阅读说明：本技术 用于车门的驱动装置 (Drive device for a vehicle door ) 是由 A·维尔特 J·巴尔斯 于 2018-07-06 设计创作，主要内容包括：本发明涉及一种用于枢转车门的驱动装置,包括：第一壳体部件(3)；第二壳体部件(4),其中,第一壳体部件(3)和第二壳体部件(4)被设计成能够在驱动装置(1)的轴向延伸方向(x)上相对于彼此移动；主轴杆(12),其可旋转地布置在第一壳体部件(3)和第二壳体部件(4)中的一个上；和主轴螺母(13),其不可旋转地布置在第一壳体部件(3)和第二壳体部件(4)中的另一个上；制动装置(19),其包括第一制动元件和第二制动元件,第一制动元件不可相对旋转地连接至主轴杆(12),第二制动元件不可相对旋转地连接至第一壳体部件(3)和第二壳体部件(4)中的一个,其中,第一制动元件能够与第二制动元件相互作用以产生制动力；和用于产生磁场的磁体布置结构。本发明的目的是限定一种用于枢转车门的驱动装置(1),从而为车门提供简单且可靠的自动枢转和灵活的保持力,以使得第一制动元件和第二制动元件中的至少一个可通过磁场在主轴杆(12)的轴向方向(x)上移位。(The invention relates to a drive device for pivoting a vehicle door, comprising: a first housing part (3); a second housing part (4), wherein the first housing part (3) and the second housing part (4) are designed to be movable relative to each other in an axial extension direction (x) of the drive device (1); a spindle shaft (12) rotatably arranged on one of the first housing part (3) and the second housing part (4); and a spindle nut (13) which is arranged non-rotatably on the other of the first housing part (3) and the second housing part (4); a brake device (19) comprising a first brake element which is non-rotatably connected to the spindle shaft (12) and a second brake element which is non-rotatably connected to one of the first housing part (3) and the second housing part (4), wherein the first brake element can interact with the second brake element to generate a braking force; and a magnet arrangement for generating a magnetic field. The object of the invention is to define a drive device (1) for pivoting a vehicle door, which provides a simple and reliable automatic pivoting and a flexible retaining force for the vehicle door, so that at least one of the first and second brake elements can be displaced in the axial direction (x) of the spindle shaft (12) by means of a magnetic field.)

1. A drive arrangement for a pivotable vehicle door, comprising:

a first housing part (3),

a second housing part (4), wherein the first housing part (3) and the second housing part (4) are designed to be movable relative to each other in an axial direction (x) of extension of the drive device (1),

a spindle shaft (12) rotatably arranged on one of the first housing part (3) and the second housing part (4), and

a spindle nut (13) which is arranged non-rotatably on the other of the first housing part (3) and the second housing part (4),

a braking device (19) comprising: a first brake element (20) which is connected to the spindle shaft (12) in a rotationally fixed manner; a second brake element (22) which is connected to one of the first housing part (3) and the second housing part (4) in a rotationally fixed manner, wherein the first brake element (20) can interact with the second brake element (22) in order to generate a braking force, and

magnet arrangement (23) for generating a magnetic field, characterized in that,

at least one of the first brake element (20) and the second brake element (22) can be displaced in the axial direction (x) of the spindle shaft (12) by means of a magnetic field.

2. The drive according to claim 1, characterized in that the first housing part (3) and the second housing part (4) are components of a housing (2) of the drive (1), wherein the first housing part (3) and the second housing part (4) are arranged concentrically to each other.

3. The drive arrangement according to claim 1 or 2, characterized in that the magnet arrangement (23) comprises an electromagnet (24).

4. The drive device according to one of the preceding claims, characterized in that the magnet arrangement (23) comprises a permanent magnet (25).

5. The drive device according to claim 4, characterized in that the permanent magnet (25) causes the one of the first brake element (20) and the second brake element (22) which is designed to be axially displaceable to be magnetically attracted towards the other one of the first brake element (20) and the second brake element (22).

6. The drive device according to any one of the preceding claims, characterized in that one of the first brake element (20) and the second brake element (22) is displaceable in the axial direction (x) towards the other of the first brake element (20) and the second brake element (22) such that the first brake element (20) and the second brake element (22) can contact each other.

7. Drive arrangement according to any one of the preceding claims, characterized in that the first brake element (20) has a first friction surface (20a) and the second brake element (22) has a second friction surface (22 a).

