EP3922592A1 - Scissors lift - Google Patents

Abstract

The invention relates to a scissor lift table with at least one scissors arranged between an upper part defining an upper table surface and a base part with at least two scissors-like crossing scissor legs which can be pivoted about a scissor axis and which couple to the upper part and the base part, and with a drive comprising a drive motor, as well as with an erecting member for spreading the scissor legs apart, the erecting member connected to the winding member so as to absorb tensile force via a traction means, with curved rails facing each other with their curvature being arranged on at least two opposing scissor leg halves of the two scissor legs, to which the erecting member is coupled, and with a linkage arrangement with in each case at least one rod part is coupled on the same side of the scissors axis to one of the two scissor legs, according to the invention the curvature of the two curved rails facing one another n is designed in such a way that when the positioning element is moved along the two curved rails while performing the lifting movement, the drive motor is subjected to at least a substantial and / or predominant part of the lifting movement with at least essentially constant power consumption. (Fig. 1).

Description

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

Such scissor lift tables are often exposed to high loads, for example when lifting heavy objects. Here, the traction device is exposed to very high loads which, under certain circumstances, can also lead to it tearing. On the other hand, in certain applications, for example when people are or may be present on the upper part of the table during the lifting movement, a very high operational reliability of the scissor lift table must be ensured. This means that corresponding safety tolerances are often required for the lifting table. For example, in the event that the upper part is to be approved for the presence of people, a tenfold safety is required, ie that the lifting table must be designed for ten times higher forces or mechanical loads than those that occur during normal, intended operation. This also applies in particular to the safety with regard to the pulling means tearing, which is also referred to as "safety in the event of a belt break" when a belt is used as the pulling means. It goes without saying that compliance with such safety tolerances requires considerable structural and thus also cost expenditure.

Furthermore, with scissor lift tables it is often desired nowadays that they have a comparatively low energy consumption while meeting the other requirements such as, for example, a design for lifting corresponding weights. The energy consumption with frequent actuation of the lifting table can make up a substantial part of the operating costs, whereby the energy consumption should also be as low as possible for general ecological reasons.

A generic lifting table is, for example, from DE 10 2006 006 467 A1 known. Due to the linkage arrangements, which are coupled with at least one linkage part on the same side of the scissor axis to one of the scissor legs and interacts with this when the erecting member is actuated and exerts an erecting force on the respective scissor leg, this scissor lift table is particularly suitable for high loads and large lifting heights suitable. With such loads on the lifting table with high loads and great lifting heights, however, the aforementioned problems with regard to operational safety and energy-efficient operation arise in a special way.

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.

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

According to the invention, the curvatures of the two curved rails facing one another are designed in such a way that when the erecting member is moved along the two curved rails with force-transmitting coupling to this while carrying out the lifting movement, the drive motor of the drive is stressed over at least a substantial and / or over at least the predominant part of the lifting movement with at least essentially constant power consumption. The at least essentially constant power consumption ensures, on the one hand, a particularly high operational reliability of the lifting table. Power consumption peaks, which would lead to a correspondingly high load on the traction mechanism and thus make a corresponding mechanical design of the lifting table necessary, taking into account the necessary safety tolerances, are avoided. This is especially true if the upper part of the lifting table is to be suitable or approved for receiving people, where particularly high safety tolerances are required. By avoiding power peaks and the at least substantially constant power consumption of the drive motor over at least the major part of the lifting movement, the lifting table can be constructed more simply, which also saves material. Because of this material saving, on the other hand, the drive motor can be designed for lower powers or can be operated with lower power consumption, which reduces the energy consumption when the lifting table is actuated. On the other hand, however, it has been shown that the energy efficiency of the lifting table can be significantly improved, for example by ≥ 10-20% or ≥ 30%, by the even or more uniform power consumption of the drive motor itself and the corresponding avoidance of strong fluctuations in power consumption or power consumption peaks. , possibly up to 50%. Furthermore, as a result of this, the lifting table exhibits less wear, precisely because of the particularly uniform power consumption and thus also uniform or more uniform loading of moving or force-loaded, in particular tensile loaded parts, for example the traction mechanism, bearings or the like.

