Telescopic column

Abstract

Telescopic column (1), having the following features: - at least two telescopic elements (7, 21, 23, 25, 27) which can be moved linearly relative to one another, - at least one drive unit (81) connected to a first of the telescopic elements, - at least one connecting element (45) through which a force can be transmitted from the drive unit to a second of the telescopic elements, - a monitoring unit (51) with a detector element corresponding to the connecting element, wherein the monitoring unit is designed such that an operating parameter of the connecting element can be detected by means of the detector element, wherein the detector element has a pre-tensionable lever arm (53) by means of which a tensioning force defined by the pre-tension can be exerted on the connecting element, - a counterforce element by which a counterforce can be exerted on the connecting element, so that a basic tension of the connecting element generated in this way forms the operating parameter, - whereby when the operating parameter is detected outside of pre-definable operating parameters, a defined change in the operating state of the drive unit can be carried out.

Description

[0001] The invention relates to a telescopic column.

[0002] Telescopic columns are used in numerous areas of technology. With a telescopic column, an object or device can be moved into different positions. In typical designs, the telescopic column has several nested round, rectangular, or polygonal, often tubular column elements that can be extended and retracted relative to each other using a motor-driven mechanism. Directly adjacent tubes have a maximum extendability so that a certain overlap of the tubes is always guaranteed to maintain stability. A distinction must be made between floor-mounted and ceiling-mounted telescopic columns. While the former are used, for example, in operating tables, where they allow the table to move up and down, the latter are attached to the ceiling or a tripod for mobile support of X-ray machines, for example.The X-ray machine is thus vertically adjustable. A multi-joint arm can also be attached between the telescopic column and the X-ray machine, allowing additional horizontal movement.

[0003] When using a steel cable, belt, or chain to move the telescopic column, there is always a risk of a break and uncontrolled lowering, i.e., extension, of the telescopic column. In this case, there is an acute risk of injury or damage. Therefore, a safety mechanism must be provided to reliably stop the movement in the event of a break.

[0004] US Pat. No. 3,902,070 A discloses a ceiling-mounted telescopic mount with a system for detecting cable tension. A compression spring is arranged between a mount and a plunger, which is connected to one end of the cable to be monitored. A pair of electrical switches is arranged above and below the plunger.

[0005] It is therefore an object of the present invention to provide a simple and safe solution that can be implemented in a comparatively simple and compact manner.

[0006] In one embodiment of the invention, a telescopic column is provided, comprising the following features: - at least two telescopic elements that can move linearly against each other, - at least one drive unit connected to a first of the telescopic elements, - At least one connecting element through which a force can be transmitted from the drive unit to a second of the telescopic elements, - a monitoring unit designed to detect an operating parameter of the connecting element, - whereby when the operating parameter is detected outside a pre-definable range, a defined change in the operating state of the drive unit can be carried out.

[0007] By monitoring the connecting element, failure, wear or a general error in the system can be easily and reliably detected and the operating status of the drive unit can be adjusted accordingly. For example, the drive unit could be switched off if the connecting element fails or is about to fail. For this purpose, a blocking mechanism is advantageously provided which prevents further extension of the telescopic column. Alternatively or additionally, an alarm can also be issued. Depending on its specific design and the application, the status of the connecting element can, for example, be monitored to determine whether the drive unit is connected to the second telescopic element. If the connecting element is designed as a rope, belt or chain, it could therefore be monitored to see whether the rope, belt or chain has broken. Alternatively, the tension in the rope, belt or chain could be used to determine whether the drive unit is damaged.The chain can be checked for signs of aging and wear so that the connecting element can be replaced preventively.

[0008] In a preferred embodiment of the invention, the telescopic column comprises a second drive unit and a second connecting element through which a force can be transmitted from the second drive unit to the second of the telescopic elements. Such a redundant drive system can prevent an accident even in the event of a total failure of the first connecting element and enable the intended change in operating state. Alternatively, continued operation of the telescopic column can also be ensured. In this case, an alarm is preferably also issued.

[0009] According to the invention, the monitoring unit has the following features: - A detector element corresponding to at least one of the connecting elements and detecting its operating state.

[0010] Preferably, a switching element is provided which interacts with the detector element and by means of which a switching operation can be carried out by means of which the operating state of at least one of the drive units can be influenced.

[0011] This design ensures in a simple way that if the state of the connecting element is detected outside of definable parameters, the drive unit is switched off, for example, by a simple switching operation.

[0012] According to the invention, the telescopic column further has the following features: - the detector element comprises a pre-tensionable lever arm, by means of which a defined tensioning force can be exerted on the connecting element, - a counterforce element by which a counterforce can be exerted on the connecting element, - a basic tension of the connecting element generated by clamping force and counterforce forms the operating parameter.

[0013] Preferably, the clamping force and the counterforce are selected such that in the normal operating state of the connecting element there is a balance between the two forces and the lever arm is held in an equilibrium position.

[0014] Preferably, the connecting element is designed such that a change in the basic tension changes the equilibrium such that the lever arm can be deflected from its equilibrium position.

[0015] Preferably, the switching element is designed such that the switching operation is carried out when the lever arm is deflected from its equilibrium position.

[0016] This design allows for simple and reliable mechanical and / or electronic monitoring of the condition of a rope, belt, or chain. In the case of a rope, with sufficient sensitivity, wear-related stretching can also be detected and the rope replaced before failure.

[0017] In a preferred embodiment of the invention, the drive unit comprises a shaft on which the connecting element is arranged so that it can be wound up and unwound, so that when the connecting element is wound up or unwound, the connecting element can be moved linearly relative to the first telescopic element through its connection to the second telescopic element. This design is particularly compact and easy to manufacture, as well as particularly reliable.

[0018] In a preferred embodiment of the invention, the connecting element is designed such that if the connecting element fails, the counterforce is completely or partially eliminated. This can be particularly easily detected and evaluated as a change in the state of the connecting element using a mechanical force gauge.

[0019] The described aspects of the invention with respect to the drive system, the safety system, and the damping system can, in and of themselves, already provide significant advantages over known solutions. However, a particularly preferred embodiment of the invention comprises at least two of these systems, ideally all three. Thus, according to embodiments of the invention, the drive system and the safety system work together in an optimally coordinated manner. The damping system also works together in a coordinated manner with the drive system.

[0020] Some models of telescopic column tubes feature a stopper mounted at the end, mechanically limiting the maximum travel and defining a specific end position for the movement. When the tubes move against each other, the stoppers come into contact at full speed, which places stress on the material and causes a loud noise. This noise is particularly disruptive in medical applications. Furthermore, the impact creates a shock that impairs operating comfort, for example, by affecting an operator's hand.

[0021] It is therefore a further object of the present invention to provide a telescopic column which avoids such disadvantages.

