EP3235986B1 - Door drive - Google Patents

Description

The invention relates to a door drive with an output shaft for coupling the door drive to a power transmission element. The invention also relates to a method for assembling a door drive.

The problem with door drives is that the door drive has to be adapted to different mounting positions. In particular, the vertical distance between the door lintel and the installed door drive can assume different values depending on the installation conditions. So that a variant of the door drive can be operated in different assembly positions, it is known from the prior art to extend the output shaft of the door drive with an extension element if necessary. In this case, the length of the extension element is usually chosen so that the force transmission element, which is usually formed by a linkage and is attached to the end of the extension element spaced apart from the door drive, is arranged essentially horizontally. The disadvantage here is that the extension element is kept in several different lengths and an extension element with the required length has to be selected when installing the door drive. Alternatively, an extension element of great length can be kept in stock, the extension element first having to be brought to the required length when the door drive is installed, for example by sawing off, which is also disadvantageous. A door drive known from the prior art is shown in FIG DE 298 14 354 U1 disclosed.

It is therefore the object of the invention to provide a door drive which can be easily adapted to different mounting positions. In particular, it is the object of the invention to provide a door drive which can be flexibly adapted to different mounting positions with an adjustable-length output shaft, in particular the connection between the output shaft and the power transmission element being free of play. Furthermore, it is the object of the invention to specify a method for assembling a door drive which enables a door drive to be assembled in a simple manner.

The previously derived and indicated object is achieved on the basis of the door drive described at the beginning by the features of claim 1, based on the fact that the output shaft comprises a hollow shaft and a shaft insert, the shaft insert being insertable into the hollow shaft, the shaft insert having at least one first clamping element and having at least one second clamping element, wherein the clamping elements of the shaft insert can be moved from a first spatial arrangement into a second spatial arrangement by relative displacement transversely to the axis of rotation of the hollow shaft, the shaft insert being movable in the first spatial arrangement in the hollow shaft and the shaft insert being movable in the hollow shaft the second spatial arrangement in the hollow shaft is fixed in a non-positive and / or positive manner.

In this way, it is achieved on the one hand that the door drive can be easily and flexibly adapted to different mounting positions with a length-adjustable output shaft. Furthermore, on the other hand, a play-free connection between the shaft insert and the hollow shaft can thereby be achieved in a particularly simple and cost-effective manner, see above that a power transmission from the door drive via a power transmission element to the door to be driven is also as free of play as possible. Advantageous further developments of the invention are given in the dependent claims, the description and in the figures.

A relative displacement of the clamping elements to one another transversely to the axis of rotation of the hollow shaft describes a displacement of at least one of the clamping elements along a direction that is not parallel to the axis of rotation of the hollow shaft. This shift can run at an angle different from zero degrees to the axis of rotation of the hollow shaft, in particular, but not according to the invention, the shift can be perpendicular to the axis of rotation of the

Run hollow shaft. In particular, the axis of rotation of the shaft insert and the axis of rotation of the hollow shaft match.

The force transmission element can preferably have a scissor linkage or a slide rail linkage.

Furthermore, it can be provided that the clamping elements of the shaft insert can be moved from the second spatial arrangement into the first spatial arrangement by relative displacement transversely to the axis of rotation of the hollow shaft with respect to one another. This ensures that the fixing of the shaft insert in the hollow shaft is reversible. Thus, if necessary, for example for maintenance or repair, the shaft insert can be moved in the hollow shaft or removed from the hollow shaft.

Furthermore, it can be provided that the shaft insert is steplessly displaceable in the hollow shaft when the clamping elements are in the first spatial arrangement. This ensures that the length of the part of the shaft insert protruding from the hollow shaft can be adjusted extremely flexibly to different lengths.

Furthermore, it can be provided that the shaft insert has a length of at least 40 mm, preferably at least 50 mm and particularly preferably at least 70 mm. This ensures that the door drive is also suitable for assembly positions that require a relatively long extension of the shaft.

