Lifting device

Abstract

The invention relates to a lifting device for raising and lowering a work platform (2) relative to a base frame (3), comprising a base frame (3), a work platform (2), at least one first stationary linear guide rail (4.1) attached to the base frame (3) at an acute angle, and at least one second stationary linear guide rail (4.2) attached to the base frame (3) at the same acute angle and mirror-symmetrically to the first stationary linear guide rail (4.1), at least one first movable linear guide rail (5.1) connected to the work platform (2) at an opposite acute angle, and at least one second movable linear guide rail (5.2) connected to the work platform (2) at an acute angle and mirror-symmetrically to the first movable linear guide rail (5.1), as well as at least one first sliding block element (6.1) comprising a first sliding block body (6a) which is mounted in a longitudinally adjustable manner on the first stationary linear guide rail (4.1) and a second sliding block body (6b) which is mounted in a longitudinally adjustable manner on the first movable linear guide rail (5.1) and at least a second sliding block element (6.2) comprising a third sliding block body (6c) which is mounted in a longitudinally adjustable manner on the second stationary linear guide rail (4.2) and a fourth sliding block body (6d) which is mounted in a longitudinally adjustable manner on the second movable linear guide rail (5.2).

Description

The invention relates to a lifting device for raising and lowering a working platform relative to a base frame.EP 1 190 981 A1 describes a scissor lift table having a lower frame, an upper frame forming a working plane or a table, and a scissor mechanism acting between the lower frame and the upper frame, wherein the scissor mechanism comprises intersecting inner and outer scissor members which can be actuated for raising or lowering the upper frame, and wherein drive means are assigned to at least one pair of the intersecting scissor members, and wherein two cams are assigned to the one scissor member and two carriages, slides or the like which can be moved towards and away from one another along the scissor member on the cams are assigned to the one scissor member and two carriages, slides or the like as drive means which can be moved towards and away from one another along the scissor member.EP 2 019 076 A1 describes a scissor lift device having at least two scissor members connected in pairs by a pivot axis, wherein the pivot axis is arranged between the respective end sections of the scissor members, and having a drive for raising and lowering the scissor members by means of a traction means, wherein the scissor lift device is equipped with two coupling bridges connected by a guide and with shear struts arranged pivotably on a coupling bridge, which are each pivotably connected to a scissor member, wherein at least one coupling bridge carries a deflection roller for the traction means, and wherein the one coupling bridge is equipped with the shear struts, which are each connected to a scissor member on a common side with respect to the pivot axis, and the other coupling bridge is equipped with an expansion body, which, on a side facing away from the thrust braces, bears with respect to the pivot axis against two curved contact paths which are each assigned to a scissor member.DE 20 2015 003 870 U1 describes a lifting device for lifting and lowering motor vehicles, comprising a receiving plate and a lifting mechanism which has a lifting drive, a first and a second frame, wherein the first and the second frame are designed to be displaceable relative to one another by means of the lifting drive and the lifting drive, the first and the second frame are arranged in a common horizontal plane, and wherein the first and the second frame are each connected to the receiving plate by means of at least four upper lifting rods, and wherein the first and the second frame are each connected to a floor support by means of at least four lower lifting rods, and wherein a first spreading element is provided which is provided between a first side of the lifting drive and the first frame.It is an object of the invention to provide a lifting device for raising and lowering a working platform relative to a base frame, which device, in a lowered state, has a compact structure and is constructed from the simplest possible, in particular cost-effective machine elements.The object is achieved by a lifting device for raising and lowering a working platform relative to a base frame, comprising:a base frame,a working platform,at least one first stationary linear guide rail fastened at an acute angle to the base frame and at least one second stationary linear guide rail fastened at the same acute angle mirror-symmetrically to the first stationary linear guide rail on the base frame,at least one first stroke-movable linear guide rail connected to the working platform at an opposite acute angle and at least one second stroke-movable linear guide rail connected to the working platform at an acute angle mirror-symmetrically to the first stroke-movable linear guide rail, andat least one first sliding block element, which has a first sliding block body, which is mounted on the first stationary linear guide rail in a longitudinally adjustable manner and has a second sliding block body, which is mounted on the first linear guide rail in a longitudinally adjustable manner, andat least one second sliding block element, which has a third sliding block body, which is mounted on the second stationary linear guide rail in a longitudinally adjustable manner and has a fourth sliding block body, which is mounted on the second linear guide rail in a longitudinally adjustable manner in a stroke-movable manner.The base frame can have a base plate, a supporting frame or other supporting means, by means