Due to the uniform power consumption of the drive motor due to the appropriately adapted curvature of the curved rails, which interact with the erecting element, the lifting table also has a particularly simple, durable and low-maintenance design. 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, by means of an electronic power control device, so that the drive motor is operated with controlled power. However, this makes the provision of a corresponding electronic control circuit necessary. Such a design of such a motor with power control is, however, very expensive, requires a complicated regulating and control circuit and is associated with high costs. Another essential problem of such a power-controlled electric motor is, however, that such an operating mode is not free from control errors, which, however, would in turn require a correspondingly high safety design of the lifting table. Furthermore, in the event that only an electronic power control of the electric drive motor were to take place, the forces exerted on the traction means such as a belt, in particular tensile forces, would not be mechanically precisely defined over the course of the lifting movement. It must be taken into account here that in conventional lifting tables the traction means is acted upon with different tensile forces in different areas of the lifting movement, namely depending on the respective construction and force transmission conditions during the lifting movement. However, these disadvantages are avoided in the lifting table according to the invention, since the curved rails are mechanically particularly stable and because of the adaptation of the curvature structurally exactly defined and practically not failure-prone measure is provided so that during at least the predominant part of the stroke movement the drive motor, in particular in the form of an electric motor, is operated or used with an at least substantially constant power consumption.

An "at least essentially" constant power consumption of the drive motor, with which it is stressed when performing 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 mean value of the power consumption takes place over the described essential and / or predominant part of the lifting movement or the essential or predominant part of the movement of the erecting element along the curved rail.

During the lifting movement, the drive motor is preferably operated at an at least essentially constant speed and / or the winding member for winding and / or unwinding the traction means is operated at an at least essentially constant speed. If necessary, the drive motor can thus be controlled with a speed control or speed regulation, which changes the speed to a predetermined setpoint or in relation to the lifting movement on a predetermined setpoint curve, in which the setpoint changes in a predetermined manner via the lifting movement or the position of the positioning element on the curved rails , adjusts or regulates. It goes without saying that there is a corresponding control device for the drive motor in each case for this purpose. This also enables a particularly safe mode of operation and a structurally simple design of the lifting table, in particular also with regard to the electronic control means for operating the drive motor, in particular as an electric motor.

The "at least essential part" of the lifting movement, in which the drive motor, such as the electric motor in particular, is operated or used with an at least substantially constant power consumption, is understood to be ≥ 20% or ≥ 25%, possibly ≥ 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 an electric motor, is operated or used with an at least substantially constant power consumption, is understood to be ≥ 50% or ≥ 70%, possibly ≥ 80% or at least almost 100% of the Lifting movement. The mentioned "lifting movement" is generally understood within the scope of the invention to mean the maximum lifting movement of the lifting table, that is between its maximum retracted position with a minimum distance between the upper part and the base part and its maximum extended position with a maximum distance between the upper part and the base part. If necessary, the predominant part of the lifting movement can also relate to a certain displacement position of the lifting table, in which the upper part relates to an intermediate position between its completely moved together and its completely extended position. In particular, the majority of the lifting movement can also relate to a lifting movement in which the lifting table is extended by ≥ 25% and ≤ 75% based on the maximum distance between the upper part and the base part. It goes without saying that there may be deviations in the at least essentially constant power consumption of the drive motor at the start and / or end region of the lifting movement. The "at least substantial part" or "at least predominant part" of the lifting movement mentioned in each case is preferably formed in the middle part of the lifting movement or the travel path of the erecting element along the curved rails, i.e. preferably by ≥ 5% or ≥ 10% or ≥ 15% of spaced apart from the end regions of the lifting movement or displacement movement. The statements on the stroke also apply accordingly to the travel of the erecting member along the curved rails facing each other, so that over the maximum stroke of the lifting table the erecting element moves from the start to the end point of its travel path along the curvature of the curved rails.

Due to the design of the lifting table according to the invention, in which an at least substantially constant power consumption of the drive motor is given at least over a substantial part or a predominant part of the lifting movement, practically any drive motors can be used for the drive, in particular practically any electric motors, such as direct current, AC, synchronous, asynchronous motors or the like, without being limited to them. This requires a further flexibility in the construction of the lifting table according to the respective requirements.

