SHEARING HUBTIAN

Description

[0001] The invention relates to a scissor lift table according to the preamble of claim 1.

[0002] Scissor lift tables of this type are often subjected to high loads, for example when lifting heavy objects. In this case, the traction mechanism is exposed to very high loads, which under certain circumstances can even lead to it breaking. On the other hand, in certain applications, for example when people are or may be on the upper section of the table during the lifting movement, a very high level of operational reliability of the scissor lift table must be guaranteed. This means that corresponding safety tolerances are often required for the lift table. For example, if the upper section is to be permitted for people to be present, a ten-fold safety factor is required, i.e. the lift table must be designed to withstand forces or mechanical loads ten times higher than those that occur during normal, intended use.This particularly applies to safety in the event of the traction device breaking, which, when a belt is used as the traction device, is also referred to as "safety in the event of a belt break." It is understood that maintaining such safety tolerances requires considerable structural and therefore costly effort.

[0003] Furthermore, scissor lifts are often desired today to have comparatively low energy consumption while meeting other requirements, such as being designed to lift appropriate weights. Energy consumption during frequent operation of the lift table can account for a significant portion of operating costs, and for general ecological reasons, energy consumption should be kept as low as possible.

[0004] A lifting table of this type is known, for example, from DE 10 2006 006 467 A1. Due to the rod arrangements, which each couple to one of the scissor legs with at least one rod section on the same side of the scissor axis and interact with the raising element when actuated, exerting an raising force on the respective scissor leg, this scissor lift table is particularly suitable for heavy loads and great lifting heights. However, with such loads on the lifting table with heavy loads and great lifting heights, the aforementioned problems regarding operational safety and energy-efficient operation become particularly apparent.

[0005] EP 2019076A1 discloses a scissor lift device with two coupling bridges connected by a guide and with scissor struts pivotably mounted on a coupling bridge. To transmit the lifting force, the first coupling bridge of the scissor lift device is equipped with push rods, each connected to a scissor link, and the second coupling bridge is equipped with a spreader element that rests against two curved contact tracks, each associated with a scissor link. This achieves a nearly constant energy absorption of the drive, independent of the lifting height.

[0006] DE 10359490 A1 describes a scissor lift table with two parallel, spaced-apart scissors arranged between a base unit on the one hand and a support unit that can be moved up and down on the other, with scissor legs that can be pivoted relative to each other. The scissor lift table also has a lifting device that has at least one spreading unit coupled between the scissor legs to a drive device via a windable or adjustable traction mechanism arrangement. Reliable operation is promoted by the fact that the spreading unit is loosely coupled to the traction mechanism arrangement, and an end of the traction mechanism arrangement facing away from the drive device is connected to the lift table or a separate holding device by means of a traction mechanism holder outside the spreading unit.

[0007] WO 2012 / 135078 A2 describes a scissor lift comprising a load support, a lifting support, and at least one scissor assembly defined between the load support and the lifting support, and comprising a drive device for opening and closing the scissors. The at least one scissor assembly is further defined by a pair of arms attached to a pivot point, and the pair of arms further comprises curved outer surfaces that engage a portion of a drive device to urge the scissor arms apart and to move the load support relative to the lifting support.

[0008] The invention is therefore based on the object of providing a generic scissor lift table which has a particularly high level of operational reliability and low or reduced energy consumption for its operation.

[0009] The object is achieved by a scissor lift table according to claim 1. Further advantageous embodiments emerge from the subclaims.

[0010] According to the invention, the traction mechanism is designed as a spiral-shaped traction mechanism that winds itself up, and the curvatures of the two mutually facing curved rails are designed such that when the erection element moves along the two curved rails with force-transmitting coupling to them and during the lifting movement, the drive motor of the drive is loaded with at least a substantially constant power consumption over at least a significant and / or at least the majority of the lifting movement. The at least substantially constant power consumption ensures, on the one hand, a particularly high level of operational reliability of the lifting table. Power consumption peaks, which would lead to a correspondingly high load on the traction mechanism and thus, taking into account the necessary safety tolerances, necessitate a corresponding mechanical design of the lifting table, are avoided.This is especially true if the upper section of the lifting table is intended to be suitable or approved for accommodating persons, where particularly high safety tolerances are required. By avoiding power peaks and ensuring the drive motor's at least essentially constant power consumption over at least the majority of the lifting movement, as provided by the invention, the lifting table can be constructed in a simpler manner, which also results in material savings. However, due to this material savings, the drive motor can be designed for lower power or operated with lower power consumption, which reduces energy consumption when operating the lifting table.On the other hand, it has been shown that simply ensuring a consistent or more consistent power consumption of the drive motor itself and avoiding significant fluctuations in power consumption or power consumption peaks can significantly improve the energy efficiency of the lifting table, for example, by ≥ 10-20% or ≥ 30%, or even up to 50% if necessary. Furthermore, this results in less wear on the lifting table, precisely due to the particularly consistent power consumption and thus also consistent or more consistent stress on moving or force-loaded parts, especially those subject to tensile stress, for example, the traction mechanism, bearings, or the like.