of which the entire lifting device can be set up at a desired location. The desired space may be a fixed area, such as the floor in a building or hall. Instead of a stationary placement of the lifting device, however, the lifting device can also be mounted on a vehicle. For this purpose, the lifting device can be fastened to a chassis or chassis of the vehicle by means of the base frame. The base frame of the lifting device can then optionally also be a component of the vehicle. The vehicle may be, for example, a sensorless transport vehicle, in particular an autonomous vehicle. The vehicle can be equipped, for example, with omnidirectional wheels in order to be able to move the lifting device not only in the plane, but also to be able to rotate or turn about arbitrary pivot points. The base frame can thus also comprise fastening means or form these in order to be able to fasten the lifting device to the vehicle.The working platform can form a working platform with a closed surface or a support platform. Objects, such as components, can be stored and transported on this working platform in a manufacturing and / or assembly environment, for example. By raising the working platform, such objects can be picked up. By lowering the working platform, these transported objects can be deposited again. The lifting device can optionally also be used to be able to position the lifted object accurately in its relative height position with respect to another object. The working platform can, however, also be formed by a frame or other supporting bodies which are to be adjusted in height relative to the base frame. If necessary, the lifting device can be a component integrated into a larger device or machine, which has the task of carrying out a lifting movement. The working platform can thereby form a connection means, on which components to be adjusted in height can be attached. In this case, the work which the working platform is intended to perform is the height adjustment of this connected component.At least one first stationary linear guide and one second stationary linear guide are fastened to the base frame. In the simplest embodiment, a single first stationary linear guide and a single second stationary linear guide may be sufficient if appropriate. In a further developed embodiment, exactly two first stationary linear guides and exactly two second stationary linear guides can be fastened to the base frame. In such an embodiment, a first pair of a first stationary linear guide and a second stationary linear guide can be arranged on the one lateral edge region of the lifting device or on the one lateral edge region of the base frame and of the working platform, and a second pair of a first stationary linear guide and a second stationary linear guide can be arranged on the opposite other lateral edge region of the lifting device or on the opposite other lateral edge region of the base frame and of the working platform. In an embodiment which is still further developed, three or even more pairs of first stationary linear guides and second stationary linear guides can be arranged, for example, on the one lateral edge region of the lifting device or on the one lateral edge region of the base frame and of the working platform in order to absorb very high loads.The respective first stationary linear guide rail is fastened to the base frame at an acute angle. This means that the first stationary linear guide rail extends with its longitudinal extension, which specifies the adjustment direction for the first sliding block element adjustably mounted on the first stationary linear guide rail, at an acute angle to the horizontal plane of the base frame. The respective first stationary linear guide rail is rigidly fastened to the base frame. The first stationary linear guide rail can therefore not move relative to the base frame or rotate or pivot relative to the base frame.Likewise, the respective second stationary linear guide rail is fixed to the base frame at an acute angle. This means that the second stationary linear guide rail extends with its longitudinal extension, which specifies the adjustment direction for the second sliding block element adjustably mounted on the second stationary linear guide rail, at an acute angle to the horizontal plane of the base frame. The respective second stationary linear guide rail is rigidly fastened to the base frame. The second stationary linear guide rail can therefore not move relative to the base frame or rotate or pivot relative to the base frame.The size of the acute angle can in principle be freely selected. The acute angle can lie in particular in the range between 5 and 45 degrees. The size of the acute angle determines the translation of the linear movement length of the respective sliding block element along the stationary linear guide rail in relation to the lifting height which the working platform carries out during an adjustment of the sliding block elements. The ratio of the linear movement length of the respective sliding block element along the stationary linear guide rail to the lifting height which the working platform executes during an adjustment of the sliding block elements is linear over the entire adjustment path. This represents a particular advantage which the lifting device according to the invention has compared to the known designs of scissor lifting devices. In conventional scissor-type lifting devices, the angles of attack of the scissors change continuously due to their construction, wherein in a low starting position the scissors are in a highly flat angular position from which the scissors must emerge in order to be able to assume larger angular positions. This leads to excessive drive forces in drives of the scissors lifting devices, which are intended to move the scissors automatically in a driven manner in order to lift the lifting