[0022] This object is achieved by a telescopic column according to embodiments of the invention. One embodiment of the invention relates to a telescopic column having the following features: - at least two telescopic elements movable relative to each other between two end positions, - at least one damper unit which is designed such that a force which slows down the relative movement of the telescopic elements can be exerted on at least one of the telescopic elements before at least one of the end positions is reached.

[0023] In embodiments of the invention, the telescopic elements are movable linearly relative to one another. In addition, a rotational movement can be performed simultaneously or alternatively. The damper unit is preferably independent of a drive of the telescopic column. This reduces the design effort. The damper unit reliably initiates a braking process through the decelerating force before the end position is reached, which reduces the relative speed of the telescopic elements to one another. This may result in contact between the stoppers in the respective end position at a significantly reduced speed. This protects the material and avoids loud impact noises. Operating comfort is increased. Alternatively, the damper unit can be designed in such a way that separate stoppers are no longer required. In this case, the damper unit brakes the movement to a standstill.However, a separate stopper can also be provided in this design. In preferred embodiments, the damper unit has an absorption element that can absorb kinetic energy. This allows for efficient damping of the movement, as is common with shock absorbers, and prevents hard impacts and vibrations.

[0024] The damper unit preferably interacts with both telescopic elements to generate the force. Thus, mechanical or electromechanical components of the damper unit can be connected to both telescopic elements and designed to interact accordingly. If additional telescopic elements are provided, one or more damper units can be arranged between two of the telescopic elements in preferred embodiments.

[0025] In a preferred embodiment of the invention, the damper unit is designed such that the generated force continuously slows down the movement of the two telescopic elements until they reach their end positions. In this case, stoppers are not absolutely necessary. Alternatively, stoppers can be provided redundantly, for example, in the event of a damper unit failure, to prevent uncontrolled extension or retraction of the telescopic column or separation of the telescopic elements, which could lead to an accident. They can also relieve the damper unit if it remains in the extended state for a longer period.

[0026] In a preferred embodiment of the invention, the damper unit comprises at least one damping element and a stop, wherein the damping element can be brought into operative contact with the stop to generate the force. This design is mechanically simple and reliable. Furthermore, it allows for a particularly space-saving design.

[0027] The damping element is preferably mounted on one of the telescopic elements. This can be done, for example, by screwing or gluing, which is particularly easy to implement. Preferably, the stop is mounted on the other of the telescopic elements in such a way that the stop can be brought into operative contact with the damping element before the end position is reached. This allows for reliable and cost-effective damping with a simple design and a space-saving design.

[0028] In a preferred embodiment of the invention, a further stop is mounted on the other of the telescopic elements in such a way that the further stop can be brought into operative contact with the damping element before the other end position is reached. This allows for easy damping near both end positions.

[0029] The damping element is preferably mounted in a hole-like recess in one of the telescopic elements. This is a particularly space-saving design. It is therefore easy to assemble and disassemble. The stop is then preferably mounted on the other of the telescopic elements in such a way that the stop can be brought into active contact with the damping element before the end position is reached. This allows the movement to be reliably slowed down.

[0030] In a preferred embodiment of the invention, the damping element comprises the following features: - A housing in which a stamp is movably arranged, - A spring element that can generate a force between the punch and the housing.

[0031] Comparable damping elements are known from other applications, such as damping drawers when closing. They are cost-effective and compact, and experience has shown them to operate reliably.

[0032] Preferably, a fluid-filled cavity is formed in the housing, in which the spring element and the plunger are arranged. The fluid is pressed into a further cavity through a hole-like taper integrated into the plunger or provided separately. This absorbs the kinetic energy and dampens the movement. This enables particularly uniform deceleration and damping of the movement. Preferably, the plunger can be brought into operative contact with the stop. As soon as the telescopic elements are moved in the opposite direction, the spring element pushes the plunger back to its original position, so that braking can occur again during the next process.

[0033] Alternatively, a gas that can be compressed by the piston can be introduced into the housing so that the kinetic energy can be converted.

[0034] In a preferred embodiment of the invention, the telescopic elements have coordinated circumferential dimensions and are nested within one another, so that from the outer to the inner telescopic element, an inner surface of the outer telescopic element corresponds to an outer surface of the next inner telescopic element via a damper unit, with a damping element of the damper unit being mounted on the outer surface and a stop of the damper unit being mounted on the corresponding inner surface. This is particularly advantageous for telescopic columns with several nested telescopic elements, since the braking force can thus be transmitted to several of the telescopic elements via several damper units. This arrangement can also be implemented in reverse.

[0035] Ceiling-mounted telescopic columns, in particular, are often equipped with complex cable drives, which require correspondingly large installation volumes. At the same time, particularly in the medical field, stringent safety requirements exist. A further object of the invention is to provide a telescopic column that is compact and simple in design while simultaneously meeting high safety standards.

[0036] This object is achieved by a telescopic column according to embodiments of the invention. One embodiment of the invention relates to a telescopic column comprising at least two telescopic elements that can be moved linearly relative to one another, further comprising a drive system comprising the following features: - a drive unit with a first coupling element, - an output unit with a shaft, a windable connecting element and a second coupling element connected to the shaft in a rotationally fixed manner, wherein the connecting element is connected to the shaft and at least one of the movable telescopic elements, - a brake unit designed to transmit such a large holding force to the second coupling element that the telescopic elements are held in their relative position to one another, - the brake unit is further designed such that when the first coupling element is subjected to a drive torque, the holding force is reduced such that the telescopic elements become movable relative to one another, and - the brake unit is further designed such that when the second coupling element is subjected to an output-side torque, the holding force acting on the second coupling element can be increased.

[0037] The brake unit offers a high degree of safety with a compact design, as is particularly necessary in medical applications. The two coupling elements are preferably made of steel or a similarly resilient material and can be designed compactly. In this embodiment of the invention, a distinction is made between the drive side and the output side. To move the telescopic elements, i.e. to extend or retract the telescopic column, a force generated by the drive unit, for example by a motor, is transferred to the first coupling element. This is then set in rotation, for example. The force flow occurring up to this point defines the drive side and a drive-side force or a drive-side torque.In a telescopic column, the constant force of gravity, in the absence of a corresponding counterforce, tends to change the relative position of the telescopic elements in most operating conditions. With ceiling-suspended telescopic columns, this is always the case when the telescopic column is not fully extended. When fully extended, holding elements usually stabilize the telescopic elements against each other so that the telescopic column does not fall apart. As long as the telescopic column is not fully extended, the gravitational force must be compensated for by another means. It exerts a force on the telescopic elements, which exerts a torque via the connecting element on the shaft and thus on the second coupling element connected to it. This force flow defines the output side of the telescopic column.If the output torque were not compensated, the telescopic column would move uncontrollably into its fully extended state. However, the braking unit compensates for the output torque through the holding force permanently present in the absence of drive-side torque, allowing the telescopic column to be held in any position. No drive-side force is required for this, so the drive unit only needs to be activated to move it. The torque permanently acting on the output side when the column is not fully extended further increases the holding force, preventing uncontrolled extension even when the load increases. In contrast to conventional systems, the drive system features extremely compact dimensions and is mechanically simple to implement. Furthermore, it meets the high safety standards in the medical field.However, embodiments of the invention can also be used in other areas, for example in production plants or workshops.