The determination of the curvatures of the cam tracks, through the adaptation of which the drive motor is stressed over at least a substantial part and / or the predominant part of the stroke with at least essentially constant power consumption, can, for example, be determined by computer, in particular using an iterative method such as a simulation method . For example, the travel path of the respective curved rail, over which the erecting element moves along the given curved rail while performing the lifting movement, can be divided into a plurality of grid or iteration points, which can be distributed at least essentially evenly over the length of the travel path . It goes without saying that the distribution of the raster points (iteration points) mentioned can possibly also take place unevenly over the length of the travel path or in partial areas of the same, in which, for example, larger changes in the power consumption are to be expected, which are caused by the The shape of the curved rail is to be captured and to be changed to an at least substantially constant power consumption, a denser point grid or additional grid points can be provided. For example, the travel path of a curved rail can be subdivided into 10, for example 20 or 30 or also 50 or 100 or more grid points. With regard to the respective grid point, the required curvature or the required radius of curvature can then be calculated using a suitable calculation method, as is known per se in the prior art for calculating force transmissions in a mechanical arrangement with at least essentially rigid components of a force transmission mechanism , which leads to an at least substantially constant power consumption of the drive motor. If, for example, for a given grid point along the travel path of the curved rail, a given curvature of the curved rail would result in too high a power consumption at this grid point for it to be regarded as at least essentially constant within the specified tolerances, then the Radius of curvature of one or both of the curved rails can be reduced. If the power consumption for this given grid point 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 process can optionally 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, in a first step the power consumption is equalized to a certain level, for example with a deviation of +/- 20% from the mean value of the power consumption is calculated over the entire travel path, so that then subsequently in a second calculation cycle the curvature of the curved rail is made more uniform, 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 reached under further iteration stages, for example a deviation of +/- 5% or + / - 3% of the average power consumption or the like. With an increasing iteration cycle, for example, the number of raster points over the line of curvature can also be increased. Based on the curvatures of the curved rail at the grid points determined in this way, the overall curvature of the respective curved rail can preferably be achieved, for example, by a suitable interpolation, for example a spline interpolation, in particular, for example, by a cubic spline interpolation such as a cubic C2 spline or by other suitable interpolation methods higher degree can be determined or defined.

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

In this calculation of the power consumption of the drive motor at the respective grid point, the speed given at this grid point can be taken into account, with which the positioning element is moved at this grid point along the curvature of the curved rail. In particular, an at least substantially constant or a constant speed of rotation of the winding member for winding and / or unwinding the traction means can be applied here. In particular, the speed of the winding member can also be assigned a correction factor, which takes into account that when the traction device is wound up and / or unwound, it is wound onto itself in a spiral and as a result the wound or unwound length changes with one rotation of the winding member of the traction means changes, so that, taking into account the changing diameter of the wound traction means, a constant movement speed of the traction means is corrected. Since the increase in the winding radius is known due to the given thickness of the traction device, this correction can be carried out with little effort. The "at least substantially" constant speed of the winding member and / or the pulling speed of the traction means can be +/- 20% or +/- 10%, preferably +/- 5% or +/- 3% of 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 be increased by +/- 20% or +/- 10%, preferably by +/- 5% or + / - 3% deviate from the respective mean value, which can apply to ≥ 20% or ≥ 30%, preferably ≥ 50% or ≥ 70% or ≥ 80% of the stroke movement, in particular also in the area of at least essentially constant power consumption of the drive motor.

Alternatively, for example, the curvature of the curved rails, which leads to an at least substantially 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, which largely corresponds to the lifting table to be put on the market, if necessary except for the design of the curved rails and the drive and the control and / or regulating means provided for this. Based on the model or prototype, which is the result of this experimental determination, a large number of structurally identical lifting tables can then be produced. The experimental determination can, for example, be carried out in such a way that, starting from a predetermined curvature of the curved rails of a given lifting table, the power consumption of the drive motor is measured as a function of the displacement position of the lifting table over its movement, preferably over its entire stroke. In the areas in which the power consumption exceeds or falls below a specified tolerance of the target value, the curvature of this sub-area of the curve rail can then be changed and adapted in such a way that the power consumption lies within the specified tolerance range and results in an at least substantially constant power consumption. This method can also be carried out iteratively in order to successively adapt the curvature of the curved rails over several adaptation 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 stroke movements, within the desired tolerance range. It goes without saying that after determining the curvature of the curved rails adapted in this way, the arrangement of a power consumption measuring device for the drive motor is no longer necessary for a lifting table that is brought into circulation in series, and that which is brought into circulation Lifting table can thus be designed to be particularly simple structurally.