[0011] Due to the consistent power consumption of the drive motor, achieved through the correspondingly adapted curvature of the curved rails, which interact with the support mechanism, the lifting table is designed to be particularly simple, durable, and low-maintenance. In principle, it would be conceivable to achieve a constant power consumption of the drive motor, for example, in the form of an electric motor, using an electronic power control device, so that the drive motor operates with controlled power. However, this requires the provision of a corresponding electronic control circuit. Such a design of such a motor with power control is very complex, requires a complicated control and regulation circuit, and is associated with high costs.A further significant problem with such a power-controlled electric motor, however, is that such operation is not free from control errors, which in turn would require a correspondingly high level of safety design for the lifting table. Furthermore, if the power of the electric drive motor were to be controlled electronically, the forces exerted on the traction device, such as a belt, in particular tensile forces, would not be mechanically precisely defined over the course of the lifting movement. It should be noted here that with conventional lifting tables, the traction device is subjected to different tensile forces in different areas of the lifting movement, depending on the respective design and power transmission conditions during the lifting movement.However, these disadvantages are avoided in the lifting table according to the invention, since the curvature adjustment of the curved rails provides a measure that is mechanically particularly stable and structurally precisely defined and practically not susceptible to failure, so that during at least the predominant part of the lifting movement, the drive motor, in particular in the form of an electric motor, is operated or stressed with an at least substantially constant power consumption.

[0012] An "at least substantially" constant power consumption of the drive motor, with which it is loaded when carrying out the lifting movement, is given in particular if the power consumption is ≤ 20% or ≤ 10%, preferably ≤ 5%, particularly preferably ≤ 3.5% or in particular ≤ 2% of the average value of the power consumption over the described essential and / or predominant part of the lifting movement or the essential or predominant part of the movement of the setting element along the curved rail.

[0013] During the lifting movement, the drive motor is preferably operated at an at least substantially constant speed and / or the winding element for winding and / or unwinding the traction means is operated at an at least substantially constant speed. If necessary, the drive motor can thus be controlled by a speed control or speed regulation, which sets or regulates the speed to a predetermined setpoint or, with respect to the lifting movement, to a predetermined setpoint curve, in which the setpoint changes in a predetermined manner via the lifting movement or the position of the setting element on the curved rails. It is understood that a corresponding control device for the drive motor is provided for this purpose.This also enables particularly safe operation and a structurally simple design of the lifting table, in particular with regard to the electronic control means for operating the drive motor, in particular as an electric motor.

[0014] The "at least substantial part" of the lifting movement, in which the drive motor, such as in particular the electric motor, is operated or stressed with an at least substantially constant power consumption, is understood as ≥ 20% or ≥ 25%, optionally ≥ 30% or ≥ 40% of the lifting movement. The "at least predominant part" of the lifting movement, in which the drive motor, such as in particular the electric motor, is operated or stressed with an at least substantially constant power consumption, is understood as ≥ 50% or ≥ 70%, optionally ≥ 80% or at least almost 100% of the lifting movement. Within the scope of the invention, the aforementioned "lifting movement" is generally understood to refer to the maximum lifting movement of the lifting table, i.e., between its maximally retracted position with minimal distance between the upper part and the base part and its maximally extended position with maximum distance between the upper part and the base part.If necessary, the predominant part of the lifting movement can also refer to a specific travel position of the lifting table, in which the upper part occupies an intermediate position between its fully retracted and its fully extended position. In particular, the predominant part of the lifting movement can also refer to a lifting movement in which, based on the maximum distance between the upper part and the base part, the lifting table is extended by ≥ 25% and ≤ 75%. It is understood that deviations from the at least essentially constant power consumption of the drive motor can occur at the start and / or end of the lifting movement. The respectively mentioned "at least substantial part" or "at least predominant part" of the lifting movement is preferably in the middle part of the lifting movement orof the travel path of the positioning element along the curved rails, i.e., preferably spaced ≥ 5%, ≥ 10%, or ≥ 15% from the end regions of the lifting movement or travel movement. The statements regarding the lifting path also apply accordingly to the travel path of the positioning element along the mutually facing curved rails, so that over the maximum stroke of the lifting table, the positioning element moves from the start to the end point of its travel path along the curvature of the curved rails.

[0015] Due to the inventive design of the lifting table, in which the drive motor's power consumption remains at least substantially constant over at least a significant portion or a predominant portion of the lifting movement, virtually any drive motor can be used for the drive, in particular virtually any electric motor, such as direct current, alternating current, synchronous, asynchronous, or the like, without being limited thereto. This allows for further flexibility in the design of the lifting table according to the respective requirements.