Furthermore, it can be provided that the shaft insert has a first engagement element, in particular with an engagement for a tool, wherein the clamping elements can be moved from the first spatial arrangement into the second spatial arrangement by adjusting the engagement element, the first engagement element in particular by a Screw, preferably an expansion screw is formed. What is achieved hereby is that the adjustment of the engagement element, the clamping elements from the first spatial arrangement into the second spatial arrangement, is possible in a simple manner.

Furthermore, it can be provided that the shaft insert has a second engagement element, in particular with an engagement for a tool, the clamping elements from the second spatial arrangement into the first by adjusting the engagement element Spatial arrangement can be moved, the second engagement element being formed in particular by a screw, preferably an expansion screw. What is achieved hereby is that the adjustment of the engagement element, the clamping elements from the second spatial arrangement into the first spatial arrangement, is possible in a simple manner.

Furthermore, it can be provided that the first engagement element and the second engagement element are formed by a single engagement element, the individual engagement element being formed in particular by a screw, preferably an expansion screw. This ensures that both the moving of the clamping elements from the first spatial arrangement into the second spatial arrangement and the moving of the clamping elements from the second spatial arrangement into the first spatial arrangement can be carried out by adjusting a single engagement element.

Furthermore, it can be provided that the shaft insert has a cover sleeve, the cover sleeve at least partially surrounding the part of the shaft insert protruding from the hollow shaft. This ensures that the visible part of the output shaft has a visually particularly pleasing outer contour. This also ensures that the shaft insert is protected from contamination and mechanical influences, in particular vandalism. Furthermore, this outer contour can be designed independently of the shaft insert. In particular, the cover sleeve can be made from a different material than the shaft insert and / or have a different color and / or have a different surface quality.

Furthermore, it can be provided that the hollow shaft and / or the shaft insert has at least one holding element, the holding element or the holding elements fixing the shaft insert in a non-positive and / or form-fitting manner in the hollow shaft when the clamping elements are in the first spatial arrangement. This means that the assembly of the door drive is made much easier, since a fitter can insert the shaft insert into the hollow shaft and then have both hands free, for example to move the clamping elements into the second spatial arrangement. In particular, the holding force of the holding element is selected such that the holding element is able to hold at least the dead weight of the shaft insert, in particular at least the dead weight of the shaft insert and a force transmission element. In particular, the holding force of the holding element is selected such that the shaft insert can be moved manually, preferably continuously, in the hollow shaft when the clamping elements are in the first spatial arrangement.

Furthermore, it can be provided that the holding element is formed by an elastic ring, in particular made of rubber, the ring in particular being arranged in a circumferential groove in one of the clamping elements. This means that the clamping element can be manufactured particularly cost-effectively and can be easily integrated into the output shaft.

It can also be provided that the length of the shaft insert is greater than the length of the hollow shaft, in particular the length of the shaft insert being less than 300%, preferably less than 200%, particularly preferably less than 150% of the length of the Hollow shaft. This means that even if the hollow shaft is filled with the shaft insert over its entire length, one end of the shaft insert protrudes from the hollow shaft. This end can then be connected to the force transmission element for power transmission between the door drive and the power transmission element.

Furthermore, in embodiments not according to the invention, it can be provided that the shaft insert has a non-circular outer profile and the hollow shaft has a corresponding non-circular inner profile, the non-circular outer profile of the shaft insert engaging the non-circular inner profile of the hollow shaft. This ensures that the shaft insert is reliably protected against rotation relative to the hollow shaft when it is inserted into the hollow shaft. This means that relatively high torques can also be transmitted between the hollow shaft and the shaft insert.

In particular, the outer profile of the shaft insert can be polygonal, for example triangular, square, pentagonal or hexagonal, the hollow shaft having a corresponding polygonal, for example triangular, square, pentagonal or hexagonal inner profile.