[0038] If the telescopic column is to be retracted, a drive-side torque must be generated, which reduces the holding force. At the same time, the two coupling elements can preferably come into active contact, so that the torque is transferred to the shaft and the connecting element is wound up. The direction of the torque must be selected accordingly. The telescopic column is then retracted. If, however, the telescopic column is to be extended, a drive-side torque is generated in the other direction, which also reduces the holding force. At the same time, the connecting element is unwound, and the telescopic column is extended under the influence of gravity.

[0039] For telescopic columns located on the ground, often referred to as lifting columns, the statements apply in reverse with regard to the interaction of the drive with the gravitational force, so that when the telescopic column is extended, it works against the gravitational force and when retracted, it works with the gravitational force. Otherwise, all the advantages and design features mentioned in the embodiments of the invention described here can also be transferred to lifting columns with minor modifications and used analogously.

[0040] In preferred embodiments of the invention, one of the telescopic elements is fixedly connected to or mounted on the ceiling or floor of a room. This could be, for example, a treatment room or a workshop. It is also possible for the telescopic element to be connected to a frame. The second or more further telescopic elements are each linearly movable relative to the first telescopic element and can be extended or retracted from it. The telescopic elements are typically interconnected with decreasing outer diameters or circumferences. The drive unit is preferably connected to the mounted or fixed telescopic element. The connecting element transmits a force generated by the drive unit to the second or innermost of the telescopic elements, thus enabling the telescopic column to be extended and retracted. The innermost of the telescopic elements causes the remaining telescopic elements, if present, to be extended or retracted.Alternatively, the power can be transmitted directly to all other telescopic elements, allowing them to be moved directly by the drive unit. This would be advantageous, for example, in synchronized telescopic columns.

[0041] In a preferred embodiment of the invention, the connecting element is designed as a cable, belt, or chain. This enables simple and cost-effective, yet reliable and safe power transmission. Preferably, the connecting element is connected to the shaft in such a way that it can be wound up or unwound as the shaft rotates. Designs with steel cables are particularly preferred.

[0042] In a preferred embodiment of the invention, the brake unit comprises a spring element and a braking surface. The spring element is designed such that, due to a preload, it can be brought into frictional contact with the braking surface to generate the holding force, and such that it can be brought into operative contact with the coupling elements, thereby altering its spring tension. For example, the coupling elements, the spring element, and the brake unit form a wrap spring clutch unit. This allows for a particularly compact design, so that little space is required for the drive unit and the brake unit. At the same time, this embodiment of the invention can be adapted to various situations through the dimensioning and design of the spring element and the housing.

[0043] The braking surface can, for example, be formed on the inside of a housing surrounding the spring element. The preload to generate the holding force presses the spring element, which may be round, outward against the braking surface. Alternatively, the braking surface can be formed on the outside of an element, such as a cylindrical mandrel, which is surrounded by the spring element. Here, the preload acts in reverse. The following explanations and advantages each refer to a housing with a spring element inside. However, they are easily transferable to an external spring element and a braking element inside.

[0044] In a preferred embodiment of the invention, the operative contact between the coupling elements and the spring element can be created by at least one coupling element formed on each of the coupling elements and at least one corresponding coupling element of the spring element. These can, for example, be axially extending claw-like extensions located within the spring element, which correspond to an extension of the spring element. Upon rotation of the coupling element and the coupling elements, the latter presses on the extension of the spring element and, in the case of a helical or wrap spring design, pushes it open or closed depending on the direction of rotation. In this way, the spring tension is increased or decreased with respect to the surrounding housing. In this way, the holding force of the brake unit can be influenced by the drive unit.

[0045] In a preferred embodiment of the invention, each of the coupling elements has at least two coupling elements, and the spring element has two coupling elements, each corresponding to one of the coupling elements of the coupling elements, wherein one of the coupling elements of the coupling elements comes into operative contact with one of the coupling elements of the spring element upon clockwise rotation of the coupling element, and the other of the coupling elements of the coupling elements comes into operative contact with the other of the coupling elements of the spring element upon counterclockwise rotation of the coupling element, so that an operative contact that changes the spring tension in an analogous manner can be generated regardless of the respective direction of rotation of the respective coupling element. In this context, analogous means that the operative contact changes in the same or almost the same way, i.e. the holding force is increased or decreased.This makes it possible to provide a drive system for a telescopic column in which the power is transmitted from the drive unit to the brake unit, or from the output unit to the brake unit, regardless of the direction of rotation. Consequently, this need not be taken into account when designing a corresponding telescopic column.

[0046] This is particularly advantageous in preferred embodiments of the invention, which comprise a further drive system which is constructed analogously to the first drive system and functions as a redundant drive system. The second drive system can be designed completely separately. Alternatively and preferably, both drive units are driven by a common motor so that they operate synchronously. In this case, it can be structurally advantageous to operate both shafts in opposite directions of rotation in order to achieve the most compact and simple design possible. For example, both drive units can be mounted parallel and closely spaced and can be rotated simultaneously in opposite directions by the motor via a drive wheel located between them. Alternatively, other common drives such as bevel gears, spur gears, belts, etc. can be used.The rotation-independent transmission of the active contact ensures that the same effect, i.e., extension and retraction of the telescopic column, is achieved when the forces are transferred from the respective drive unit to the output unit. For example, one of the drive units can be configured as the main drive unit and extend and retract the telescopic column during normal operation. The second drive unit is then designed as a redundant safety system and executes the movements in parallel. In the event of a failure of the first drive system, for example, due to the connecting element breaking off, the gravitational force is immediately absorbed by the safety system, preventing uncontrolled extension or retraction.

[0047] In a preferred embodiment of the invention, each of the coupling elements has at least a third coupling element, wherein the coupling elements of the coupling elements are designed such that one of the coupling elements of each of the two coupling elements can be brought into direct operative contact as soon as one of the first or second coupling elements of the coupling elements is in operative contact with one of the coupling elements of the spring element. This achieves a simultaneous reduction in the holding force and a direct engagement of the coupling elements, so that when the holding force is reduced, the input and output sides of the drive are in direct operative contact via coupling elements and a torque from the motor is transmitted directly. The movable telescopic element is then held and moved directly by the motor.