[0016] The determination of the curvatures of the curved paths, by adapting which the drive motor is subjected to at least a substantial portion and / or the majority of the stroke with at least substantially constant power consumption, can be determined, for example, mathematically, in particular using an iterative method such as a simulation method. For example, the travel path of the respective curved rail, over which the positioning element moves along the given curved rail while performing the stroke movement, can be divided into a plurality of grid or iteration points, which can be arranged at least substantially evenly distributed over the length of the travel path.It is understood that the distribution of the aforementioned grid points (iteration points) can, if necessary, also be uneven over the length of the travel path, or that a denser point grid or additional grid points can be provided in partial areas thereof in which, for example, larger changes in power consumption are to be expected, which changes must be absorbed by the shape of the curved rail and changed to an at least essentially constant power consumption. For example, the travel path of a curved rail can be divided into ≥ 10, for example ≥ 20 or ≥ 30 or even ≥ 50 or ≥ 100 or more grid points. With regard to the respective grid point, the required curvature or iteration can then be determined using a suitable calculation method, as is known in the prior art for calculating force transmissions in a mechanical arrangement with at least essentially rigid components of a force transmission mechanism.the required radius of curvature can be calculated, which leads to an at least essentially constant power consumption of the drive motor. If, for example, it turns out that for a given grid point along the travel path of the curved rail, with a specified curvature of the curved rail at this grid point, the power consumption would be too high to be considered at least essentially constant within the specified tolerances, the radius of curvature of one or both of the curved rails can be reduced. If for this given grid point the power consumption would be too low in relation to the given scissor lift table, the curvature of one or both of the curved rails can be increased at this point.This method can, if necessary, be carried out in several stages, so that, for example, starting from a given scissor lift table with given curvatures of the curved rails along the travel path, an equalization of the power consumption to a certain level is calculated in a first step, for example with a deviation of + / - 20% from the mean value of the power consumption over the entire travel path, so that then, in a second calculation cycle, the curvature of the curved rail is further equalized, for example to a maximum deviation of the power consumption of + / - 10% from the said mean value of the power consumption, etc., until the desired level of an essentially constant power consumption is achieved in further iteration stages, for example a deviation of ≤ + / - 5% or ≤ + / - 3% from the mean power consumption or the like.As the iteration cycle increases, the number of grid points along the curve line can also be increased. Based on the curvatures of the curved rail at the grid points determined in this way, the total curvature of the respective curved rail can be determined or defined, for example, by a suitable interpolation, such as a spline interpolation, specifically, a cubic spline interpolation such as a cubic C2 spline, or by other suitable interpolation methods, preferably of a higher degree.

[0017] The course of the curvature line of the curved path of one or preferably both curved rails of the opposite scissor legs of the scissors, which interact with the erecting member, generally deviates from the shape of a circular arc and / or elliptical segment and / or hyperbolic segment or generally deviates from the shape of a segment of a conic section, and therefore does not represent such a segment. The curvature line of the curved path of one or preferably both of the opposing curved rails can, for example, each have at least one segment with at least one or more inflection points. This applies in each case to the part of the curved path along which the erecting member is moved in order to load the drive motor with at least essentially constant power consumption over at least a substantial and / or the predominant part of the lifting movement.

[0018] When calculating the power consumption of the drive motor at the respective grid point, the speed at which the positioning element is moved at this grid point along the curvature of the curved rail can be taken into account. In particular, an at least essentially constant or a constant speed of the winding element for winding and / or unwinding the traction device can be assumed. Further in particular, the speed of the winding element can also be assigned a correction factor which takes into account the fact that when the traction device is wound and / or unwound, it is wound spirally onto itself and that this changes the wound or unwound length of the traction device with one rotation of the winding element, so that a constant travel speed of the traction device is corrected taking into account the changing diameter of the wound-up traction device.Since the increase in the winding radius due to the given thickness of the traction device is known, this correction can be implemented with little effort. The "at least essentially" constant speed of the winding element and / or traction device's pulling speed can deviate by ≤ + / - 20% or ≤ + / - 10%, preferably by ≤ + / - 5% or ≤ + / - 3% from the respective mean value over the entire lifting movement of the lifting table or a corresponding deviation from a target value. Accordingly, the lifting speed of the lifting table can deviate from the respective mean value by ≤ + / - 20% or ≤ + / - 10%, preferably by ≤ + / - 5% or ≤ + / - 3% over the lifting movement of the lifting table with winding or unwinding of the traction means by a certain predetermined length, which can apply to ≥ 20% or ≥ 30%, preferably ≥ 50% or ≥ 70% or ≥ 80% of the lifting movement, in particular also in the range of at least substantially constant power consumption of the drive motor.