It can further be provided that the hollow shaft has internal teeth and the shaft insert has external teeth, the external teeth engaging the internal teeth when the shaft insert is inserted in the hollow shaft. This prevents rotation of the shaft insert in the hollow shaft.

The door drive can in particular be arranged directly on or in the door leaf, on or in a wall, on or in a door frame or on or in the floor. The door drive can in particular be selected from the group of overhead door closers, door closers mounted in the door, frame door closers or floor springs. The door drive can be designed as a mechanical door drive or as a door drive operated with an auxiliary power.

Mechanical door drives are often referred to as door closers or door closing devices with a controlled closing process. A door closer is able to store at least part of the energy used by the person entering the door during the opening process of the door. After releasing the door leaf by the person entering the door, the door closer can use the stored energy to automatically close the door leaf again.

A door drive operated with auxiliary power can in particular be an electrical and / or electromechanical and / or electrohydraulic and / or pneumatic door drive, with the door leaf, i.e. by means of electrically and / or electromechanically and / or electrohydraulically and / or pneumatically generated auxiliary power, can be closed and / or opened. The helper can be dimensioned in such a way that the helper has a supporting effect, that is to say that the person entering the door has to use less force when opening and / or closing the door. The assistant can also be dimensioned such that the door is automatically opened by the assistant, that is to say that no personal effort has to be used by the walker in addition to the assistant. The auxiliary force is preferably adjustable, in particular as a function of the opening angle of the door leaf. If the auxiliary power fails, door drives operated with auxiliary power preferably continue to perform the functions of a mechanical door drive, in particular the function of automatically closing or opening the door.

Door drives can preferably have at least one safety device. The safety device can, for example, in particular limit the opening force and / or the opening speed. In addition or as an alternative, the safety device can in particular monitor the swivel range of the door leaf and trigger a safety function if a person or an object comes into the swivel range of the door leaf. A safety function can include, for example, stopping the door leaf, reducing the speed of the door leaf or reversing the movement of the door leaf.

Door drives can preferably have at least one monitoring device. The monitoring device can in particular have sensors that can detect dangerous environmental conditions, such as B. fires, smoke or dangerous concentrations of gases (e.g. carbon monoxide). The monitoring device can trigger a safety function after the detection of dangerous environmental conditions. A safety function can include, for example, overriding an automatic door opening function. The monitoring device and the safety device can be designed separately or can be formed by a common device.

Door drives can preferably have at least one pulse generator. The pulse generator can in particular give the command to open and / or close the door. The command given by the pulse generator is processed by a controller, the controller controlling the door leaf movement commanded by the pulse generator. Impulse generators are divided into conscious impulse generators (e.g. switches, buttons), via which the door leaf movement is consciously initiated, and unconscious impulse generators (e.g. light barriers, radar, contact mats), via which the door leaf movement unconsciously when the impulse generator is entered monitored area is initiated.

Furthermore, door drives can preferably control or regulate the closing movement of the door leaf in such a way that the closing process can be delayed for an, in particular adjustable, time. This damping function is also referred to as closing delay.

Furthermore, door drives can preferably comprise a housing. The housing can preferably have a substantially cuboid shape. The housing can preferably have at least one first opening for coupling the output drive arranged in the housing to a force transmission element. It can also be provided that a second opening opposite the first opening is provided in the housing for coupling the output to a force transmission element. Decorative elements that essentially completely cover parts of the housing or also the housing can be arranged on the housing. The housing is preferably made of one material manufactured. In particular, the housing can be made from a metallic material. It is also preferred that the housing is formed in one piece. The housing can also be formed by several sections. The housing can be made at least partially from plastic.

• Montieren des Türantriebs nach einem der Ansprüche 1 bis 11 an einer Tür
• Einsetzen des Welleneinsatzes in die Hohlwelle
• Verbringen der Klemmelemente aus der ersten räumlichen Anordnung in die zweite räumliche Anordnung.