tables, i.e. the working platform. Therefore, in the known scissors-type lifting devices, the drives must also be designed to be relatively powerful in order to be able to move the scissors out of the low starting position. Hydraulic drives are often therefore provided there, which however have the disadvantage that they require complex additional units and their overall size is relatively large and therefore the entire overall size of the lifting device cannot be particularly flat.The lifting device according to the invention is, however, based on another lifting principle, in which the lifting speed and the lifting forces behave linearly, so that even in a low position of the working platform, in particular also in the lowest position of the working platform, the driving force is constant at the same lifting speed. Thus, lower-power drives can be used, which are also more cost-effective and which have a smaller overall size. As a result, a lifting device can be created which has a particularly low overall height in its low starting position.A first stationary linear guide rail and a second stationary linear guide rail are always arranged in opposite directions with their acute angle alignments. This means that, for example, the first stationary linear guide rail extends obliquely from an edge region of the base frame in the direction of the center of the lifting device in an ascending orientation, and the second stationary linear guide rail extends obliquely from an opposite edge region of the base frame also in the direction of the center of the lifting device in an ascending orientation. The first stationary linear guide rail thus points upwards towards the second stationary linear guide rail. The first stationary linear guide rail and the second stationary linear guide rail preferably lie with their longitudinal extents in the same vertical plane. The second stationary linear guide rail is accordingly arranged mirror-symmetrically with respect to the first stationary linear guide rail.In a modified embodiment, the first stationary linear guide rail can extend obliquely from a central region of the lifting device in the direction of an edge region of the base frame in an ascending orientation, and the second stationary linear guide rail can extend obliquely from a likewise central region of the lifting device in the direction of an opposite edge region of the base frame in an ascending orientation. The first stationary linear guide rail thus points upwards away from the second stationary linear guide rail. The first stationary linear guide rail and the second stationary linear guide rail are also preferably located with their longitudinal extents in the same vertical plane. In this case, too, the second stationary linear guide rail is arranged mirror-symmetrically with respect to the first stationary linear guide rail.The first linearly movable guide rail that can be moved in a stroke manner and the second linearly movable guide rail that can be moved in a stroke manner are connected to the working platform. The first linear guide rail, which can move in a stroke, is arranged at an acute angle opposite to the first stationary linear guide rail. In the same way, the second linearly guide rail, which can move in a stroke, is arranged at an acute angle opposite to the second stationary linearly guide rail.The first sliding block element comprises the first sliding block body and the second sliding block body. The first sliding block body and the second sliding block body are connected to one another by the first sliding block element.The second sliding block element comprises the third sliding block body and the fourth sliding block body. By the second sliding block element, the third sliding block body and the fourth sliding block body are connected to each other.In an embodiment variant in which the first linearly guide rail that can be moved in a stroke manner and the second linearly guide rail that can be moved in a stroke manner are also rigidly connected to the working platform, the first sliding block body and the second sliding block body can likewise be rigidly connected to one another. Optionally, the first slider body and the second slider body may be manufactured as a one-piece first slider element. In the same way, the third sliding block body and the fourth sliding block body can likewise be rigidly connected to one another. If appropriate, the third sliding block body and the fourth sliding block body can also be produced as a one-piece second sliding block element.The lifting mobility of the first lifting linear guide rail and the second lifting linear guide rail results from the fact that the respective lifting linear guide rail is rigidly connected to the working platform and it thus rises or lowers with the working platform, or from the fact that at least the respective end section of the respective lifting linear guide rail coupled to the working platform rises or lowers together with the working platform.In order to raise or lower the working platform relative to the base frame, the at least one first sliding block element and the at least one second sliding block element are adjusted relative to one another in a horizontal plane. The horizontal plane extends parallel to the plane of the working platform or parallel to the plane of the base frame.If the first stationary linear guide rail extends obliquely from an edge region of the base frame in the direction of the center of the lifting device in an ascending orientation and the second stationary linear guide rail extends obliquely from an opposite edge region of the base frame also in the direction of the center of the lifting device in an ascending orientation, the working platform is raised relative to the base frame in that the first sliding block element and the second sliding block element are moved towards one