8. Drive arrangement according to claim 7, characterized in that the first friction surface (20a) and the second friction surface (22a) are opposite each other and arranged perpendicular to the axial direction (x) of the spindle shaft (12).

9. The drive device according to any one of the preceding claims, characterized in that the magnet arrangement (23) is arranged on the first brake element (20) or the second brake element (22).

10. The drive device according to any one of the preceding claims, wherein the magnet arrangement (23) is arranged on a second brake element (22) which is connected non-rotatably to one of the first housing part (3) and the second housing part (4).

Technical Field

The invention relates to a drive device for a pivotable vehicle door according to the invention.

Background

From practice, drive devices for pivotable vehicle doors are known which are articulated at a first end to a body part of the vehicle and at a second end to the vehicle door. The drive device is usually designed as a linear drive, so that in operation the first end of the drive device and the second end of the drive device can be moved linearly relative to one another, thus pivoting the vehicle door in a motor-driven manner. The function of the drive means is therefore to ensure that the door can be pivoted automatically between the closed position and the open position and further to park the door in any position between the fully closed and the fully open position. Therefore, the drive device for pivotable vehicle doors should provide, in addition to the driving function, also a braking function during the displacement of the vehicle door.

DE 19752543 a1 discloses a magnetic brake having a first non-rotatable brake element and a second rotatable brake element. In the braking position of the magnetic brake, the first brake element and the second brake element are connected to one another in a frictional or form-fitting manner, such that the first brake element is held or at least braked by the second brake element. The magnetic brake comprises an electromagnet which, by means of a suitable current supply, displaces the first and second brake elements relative to each other into a braking position or a disengagement position, wherein in the braking position the braking force has a specific value. The magnetic brake comprises, in addition to the electromagnet, a permanent magnet and a spring device which biases the first and second brake elements towards the braking position. A disadvantage of the disclosed magnetic brake is that the braking force cannot be flexibly adjusted, but assumes substantially only a specific value in the braking position.

DE 102007026796 a1 discloses a door brake mechanism for a vehicle door, wherein the door brake mechanism comprises a brake device, wherein the brake device comprises a first brake element and a second brake element, which respectively have friction surfaces facing each other, wherein a rotational movement of the first brake element relative to the second brake element is decelerated by the contact of the friction surfaces. Wherein the first and second braking elements are made of a ferromagnetic material, wherein the braking elements are reversibly magnetizable. The brake device also includes a spring element that biases the first brake element relative to the second element toward a disengaged position of the brake device. A disadvantage of the disclosed door brake mechanism is that the braking force of the brake device is significantly influenced by the spring element and the electromagnet must also be energized in order to achieve a permanent braking action. By providing a spring, the brake device is also prone to failure.

DE 3906069 a1 discloses a brake device comprising a first brake element and a second brake element, each brake element having a brake pad and at least one compression spring associated with each brake element. The brake device has a housing in which a current-carrying electromagnetic coil is accommodated. The compression spring associated with each braking element biases the braking elements such that the respective brake pads are in contact with each other, whereby the braking device is in a braking position. By energizing the coils, the braking elements are displaced relative to each other such that the braking device enters the disengaged position, i.e. the brake pads of the braking elements are no longer in contact. A disadvantage of the disclosed brake device is that an additional spring is associated with each brake element, as a result of which the sensitivity of the brake device to faults increases and the braking force cannot be controlled accurately.

DE 102015221067 a1 discloses a drive device for a pivotable vehicle door, which drive device comprises a first housing part and a second housing part, wherein the first housing part and the second housing part are designed to be movable relative to one another in the axial extension direction of the drive device. The spindle shaft is rotatably arranged on the first housing part and the spindle nut is non-rotatably arranged on the second housing part. A drive device is arranged in the first housing part, wherein the drive device comprises an electric motor. The electric motor has a housing, wherein a first braking element is rigidly connected to an inner wall of the housing, which first braking element is formed by a resetting element and a permanent magnet element rigidly connected to the resetting element. Furthermore, the electric motor comprises a drive shaft on which a second braking element is arranged in a non-rotatable manner, which second braking element is likewise formed by a restoring element and a permanent magnet element. The intermediate elements are arranged between the permanent magnet elements. The permanent magnet elements serve to generate a braking force between the braking elements and thus to decelerate the drive shaft of the electric motor. A disadvantage of the disclosed drive is that the braking force is constant and the holding force is not variable, since it is defined by the permanent magnet and cannot be further changed.