Based on the method for assembling a door drive described at the beginning, the previously derived and indicated object is also achieved in that the method comprises the following steps:

• Mounting the door drive according to one of Claims 1 to 11 on a door
• Insertion of the shaft insert into the hollow shaft
• Moving the clamping elements from the first spatial arrangement into the second spatial arrangement.

This means that the door drive can be easily adapted to different mounting positions. Advantageous further developments of the invention are given in the dependent claims, the description and in the figures.

Furthermore, it can be provided that a force transmission element is connected to the shaft insert. This ensures that forces can be transmitted between the door drive and the shaft insert.

Furthermore, it can be provided that the shaft insert is inserted and fixed so deeply into the hollow shaft that the force transmission element runs essentially horizontally in the assembled state. This ensures that the visual appearance of the door drive in interaction with the force transmission element and the door is appealing to the viewer. A force transmission element that does not run horizontally is usually interpreted by an observer as a technical defect.

Features and details that are described in connection with the door drive according to the invention also apply in connection with the method according to the invention and vice versa.

In particular, a method that can be carried out with a door drive according to one of Claims 1 to 11, and a door drive on which a method according to one of Claims 12-14 can be carried out, are protected.

• Fig. 1 zeigt schematisch einen erfindungsgemäßen Türantrieb 1 gemäß einer ersten Ausgestaltung der Erfindung,
• Fig. 2 schematisch drei Welleneinsätze 5 gemäß verschiedener Ausgestaltungen
• Fig. 3a - 3c schematisch eine Schnittdarstellung eines erfindungsgemäßen Türantriebs 1 gemäß einer ersten Ausgestaltung der Erfindung in drei verschiedenen Montagepositionen und
• Fig. 4a - 4c schematisch eine Schnittdarstellung eines nicht erfindungsgemäßen Türantriebs 1 in drei verschiedenen Montagepositionen.

The invention is explained in more detail below on the basis of exemplary embodiments. Technical features with the same function are provided with identical reference symbols in the figures. Show it:

• Fig. 1 shows schematically a door drive 1 according to the invention according to a first embodiment of the invention,
• Fig. 2 schematically three shaft inserts 5 according to different configurations
• Figures 3a-3c schematically a sectional view of a door drive 1 according to the invention according to a first embodiment of the invention in three different assembly positions and
• Figures 4a-4c schematically a sectional illustration of a door drive 1 not according to the invention in three different assembly positions.

In Fig. 1 a door drive 1 according to the invention with an output shaft 2 is shown. The output shaft 2 has a hollow shaft 4 and a shaft insert 5. The door drive 1 is coupled to a force transmission element 3. Forces between the door drive and a door to be driven, which is not shown here, can be transmitted via the force transmission element 3.

Fig. 2 shows three different shaft inserts 5. Each shaft insert 5 has a first clamping element 5a and a second clamping element 5b. The clamping elements 5a, 5b of each shaft insert 5 can be moved from a first spatial arrangement into a second spatial arrangement by relative displacement transversely to the axis of rotation of the hollow shaft 4 to one another and / or by rotation to one another.

The first clamping element 5a in the Fig. 2 Shaft insert 5 depicted in the center, not according to the invention, has a holding element 11 in the form of a rubber ring, the rubber ring being arranged in a groove, the groove being arranged in the outer contour of the shaft insert 5. The holding element 11 fixes the shaft insert 5 non-positively and / or positively in the hollow shaft 4 when the clamping elements 5a, 5b are in the first spatial arrangement. The Indian Fig. 2 shaft insert 5 shown in the middle and the one in the Fig. 2 Shaft insert 5 shown on the left each have external toothing 7. The shaft inserts 5 each have an engagement element 8, the engagement element 8 being formed by an expansion screw. The engagement element 8 of the right shaft insert 5 is covered and not shown. By adjusting the engagement element 8, the clamping elements 5a, 5b can be brought from the first spatial arrangement into the second spatial arrangement and from the second spatial arrangement into the first spatial arrangement.