another. Accordingly, the working platform is lowered relative to the base frame by moving the first slide block element and the second slide block element away from each other.If the first stationary linear guide rail extends obliquely from a central region of the lifting device in the direction of an edge region of the base frame in an ascending orientation and the second stationary linear guide rail extends obliquely from a likewise central region of the lifting device in the direction of an opposite edge region of the base frame in an ascending orientation, the working platform is raised relative to the base frame by the first sliding block element and the second sliding block element being moved away from one another. Accordingly, the working platform is lowered relative to the base frame by moving the first sliding block element and the second sliding block element towards each other.The moving towards each other and the moving away from each other of the first sliding block element and the second sliding block element can be carried out automatically by at least one drive device. In principle, electric drives, hydraulic drives or pneumatic drives can be used as desired for this purpose. For a very compact construction with as few drive components as possible, electrical drives are particularly suitable.The respective selected drive device may comprise a respective motor which generates a drive torque. The drive device can comprise a wide variety of articulated couplings and / or transmission types in order to convert the drive torque provided by the motor into a couple of forces which respectively move the first sliding block element and the second sliding block element in opposite directions. Thus, the drive device may comprise a spindle driven by the drive torque of the motor and transmitting a respective linear axial force to the first slider element and the second slider element. However, the drive device may also comprise ropes, chains or belts, which convert the drive torque of the motor into a respective linear movement of the first sliding block element and the second sliding block element.The first stationary linear guide rail, the second stationary linear guide rail, the first stroke-movable linear guide rail and / or the second stroke-movable linear guide rail can each be formed by a respective profile guide rail which has an outer guide surface and the respectively corresponding first sliding block body, second sliding block body, third sliding block body and / or fourth sliding block body can be formed by a guide slide which runs on the respective profile guide rail and has an inner counter guide surface.The respective profile guide rail can be, for example, a T guide rail or a differently configured guide rail, for example having a C-shaped or a circular profile. The respective profile guide rail can be designed as an individual rail or, for example, also as a double rail with two profile bodies. A sliding film can be inserted between the respective profile guide rail and the respectively corresponding first sliding block body, second sliding block body, third sliding block body and / or fourth sliding block body, in order to be able to keep the friction between the sliding pairings as low as possible.Alternatively, the first stationary linear guide rail, the second stationary linear guide rail, the first stroke-movable linear guide rail and / or the second stroke-movable linear guide rail can each be formed by a respective profiled sliding block guide rail which has an inner guide surface and the respectively corresponding first sliding block body, second sliding block body, third sliding block body and / or fourth sliding block body can be formed by a sliding block running in the respective profiled sliding block guide rail and having an outer counter-guide surface.Here, too, the respective profile guide rail can be, for example, a T-slot guide rail or a differently configured slot guide rail, for example having a C-shaped or a circular profile. The respective profile groove guide rail can be designed as an individual rail or, for example, also as a double rail with two profile bodies. A sliding film can be inserted between the respective profile groove guide rail and the respectively corresponding first sliding block body, second sliding block body, third sliding block body and / or fourth sliding block body, in order to be able to keep the friction between the sliding pairings as low as possible.The acute angle between the base frame and the first stationary linear guide rail, the acute angle between the base frame and the second stationary linear guide rail, the acute angle between the working platform and the first linearly movable rail, and the acute angle between the working platform and the second linearly movable rail can each be between 5 and 40 degrees, in particular between 10 and 20 degrees.In the case of an embodiment in which the first linear guide rail that can be moved in a stroke and the second linear guide rail that can be moved in a stroke are rigidly fastened to the working platform, the respective acute angles, not only of the stationary linear guide rails but also of the linear guide rails that can be moved in a stroke, are always constant.In the case of an embodiment in which the first linearly movable guide rail that can be moved in a stroke and the second linearly movable guide rail that can be moved in a stroke are pivotably mounted on the working platform, only the acute angles of the stationary linearly movable guide rails are constant. In this embodiment, the stroke-movable linear guide rails pivotably mounted on the working platform can also assume angles greater than 40 degrees.The lifting device can have at least one drive device which is designed for automatic adjustment of the at least one first sliding block element and the at least one second sliding