Disclosure of Invention

The object of the invention is to provide a drive device for a pivotable vehicle door, which provides a simple and reliable automatic pivoting and a flexible retaining force for the vehicle door.

The above object is achieved by a drive device having features according to the present invention.

According to one aspect of the invention, a drive device for a pivotable vehicle door is provided, comprising a first housing part and a second housing part, wherein the first housing part and the second housing part are designed to be movable relative to each other in the axial extension direction of the drive device. The drive device further comprises a spindle rod, wherein the spindle rod is rotatably arranged on one of the first housing part and the second housing part. The driving device further includes: a spindle nut non-rotatably disposed on the other of the first housing member and the second housing member; and a braking device. The braking device includes therein: a first brake element connected to the spindle shaft in a rotationally fixed manner; and a second brake element non-rotatably connected to one of the first and second housing components, wherein the first brake element is interactable with the second brake element to generate a braking force. Finally, the drive device comprises a magnet arrangement for generating a magnetic field. The drive device according to the invention is characterized in that at least one of the first brake element and the second brake element is displaceable in the axial direction of the spindle shaft by means of a magnetic field. This advantageously makes it possible to influence the braking force caused by the braking device in a controlled manner by controlling the magnetic field strength of the magnetic field. It is particularly advantageous that by setting the magnetic field strength, the door can be held continuously in all circumstances and external situations, such as temperature, opening angle and forces acting on the door from the outside.

The first housing part and the second housing part are advantageously part of a housing of the drive device, wherein the first housing part and the second housing part are arranged concentrically with respect to one another. The housing advantageously makes it possible to protect the movable mechanical and electrical components of the drive from dust and other external influences. Furthermore, contact by the user with the internal components of the drive device and possible injury during the procedure are thus avoided.

In a particularly preferred embodiment, the magnet arrangement comprises an electromagnet. It is thereby particularly advantageously achieved that the magnetic field strength and thus the braking force generated by the braking device can be defined by determining the current strength flowing through the electromagnet. The braking device preferably comprises an electric controller, which can control the current intensity or the electric power of the electromagnet. The control of the current strength or the electrical power of the electromagnet is particularly preferably programmable, so that a predetermined behavior of the braking device can be achieved in accordance with the prevailing circumstances at any time. In this case, the current strength or the electrical power controlled by the electrical controller depends on external parameters, such as the instantaneous acceleration of the pivotable vehicle door or the force acting on the pivotable vehicle door from the outside.

The magnet arrangement preferably comprises a permanent magnet. This advantageously makes it possible to provide a permanent braking force by means of the braking device without requiring additional electrical power. The braking force can be conveniently determined by appropriate selection of the permanent magnets or the strength of the magnetic field generated by the permanent magnets. The braking device particularly preferably comprises an electromagnet and a permanent magnet, since a braking force is thereby generated even in the switched-off state of the electromagnet, wherein the braking force can be reduced and increased by appropriately selecting the direction of the current through the electromagnet.

The one of the first and second braking elements which is designed to be axially displaceable is particularly advantageously magnetically attracted towards the other of the first and second braking elements by the permanent magnet. In a further refinement, one of the first and second brake elements may be displaced in the axial direction of the spindle shaft towards the other of the first and second brake elements until the first and second brake elements may contact each other. The first brake element particularly preferably has a first friction surface and the second brake element has a second friction surface. In this case, the first friction surface and the second friction surface are advantageously arranged opposite each other and substantially perpendicular to the axial direction of the spindle shaft. Advantageously, the braking force generated by friction between the free surfaces on the spindle shaft can thus be set by controlling the electromagnets as the case may be. In particular, it is proposed that the first brake element and the second brake element can be displaced relative to one another until the first brake element and the second brake element do not come into contact with one another. In this case, both manual opening of the door and motorized movement of the door are facilitated, so that the electric motor provided in the drive device can advantageously be of small size.