The clamping elements 5a, 5b in the Fig. 2 Shaft insert 5 shown on the right can be assembled so that they form an essentially cylindrical body. Here, both clamping elements 5a, 5b have the shape of a cylinder, one of the two surfaces of the cylinder each running at an angle to the axis of symmetry of the cylinder. The inclined surfaces of the clamping elements 5a, 5b intersect the symmetry axis of the respective cylinder at the same angle. In the assembled arrangement of the clamping elements 5a, 5b, the inclined surfaces of the cylinders form the contact surface between the clamping elements 5a, 5b. In particular, the clamping elements 5a, 5b have identical radii. In this case, the clamping elements 5a, 5b can be produced particularly easily by cutting an individual circular cylinder at an angle. By incorporating an external toothing 7 is from the in Fig. 2 Shaft insert 5 shown on the right of the Fig. 2 Shaft insert 5 shown on the left can be produced.

The clamping elements 5a, 5b in the Fig. 2 Shaft insert 5 shown in the middle, not according to the invention, can also be assembled in such a way that they form a substantially cylindrical body. Here, however, one of the clamping elements 5a, 5b has a recess and the other of the clamping elements 5a, 5b has a corresponding nose, the nose being insertable into the recess of the respective other clamping element 5a, 5b. Apart from the nose or the corresponding recess and the external toothing 7, both clamping elements 5a, 5b essentially have the shape of a straight circular cylinder. The clamping elements 5a, 5b in the Fig. 2 The shaft insert 5 shown in the middle can be produced particularly easily by cutting a circular cylinder accordingly.

The Figures 3a to 3c show a sectional view of a door drive 1 according to the invention according to a first embodiment of the invention in three different assembly positions. The output shaft 2 here has a hollow shaft 4 and a shaft insert 5. The shaft insert 5 has a first clamping element 5a and a second clamping element 5b. The clamping elements 5a, 5b are connected to one another by the engagement element 8. The engagement element 8 is formed by a screw. The engagement element 8 has an engagement 9 for a tool, for example a screwdriver. The engagement element 8 connects the shaft insert 5 with a power transmission element 3 in such a way that a rotation of the shaft insert 5 around the longitudinal axis of the shaft insert 5 also leads to a rotation of the power transmission element 3 around the longitudinal axis of the shaft insert 5 and vice versa. The shaft insert 5 is thus non-rotatably connected to the force transmission element 3.

As the Figures 3a to 3c show, the shaft insert 5 can be pushed to various positions within the hollow shaft 4 and fixed there. The fixation takes place in that the clamping elements 5a, 5b of the shaft insert 5 are moved from the first spatial arrangement into the second spatial arrangement by relative displacement transversely to the axis of rotation of the hollow shaft 4. In the first spatial arrangement, the shaft insert 5 is freely displaceable in the hollow shaft 4. By means of a tool (not shown), the screw which forms the engagement element 8 can be tightened via the engagement 9. As a result, the first clamping element 5a is displaced transversely to the axis of rotation of the hollow shaft 4. The displacement of the first clamping element 5a relative to the second clamping element 5b takes place along the contact surface of the clamping elements 5a, 5b and thus in the Figures 3a to 3c down to the right. The axis of rotation of the hollow shaft 4 runs in the Figures 3a to 3c perpendicular. The axis of rotation of the shaft insert 5 and the axis of rotation of the hollow shaft 4 match. As a result of the displacement of the first clamping element 5a relative to the second clamping element 5b, the shaft insert 5 is clamped within the hollow shaft 4 and is thus fixed within the hollow shaft 4 without play. The fixation can be canceled by loosening the screw that forms the engagement element 8.