The at least essentially constant power consumption of the drive motor over at least a substantial part and / or at least the predominant part of the lifting movement includes that at the beginning and / or at the end of the lifting movement, of course, larger deviations of the at least substantially constant value or Mean value of the power consumption over the stroke. This corresponds to the approach of the lifting table when the lifting movement is initiated and / or the end area of the lifting movement in which the power consumption is reduced in order to end the lifting movement. Said start and end ranges of the stroke movement, in which the power consumption of the drive motor deviates from the at least essentially constant value, including its specified tolerance range, can for example each independently be 15% or 10%, particularly preferably 5% of the total Amount of travel of the erecting member on the curved rails interacting with the erecting member.

The lifting table is preferably designed in such a way that, in a first partial area of the lifting movement, the force for lifting the upper part is mainly applied by the interaction of the erecting element with the curved rails and that in a second part of the lifting movement the force for lifting the upper part is predominantly due to the interaction of the erecting element is applied with the linkage arrangement, and that the curved rails have such a curvature that in the transition area between the first part and the second part of the lifting movement, the drive motor is subjected to an at least substantially constant power consumption. In particular, this transition area should be understood as an “essential part” of the lifting movement according to claim 1. As a result, the lifting table can also be moved particularly uniformly in the sub-area of the lifting movement in which the described transition of force transmission occurs, in particular also with an at least substantially constant power consumption of the drive motor. The curvature of the curved rails is particularly adapted in order to move the lifting table with at least essentially constant power consumption in this transition area as well. It has been found that this transition area is particularly critical with regard to an even lifting movement and otherwise it can lead to larger deviations or fluctuations in conventional lifting tables, such as a collapse in power consumption, which with conventional lifting tables with certain irregularities in the movement and thus, under certain circumstances, can also lead to high load stresses on the components of the lifting table, in particular the traction device, in particular due to the load change. However, this is avoided by the design of the lifting table according to the invention. This transition area of the power transmission can take place in particular in the second half or in the last third or last quarter of the maximum travel path of the erecting member along the curvature of the curved rails or the lifting movement. Said transition of the force transmission mechanisms can usually take place in the range of 60-90% or 70-80% of the travel path of the erecting element along the curvature of the curved rail, with reference to 0% of the travel path when the lifting table is fully collapsed. A substantial part of the lifting movement can also generally be present if it makes up ≥ 30% or ≥ 40% of the maximum lifting movement of the lifting table.

The curvatures of the cam tracks are preferably adapted in such a way that the lifting speed of the winding member for the traction means is at least substantially constant of the upper part is at least substantially constant. This enables a particularly uniform movement of the lifting table and also a 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 without the start and end area of the lifting movement, the curvatures of the cam tracks can be adapted and designed in such a way that the lifting speed with a tolerance of ≤ ± 10% or ≤ ± 5% at a constant speed of the winding element , preferably ≤ ± 3% or ≤ ± 2% around the mean value or setpoint fluctuates. The nominal value of the lifting speed can hereby be set by selecting the speed of the winding element.

The curvatures of the curved rails on the two scissor legs of the scissors, which cooperate with the erecting element during the lifting movement of the upper part, are preferably different. For example, one of the curved rails can have a greater mean slope in the first half of the travel path of the erecting member over the curved rail than the other curved rail and a smaller slope than the other curved rail in the second half of the travel path. Independently of this or in combination with this, the curvature of at least one or both of the curved rails of the scissor legs of a pair of scissors can be designed in such a way that the absolute maximum of the height profile in relation to the travel path of the erecting member is closer to one of the two end points of the travel path of the erecting member along the curved rails than to the other end of the travel path. For example, said absolute maximum of the height profile can be arranged closer to the end of the travel path facing the scissors axis than to the end of the travel path facing away from the scissors axis. This makes the curvature of the curved rails particularly special be easily adapted in order to enable an at least substantially uniform power consumption of the motor over the entire travel path of the erecting member or the entire stroke path. If necessary, however, the curvatures of the two curved rails on the two scissor legs of the scissors can also be the same.