In an advantageous embodiment, the magnet arrangement is arranged on the first braking element or the second braking element. It is particularly advantageously provided that the magnet arrangement is arranged on a second brake element which is non-rotatably connected to one of the first housing part and the second housing part. Advantageously, the installation space required for the braking device is reduced, so that the entire drive device is designed more space-saving. It is advantageously provided that the magnetic field which can be generated by the magnet arrangement penetrates the one of the first braking element and the second braking element which is designed to be axially displaceable. The axial displacement of the brake element or the braking force between the first brake element and the second brake element is therefore advantageously controlled by means of the magnetic field strength.

In a further refinement, it is particularly advantageously provided that the one of the first braking element and the second braking element which is designed to be axially displaceable is designed to be at least partially ferromagnetic. Thereby, it is advantageously achieved: the magnet arrangement exerts a force in the axial direction on the one of the first braking element and the second braking element which is designed to be axially displaceable by means of a magnetic field generated by the magnet arrangement. The magnetic flux of the magnet arrangement and thus the braking force of the brake device can be controlled particularly advantageously by an electric controller.

Advantageously, the drive means comprises a ball bearing, wherein the ball bearing radially surrounds a portion of the spindle shaft and rotatably supports the spindle shaft. The ball bearing is particularly preferably arranged between the spindle nut and the braking device. By spacing the ball bearing from the magnet arrangement, the ball bearing is advantageously prevented from influencing the magnetic field of the magnet arrangement within the braking device or, conversely, from influencing the metal components of the ball bearing.

In a further development of the drive device, the housing comprises a third housing part. In the third housing part, a drive means for driving the spindle shaft is preferably arranged. In this case, the first fastening device for articulation to one of the vehicle door and the vehicle body is advantageously arranged on the end of the first housing part remote from the third housing part. It is furthermore advantageously provided that a second fastening device for articulation to the other of the vehicle door and the vehicle body is arranged on an end of the third housing part remote from the first housing part. Wherein one of the first and second fixing means is designed as a spherical seat. Particularly preferably, the other of the first and second fixing means is designed as a spherical engagement eye. The drive device can thus advantageously be arranged hingedly between the vehicle body and the vehicle door to be pivoted relative to the vehicle body.

In a particularly preferred embodiment, the end of the third housing part remote from the first housing part is at least partially made of plastic. Advantageously, the overall weight of the drive device is thus reduced. Particularly advantageously, the end of the second fastening device facing the third housing part is accommodated in a form-fitting manner in the end of the third housing part facing away from the first housing part and is made partially of plastic. Particularly preferably, an over-molding of the end of the second fastening device facing the third housing part is provided. Advantageously, this results in a particularly high strength and a good sealing of the fixing means against external influences, such as moisture.

The end of the first fastening device facing the first housing part is advantageously accommodated in a force-fitting manner at least partially in the first housing part. In particular, it is preferably provided that the end of the first fastening device facing the first housing part is pressed into an opening in the first housing part. The first housing part is preferably hollow-cylindrical here and concentrically surrounds the end of the first fastening device facing the first housing part.

In a preferred embodiment, the first fastening device has a radially encircling first groove, wherein a part of the first housing part that tapers inward with respect to the inner diameter projects into the groove. Advantageously, therefore, the first fixing means is firmly accommodated in the first housing part in the axial direction and is fixed so as not to be displaceable in the axial direction.

Advantageously, the first fastening device has a second radially encircling groove, wherein a sealing ring is provided in the second radially encircling groove, which sealing ring seals the first fastening device against the first housing part. Therefore, the intrusion of moisture into the housing is advantageously prevented.

In a particularly preferred embodiment, the other of the first housing part and the second housing part comprises at least one groove, which extends parallel to the axial extension of the spindle shaft. The spindle nut advantageously has at least one radial projection which projects into the at least one groove. Thus, a drive arrangement is advantageously provided in which no external torque support of the spindle nut is required.

In a further refinement of the drive device, it is provided that the spindle nut is displaceable along the axial extension of the at least one groove. The spindle nut can thus advantageously be displaced in the axial extension direction of the drive device or of the spindle shaft by rotating the spindle shaft with an external thread, which in turn engages with an internal thread provided in the spindle nut.

The at least one groove is advantageously designed as a negative (negative) shape of the at least one radial projection. Advantageously, the spindle nut is guided precisely along the slot and the spindle nut is supported relative to the housing with respect to the torque transmitted through the spindle shaft.