[0019] Alternatively, the curvature of the curved rails, which leads to an at least essentially constant power consumption of the drive motor, can also be determined experimentally, for example, on a model of a lifting table, preferably a 1:1 model that largely corresponds to the lifting table to be marketed, possibly with the exception of the design of the curved rails as well as the drive and the control and / or regulation means provided for it. Based on the model or prototype resulting from this experimental determination, a large number of identical lifting tables can then be manufactured.The experimental determination can be carried out, for example, by measuring the power consumption of the drive motor as a function of the travel position of the lifting table over its travel movement, preferably over its entire stroke, based on a predetermined curvature of the curved rails of a given lifting table. In the areas where the power consumption exceeds or falls below a predetermined tolerance from the target value, the curvature of this section of the curved rail can then be changed and adjusted such that the power consumption lies within the predetermined tolerance range and results in an at least essentially constant power consumption.This process can also be performed iteratively to successively adjust the curvature of the curved rails over several adjustment cycles, so that at the end of the iteration process, the power consumption of the drive motor is at least essentially constant, at least over the majority of the lifting movements, within the desired tolerance range. It is understood that after determining the curvature of the curved rails adjusted in this way, the installation of a power consumption measuring device for the drive motor is no longer necessary for a lifting table placed on the market in series production, and the lifting table placed on the market can thus have a particularly simple design.

[0020] The at least substantially constant power consumption of the drive motor over at least a significant portion and / or at least the majority of the lifting movement implies that at the beginning and / or end of the lifting movement, larger deviations from the at least substantially constant value or average of the power consumption over the lifting path may naturally occur. This corresponds to the start-up of the lifting table at the initiation of the lifting movement and / or the end range of the lifting movement, at which the power consumption is reduced to terminate the lifting movement.The said initial and final ranges of the lifting movement, in which the power consumption of the drive motor deviates from the at least substantially constant value, including its predetermined tolerance range, can, for example, each independently of one another be ≤ 15% or ≤ 10%, particularly preferably ≤ 5% of the total travel path of the actuating element over the curved rails interacting with the actuating element.

[0021] Preferably, the lifting table is designed such that, in a first part of the lifting movement, the force for raising the upper part is applied predominantly by the interaction of the positioning element with the curved rails, and that, in a second part of the lifting movement, the force for raising the upper part is applied predominantly by the interaction of the positioning element with the rod arrangement. The curved rails have a curvature such that, in the transition region between the first and second parts of the lifting movement, the drive motor is subjected to an at least substantially constant power consumption. This transition region, in particular, is understood as the "essential part" of the lifting movement according to claim 1.This allows the lifting table to be moved particularly smoothly, even in the partial range of the lifting movement in which the described transition in the power transmission occurs, and in particular with an at least essentially constant power consumption of the drive motor. The curvature of the curved rails is specially adapted to enable the lifting table to move with at least essentially constant power consumption, even in this transition range. It has been found that this transition range is particularly critical with regard to a smooth lifting movement, and that conventional lifting tables can otherwise experience considerable deviations or errors.Fluctuations such as a drop in power consumption can lead to certain irregularities in the travel movement with conventional lifting tables and thus under certain circumstances also to high load stresses on the components of the lifting table, in particular the traction device, particularly due to load changes. However, this is avoided by the design of the lifting table according to the invention. This transition area of the power transmission can occur in particular in the second half or in the last third or last quarter of the maximum travel path of the erection element along the curvature of the curved rails or the lifting movement. The said transition of the power transmission mechanisms can usually occur in the range of 60-90% or 70-80% of the travel path of the erection element along the curvature of the curved rail, with reference to 0% of the travel path when the lifting table is fully retracted.A significant part of the lifting movement can also generally be present if it represents ≥ 30% or ≥ 40% of the maximum lifting movement of the lifting table.

[0022] Preferably, the curvatures of the curved paths are adapted such that, with an at least substantially constant speed of the winding element for the traction means, the lifting speed of the upper part is at least substantially constant. This enables particularly uniform movement of the lifting table and, moreover, particularly simple control of the lifting movement, namely by setting or regulating the speed of the winding element. Over the middle range of the lifting movement, i.e. preferably excluding the start and end ranges of the lifting movement, the curvatures of the curved paths can be adapted and designed such that, with a constant speed of the winding element, the lifting speed fluctuates around the mean value or target value with a tolerance of ≤ ± 10% or ≤ ± 5%, preferably ≤ ± 3% or ≤ ± 2%. The target value of the lifting speed can thus be set by selecting the speed of the winding element.

[0023] Preferably, the curvatures of the curved rails on the two scissor arms of the scissor, which interact with the erection member during the lifting movement of the upper part, are different. For example, one of the curved rails can have a greater average gradient than the other curved rail in the first half of the travel path of the erection member over the curved rail, and a smaller gradient than the other curved rail in the second half of the travel path. Independently of this or in combination therewith, the curvature of at least one or both of the curved rails of the scissor arms of a scissor can be designed such that the absolute maximum of the height profile with respect to the travel path of the erection member is closer to one of the two end points of the travel path of the erection member along the curved rails than to the other end region of the travel path.For example, the absolute maximum of the height profile can be located closer to the end of the travel path facing the scissor axis than to the end of the travel path facing away from the scissor axis. This allows the curvature of the curved rails to be adjusted particularly easily to enable at least a substantially uniform motor power consumption over the entire travel path of the positioning device or the entire lifting path. However, the curvatures of the two curved rails on the two scissor legs of the scissor can also be the same if necessary.