The different curvature of the two curved rails, which are arranged on the two legs of a pair of scissors, can alternatively or additionally also be designed in such a way that the two curved rails each have a curved region that interacts with the erecting element and that provides a travel path for the erecting element along the curved rail between the forms fully retracted position of the lifting table with a starting point of the travel and its maximum extended position with an end point of the travel. The two curve areas of the two curved rails each have a height profile, the height profile having an absolute maximum in relation to the connecting line between the start and end point of the travel path. The absolute maxima of the two curve areas can have at least essentially the same height. The “height” of the maxima is understood here to mean the distance between the same and the respective connecting line or base line of the respective height profile of the named curve area. If necessary, the two absolute maxima of the two curved rails can also have a different distance from the respective connection or base line, for example in a curve area with an asymmetrical curve shape to the maximum, the maximum can have a greater height than the maximum of the other curved rail. As a result, the respective curve progression can be particularly adapted in each case in order to achieve the object according to the invention and / or to form an advantageous design of the lifting table, also with regard to a uniform lifting movement of the same.

The positioning element is preferably designed in such a way that it comprises a spreader 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 element preferably comprises a deflection device for the traction means such as a deflection roller, which is arranged on the rod arrangement, the longitudinal axis of the deflection roller or, accordingly, the deflection axis of the deflection device being arranged transversely or perpendicularly to the lifting direction of the lifting table. The deflection device is preferably arranged on the opposite side of the curved rails with respect to the scissor axis. The deflection device is preferably arranged on the axis of the rod arrangement which articulates the two rod parts with one another or is provided by this. The traction means is preferably fastened with one end region to the winding member so as to absorb tensile force, guided around the deflection device and fastened to the expansion roller so as to absorb tensile force, or guided around the expansion roller and fastened to a scissors arm or another area of the lifting table so as to absorb tensile force, such as, for example, also to the upper part of the same, whereby this attachment can be designed as a fixed point for the traction means. The winding element can preferably be arranged in relation to the scissors axis on the same side of the scissors as the spreading element, 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 with respect to the scissors axis the linkage arrangement provided side of the scissors be arranged. In general, when the winding member is actuated while the traction means is wound up by the traction means, a force is exerted on the erecting member or, in particular, on the spreading roller and the deflection device exerted on the linkage arrangement, which move them towards one another or apply force in the direction of one another, so that the lifting table is extended as a result. By rotating the winding element in the unwinding direction of the traction mechanism, the free length of the same protruding from the winding element is lengthened and the force applied to the expansion roller and the axis of the rod arrangement is reduced so that the lifting table retracts or contracts, preferably under its own weight.

The lifting table preferably has at least two scissors, each with at least two scissor legs which cross each other like legs and can be pivoted about a scissor axis, the at least two scissors being arranged laterally from one another on the lifting table. The two scissors are preferably designed to be identical to one another.

Figur 1:

eine schematische Darstellung eines erfindungsgemäßen Hubtisches in vollständig ausgefahrener Anordnung,

Figur 2:

eine seitliche Ansicht des Hubtisches nach Figur 1 in vollständig zusammengefahrenem Zustand,

Figur 3:

eine Darstellung des Schnittes B-B des Hubtisches gemäß Figur 2,

Figur 4:

eine Draufsicht des Hubtisches nach Figur 2,

Figur 5:

eine schematische Seitenansicht der beiden Kurvenschienen des Hubtisches nach Figur 1.

The invention is described below by way of example using an exemplary embodiment. All the features of the exemplary embodiment are also disclosed in general within the scope of the invention, either independently or in combination with one another. Show it:

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 Figure 1 when fully collapsed,

Figure 3:

a representation of the section BB of the lifting table according to Figure 2 ,

Figure 4:

a top view of the lift table according to Figure 2 ,

Figure 5:

a schematic side view of the two curved rails of the lifting table according to Figure 1 .

the Figures 1 to 5 describe an embodiment of a scissor lift table 1 according to the invention.

The scissor lift table 1 has at least one scissors 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. The respective scissors 4 have at least two scissor-like crossing arms 5 which can be pivoted about a scissor axis 4a, a first end area 5a of the respective scissor arm 5 being coupled to the upper part 2 and a second end region 5b of the respective scissor arm 5 being coupled to the base part 3 . By pivoting the scissor legs 5 about the scissors axis 5a, the opening angle of the scissors changes, the opening angle increasing by reducing the distance between the upper part and the base part and decreasing by increasing the distance between the upper part and the base part. The lifting table also has a drive 6 with a drive motor, here an electric motor 6a, for mutual pivoting of the scissor legs relative to one another in order to raise or lower the table surface relative to the base part by actuating the drive. Furthermore, a positioning member 7 is provided, through the movement of which, by means of the drive, transversely to the scissor axis 4a, the scissor legs 5 can be spread apart or contracted. The erecting element 7 is connected to the drive 6 via a traction means 9 which 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 leg halves 5c of the two scissor legs 5, which are arranged on one side of the scissor axis 4a and either facing the upper part 2 or the base part 3 are arranged with their curvature facing each other curved rails 10, wherein the erecting member 7 is coupled to or rests on both curved rails 10 and relative to these in their longitudinal direction along the curvature by actuating the drive 6 of the traction means 9 wound up or unwound through them is to perform the lifting movement of the scissor lift table.