The drive device advantageously comprises a drive element, wherein the drive element is arranged concentrically in the drive housing relative to the third housing part. It is particularly advantageously provided that the drive housing is designed as a hollow cylinder and is welded along its outer circumference and at least partially to the third housing part. It is thereby advantageously achieved that the drive element or the received drive housing is arranged particularly securely and firmly in the third housing part. Furthermore, it is advantageous that further installation options can be implemented, such as for example the routing of the required supply lines, in particular for the operation of the magnet arrangement provided in the brake device. For this purpose, a corresponding gap is provided between the outer circumference of the drive housing and the inner circumference of the third housing part, through which gap the supply lines can be routed.

It is advantageously provided that the first housing part is sealed in translation relative to the second housing part by means of a sealing ring. Thus, a sufficient sealing against moisture is advantageously achieved even during displacement of the first housing part relative to the second housing part. In an advantageous embodiment, in order to prevent the sealing ring from being displaced in the axial direction during the displacement of the first housing part relative to the second housing part, the sealing ring is prevented from being displaced in the axial direction by means of a fixing element. The fastening element is particularly preferably designed as a sliding bush. The sliding bush can advantageously be fixed to the second housing part by means of a latching element. This particularly advantageously makes it possible to replace the sealing ring in a simple manner. In a preferred embodiment, the sealing ring is additionally secured against axial displacement by means of at least one support ring.

Other advantages, features and characteristics of the present invention will become apparent from the following description of the preferred embodiments, as well as from other aspects.

Drawings

The present invention will now be explained in more detail based on preferred embodiments thereof with reference to the accompanying drawings.

Fig. 1 shows a longitudinal section through an embodiment of the drive according to the invention.

Fig. 2 shows an enlarged view of the braking device of the drive device of fig. 1.

Fig. 3 shows a vehicle door arranged on a vehicle body component and having a drive.

Detailed Description

Fig. 1 is a sectional view of a preferred embodiment of a drive device 1. The drive device 1 comprises a housing 2, which housing 2 comprises a first housing part 3, a second housing part 4 and a third housing part 5. The first, second and third housing parts 3, 4, 5 are each designed as hollow cylinders arranged approximately concentrically to one another. The first housing member 3 is made of steel, and a first end 3a of the first housing part 3 remote from the second housing part 4 has an opening in which a first fixing device 6 is at least partially accommodated for hinging the drive device 1 to one of a vehicle body and a vehicle door.

The first fastening device 6 has a ball joint eye 6a on the end remote from the first housing part 3, wherein the end 6b of the first fastening device 6 remote from the ball joint eye 6a has a first radial circumferential groove 6c and a second radial circumferential groove 6 d. The first radial surrounding groove 6c is arranged closer to the ball engagement hole 6a than the second radial surrounding groove 6 d. In the region of the first radial circumferential groove 6c, the first housing part 3 has a tapering 3b, the tapering 3b of the first housing part 3 thus being formed to protrude into the first radial circumferential groove 6a, so that the first fixing means 6 is axially fixed to the first housing part 3. Furthermore, a sealing ring 7 is provided in the second radial circumferential groove 6d of the first fixing means 6, which sealing ring seals the first fixing means 6 with respect to the first housing part 3.

The first housing part 3 has a smaller outer diameter relative to the second housing part 4 and is displaceably concentrically accommodated at least partially in the hollow-cylindrical second housing part 4. In order to seal the first housing part 3 with respect to the second housing part 4, a sealing device 8 is provided at the first end 4a of the second housing part 4. The sealing device 8 is fixed in the axial direction of the drive device 1 by means of a sliding bush 9. The sliding bush 9 has a latching element 9a designed as a spring hook. The sealing device 8 is arranged in the radial direction between the inner wall 4b of the second housing part 4 and the outer wall 3c of the first housing part 3. The sealing device 8 comprises two support rings 8a, 8b, between which two support rings 8a, 8b a sealing ring 8c is fixed in the axial direction. The sealing ring 8c is preferably designed as an X-ring. This advantageously enables the first housing part 3 and the second housing part 4 to be displaced relative to one another, wherein the penetration of moisture or dirt into the housing 2 is prevented by means of the sealing device 8.

The second housing part 4 projects with its second end 4c remote from the first end 4a at least partially into the first end 5a of the third housing part 5. The second end 4c of the second housing part 4 has an annular cantilever 4d, which annular cantilever 4d abuts against the inner step 5b of the third housing part 5. This ensures that the second housing part 4 is fixed in the axial direction towards the first fixing means 6. A ball bearing 11, which radially surrounds and thus rotatably supports a spindle shaft 12 which passes at least partially concentrically through the housing 2, abuts against the front surface of the cantilever 4d facing away from the step 5b of the third housing part 5.