block element relative to one another.The moving towards each other and the moving away from each other of the first sliding block element and the second sliding block element can be carried out automatically by at least one drive device. In principle, electric drives, hydraulic drives or pneumatic drives can be used as desired for this purpose. For a very compact construction with as few drive components as possible, electrical drives are particularly suitable.The respective selected drive device may comprise a respective motor which generates a drive torque. The drive device can comprise a wide variety of articulated couplings and / or transmission types in order to convert the drive torque provided by the motor into a couple of forces which respectively move the first sliding block element and the second sliding block element in opposite directions. Thus, the drive device may comprise a spindle driven by the drive torque of the motor and transmitting a respective linear axial force to the first slider element and the second slider element. However, the drive device may also comprise ropes, chains or belts, which convert the drive torque of the motor into a respective linear movement of the first sliding block element and the second sliding block element.The at least one drive device can be configured for synchronously adjusting the at least one first sliding block element and the at least one second sliding block element in opposite directions.In order to ensure that the working platform remains in its horizontal orientation during a raising and / or lowering and does not tilt in an undesired manner, and / or in order to ensure that the kinematic mechanism does not tilt or jam, the movements of the first sliding block element and of the second sliding block element can be coupled. Such a coupling can be effected, for example, mechanically via a corresponding coupling joint or via a transmission.If the first sliding block element is moved by means of its own first drive and the second sliding block element is moved by means of its own second drive, the two drives can also be coupled by control, for example in the case of electric drives.The drive device may comprise a motor and a spindle driven by the motor, which spindle adjustably couples the first sliding block element to the second sliding block element relative to one another.Such a motor-spindle unit can comprise, for example, an electric motor. In a concrete variant embodiment, the spindle can be designed as an extension of the motor shaft. This means that the spindle does not move in its axial direction relative to the motor housing. In such an embodiment variant, the spindle can, for example, carry a spindle nut which can be linearly adjusted in the axial direction to the spindle by a rotational movement of the spindle driven by the motor. The spindle nut can be connected to the first sliding block element, for example, or can be formed integrally with the first sliding block element, and the motor housing can be connected to the second sliding block element.In an alternative specific embodiment variant, the spindle can be mounted axially displaceably within the motor housing. This means that, during a rotation of the motor shaft, which in this case is then designed as a hollow shaft in which the spindle runs, the spindle is adjusted in the axial direction relative to the motor housing. In this case, the one end of the spindle can be coupled rotatably, for example, to the first sliding block element, and the motor housing can be connected to the second sliding block element.The first stroke-movable linear guide rail can be fastened to the working platform at a fixed acute angle and the second stroke-movable linear guide rail can be fastened to the working platform at the same fixed acute angle in mirror symmetry with the first stroke-movable linear guide rail, wherein the first sliding block body and the second sliding block body are rigidly connected to one another to form the first sliding block element and the third sliding block body and the fourth sliding block body are rigidly connected to one another to form the second sliding block element.A rigid connection both of the first stationary linear guide rail and the second stationary linear guide rail and of the first stroke-movable linear guide rail and of the second stroke-movable linear guide rail always ensures an exact parallel alignment of the working platform with respect to the base frame. If the base frame is set up on a horizontal plane, it is thus also ensured that the working platform is always in the horizontal orientation, i.e. at each adjustable lifting height.At least one first drive device can be integrated into the first stationary linear guide rail and / or into the first linear guide rail that can be moved in a stroke manner and can be designed for the driven adjustment of the first sliding block element, and at least one second drive device can be integrated into the second stationary linear guide rail and / or into the second linear guide rail that can be moved in a stroke manner and can be designed for the driven adjustment of the second sliding block element.In such an embodiment, the first drive device and the second drive device can be linear drives. The respective linear drive can be an electric linear drive. The respective linear drive can be driven by means of spindles, belts, in particular toothed belts or toothed racks. The motor required for this purpose may be an electric motor.The at least one first linear drive and the at least one second linear drive can be coupled in terms of control technology, for example in the case of electric drives, such that the lifting movement on the first stationary linear guide rail and the first linearly guide rail which can be moved in a lifting manner can be adapted to the lifting movement on the second stationary linear