[0048] In an alternative embodiment, the coupling elements of the coupling elements each have a recess designed and arranged such that the coupling elements of the spring element can be accommodated therein in the event of operative contact, such that one of the coupling elements of both coupling elements can be brought into operative contact. In this embodiment, a simultaneous reduction of the holding force and direct engagement of the coupling elements are achieved, so that when the holding force is reduced, the input and output sides of the drive are in direct operative contact, and a torque from the motor is transmitted directly.

[0049] Further advantages, features, and details of the invention will become apparent from the following exemplary embodiments of the invention described with reference to the figures. These show: Fig. 1 a telescopic column, Fig. 2 the telescopic column in partially extended state, Fig. 3 a sectional view of the telescopic column according to Fig. 1, Fig. 4 a detailed view of a drive unit of the telescopic column according to Fig. 1, Fig. 5 a sectional view of the drive unit according to Fig. 4, Fig. 6 an exploded view of the coupling unit of the drive unit according to Fig. 4, Fig. 7 the coupling unit of the Fig. 6 viewed from the output side, Fig. 8 the coupling unit of the Fig. 6 from the viewpoint of the drive side; Fig. 9 to 11 the coupling unit of the Fig. 6 from both perspectives in different operating states, Fig. 12 a detailed view of the coupling unit of the Fig. 6, Fig. 13 a shock absorber for a telescopic column, Fig. 14 the shock absorber Fig. 13 in a detailed view, Fig. 15 to 17 the shock absorber Fig. 13 in a schematic sectional view in different operating states, Fig. 18 and Fig. 19 the shock absorber Fig. 13 in the telescopic column, Fig. 20 to 24 a monitoring unit for a telescopic column, Fig. 25 to 27 show a schematic representation of the function of the monitoring unit.

[0050] Fig. 1 shows a telescopic column in a design as a ceiling mount 1. At the upper end, a mounting plate 3 is arranged, by means of which the ceiling mount 1 can be fastened to the ceiling of a room via four screw holes 5. This can be, for example, a medical examination room, an operating room, a workshop hall or a production facility. A column element 7 is fastened to the mounting plate 3 and extends vertically downwards when installed. The column element 7 is almost square in terms of its base area with slightly chamfered corners. In other embodiments, the base area can also have other geometries, for example, be round or triangular. The base area can also change in a downward direction. A housing 9 is arranged on the side of the column element 7. The functional elements of a drive unit are arranged partly in the housing 9 and partly in the upper region of the column element 7.A motor 11 is arranged beneath the housing 9 and is designed to interact with the elements of the drive unit. The internal structure of the drive unit is shown in the drawing. Fig. 4 and Fig. 5 described in detail.

[0051] Alternatively, such designs are also possible for telescopic columns that are mounted on the floor. In this case, the outermost column element, or in other designs, the innermost column element, is attached to the floor or a mobile or movable frame, and the inner and outer column elements are extended or retracted upwards when the drive unit is activated.

[0052] In the Fig. 2, the ceiling mount 1 is shown in a different operating state. Within the column element 7, four further column elements 21, 23, 25 and 27 are arranged one inside the other. The size of their respective base area decreases in each case, so that column element 27 has the smallest base area. The four column elements 21, 23, 25 and 27 are linearly movable relative to the column element 7, 21, 23 or 25 that is immediately further out. In this way, column element 21 can be moved downwards out of column element 7. Analogously, column element 23 can be moved linearly downwards out of column element 21, and so on. At the lower end of column element 27, a support plate 31 is arranged, to which a load to be lifted or lowered can be attached. Alternatively, the load can also be connected directly to column element 27 through the support plate. This could be, for example, an X-ray apparatus.The drive unit and motor 11 can be controlled via a control unit (not shown), which may be designed as a remote control or handle, for example, and thus extend the column elements 21, 23, 25, and 27 downwards and retract them upwards. The attached load is lowered or raised accordingly.

[0053] In the Fig. Figure 3 shows a sectional view of the ceiling mount 1. Within the column element 7 fastened below the support plate 3, the four further column elements 21, 23, 25 and 27 are shown in the retracted state. Above the four column elements 21, 23, 25 and 27, part of the drive unit is mounted in the column element 7. This comprises a first cable drum 33, which is rotatably mounted in the housing and on which a cable 35 is wound. The cable 35 is connected at the other end to the support plate 31 by means of a fastening unit 37. When the cable drum 33 rotates clockwise in this illustration, the cable 35 is unwound from the cable drum 33, causing the column element 27, and subsequently the column elements 21, 23 and 25, to continuously lower due to gravity.Depending on the prevailing friction conditions or design, the lowering can also occur discontinuously, for example, by extending column elements 21, 23, 25, and 27 one after the other. In this way, the ceiling support 1 can be extended downward and the attached load lowered. When the cable drum 33 is rotated counterclockwise, an upward force is exerted on the support plate 31, causing the column elements 21, 23, 25, and 27 to retract.

[0054] In the illustrated embodiment according to the invention, a further cable drum 43 is provided, on which a cable 45 is wound. The cable 45 is in turn connected to the support plate 31 via a fastening unit 47, which is connected to the support plate 31 via a spring 49. The spring serves to relieve the cable 45 if, due to tolerance differences or expansion of the components, different speeds of the cables 35 and 45 arise during operation. With regard to the direction of rotation, the cable 45 is wound onto the cable drum 43 in the opposite direction to the cable 35, so that when the cable drum 43 rotates, it is unwound counterclockwise and wound up clockwise. In order to lower the support plate 31 and thus to extend the ceiling support 1, it is therefore necessary that, as shown in the illustration, Fig. 3, the cable drum 33 must be rotated clockwise and the cable drum 43 counterclockwise simultaneously. Accordingly, to retract the ceiling support 1, the cable drum 33 must be rotated counterclockwise and the cable drum 43 clockwise. The cable drum 43 and the cable 45 wound on it primarily serve as a redundant safety mechanism in the event that the cable 35 wears or breaks during use. In this case, the support plate 31 and thus the column elements 21, 23, 25, and 27 would be held by the cable 45 and would also continue to be movable.

[0055] The ceiling mount 1 further comprises a monitoring unit 51, the structure and function of which can be seen from the Fig. 20 to 27 are described in detail.

[0056] In the Fig. 4 shows a partial view of essential parts of the drive unit. It comprises a main drive unit 61 and a safety unit 81. The main drive unit 61 has a shaft 63, which is mounted via three bearing points 65 in the drive housing 9 (not shown here) or in the column element 7. The cable drum 33 with the cable 35 is fastened to the shaft 63. On the drive side, the main drive unit 61 has a worm gear 67, which can be set in rotation via a drive shaft 17 of the motor 11. The worm gear 67 is defined radially and axially, but it can rotate about the shaft 63. The power transmission between the worm gear 67 and the shaft 63 takes place via a coupling unit 69, the function of which is determined by the Fig. 5 to 12 are explained in detail.