[0024] The different curvatures of the two curved rails, which are arranged on the two legs of a scissor, can alternatively or additionally be designed such that the two curved rails each have a curved section that interacts with the positioning element, forming a travel path for the positioning element along the curved rail between the fully retracted position of the lifting table, with a starting point of the travel path, and its maximally extended position, with an end point of the travel path. The two curved sections of the two curved rails each have a height profile, with the height profile having an absolute maximum with respect to the connecting line between the starting and end points of the travel path. The absolute maxima of the two curved sections can have at least essentially the same height. The "height" of the maxima is defined as the distance between the respective connecting orThe baseline of the respective height profile of the aforementioned curve section is understood. Optionally, the two absolute maxima of the two curved rails can also have a different distance from the respective connecting or base line. For example, in a curved section with an asymmetric curve profile relative to the maximum, the maximum can have a greater height than the maximum of the other curved rail. As a result, the respective curve profile can be specially adapted in order to achieve the object of the invention and / or to create an advantageous design of the lifting table, also with regard to its uniform lifting movement.

[0025] The erection member is preferably designed such that it comprises a spreading roller which rests on both curved rails of the two scissor legs and can be moved along these during the lifting movement of the lifting table. Furthermore, the erection member preferably comprises a deflection device for the traction means, such as a deflection pulley, which is arranged on the rod arrangement, wherein the longitudinal axis of the deflection pulley or correspondingly the deflection axis of the deflection device is arranged transversely or perpendicular to the lifting direction of the lifting table. The deflection device is preferably arranged on the side of the curved rails opposite the scissor axis. The deflection device is preferably arranged on the axis of the rod arrangement which articulates the two rod parts to one another or is provided by this.The traction means is preferably fastened at one end region to the winding element in a way that absorbs the tensile force, is guided around the deflection device and fastened to the spreading roller in a way that absorbs the tensile force, or is guided around the spreading roller and fastened to a scissor arm or another area of the lifting table in a way that absorbs the tensile force, such as, for example, to the upper part of the same, wherein this fastening can be designed as a fixed point for the traction means. The winding element can preferably be arranged on the same side of the scissors as the spreading element in relation to the scissors axis, but if necessary the traction means can also be guided around one or more further deflection devices, so that the winding element can also be arranged on the side of the scissors provided with the rod arrangement in relation to the scissors axis. In general, by actuating the winding element while the traction means is wound up, a force is exerted on the setting element orSpecifically, the force is exerted on the spreading roller and the deflection device on the rod assembly, which move them toward each other or apply force in the direction of each other, thereby extending the lifting table. By rotating the winding element in the unwinding direction of the traction device, the free length protruding from the winding element is extended, thus reducing the force exerted on the spreading roller and the axis of the rod assembly relative to each other, so that the lifting table retracts or contracts, preferably under its own weight.

[0026] The lifting table preferably has at least two scissors, each with at least two scissor legs that intersect in a limb-like manner and can be pivoted about a scissor axis. The at least two scissors are arranged laterally from one another on the lifting table. The two scissors are preferably structurally identical to one another.

[0027] The invention is described below using an exemplary embodiment. All features of the exemplary embodiment are disclosed independently or in combination with one another, also generally within the scope of the invention. The figures show: Figure 1: a schematic representation of a lifting table according to the invention in a fully extended arrangement, Figure 2: a side view of the lifting table according to Figure 1 in fully retracted state, Figure 3: a representation of the section BB of the lifting table according to Figure 2 , Figure 4: a top view of the lifting table according to Figure 2 , Figure 5: a schematic side view of the two curved rails of the lifting table according to Figure 1 .

[0028] The Figures 1 to 5 describe an inventive design of a scissor lift table 1.

[0029] The scissor lift table 1 has at least one scissor 4 arranged between an upper part 2 defining an upper table surface 2a and a base part 3, here two laterally spaced scissors 4 to increase the stability of the lift table. Each scissor 4 has at least two scissor-like intersecting scissor arms 5 pivotable about a scissor axis 4a, wherein a first end region 5a of each scissor arm 5 is coupled to the upper part 2 and a second end region 5b of each scissor arm 5 is coupled to the base part 3. By pivoting the scissor arms 5 about the scissor axis 5a, the opening angle of the scissors changes, wherein the opening angle increases as the distance between the upper part and the base part decreases and decreases as the distance between the upper part and the base part increases.The lifting table further comprises a drive 6 with a drive motor, here an electric motor 6a, for pivoting the scissor arms relative to one another in order to raise or lower the table surface relative to the base part by actuating the drive. Furthermore, a setting element 7 is provided, the movement of which, by means of the drive transversely to the scissor axis 4a, allows the scissor arms 5 to be spread apart or contracted. The setting element 7 is connected to the drive 6 via a traction means 9 that can be wound up and unwound by a winding element 8 and can be actuated by the latter. On at least two mutually facing scissor arm halves 5c of the two scissor arms 5, which are arranged on one side of the scissor axis 4a and face either the upper part 2 or the base part 3, curved rails 10 are arranged, facing one another with their curvature, wherein the setting element 7 couples to or detaches from both curved rails 10.rests against them and can be moved relative to them in their longitudinal direction along the curvature by actuating the drive 6 of the traction means 9 wound up or unwound by this in order to carry out the lifting movement of the scissor lifting table.