guide rail and the second linearly guide rail which can be moved in a lifting manner, i.e. can be synchronised.The first linear guide rail that can be moved in a stroke can be mounted on the working platform such that it can be pivoted at an acute angle and the second linear guide rail that can be moved in a stroke can be mounted on the working platform such that it can be pivoted at an acute angle in a mirror-symmetrical manner with respect to the first linear guide rail that can be moved in a stroke, and / or the first sliding block body and the second sliding block body are connected to one another in a rotary joint in order to form the first sliding block element, and the third sliding block body and the fourth sliding block body are connected to one another in a rotary joint in order to form the second sliding block element.In such a special development of the invention, tilting of the working platform can also be carried out in a targeted manner by a different adjustment of the first sliding block element and of the second sliding block element. Nevertheless, by synchronously moving the first sliding block element and the second sliding block element, a purely horizontally oriented raising and lowering of the working platform can be carried out.Specific exemplary embodiments of the invention are explained in more detail in the following description with reference to the appended figures. Specific features of these exemplary embodiments may represent general features of the invention, if appropriate also individually or considered in further combinations, regardless of the specific context in which they are mentioned.The following are shown: FIG. 1 is a perspective view of a basic embodiment of a lifting device according to the invention, FIG. 2 shows a first embodiment of a lifting device with rigidly fastened stationary and stroke-movable linear guide rails in a lifted configuration, FIG. 3 shows the first embodiment of a lifting device according to FIG. 2 with rigidly fastened stationary and stroke-movable linear guide rails in a lowered configuration, FIG. 4 shows a second embodiment of a lifting device with rigidly fastened stationary linear guide rails which are movably mounted on the working platform and which can be moved in a lifting manner in an obliquely raised configuration, and FIG. 5 shows the second embodiment of a lifting device according to FIG. 4 with rigidly fastened stationary linear guide rails which are mounted movably on the working platform and which can be moved in a lifted configuration.FIGS. 1 to 5 show various embodiments of lifting devices 1.The respective lifting device 1 serves for raising and lowering a working platform 2 relative to a base frame 3, whereby a compact structure is created in a lowered state and the lifting device 1 is constructed from the simplest possible machine elements.FIG. 1 shows a lifting device 1 for raising and lowering a working platform 2 relative to a base frame 3.The lifting device 1 comprises at least one first stationary linear guide rail 4.1 fastened to the base frame 3 at an acute angle and at least one second stationary linear guide rail 4.2 fastened to the base frame 3 at the same acute angle in mirror symmetry with the first stationary linear guide rail 4.1.In the case of the present exemplary embodiments, the lifting device 1 has exactly two first stationary linear guides 4.1 and exactly two second stationary linear guides 4.2. In such an embodiment, a first pair of a first stationary linear guide 4.1 and a second stationary linear guide 4.2 can be arranged on the one lateral edge region of the lifting device 2 or on the one lateral edge region of the base frame 3 and of the working platform 2, and a second pair of a first stationary linear guide 4.1 and a second stationary linear guide 4.2 can be arranged on the opposite other lateral edge region of the lifting device 1 or on the opposite other lateral edge region of the base frame 3 and of the working platform 2.The lifting device 1 also comprises at least one first linearly movable guide rail 5.1 connected to the working platform 2 at an opposite acute angle and at least one second linearly movable guide rail 5.2 connected to the working platform 2 at an acute angle in mirror symmetry with the first linearly movable guide rail 5.1.In the case of the present exemplary embodiments, the lifting device 1 has exactly two first linear guides 5.1 that can be moved in a lifting manner and exactly two second linear guides 5.2 that can be moved in a lifting manner. In such an embodiment, a first pair of a first linear guide 5.1 that can be moved in a stroke manner and a second linear guide 5.2 that can be moved in a stroke manner can be arranged on the one lateral edge region of the lifting device 2 or on the one lateral edge region of the base frame 3 and of the working platform 2, and a second pair of a first linear guide 5.1 that can be moved in a stroke manner and a second linear guide 5.2 that can be moved in a stroke manner can be arranged on the opposite other lateral edge region of the lifting device 1 or on the opposite other lateral edge region of the base frame 3 and of the working platform 2.The lifting device 1 furthermore comprises at least one first sliding block element 6.1, which has a first sliding block body 6 a, which is mounted on the first stationary linear guide rail 4.1 in a longitudinally adjustable manner and which has a second sliding block body 6 b, which is mounted on the first linearly guide rail 5.1 in a longitudinally adjustable manner.The lifting device 1 also comprises at least one second sliding block element 6.2, which has a third sliding block body 6c, which is mounted on the second stationary linear guide rail 4.2 in a longitudinally adjustable manner and which has a fourth sliding block body 6d, which is mounted on the second linearly guide