[0057] The safety unit 81 is constructed analogously to the main drive unit 61. It also comprises a shaft 83, which is mounted on three bearings 85. The cable drum 43 with the cable 45 is fastened to the shaft 83. A worm gear 87 is also provided in a similar manner, which also engages with the drive shaft 17. The opposite arrangement of the two worm gears 67 and 87 with respect to the drive shaft 17 ensures that when the drive shaft 17 rotates, the two worm gears 67 and 87 each rotate in opposite directions. Due to the opposite winding direction of the two cables 35 and 45, when the drive shaft 17 rotates in one direction, both cables 35 and 45 are unwound and when it rotates in the opposite direction, they are wound up. In the safety unit 81, the power transmission between the worm gear 87 and the shaft 83 also takes place via a coupling unit 89, which is constructed analogously to the coupling unit 69.

[0058] In the Fig. Figure 5 shows a sectional view of the drive unit. It shows the shafts 63 and 83 of the main drive unit 61 and the safety unit 81. A further explanation of the Fig. The elements described in Figure 4 will be omitted here; instead, the operation of the coupling units 69 and 89 will be explained. The worm gears 67 and 69 are larger in terms of their inner diameter than the outer diameter of the shafts 63 and 83, respectively. Therefore, a rotary motion of the worm gears 67 and 69 is not transmitted to the shafts 63 and 83 through direct contact. The transmission of power is explained using the coupling unit 69 as an example. The coupling unit 89 functions analogously.

[0059] The coupling unit 69 comprises, on the drive side, a first coupling element 91 which is firmly connected to the worm gear 67 via screws 92 and pins (not shown here). The inner diameter of the coupling element 91 is also larger than the outer diameter of the shaft 63, so that here too no direct torque is transmitted to the shaft 63. The coupling unit 69 has, on the output side, a second coupling element 93 which is arranged axially opposite the coupling element 91. The inner diameter of the coupling element 93 is fixedly mounted on the shaft 63. A rotary movement of the coupling element 93 therefore exerts a torque on the shaft 63, which also causes the shaft 63 to rotate in the same direction. A rotary movement of the shaft 63 generated on the output side also exerts a torque on the coupling unit 93.The clutch unit 69 further includes a wrap spring 94, which serves as a holding mechanism. The detailed structure and operation of the clutch unit 69 are described in detail in the . Fig. 6 to 12 described.

[0060] In the Fig. 6, the two coupling elements 91 and 93, as well as the wrap spring 94, are shown in an exploded view, axially pulled apart. The coupling element 91 has a ring-like base element 101, in which screw holes 102 are provided for receiving the screws 92 (not shown here) (cf. Fig. 5) and / or pins are provided. Radially outside the base element 101 are three claw-like coupling elements 103a, 103b and 103c, which extend axially in the direction of the coupling element 93. The coupling element 93 has a shaft seat 105, which is similar to the base element 101 in terms of its external shape. However, the inner diameter of the shaft seat 105 is matched to the diameter of the shaft 63 or 83, so that after installation there is a frictional or fit connection. For this purpose, the shaft seat 105 has an axially extending groove 106 on the inner diameter, which engages with a corresponding projection on the shaft 63 or 83 or a key and supports the torsion-proof coupling. In comparison, the base element 101 only sits loosely on the shaft 63 or 83, and is therefore not connected to it in a rotationally fixed manner.Radially outwardly, the coupling element 93 has three claw-like coupling elements 107a, 107b and 107c, which extend axially in the direction of the coupling element 91.

[0061] The coupling elements 103a, 103b, and 103c and 107a, 107b, and 107c can be considered sections of a cylinder jacket, thus having a circumferentially curved shape. Their circumferential dimensions are selected to be so small that a comparatively large distance remains between them. When the two coupling elements 91 and 93 are axially joined, one of the coupling elements 103a, 103b, and 103c is located between two of the coupling elements 107a, 107b, and 107c. Similarly, one of the coupling elements 107a, 107b, and 107c is located between two of the coupling elements 103a, 103b, and 103c. At the end, the coupling elements 103a, 103b and 103c are then located slightly radially apart outside the outer circumference of the shaft seat 105. Analogously, the coupling elements 107a, 107b and 107c are located slightly radially apart outside the outer circumference of the base element 101.The coupling elements 103a, 103b, and 103c and 107a, 107b, and 107c are also selected to be so small in terms of their circumferential dimensions that a defined distance exists between each of the coupling elements 103a, 103b, and 103c and the adjacent two coupling elements 107a, 107b, and 107c, thus preventing a complete cylindrical shell from being formed even in assembled form. For example, if the coupling elements 103a, 103b, and 103c and 107a, 107b, and 107c are initially aligned centrally relative to one another, the coupling element 93 can be rotated by a defined angle until it comes into contact with another of the components.

[0062] The spiral-shaped wrap spring 94 is arranged radially outside the coupling elements 103a, 103b, and 103c and 107a, 107b, and 107c, wrapping around them. The wrap spring 94 has a radially inwardly bent end 109 (output side) or 109' (drive side) at each end, to which one of the coupling elements 103a and 103b or 107b and 107c can exert a circumferential force on the wrap spring 94. The end 109 lies between the coupling elements 103b and 107b, and can therefore come into operative contact with them depending on the rotation. The end 109' lies between the coupling elements 103a and 107c and can similarly come into operative contact with them. Due to their arrangement, the coupling elements 103c and 107a do not come into contact with the ends 109 and 109' in any operating state. For axial fixation of the wrap spring 94, the coupling elements 103a, 103b and 103c and 107a, 107b and 107c each have a radially outer projection 111 at the end.

[0063] In the Fig. 7, the coupling unit 69 is shown in a three-dimensional representation in the assembled state, viewed from the output side. The coupling unit 69 comprises a brake housing 113 on the outside, which is secured against rotation in the housing of the ceiling mount 1. In the illustrations of Fig. 4, Fig. 5 and Fig. 6, the brake housing has been omitted for clarity. Fig. 7 shows how the coupling elements 103a, 103b and 103c are located at the ends outside the outer circumference of the shaft seat 105 and, due to the distance between the coupling elements 103a, 103b and 103c and 107a, 107b and 107c, a limited, independent rotation of the coupling elements 91 and 93 relative to one another is possible.

[0064] The wrap spring 94 is wound and dimensioned in such a way that it must be radially contracted, i.e., radially reduced in size, during installation in the brake housing 113. The wrap spring 94 is held under tension radially by the brake housing 113 and axially by the projections 111, so that the wrap spring 94 cannot immediately relax again and is held in a pre-tensioned state. In this state, the wrap spring 94 is therefore not rotatable in the brake housing 113 and, according to its design, develops a defined holding force. The coupling element 93 can be rotated through a small angle until, depending on the direction of rotation, either the coupling element 107b presses against the end 109 (as in Fig. 7) or the coupling element 107c towards the end 109' (cf. Fig. 8). The end 109 of the wrap spring 94 lies between coupling elements 103b and 107b.