The traction means 9 can for example be designed as one or more belts, chains or the like. The traction means is preferably designed to be deformable or flexible. The traction means preferably has no elongation in length when the lifting table is actuated. Furthermore, a linkage arrangement 11 is provided which, with at least one linkage part 11a on the same side of the scissor axis 4a, is coupled to one of the two scissor legs 5 and, when the erecting member 7 is actuated, interacts with this and exerts an erecting force on the respective scissor leg 5. The traction means is guided around a deflection device, which is used here by the axis 11b connecting the two rod parts 11a, or around another deflection device. For example, the deflection device can also be arranged longitudinally displaceably 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 on the scissor leg section (s) arranged above or below the same.

The erecting member 7 preferably engages directly on the respective section of the scissor arm 5, possibly also on a force transmission means fixed on this, which is preferably rigid, such as, for example, curved guides fixed on this. The respective linkage part 11a of the linkage arrangement 11 is designed here as a rigid component, the respective Rod part can optionally also be designed in several parts, wherein the individual rod parts can be connected to one another in an articulated manner. The respective rod part can for example also be designed as a toggle lever, wherein the deflection device can form the joint. The linkage arrangement 11 as a whole or the respective linkage part can optionally also consist of several individual parts which are coupled to one another in a force-transmitting manner. When the lifting table is fully set up, the angle of the rod part 11a fixedly attached to it 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 approx. 105 °. What is meant here is the angle open towards the scissors axis 4a. The angle between the linkage parts 11a, which interact in a force-transmitting manner with the deflecting device, with the deflecting device as the base or the angular articulation point-deflection roller axis-articulation point can generally be approx. 60 ° to 120 °, for example 75-105 ° or 80 ° to 100 °, in particular approx. 90 °. The angle enclosed by the scissor legs 5 and open towards the upper table level 2a or towards the upper part 2 can be 150 ° or 120 °, for example approx. 115 °, preferably 90 ° or optionally also 90 ° in the maximum lifting position of the lifting table be.

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

The curvature of the two facing curved rails 10 is designed in such a way that when the erecting member 7 is moved along the two curved rails 10 while performing the lifting movement, the drive motor of the drive 6 over at least a substantial part and / or at least the predominant part of the lifting movement with at least substantially constant power consumption.

The predominant part of the travel path of the erecting member 7 along the curved rails with at least substantially constant power consumption of the drive motor 6a is arranged here in the central area of the travel path and extends over approximately 80% of 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 essentially the same length.

The curvature of the cam tracks 10 embodied according to the invention can take place, for example, by a computational simulation of the stroke movement or the power consumption of the drive motor or can be determined by means of such a simulation. This is possible because the lifting table is made up of at least essentially rigid components - with the exception of the traction mechanism - so that a mechanically defined system is present due to the given lever ratios and force transmission ratios between the components. The curve rails can therefore be defined or approximated with regard to their curvature by a grid of points (iteration points), so that the force relationships can be calculated over the stroke movement in each grid point. The curvature of the curved rails 10 can thus be adapted or configured in such a way that the power consumption of the drive motor is at least substantially constant within each grid point of the given tolerance range. This process can be repeated with an increasingly reduced tolerance range. The overall curve of the curvature course of the respective curved rail can then be determined or defined, for example, by a suitable interpolation, for example a spline interpolation such as, for example, a cubic spline interpolation. The course of the line of curvature of the curved paths, over their entire travel path of the drive element along the curved rails, is thereby different from the shape of a circular arc section or elliptical section, as is usually found in conventional lifting tables of the generic type.

The course of the lines of curvature of the two curved paths 10 on opposite scissor legs 5 of the scissors 4, which interact with the erecting element 7, deviates from the shape of a circular arc, elliptical and hyperbolic section, or generally a section of the curvature of a conical section, and can each have one or have several turning points.