As from the Figures 3b and 3c As can be seen, the hollow shaft 4 has internal teeth 6 and the shaft insert 5 has external teeth 7, the external teeth 7 engaging the internal teeth 6 when the shaft insert 5 is inserted in the hollow shaft 4. The design of the shaft insert 5 in the Figures 3a to 3c thus corresponds to the design of the Fig. 2 shaft insert shown on the left 5.

The Figures 4a to 4c show a sectional view of a door drive 1 not according to the invention according to a further embodiment of the invention in three different assembly positions. The Figures 4a to 4c differ from the Figures 3a to 3c by the design of the shaft insert 5. The design of the shaft insert 5 in the Figures 4a to 4c corresponds to the design of the Fig. 2 shaft insert shown in the middle 5.

As the Figures 4a to 4c show, the shaft insert 5 can be pushed to various positions within the hollow shaft 4 and fixed there. The fixation takes place in that the clamping elements 5a, 5b of the shaft insert 5 are brought from the first spatial arrangement into the second spatial arrangement by rotating them relative to one another. In the first spatial arrangement, the shaft insert 5 is freely displaceable in the hollow shaft 4. By means of a tool (not shown), the screw which forms the engagement element 8 can be tightened via the engagement 9. As a result, the first clamping element 5a rotates relative to the second clamping element 5b. The rotation takes place around the axis of rotation of the hollow shaft 4. The axis of rotation of the hollow shaft 4 runs in the Figures 4a to 4c perpendicular. The axis of rotation of the shaft insert 5 and the axis of rotation of the hollow shaft 4 match. As a result of the rotation of the first clamping element 5a relative to the second clamping element 5b, the shaft insert 5 is clamped within the hollow shaft 4 and is thus fixed within the hollow shaft 4 without play. The jamming is promoted by the internal toothing 6 of the hollow shaft 4 and by the external toothing 7 of the shaft insert 5. The fixation can be canceled by loosening the screw that forms the engagement element 8.

Furthermore, the shaft insert 5 has a cover sleeve 10, the cover sleeve 10 partially surrounding the part of the shaft insert 5 protruding from the hollow shaft 4. Here, the cover sleeve 10 covers the external toothing 7 of the shaft insert 5, whereby the door drive 1 has an attractive external appearance and the shaft insert 5 is protected from dirt and mechanical influences, in particular vandalism.

List of reference symbols

1

Door drive

2

Output shaft

3

Power transmission element

4th

Hollow shaft

5

Shaft insert

5a

first clamping element

5b

second clamping element

5a, 5b

Clamping elements

6th

Internal gearing

7th

External toothing

8th

Attack element

9

attack

10

Cover sleeve

11

Retaining element

Claims (14)