[0065] In the Fig. 8 is the coupling unit 69 in analog representation to Fig. 7, but here viewed from the drive side. Here, it can be seen how the wrap spring 94 is held axially by the projections 111 and is thus axially fixed overall. The second end 109' of the wrap spring 94 lies between the coupling elements 103a and 107c.

[0066] After the coupling unit 69 or 89 has been mounted on the shaft 63 or 83 and the load has been absorbed, a torque generated on the output side by the column elements 21, 23, 25, and 27 via the cables 35 or 45 and the cable drums 33 or 43 acts on the respective coupling element 93 due to the force of gravity. This torque is then rotated depending on the direction of rotation until either the coupling element 107b presses against the end 109 or the coupling element 107c presses against the end 109'. The respective end 109 or 109' is consequently subjected to a force acting in the circumferential direction. Due to the winding direction of the wrap spring 94, this force exerts a force on the wrap spring 94 in both cases, which tends to expand it. Due to the surrounding brake housing 113, the force does not cause an actual expansion but rather an increase in the frictional contact of the wrap spring 94 with the brake housing 113.The initial holding force due to the preload and this increased friction completely compensates for the output-side torque, preventing further rotation. Unwinding of the cable 35 or 45 and extension of the column elements 21, 23, 25, and 27 is thus prevented, and the assembly is consequently held in place. This is the basic state of ceiling support 1. Increasing the output-side torque, for example, by increasing the absorbed load, increases the pressure on the wrap spring 94 and thus the friction with the brake housing 113, so that the position is maintained even then.

[0067] In the Fig. 9, Fig. 10 and Fig. Figure 11 shows the coupling unit 69 in various operating states, viewed from the output side (left) and the drive side (right). The position of the coupling elements 103a, 103b, and 103c, or 107a, 107b, and 107c, relative to the ends 109 and 109' varies in each case.

[0068] In the Fig. Figure 9 shows an intermediate state in which none of the coupling elements 103a, 103b, and 103c, or 107a, 107b, and 107c, is in contact with the ends 109 and 109'. Accordingly, the end 109 lies freely between the coupling elements 103b and 107b. The end 109' lies freely between the coupling elements 103a and 107c.

[0069] In the Fig. 10, after rotation of the drive-side coupling element 91, the coupling element 103a is in contact with the end 109'. If the rotation continues in the same direction, the coupling element 103a will exert a force on the end 109' and move it in a clockwise direction (right illustration). The wrap spring 94 is thus radially contracted and the holding force on the brake housing 113 is reduced. After a short further rotation, the end 109' comes into contact with the coupling element 107c, which in the Fig. 11. The coupling element 93 is then moved in the same direction. This rotation is then transferred to the cable drum 33 or 43, and the cables 35 or 45 are wound up or unwound accordingly. Depending on the direction of rotation, the ceiling support 1 is thus extended or retracted.

[0070] To ensure that the drive torque is transmitted not only through contact between the coupling element 103a, the end 109', and the coupling element 107c, the dimensions of the components in the circumferential direction are selected such that, during the production of this chain of action, the coupling elements 107b and 103c are also in contact with their mutually facing side surfaces, additionally transmitting the drive torque. The end 109' is thus relieved of load.

[0071] In the Fig. 12, the relative dimensions are illustrated schematically. The coupling elements 103a, 103b, 107b, and 107c each span an angle γ, while the coupling elements 107a and 103c span an angle β. An angle α exists between the coupling elements 107a and 107b, or 107c. The same angle α exists between the coupling elements 103c and 103a, or 103b. The sizes of the angles α, β, and γ are selected such that the coupling elements 107b and 103c come into contact simultaneously when the coupling element 103a comes into contact with the end 109' and this comes into contact with the coupling element 107c. This ensures reliable torque transmission.

[0072] A drive-side rotation of coupling element 93 in the other direction has a completely analogous effect, with end 109 then establishing an active chain with coupling elements 103b and 107b, and coupling elements 103c and 107c being in direct active contact. Ceiling support 1 is extended or retracted accordingly.

[0073] When the drive shaft of the motor 11 rotates, the worm gear 67 coupled to it is subjected to a torque and set in rotation. This torque is transferred through the screw connection to the coupling element 91. When rotating clockwise from the direction of view of the drive side as shown in Fig. 8, for example, the coupling elements 103a, 103b, and 103c will rotate clockwise toward the coupling elements 107a, 107b, and 107c, initially reducing the distance between them. This results in increased pressure between the coupling element 103a and the end 109' of the wrap spring 94. The pressure built up on the end 109' of the wrap spring 94 applies a clockwise circumferential force to the spring. If the drive-side torque is sufficiently large, the wrap spring 94 will contract radially, loosening the frictional connection to the brake housing 113. As a result, the output-side torque is no longer fully compensated, causing the shaft to rotate, unwinding the cable 35 or 45, and extending the column elements 21, 23, 25, and 27. This leads to a lowering of the load.Due to the existing output-side torque, the coupling element 107c remains constantly in contact with the end 109' of the wrap spring 94, thus also rotating clockwise. As soon as the drive-side torque is eliminated due to the stopping of the rotation of the motor 11, the then no longer compensated or overcompensated output-side torque immediately leads to a widening of the wrap spring 94 and a frictional contact with the brake housing 113, thus establishing the holding force, so that the load is held at the new height.

[0074] When the worm gear 67, and thus the coupling element 91, rotates counterclockwise, the coupling elements 103a, 103b, and 103c and 107a, 107b, and 107c move closer together. In this case, the coupling element 103b interacts with the end 109 of the wrap spring 94, and the coupling element 107c interacts with the end 109' of the wrap spring 94 in a similar manner, so that the rotational movement is again transmitted to the shaft 63. In this case, the cable 35 is wound up and the load is lifted.

[0075] The clutch unit 89 between the worm gear 87 and the shaft 83 operates in a completely analogous manner. Due to the design of the clutch units 69 and 89, the direction of rotation of the torques is irrelevant. A drive-side torque always causes the wrap spring 94 to contract and the brake to release, while a driven-side torque expands the wrap spring 94 and increases the braking effect.

[0076] In the Fig. 13 shows a section of one of the column elements 21. The remaining column elements 23, 25, and 27 are constructed analogously. It has a flat and wide groove-like recess 501 on a side surface 500, in which an elongated hole 502 is formed. A shock absorber 503 is inserted and held in the elongated hole 502. The structure of the shock absorber 503 is shown in the Fig. 14 to 17 described in detail, its functionality based on the Fig. 18 and Fig. 19.