[0030] The traction means 9 can, for example, be designed as one or more belts, chains, or the like. The traction means is preferably deformable or flexible. The traction means preferably does not exhibit any longitudinal expansion when the lifting table is actuated. Furthermore, a rod arrangement 11 is provided, which couples with at least one rod part 11a on the same side of the scissor axis 4a to one of the two scissor arms 5 and, upon actuation of the erection member 7, interacts with the latter and exerts an erection force on the respective scissor arm 5. The traction means is guided around a deflection device, which in this case is the axis 11b connecting the two rod parts 11a, or around another deflection device.For example, the deflection device can also be arranged so as to be longitudinally displaceable on a guide rail, which can also be connected to the scissors axis, wherein the deflection device can only be articulated in a force-transmitting manner to the scissors leg section(s) arranged above or below the same.

[0031] The erection member 7 preferably engages directly with the respective section of the scissor leg 5, optionally also with a force transmission means fixed thereto, which is preferably rigid, such as, for example, curved guides attached thereto. The respective rod part 11a of the rod assembly 11 is designed here as a rigid component; the respective rod part can optionally also be designed in multiple parts, wherein the individual rod parts can be connected to one another in an articulated manner. The respective rod part can also be designed, for example, as a toggle lever, wherein the deflection device can form the joint. Optionally, the rod assembly 11 as a whole or the respective rod part can also consist of several individual parts that are coupled to one another in a force-transmitting manner.When the lifting table is fully erected, the angle of the fixed rod section 11a to the respective scissor arm 5 can be between 60° and 150°, for example, between 90° and 120° or between 100° and 110°, for example, approximately 105°. This refers to the angle open to the scissor axis 4a. The angle between the rod sections 11a interacting with the deflection device to transmit force, with the deflection device as the base, or the angle pivot point-deflection roller axis-pivot point, can generally be approximately 60° to 120°, for example, 75-105° or 80° to 100°, in particular approximately 90°. The angle enclosed by the scissor legs 5 and open towards the upper table level 2a or the upper part 2 can be ≤ 150° or ≤ 120°, for example approx. 115°, preferably ≥ 90° or possibly also ≤ 90° in the maximum lifting position of the lifting table.

[0032] The rod parts 11a of the rod arrangement 10 can engage in the middle area between the scissor axis and the articulation point of the scissor leg on the upper part, for example in the range of 30-70% or 35-40% with respect to the length of said scissor leg section, so that said articulation point of the rod part 11a on the scissor leg section can be arranged closer to the scissor axis than to the articulation point of the scissor leg section with the upper part of the lifting table.

[0033] The curvature of the two mutually facing curved rails 10 is designed such that when the positioning member 7 moves along the two curved rails 10 while carrying out the lifting movement, the drive motor of the drive 6 is loaded with at least a substantial part and / or at least the predominant part of the lifting movement with at least substantially constant power consumption.

[0034] The majority of the travel path of the positioning element 7 along the curved rails, with at least substantially constant power consumption of the drive motor 6a, is located in the middle region of the travel path and extends over approximately 80% of the said travel path. At the two end regions of the travel path, the power consumption of the drive motor can deviate from the at least substantially constant value. The two end regions of the travel path can have at least substantially the same length.

[0035] The curvature of the curved tracks 10 designed according to the invention can, for example, be achieved by or determined by a computational simulation of the lifting movement or the power consumption of the drive motor. This is possible because the lifting table is constructed from at least essentially rigid components - except for the traction mechanism - so that a mechanically defined system is present due to the given leverage ratios and force transmission ratios between the components. The curved rails can therefore be defined or approximated with regard to their curvature by a grid of points (iteration points) so that the force ratios over the lifting movement can be calculated at each grid point. The curvature of the curved rails 10 can thus be adapted or designed such that the power consumption of the drive motor is at least essentially constant at each grid point, within the given tolerance range.This process can be repeated with increasingly reduced tolerance ranges. The overall curve of the respective curved rail's curvature can then be determined or defined, for example, by a suitable interpolation, such as a spline interpolation such as a cubic spline interpolation. The curve of the curved tracks, over the entire travel path of the drive element along the curved rails, is thus different from the shape of a circular arc or elliptical section, as is usually the case with conventional lifting tables of this type.

