characterized by , that the spindles (9, 10) have self-locking threads. [16] Scissor lift table according to one of the preceding claims, characterized by that feet and / or roller devices are arranged on the foot section (2) and / or on the working section (3). [17] Scissor lift table according to one of the preceding claims, characterized by , that the scissor lift table (1) has an electrical or electronic control device for controlling the lifting drive device (7). [18] Scissor lift table according to one of the preceding claims, characterized by , that the drive comprises a distribution shaft which is coupled via a first gear unit to a connection device for the detachable connection of an external drive means, in particular a handheld cordless screwdriver, and is connected via two further gear units to each of the spindles (9, 10) in a rotationally fixed manner. [19] Scissor lift table according to one of the preceding claims, characterized by, that the attack element (14) is positively coupled to at least one drive element (16) arranged on the drive means (15), wherein the attack element (14) has a receptacle in which the drive element (16) is positively held. [20] Scissor lift table according to claim 19, characterized by , that the attack element (14) is designed as a one- or multi-part drive plate which is attached to the bridge element (12) and / or to a bearing housing (13) and has at least one nose extending towards the drive means (15) with a receptacle having a cross-section that is essentially U-shaped or fork-like, in which a drive element (16) of the drive means (15) is positively engaged.

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