[0077] In the Fig. 14 shows the shock absorber 503. It has a receiving element 505 at each end, each of which has a central part 507 and two guide parts 509. The guide parts 509 are wider than the central part 507, so that a groove 511 is created on each side. When installed, the housing of the column element 21, which borders the elongated hole 502, engages in the grooves 511, so that the shock absorber 503 is held and guided. The guide parts 509 have a round shape 513 at their ends. A damping element 515, which comprises a cylinder 517 and a piston 519, is arranged between the central parts 507. When axial pressure is exerted on the piston 519 and the cylinder 517, the piston 519 penetrates the cylinder 517 in a damped manner. This allows the distance between the two central parts 517 to be reduced.As the distance decreases, the force required increases due to the damping properties of the damping element 515, until the piston 519 is completely accommodated in the cylinder 517. The damping element 515 can, for example, be designed as known from drawer or door dampers. As shown in the . Fig. As can be seen in Figure 13, the width of the elongated hole 502 is not constant across its length, but is wider in the center. The central width is selected such that the guide parts 509 are completely accommodated there and can be pushed one after the other toward the axial end of the elongated hole 502, allowing the housing to engage the grooves 511 and hold the shock absorber. For assembly, the shock absorber 503 must be axially compressed so that the second guide part 509 can be placed in the wide part of the elongated hole and then pushed toward the axial end by releasing the tension on the shock absorber 503.

[0078] In the Fig. Figures 15 to 17 show the internal structure of the shock absorber schematically. The cylinder 517 is filled with a liquid 521. Alternatively, a gas can be used. A spring 523 is also arranged in the cylinder 517, which pushes a plunger 525 upwards. The plunger 525 is in turn connected to the piston 519 and can therefore be subjected to a force by the piston. The plunger 525 can be moved within the cylinder 517 against the force of the spring 523. The plunger 525 includes a channel 527 through which, when moved, the liquid 521 can flow between the two half-spaces of the cylinder 517 defined by the plunger 525. Otherwise, the plunger 525 would be blocked due to the incompressible liquid 521. The plunger 525 includes another channel 529, which is significantly wider than the channel 527.The channel 529 is provided with a valve 531 that allows the passage of liquid 521 only in one direction of movement of the plunger 525, namely an upward movement.

[0079] In the Fig. 16, the plunger 525 is in a downward motion due to a force being applied to the piston 519, compressing the spring 523. Although the comparatively narrow channel 527 allows the fluid 521 to flow, the downward movement of the plunger 525 is significantly dampened and thus slowed down. The kinetic energy is absorbed accordingly. The valve 531 is closed, so that no fluid 521 can flow through the channel 529.

[0080] In the Fig. 17, the piston 519 is no longer subjected to a force, so that the plunger 525 is moved upwards back to its original position by the spring 523. In this direction of movement, the valve 531 opens, and the fluid 521 can flow through the channels 527 and 529. The upward movement of the plunger 525 is therefore significantly less damped than the previously downward movement.

[0081] In the Fig. 18 and Fig. Figure 19 illustrates the functionality of the shock absorber 503 in the installed state. Two of the column elements 7, 21, 23, 25, and 27 (here 7 and 21) are shown as examples. The elongated hole 502, containing the shock absorber 503, is arranged in the upper area of ​​the inner column element 21, 23, 25, and 27 (here 21). Correspondingly, a round stopper 532 is attached to the lower area of ​​the outer column element 7, 21, 23, and 25 (here 7). The curvature of the stopper 532 is matched to the round shape 513. When the telescopic column is extended, the lower receiving element 505 of the shock absorber 503 engages with the stopper 532 near the maximum extension distance, so that the piston 519 is pressed into the cylinder 517. The movement is then dampened by the fluid 521 as described above, and the column element 21 is slowly and gently decelerated and stopped. The end of the movement is in Fig. 19. There is no hard impact at the end of the movement, which minimizes wear and prevents unwanted noise. For safety reasons, a stopper 533 is also attached to the column element 7, which engages with another stopper 535 in the column element 21 should a shock absorber fail. In addition, the shock absorber 503 is relieved when extended. The column element 7 also includes stoppers in the upper area (not shown here), which engage with the upper receiving element 505 of the shock absorber 503 when the column element 21 is retracted towards the end, braking and stopping the movement. Depending on the loads and speeds, several shock absorbers can be used between any two of the column elements, even in different side surfaces.

[0082] In the Fig. 20 and Fig. 21, the monitoring unit 51 is shown in two operating states. It comprises a frame 52 fastened to the inside of the column element 7, on which a bracket 53 is rotatably mounted. At the end, a roller 55 is rotatably or fixedly mounted on the bracket 53. The cables 35 and 45 are guided downwards through the bracket, with the cable 45 being in contact with the roller 55, while the cable 35 does not touch the bracket. A spring 56 is arranged between the frame 52 and the bracket 53, which applies a force to the bracket below the axis of rotation 57 towards the frame 52. As a result, the part of the bracket 53 carrying the roller 55 is pulled downwards in addition to the weight of the roller 55, until a state of equilibrium is reached due to the tension force of the cable 45, against which the roller 55 presses. Fig. In the normal state shown in Figure 3, i.e., with the cable 35 intact, the tensioning force is generated by the spring 49, via which the cable 45 is connected to the support plate 31. In this case, the cable 45 does not run vertically downwards, but is pulled slightly to the side and guided over the roller 55. This normal state is also maintained when the ceiling support 1 is extended or retracted, since almost the full load hangs on the cable 35. The cable 45 serves primarily as a safety and detector cable. If the cable 35 were to break, the full weight of the column elements 21, 23, 25 and 27, the support plate 31 and the load attached to it would hang on the cable 45. Consequently, a different force would pull on the lower end of the spring 49, disrupting the equilibrium. The cable 45 would be pulled tighter and apply a greater force to the bracket 53, which would then be deflected upwards. This stretches the spring 56. This condition is in Fig. 20, where the rope 45 is stretched almost vertically downwards by the increased downward force and thereby the roller 55 is pushed upwards.

[0083] The monitoring unit 51 is also able to detect a break in the cable 45. In this case, too, the balance with the spring 49 is disturbed, since the latter can no longer transmit tension to the cable 45. This condition is Fig. 21. The cable 45 is no longer pulled downward and is therefore correspondingly slack. The force of the spring 56 pulls the bracket 53 downward compared to the normal state, causing the roller 55 to also move downward.

[0084] The load-bearing capacity of ropes 35 and 45 is such that they are each capable of carrying the total permissible load on their own. Therefore, under normal conditions, only rope 35 is loaded, while rope 45 serves only as a safety rope. However, if one of the ropes 35 or 45 breaks, a potential safety risk exists, so the drive must be shut down or at least an alarm must be triggered. As already explained, the monitoring unit 51 is capable of detecting the breakage of any of the ropes 35 and 45 by changing the position of the bracket.