The lifting table 1 is also designed in such a way that in a first part of the lifting movement the force for lifting the upper part 2 is mainly applied by the interaction of the erecting element 7 with the curved rails 10 and in a second part of the lifting movement the force for lifting the upper part is mainly applied by the interaction of the erecting member with the rod arrangement 11 is applied, the curved rails 10 with the curvatures facing one another having such a curvature that the drive motor is subjected to an at least substantially constant power consumption in the transition area between the first part and the second part of the lifting movement. This transition area should be understood as an "essential part" of the lifting movement, since it is particularly technical Is important for the operation of the lifting table. This transition area lies here in the area of the travel path of the erection element along the curved rails, which is spaced from the end area of the travel path when the lifting table is fully collapsed by 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 distance when the lifting table is completely closed. This transition area can make up 20-30% of the travel path of the erecting element along the curved rails, without being restricted to this, whereby the "travel path" - also generally within the scope of the invention - is understood to mean the maximum travel path over the maximum lifting movement of the lifting table. It goes without saying that when the lifting table is only partially extended, the aforementioned transition area is preferably designed accordingly. It goes without saying that this can or is given in combination with the formation of the curvature of the curved rails, which results in an at least substantially constant power consumption of the drive motor over the predominant part of the lifting movement, but also independently of this. The general remarks on the curvature of the curved rails according to the invention therefore also apply to this variant.

The power consumption of the drive motor over a substantial and predominant part of the travel path of the erecting element along the curve rail from the beginning to the end point of the maximum lifting movement of the lifting table or just about the lifting movement fluctuates according to the embodiment by no more than 3% around the mean value. The curve area of the respective curved rail, at which there is an at least substantially constant power consumption of the drive motor, can extend, for example, over 70-80% of the length of the travel path of the positioning member along the curved rails. The two end areas of the travel path at which the power consumption of the motor deviates from the mean value of the essentially constant curve, can in each case represent 10% of the total length of the respective curve shape.

The curvature of the cam tracks is adapted in such a way that at a constant speed of the winding element for the traction mechanism, the lifting speed of the upper part is at least essentially constant, here by no more than 5-10% except for the beginning and end of the lifting movement of the lifting table, for example, deviates by approx. 2-3% from the mean value over the traversing movement.

The curvatures of the curved rails on the two scissor legs 5, which interact with the positioning member 7 during the lifting movement of the upper part 2, are different here, see also Figure 5 with a schematic side view of the two curved rails of the lifting table Figure 1 . Both curved rails 10 have a height profile which forms a travel path along which the erecting member 7 is moved to carry out the lifting movement of the lifting table, with an absolute maximum 10a in the middle area of the longitudinal extension of the curved rails or the travel path and an absolute maximum 10a at the end regions of the same an absolute minimum 10b of the height profile is formed. The straight connection between the two end points of said travel path, precisely the absolute minima 10b of the curve area, defines a connection or base line VL. The end points or end areas are here the contact points or the center of the contact area of the erecting member on the curve area. The absolute minima 10b of the travel path are present when the lifting table is fully collapsed or fully extended. The area B1 of the height area between the absolute maximum 10a and the absolute minimum 10b facing the scissor axis 4a on a curved rail, here the curve rail 10 after Fig. 5 , has a larger mean slope than the area B2 of the travel path facing away from the scissor axis. The maximum 10a of the height profile of this curved rail 10 is thus positioned closer to the named end region of the curve profile or end point of the travel path, which is arranged facing the scissor axis, than in the case of 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 erecting member. The other curved rail, here the rail 10 'according to Fig. 5 , can for example have a curve 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 essentially the same distance A1, A2 from the respective connection or base line VL of the respective curve area that defines the travel path of the positioning member. The curved rail 10 according to Fig. 5 is here the one on the upper scissor arm of the lifting table arrangement Fig. 1 arranged curved rail, the curved rail 10 'of the Fig. 5 is on the lower scissor arm of the lifting table arrangement Fig. 1 arranged.

The lifting table has two scissors 4 laterally spaced apart from one another, each with at least two scissor legs 5, the scissors of the scissor lifting table being constructed identically to one another and having a common scissor axis 4a.