[0036] The course of the curvature lines of both curved paths 10 on opposite scissor legs 5 of the scissors 4, which interact with the setting member 7, deviates from the shape of a circular arc, ellipse and hyperbola section, or generally a section of the curvature of a cone section, and can each have one or more turning points.

[0037] The lifting table 1 is further designed such that, in a first part of the lifting movement, the force for raising the upper part 2 is applied predominantly by the interaction of the positioning element 7 with the curved rails 10, and in a second part of the lifting movement, the force for raising the upper part is applied predominantly by the interaction of the positioning element with the rod assembly 11. The curved rails 10, with their facing curves, have a curvature such that, in the transition region between the first and second parts of the lifting movement, the drive motor is subjected to an at least substantially constant power consumption. This transition region is understood as the "essential part" of the lifting movement, as it is of particular technical importance for the operation of the lifting table.This transition area lies in the area of the travel path of the positioning element along the curved rails, which is spaced from the end region of the travel path when the lifting table is fully retracted by 60-90% or 70-80% of the travel path of the positioning element along the curve of the curved rail, with reference to 0% of the travel path when the lifting table is fully retracted. This transition area can represent 20-30% of the travel path of the positioning element along the curved rails, without being limited thereto. "Travel path" is understood—also generally within the scope of the invention—to mean the maximum travel path over the maximum lifting movement of the lifting table. It is understood that when the lifting table is only partially extended, the said transition area is preferably designed accordingly.It is understood that this can be achieved in combination with the design of the curved rails, which results in at least a substantially constant power consumption of the drive motor over the majority of the stroke movement, but also independently of this. The general statements regarding the curvature of the curved rails according to the invention therefore also apply to this variant.

[0038] According to the exemplary embodiment, the power consumption of the drive motor over a significant and predominant portion of the travel path of the positioning element along the curved rail, from the start to the end point of the maximum lifting movement of the lifting table, or even over the lifting movement, fluctuates by no more than 3% around the mean value. The curved region of the respective curved rail, at which an at least essentially constant power consumption of the drive motor exists, can, for example, extend over 70-80% of the length of the travel path of the positioning element along the curved rails. The two end regions of the travel path, at which the power consumption of the motor deviates from the mean value of the essentially constant profile, can each represent ≤ 10% of the total length of the respective curve profile.

[0039] The curvature of the curved paths is adapted in such a way that, at a constant speed of the winding element for the traction device, the lifting speed of the upper part is at least essentially constant, here except for the initial and final range of the lifting movement of the lifting table, deviating by no more than 5-10%, for example approx. 2-3%, from the average value over the travel movement.

[0040] The curvatures of the curved rails on the two scissor legs 5, which interact with the erection element 7 during the lifting movement of the upper part 2, are different here, see also Figure 5 with schematic side view of the two curved rails of the lifting table according to Figure 1Both curved rails 10 have a height profile which forms a travel path along which the erection element 7 is moved to carry out the lifting movement of the lifting table, wherein in each case an absolute maximum 10a of the height profile is formed in the middle region of the longitudinal extension of the curved rails or of the travel path and an absolute minimum 10b of the height profile is formed at the end regions thereof. The straight connection between the two end points of the said travel path, namely the absolute minima 10b of the curved region, defines a connecting or base line VL. The end points or end regions here are the contact points or the middle of the contact region of the erection element on the curved region. The absolute minima 10b of the travel path occur when the lifting table is fully retracted or fully extended.The area B1 of the height range facing the scissor axis 4a between the absolute maximum 10a and the absolute minimum 10b on a curved rail, here the curved rail 10 according to . Fig. 5 , has a greater average gradient than the area B2 of the travel path facing away from the scissors axis. The maximum 10a of the height profile of this curved rail 10 is thus positioned closer to the said end region of the curvature or end point of the travel path, which is arranged facing the scissors axis, than in the other curved rail 10'. The height profile of this curved rail 10 is thus asymmetrical with respect to the center point of the travel path of the erection device. The other curved rail, here the rail 10' according to Fig. 5, can, for example, have a curve course that is at least substantially symmetrical to the maximum 10a. The two absolute maxima 10a of the curve areas of the two curved rails 10, 10' have at least substantially the same distance A1, A2 from the respective connecting or base line VL of the respective curve area, which defines the travel path of the positioning device. The curved rail 10 according to Fig. 5 The upper scissor leg of the lifting table arrangement is Fig. 1 arranged curve rail, the curve rail 10'of the Fig. 5 is on the lower scissor leg of the lifting table arrangement according to Fig. 1 arranged.

[0041] The lifting table has two scissors 4 laterally spaced from one another, each having at least two scissor legs 5, wherein the scissors of the scissor lifting table are constructed identically to one another and have a common scissor axis 4a.