rail 5.2 in a longitudinally adjustable manner.In the case of the present exemplary embodiments, the first stationary linear guide rail 4.1, the second stationary linear guide rail 4.2, the first stroke-movable linear guide rail 5.1 and the second stroke-movable linear guide rail 5.2 are formed by a respective profile guide rail which has an outer guide surface, wherein the respectively corresponding first sliding block body 6 a, the second sliding block body 6 b, the third sliding block body 6 cand the fourth sliding block body 6 dare each formed by a guide slide which runs on the respective profile guide rail and has an inner counter-guide surface.However, the configuration of each guide rail assembly could be reversed.Thus, the first stationary linear guide rail 4.1, the second stationary linear guide rail 4.2, the first stroke-movable linear guide rail 5.1 and the second stroke-movable linear guide rail 5.2 could be formed by a respective profiled slot guide rail which has an inner guide surface, wherein the respectively corresponding first sliding block body 6 a, the second sliding block body 6 b, the third sliding block body 6 cand the fourth sliding block body 6 dare formed by a slot block which runs in the respective profiled slot guide rail and has an outer counter-guide surface.The acute angle between the base frame 3 and the first stationary linear guide rail 4.1, the acute angle between the base frame 3 and the second stationary linear guide rail 4.2, the acute angle between the working platform 2 and the first stroke-movable linear guide rail 5.1, and the acute angle between the working platform 2 and the second stroke-movable linear guide rail 5.2 can each be between 5 and 40 degrees, in particular between 10 and 20 degrees. In the case of the exemplary embodiments shown, the respective acute angle is approximately 13 degrees.The size of the acute angle determines the translation of the linear movement length of the respective sliding block element 6.1, 6.2 along the stationary linear guide rail 4.1, 4.2 in relation to the lifting height which the working platform 2 performs when the sliding block elements 6.1, 6.2 are adjusted. The ratio of the linear movement length of the respective sliding block element 6.1, 6.2 along the stationary linear guide rail 4.1, 4.2 to the lifting height which the working platform 2 performs during an adjustment of the sliding block elements 6.1, 6.2 is linear over the entire adjustment path. This represents a particular advantage that the lifting device 1 according to the invention has compared to the known designs of scissor lifting devices.The lifting devices 1 according to the invention are thus based on another lifting principle, in which the lifting speed and the lifting forces behave linearly, so that even in a low position of the working platform 2, in particular also in the lowest position of the working platform 2, the driving force is constant at the same lifting speed. Thus, lower-power drives can be used, which are also more cost-effective and which have a smaller overall size. As a result, a lifting device 1 can be created which has a particularly low overall height in its low starting position.The lifting device 1 has at least one drive device 7 which is designed for automatic adjustment of the at least one first sliding block element 6.1 and the at least one second sliding block element 6.2 relative to one another.The at least one drive device 7 can be configured for synchronously adjusting the at least one first sliding block element 6.1 and the at least one second sliding block element 6.2 in opposite directions.In the exemplary embodiments shown, the drive device 7 comprises a motor 8 and a spindle 9 driven by the motor 8, which spindle adjustably couples the first sliding block element 6.1 to the second sliding block element 6.2 relative to one another.In the embodiment according to FIGS. 2 and 3, the first linear guide rail 5.1 which can move in a stroke is fastened to the working platform 2 at a fixed acute angle and the second linear guide rail 5.2 which can move in a stroke is fastened to the working platform 2 at the same fixed acute angle in a mirror-symmetrical manner with respect to the first linear guide rail 5.1 which can move in a stroke, wherein the first sliding block body 6 aand the second sliding block body 6 bare rigidly connected to one another in order to form the first sliding block element 6.1, and the third sliding block body 6 cand the fourth sliding block body 6 dare rigidly connected to one another in order to form the second sliding block element 6.1.Instead of a single separate drive device 7, as shown in FIG. 2, at least one first drive device 7.1 can be integrated into the first stationary linear guide rail 4.1 and / or into the first linear guide rail 5.1 that can move in a stroke manner and can be designed for the driven adjustment of the first sliding block element 6.1 or of the first sliding block body 6 aand / or of the second sliding block body 6 band at least one second drive device 7.2 can be integrated into the second stationary linear guide rail 4.2 and / or into the second linear guide rail 5.2 that can move in a stroke manner and can be designed for the driven adjustment of the second sliding block element 6.2.Such separate first drive devices 7.1 and second drive devices 7.2 may be useful in the modified embodiment according to FIGS. 4 and 5.In this case, the first linear guide rail 5.1 which can be moved in a stroke can be mounted pivotably on the working platform 2 at an acute angle by means of a first pivot bearing 10.1, and the second linear guide rail 5.2 which can be moved in a stroke can be mounted pivotably on the working platform 2 at an acute angle mirror-symmetrically with respect to the first linear guide rail 5.1 which can be moved in a stroke by means of a second pivot bearing 10.2.