[0085] In the Fig. 22, the monitoring unit 51 is shown individually from the other viewing direction. A switch is mounted on the frame 52, which comprises a switch housing 54 and can be switched via a movable arm 58. The arm 58 is formed from a bent sheet metal that resiliently pushes the arm 58 away from the switch housing 54. The arm 58 is in contact with a semicircular projection 59 formed on the bracket 53, which in turn has a projection 59'. When the bracket 53 is rotated, the distance between the arm 58 and the switch housing 54 is therefore changed. When the arm 58 comes into contact with the projection 59', the arm 58 is pressed relatively close to the switch housing 54 and the switch is thus closed. This position is shown in Fig. 22 and corresponds to the normal state already explained. When one of the cables 35 or 45 breaks, the bracket 53 is moved up or down, causing the arm 58 to come into contact with the protrusion 59 above or below the projection 59'. These states are shown in the Fig. 23 (cable 35 broken) and 24 (cable 45 broken) are shown. The arm 58 therefore moves away from the switch housing 54, opening the switch. Connected electronics can thus trigger an alarm based on the switch status if one of the cables 35 or 45 breaks. The system can also be shut down.

[0086] The normal state is in the Fig. 25 is shown schematically. The support plate 31 is connected to both cables 35 and 45, with the connection to cable 45 being made via spring 49. The load is distributed between cables 35 and 45, as shown by arrows 601 and 603. The main load acts on cable 35. Cable 45 is deflected from its vertical position to the left by spring 56, creating a balance with the force acting on spring 49, as shown by arrows 605 and 607. Spring 56 is tensioned between a relaxed and a maximally tensioned state, as shown by a display 600 shown here for clarity only.

[0087] In the Fig. Figure 26 illustrates the case of a broken cable 45. The full load hangs on cable 35, represented by the long arrow 601'. As a result, very little or no force is exerted by cable 45 on spring 65, represented by the shorter arrows 605' and 607'. This allows spring 56 to relax, which is illustrated by a deflection of indicator 600. In this case, the switch is opened, and an alarm is triggered.

[0088] In the Fig. Figure 27 illustrates the case of the broken cable 35. This causes the full load to hang on the cable 45, which is represented by the longer arrow 603". Accordingly, the spring 49 is stretched and the cable 45 is tightened. Thus, a greater force acts on the spring 56, which is represented by the longer arrows 605" and 607". The spring 56 is also stretched, which in turn is illustrated by the deflection of the display 600. In this case, too, the switch is opened and an alarm is issued.

[0089] However, the monitoring unit 51 not only detects the previously described breakage of ropes 35 or 45. Rather, it also detects wear of the primarily loaded rope 35. When using steel ropes, fatigue occurs under continuous load due to the tearing or stretching of individual steel fibers. This causes the rope 35 to become slightly longer. This changes the balance of forces on rope 45, which can also be detected using a force gauge. Thus, a rope break can often be prevented in advance by timely replacement.

[0090] By means of the described safety system in combination with the described drive concept, an extremely compact, reliable and safe telescopic column can be provided, which particularly meets medical requirements. List of reference symbols 1 ceiling mount 3, 31 mounting plate 5 screw holes 7, 21, 23, 25, 27 column element 9 housings 11 Engine 17 Drive shaft 33, 43 rope drum 35, 45 rope 37, 47 fastening unit 49, 56 spring 51 Monitoring Unit 52 frames 53 brackets 54 switch housings 55 roll 57 axis of rotation 58 Arm 59 Formation 59' overhang 61 Main drive unit 63, 83 wave 65, 85 bearing point 67, 87 Worm gear 69, 89 clutch unit 81 Security Unit 91, 93 coupling element 92 screw 94 Wrap spring 101 Basic Element 102 screw hole 103a, 103b, 103c, 107,a 107b, 107c coupling element 105 Shaft seat 106 groove 109, 109' End 111 lead 113 Brake housing 500 page area 501 Deepening 502 slot 503 shock absorbers 505 receiving element 507 Middle section 509 guide part 511 groove 513 Round shape 515 Damping element 517 cylinders 519 pistons 521 Liquid 523 spring 525 stamps 527, 529 Canal 531 Valve 532, 533, 535 stoppers 600 ad 601, 601',603, 603''' arrow 605, 605', 605'' arrow 607, 607', 607'' Arrow

Claims

[1] Telescopic column (1), having the following features: - at least two telescopic elements (7, 21, 23, 25, 27) which can be moved linearly relative to one another, - at least one drive unit (81) connected to a first of the telescopic elements, - at least one connecting element (45) through which a force can be transmitted from the drive unit to a second of the telescopic elements, - a monitoring unit (51) with a detector element corresponding to the connecting element, wherein the monitoring unit is designed such that an operating parameter of the connecting element can be detected by means of the detector element, wherein the detector element has a pre-tensionable lever arm (53) by means of which a tensioning force defined by the pre-tension can be exerted on the connecting element, - a counterforce element by which a counterforce can be exerted on the connecting element, so that a basic tension of the connecting element generated in this way forms the operating parameter, - whereby when the operating parameter is detected outside of pre-definable operating parameters, a defined change in the operating state of the drive unit can be carried out. [2] Telescopic column according to claim 1, further comprising a second drive unit (61) and a second connecting element (35) through which a force can be transmitted from the second drive unit to the second of the telescopic elements. [3] Telescopic column according to claim 1 or 2, wherein the monitoring unit has the following features: - A switching element (58) cooperating with the detector element, by means of which a switching operation can be carried out by means of which the operating state of at least one of the drive units can be influenced. [4] Telescopic column according to claim 3, further comprising the following features: - the clamping force and the counterforce are selected in such a way that in the normal operating state of the connecting element there is a balance between the two forces and the lever arm is held in an equilibrium position, - the connecting element is designed in such a way that a change in the basic tension changes the equilibrium in such a way that the lever arm can be deflected from its equilibrium position, - the switching element is designed in such a way that the switching operation is carried out when the lever arm is deflected from its equilibrium position. [5] Telescopic column according to one of the preceding claims, wherein the connecting element is designed as a rope, band or chain. [6] Telescopic column according to one of the preceding claims, wherein the drive unit comprises a shaft (63, 83) on which the connecting element is arranged so as to be wound up and unwound, so that when the connecting element is wound up or unwound by its connection to the second telescopic element, the latter can be moved linearly with respect to the first telescopic element. [7] Telescopic column according to one of claims 4 to 6, wherein the counterforce element is designed as a spring element (49) arranged between the connecting element and the telescopic element. [8] Telescopic column according to one of the preceding claims, wherein a change in the operating parameter is defined by a failure or wear of the connecting element. [9] Telescopic column according to one of claims 4 to 8, wherein in the event of failure or wear of the connecting element, the counterforce is completely or partially eliminated. [10] Telescopic column according to one of the preceding claims, wherein a motor (11) comprised by the drive unit is stopped in order to change the operating state of the drive unit.

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