[0042] During the lifting movement of the lifting table, the drive motor is preferably operated at a constant speed or at a speed such that, taking into account the spirally wound traction means 9, such as a belt, and thus the effective radius of the winding member 8 increasing with increasing winding of the traction means, the lifting table is moved at an at least substantially constant lifting speed over the lifting movement, up to the end regions of the respective lifting movement.Since, for a given material thickness of the traction means 9, such as a given thickness of the belt, the effective diameter of the winding member 8, i.e. the diameter of the winding member from which the traction means is tangentially guided, is geometrically predetermined, the curvature of the curved rails 10 can be corrected accordingly, so that upon rotation of the winding member for winding or unwinding the traction means, an at least substantially constant lifting speed of the traction means results at any given point of the stroke of the lifting table and / or an at least substantially constant lifting speed of the lifting table, wherein the drive motor of the lifting table drive 1 is operated at a constant speed. This applies in each case at least for a substantial part of the lifting movement, although different conditions may apply for the initial and final ranges of the lifting movement.

[0043] The term "at least substantially" is generally understood within the scope of the invention to mean that the respective variable deviates by ≤ 20% or ≤ 10%, preferably ≤ 5% or ≤ 3%, particularly preferably ≤ 2% from the respective target value or mean value.

Claims

1. Scissor lift (1), comprising at least one scissor arranged between an upper part (2) defining an upper table surface and a base part (3), the scissor (4) having at least two scissor legs (5) crossing each other in a scissor-like manner and pivotable about a scissor axis, wherein a first end section of the respective scissor leg is coupled to the upper part and a second end section of the respective scissor leg is coupled to the base part and wherein the opening angle of the scissor changes when the scissor legs are pivoted relative to each other about the scissor axis, and comprising a drive unit (6) with a drive motor for mutually pivoting the scissor legs relative to each other in order to lift or lower the table surface relative to the base part, and with an erecting member (7) the movement of which transversely to the scissor axis spreads apart or pulls together the scissor legs, wherein the erecting member is connected to the winding element (8) via a traction means (9) in a traction-absorbing manner and the traction means can be wound onto and unwound from the winding element by actuation of the winding element by means of the drive motor, wherein curved rails (10) with their curvature facing each other are arranged on at least two mutually opposite scissor leg halves of the two scissor legs which are arranged on one side of the scissor axis and are arranged facing either the upper part or the base part, wherein the erecting member is coupled to both curved rails in a power transmitting manner and can be displaced relative thereto in the longitudinal direction thereof along the curvature thereof by actuating the drive motor while winding or unwinding the traction means onto or from the winding element in order to perform the lifting movement of the scissor lift, and wherein a linkage arrangement (11) is provided which respectively couples to one of the two scissor legs on the same side of the scissor axis with at least one linkage part and interacts with it and exerts an erecting force on the respective scissor leg when the erecting member is actuated, characterized in that the traction means is designed as a spirally self-winding traction means and the curvature of the mutually facing curved rails is designed in such a way that the drive motor is loaded with constant power consumption at least over a substantial and / or the predominant part of the lifting movement when the erecting member is displaced along the two curved rails while performing the lifting movement.

2. Scissor lift according to claim 1, characterized in that, in a first part of the lifting movement of the lift table, the force for lifting the upper part is applied predominantly by the interaction of the erecting member with the curved rails and in that, in a second part of the lifting movement, the force for lifting the upper part is applied predominantly by the interaction of the erecting member with the linkage arrangement, and in that the curved rails have such a curvature that in the transition region between the first part and the second part of the lifting movement the drive motor is loaded with an at least substantially constant power consumption.

3. Scissor lift according to claim 1 or 2, characterized in that the curvatures of the curved tracks are configured in such a way that the power consumption of the drive motor over at least a significant part and / or a predominant part of the lifting movement of the upper part deviates by a maximum of + / - 10% from the mean value of the power consumption over the middle range of the lifting movement.

4. Scissor lift according to any one of claims 1-3, characterized in that the curvature of the curved tracks is designed in such a way that at a constant speed of the winding element for the traction means the lifting speed of the upper part is at least substantially constant.

5. Scissor lift according to any one of claims 1-4, characterized in that the curvatures of the curved rails on both scissor legs of the scissor, which interact with the erecting member during the lifting movement of the upper part, are different.

6. Scissor lift according to any one of claims 1-5, characterized in that, at least in the case of one or both curved rails, the height profile of the curve region interacting with the erecting member creates a travel path for the erecting member along the curved rail between the fully retracted position of the lift table and its maximum extended position and has an absolute maximum in the central region thereof and an absolute minimum at each of the end regions, and in that the height profile is asymmetrical with respect to the maximum.

7. Scissor lift according to claim 6, characterized in that the absolute maximum of the height profile in relation to the travel distance of the erecting member is arranged closer to one end of the travel distance of the erecting member along the curved rails than to the other end of the same, preferably closer to the end of the travel distance facing the scissor axis than to the end of the travel distance facing away from the scissor axis.

8. Scissor lift according to any one of claims 1-7, characterized in that it has two laterally spaced scissors, each with at least two scissor legs, the scissors of the scissor lift being of identical design to one another.