Claims

Lifting device for raising and lowering a working platform (2) relative to a base frame (3), having: - a base frame (3), - a working platform (2), - at least one first stationary linear guide rail (4.1) fastened to the base frame (3) at an acute angle and at least one second stationary linear guide rail (4.2) fastened to the base frame (3) at the same acute angle in mirror symmetry with the first stationary linear guide rail (4.1), - at least one first strokeable linear guide rail (5.1) connected to the working platform (2) at an opposite acute angle and at least one second strokeable linear guide rail (5.2) connected to the working platform (2) at an acute angle in mirror symmetry with the first strokeable linear guide rail (5.1), and - at least one first sliding block element (6.1) having a first sliding block body (6a), which is mounted on the first stationary linear guide rail (4.1) so as to be longitudinally guided and has a second sliding block body (6b) mounted on the first linear guide rail (5.1) so as to be longitudinally guided so as to be movable in stroke, and - at least one second sliding block element (6.2) which has a third sliding block body (6c) mounted on the second stationary linear guide rail (4.2) so as to be longitudinally guided and has a fourth sliding block body (6d) mounted on the second linear guide rail (5.2) so as to be longitudinally guided so as to be longitudinally movable.Lifting device according to claim 1, characterised in that the first stationary linear guide rail (4.1), the second stationary linear guide rail (4.2), the first linearly guide rail (5.1) which can be moved in a lifting manner and / or the second linearly guide rail (5.2) which can be moved in a lifting manner is formed by a respective profile guide rail which has an outer guide surface and the respectively corresponding first sliding block body (6a), second sliding block body (6b), third sliding block body (6c) and / or fourth sliding block body (6d) is formed by a guide slide which runs on the respective profile guide rail and has an inner counter-guide surface.Lifting device according to claim 1, characterised in that the first stationary linear guide rail (4.1), the second stationary linear guide rail (4.2), the first linearly guide rail (5.1) which can be moved in a lifting manner and / or the second linearly guide rail (5.2) which can be moved in a lifting manner is formed by a respective profiled groove guide rail which has an inner guide surface and the respectively corresponding first sliding block body (6a), second sliding block body (6b), third sliding block body (6c) and / or fourth sliding block body (6d) is formed by a sliding block which runs in the respective profiled groove guide rail and has an outer counter-guide surface.Lifting device according to one of Claims 1 to 3, characterized in that the acute angle between the base frame (3) and the first stationary linear guide rail (4.1), the acute angle between the base frame (3) and the second stationary linear guide rail (4.2), the acute angle between the working platform (2) and the first linear guide rail (5.1) which can move in a lifting manner, and the acute angle between the working platform (2) and the second linear guide rail (5.2) which can move in a lifting manner are each between 5 and 40 degrees, in particular between 10 and 20 degrees.Lifting device according to one of claims 1 to 4, characterised in that the lifting device (1) has at least one drive device (7) which is designed for automatic adjustment of the at least one first sliding block element (6.1) and the at least one second sliding block element (6.2) relative to one another.Lifting device according to claim 5, characterised in that the at least one drive device (7) is designed for synchronously adjusting the at least one first sliding block element (6.1) and the at least one second sliding block element (6.2) in opposite directions.Lifting device according to one of Claims 5 to 7, characterized in that the drive device (7) comprises a motor (8) and a spindle (9) which is driven by the motor (8) and which adjustably couples the first sliding block element (6.1) to the second sliding block element (6.2) relative to one another.Lifting device according to one of Claims 1 to 7, characterized in that the first linear guide rail (5.1) which can be moved in a lifting manner is fastened to the working platform (2) at a fixed acute angle and the second linear guide rail (5.2) which can be moved in a lifting manner is fastened to the working platform (2) at the same fixed acute angle in a mirror-symmetrical manner with respect to the first linear guide rail (5.1) which can be moved in a lifting manner, wherein the first sliding block body (6a) and the second sliding block body (6b) are rigidly connected to one another in order to form the first sliding block element (6.1), and the third sliding block body (6c) and the fourth sliding block body (6d) are rigidly connected to one another in order to form the second sliding block element (6.2).Lifting device according to one of claims 1 to 8, characterised in that at least one first drive device (7.1) is integrated into the first stationary linear guide rail (4.1) and / or into the first linear guide rail (5.1) which can move in a lifting manner and is designed for the driven adjustment of the first sliding block element (6.1) and at least one second drive device (7.2) is integrated into the second stationary linear guide rail (4.2) and / or into the second linear guide rail (5.2) which can move in a lifting manner and is designed for the driven adjustment of the second sliding block element (6.2).Lifting device according to claim 9, characterised in that the first linear guide rail (5.1) movable in the stroke is mounted on the working platform (2) such that it can be pivoted at an acute angle and the second linear guide rail (5.2) movable in the stroke is mounted on the working platform (2) such that it can be pivoted at an acute angle in mirror symmetry with the first linear guide rail (5.1) movable in the stroke, and / or the first sliding block body (6a) and the second sliding block body (6b) are connected to one another in a rotary joint in order to form the first sliding block element (6.1), and the third sliding block body (6c) and the fourth sliding block body (6d) are connected to one another in a rotary joint in order to form the second sliding block element (6.2).

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