1. A door drive (1) with an output shaft (2) to couple the door drive (1) to a force transmission element (3), characterized in that the output shaft (2) comprises a hollow shaft (4) and a shaft insert (5), wherein the shaft insert (5) can be inserted into the hollow shaft (4), wherein the shaft insert (5) has at least one first clamping element (5a) and at least one second clamping element (5b), wherein the clamping elements (5a, 5b) of the shaft insert (5) can be composed such that they form a substantially cylindrical body, wherein both clamping elements (5a, 5b) have the shape of a cylinder, wherein in each case one of the two surfaces of the cylinder runs obliquely to the symmetry axis of the cylinder, wherein the oblique surfaces of the clamping elements (5a, 5b) intersect the symmetry axis of the respective cylinder at the same angle, wherein in the assembled arrangement of the clamping elements (5a, 5b), the oblique surfaces of the cylinders form the contact surfaces between the clamping elements (5a, 5b), wherein the clamping elements (5a, 5b) of the shaft insert (5) can be moved into a second spatial arrangement from a first spatial arrangement, through relative displacement transverse to the axis of rotation of the hollow shaft (4) in relation to one another, wherein the displacement of the first clamping element (5a) takes place relative to the second clamping element (5b) in this case along the contact surface of the clamping elements (5a, 5b), wherein the shaft insert (5) can be moved in the hollow shaft (4) in the first spatial arrangement and the shaft insert (5) is fixed in a force-fitting and/or positive-locking manner in the hollow shaft (4) in the second spatial arrangement.
2. The door drive (1) according to any one of the preceding claims, characterized in that the clamping elements (5a, 5b) of the shaft insert (5) can be moved into the first spatial arrangement from the second spatial arrangement through relative displacement transverse to the axis of rotation of the hollow shaft (4) in relation to one another.
3. The door drive (1) according to any one of the preceding claims, characterized in that the shaft insert (5) can be displaced in a continuous manner in the hollow shaft (4) when the clamping elements (5a, 5b) are located in the first spatial arrangement.
4. The door drive (1) according to any one of the preceding claims, characterized in that the shaft insert (5) has a first engagement element (8), in particular with engagement (9) for a tool, wherein by adjusting the engagement element (8), the clamping elements (5a, 5b) can be moved into the second spatial arrangement from the first spatial arrangement, wherein the first engagement element (8) is formed in particular by a screw, preferably by an expansion screw.
5. The door drive (1) according to any one of the preceding claims, characterized in that the shaft insert (5) has a second engagement element (8), in particular with an engagement (9) for a tool, wherein by adjusting the engagement element (8), the clamping elements (5a, 5b) can be moved into the first spatial arrangement from the second spatial arrangement, wherein the second engagement element (8) is formed in particular by a screw, preferably by an expansion screw.
6. The door drive (1) according to claim 4 or 5, characterized in that the first engagement element (8) and the second engagement element (8) are formed by a single engagement element (8), wherein the single engagement element (8) is formed in particular by a screw, preferably by an expansion screw.
7. The door drive (1) according to any one of the preceding claims, characterized in that the shaft insert (5) has a cover sleeve (10), wherein the cover sleeve (10) at least partially surrounds the part of the shaft insert (5) protruding from the hollow shaft (4).
8. The door drive (1) according to any one of the preceding claims, characterized in that the hollow shaft (4) and/or the shaft insert (5) have/has at least one retaining element (11), wherein the retaining element (11) or the retaining elements (11) fixes/fix the shaft insert (5) in a force-fitting and/or positive-locking manner in the hollow shaft (4) when the clamping elements (5a, 5b) are located in the first spatial arrangement.
9. The door drive (1) according to claim 8, characterized in that the retaining element (11) is formed by an elastic ring, in particular made of rubber, wherein in particular the ring is arranged in a circumferential groove in one of the clamping elements (5a, 5b).
10. The door drive (1) according to any one of the preceding claims, characterized in that the length of the shaft insert (5) is greater than the length of the hollow shaft (4), wherein in particular the length of the shaft insert (5) is less than 300%, preferably less than 200%, particularly preferably less than 150% of the length of the hollow shaft (4).
11. The door drive (1) according to any one of the preceding claims, characterized in that the hollow shaft (4) has an inner toothing (6) and the shaft insert (5) has an outer toothing (7), wherein the outer toothing (7) engages into the inner toothing (6) when the shaft insert (5) is inserted in the hollow shaft (4).
12. A method for assembling a door drive (1), characterized in that the method comprises the following steps:

    - assembling the door drive (1) according to any one of claims 1 to 11 on a door

    - inserting the shaft insert (5) into the hollow shaft (4)

    - moving the clamping elements (5a, 5b) from the first spatial arrangement into the second spatial arrangement.
13. The method for assembling a door drive (1) according to claim 12, characterized in that a force transmission element (3) is connected to the shaft insert (5).
14. The method for assembling a door drive (1) according to claim 12 or 13, characterized in that the shaft insert (5) is inserted deep into the hollow shaft (4) and fixed such that the force transmission element (3) runs substantially horizontally in the assembled state.

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