During the lifting movement of the lifting table, the drive motor is preferably operated at a constant speed or at a speed so that, taking into account the traction means 9, such as a belt strap, which winds itself up in a spiral, and thus the effective radius increases with increasing winding of the traction means of the winding member 8, the lifting table is moved with an at least substantially constant lifting speed over the lifting movement, except for the end regions of the respective lifting movement. Since for a given material thickness of the traction means 9, such as the given thickness of the belt strap, the effective diameter of the winding member 8, i.e. the diameter of the winding member from which the traction means is tangentially removed, is geometrically predetermined, the curvature of the curved rails 10 can be corrected accordingly, so that at Rotation of the winding member for winding or unwinding the traction means results in an at least substantially constant lifting speed of the traction means at any given point of the stroke of the lifting table and / or an at least substantially constant lifting speed of the lifting table, the drive motor of the lifting table drive 1 at a constant speed is operated. This applies in each case to at least a substantial part of the lifting movement, with other circumstances being able to exist for the starting area and the end area of the lifting movement.

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 (8)

Scissor lift table with at least one pair of scissors arranged between an upper part defining an upper table surface and a base part, the scissors having at least two scissor-like intersecting scissor legs which can be pivoted about a scissor axis, a first end area of the respective scissor leg on the upper part and a second end area of the respective scissor legs coupled to the base part and whereby the opening angle of the scissors changes by pivoting the scissor legs relative to each other about the scissor axis, and with a drive comprising a drive motor for mutual pivoting of the scissor legs to each other in order to raise or lower the table surface relative to the base part, and with an erecting element, through the movement of which transversely to the scissors axis, the scissor legs can be spread apart or contracted, the erecting element being connected to the winding element via a traction means to absorb tensile force and that Pulling means can be wound up and unwound on the winding element by actuating the winding member by means of the drive motor, with the two scissor leg halves, which are arranged on one side of the scissor axis and on at least two opposing scissor leg halves either the upper part or the base part are arranged facing each other with their curvature facing curved rails, wherein the erecting element is coupled to both curved rails in a force-transmitting manner and opposite these in their longitudinal direction along the curvature of the same by means of actuation of the drive motor while winding or unwinding the traction means on the winding element can be moved in order to carry out the lifting movement of the scissor lift table, and a linkage arrangement is provided which couples with at least one linkage part on the same side of the scissors axis to one of the two scissor legs and interacts with this when the erecting member is actuated and a erecting force on the respective scissor leg exercises, characterized in that the curvature of the two facing curved rails is designed in such a way that when the positioning member is moved along the two curved rails, the lifting movement is carried out the drive motor is stressed over at least a substantial and / or the predominant part of the lifting movement with at least essentially constant power consumption. Scissor lift table according to claim 1, characterized in that in a first part of the lifting movement of the lifting table the force for lifting the upper part is predominantly applied by the interaction of the erecting member with the curved rails and that in a second part of the lifting movement the force for lifting the upper part is mainly applied by the interaction of the erecting element with the rod arrangement is applied, and that the curved rails have such a curvature that in the transition area between the first part and the second part of the lifting movement Drive motor is claimed with an at least substantially constant power consumption. Scissor lift table according to claim 1 or 2, characterized in that the curvatures of the cam tracks are designed in such a way that the power consumption of the drive motor over at least a substantial part and / or a predominant part of the lifting movement of the upper part by a maximum of +/- 10% around the mean value of the Power consumption deviates over the middle range of the lifting movement. Scissor lift table according to one of Claims 1-3, characterized in that the curvature of the cam tracks is designed in such a way that the lifting speed of the upper part is at least substantially constant at a constant speed of the winding member for the traction means. Scissor lift table according to one of Claims 1-4, characterized in that the curvatures of the curved rails on the two scissor legs of the scissors, which interact with the positioning element during the lifting movement of the upper part, are different. Scissor lift table according to one of claims 1-5, characterized in that at least in one or both curved rails, the height profile of the curve area cooperating with the erecting element forms a travel path for the erecting element along the curved rail between the fully retracted position of the lifting table and its maximally extended position and in the middle area of the same has an absolute maximum and in each case an absolute minimum at the end areas, and that the height profile is asymmetrical with respect to the maximum. Scissor lift table according to claim 6, characterized in that the absolute maximum of the height profile in relation to the travel path of the erecting member is arranged closer to one end of the travel path of the erecting member along the curved rails than to the other end of the same, preferably closer to the end facing the scissor axis of the travel path is arranged as the end of the travel path facing away from the scissors axis. Scissor lift table according to one of claims 1-7, characterized in that it has two scissors spaced laterally from one another, each with at least two scissor legs, the scissors of the scissor lift table being constructed identically to one another.

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