The spindle shaft 12 has an external thread 12a, wherein the external thread 12a meshes with an internal thread 13a of the spindle nut 13. The spindle nut 13 is arranged non-rotatably on the second end 3d of the first housing part 3, so that during the rotary movement of the spindle shaft 12, the spindle nut 13 is displaced together with the first housing part 3 in the axial direction relative to the second housing part 4. The spindle nut 13 has a first portion 13b, which first portion 13b projects into the second end 3d of the first housing part 3, so that the spindle nut 13 and the first housing part 3 are connected to one another. The second part 13c of the spindle nut has at least one projection 13d, which projection 13d projects in the radial direction into a groove 4e extending along the inner wall 4b of the second housing part.

The spindle shaft 12 has a guide ring 14 at a first end 12b for radially guiding the spindle shaft 12 in the first housing part 3. At the second end 12c of the spindle rod 12, the spindle rod 12 has a plurality of axially extending slots 12d, the slots 12d for driving the rotational movement of the spindle rod 12. Wherein the second end 12d of the spindle rod 12 is in non-rotatable engagement with the gear wheel 15 via a slot 12d extending in the axial direction x of the spindle rod, wherein the gear wheel 15 is connected to the drive element 17 via a coupling rod 16. The drive element 17 is accommodated in a hollow-cylindrical drive housing 18, wherein an outer wall 18a of the drive housing 18 is at least partially welded to an inner wall 5c of the third housing part 5. The second fixing device 40 is arranged on the second end 5d of the third housing part 5. The fixing device 40 is designed as a spherical seat so that the drive device 1 can be hinged to one of the vehicle body and the vehicle door.

The braking device 19 is arranged axially between the gear 15 and the ball bearing 11. The structure of the braking device 19 and its mode of action will be described in more detail below with reference to fig. 2.

Fig. 2 shows an enlarged view of the braking device of the drive device of fig. 1. The braking device 19 comprises a first braking element 20, which first braking element 20 is connected to the spindle shaft 12 in a rotationally fixed manner and is mounted floating with respect to the axial direction x on a flange hub 21, which flange hub 21 presses against the slot 12d of the spindle shaft 12 in a rotationally fixed manner. The brake element 20 can thus be displaced in the axial direction of the drive 1, while the brake element 20 rotates together with the flange hub 21 or the driven spindle shaft 12. The braking element 20 is designed as an annular brake disc having a first friction surface 20a made of ferromagnetic material.

The braking device 19 further comprises a second braking element 22, which second braking element 22 is non-rotatably abutting against the inner wall 5c of the third housing part 5. The second brake element 22 thus serves as a brake stator which is fixed against rotation, wherein the second friction surface 22a of the second brake element 22 faces the first friction surface 20a of the first brake element 20, wherein in the disengaged state of the brake device 19 shown here the first friction surface 20a does not touch the second friction surface 22 a. The second brake element 22 has an annular cavity 22b, in which annular cavity 22b the magnet arrangement 23 is accommodated.

The magnet arrangement 23 comprises an electromagnet 24 and a permanent magnet 25 arranged one after the other in the axial direction of the drive device 1. The permanent magnet 25 is further away from the first brake element 20 than the electromagnet 24. The electromagnet 24 is supplied with power via a power supply line 26. The power supply line 26 extends in a gap 27 between the outer periphery 18a of the drive housing 18 and the inner wall 5c of the third housing part 5.

The mode of operation of the braking device 19 will now be described with reference to the embodiment shown in figure 2.

In the state shown in fig. 2, the first brake element 20 is displaced downwards until the first friction surface 20a and the second friction surface 22a are not in contact. Depending on the design, this state may exist in the de-energized state of the electromagnet 24 when the magnetic field of the permanent magnet 25 is oriented such that the ferromagnetic braking element 20 is repelled by the permanent magnet 25. In the present case, however, the magnetic field of the permanent magnet 25 is preferably oriented such that the first brake element 20 is attracted towards the second brake element 22. The disengaged state of the brake device 19 shown is achieved by a magnetic flux opposing the magnetic field generated by the permanent magnet 25, which is generated by the electromagnet 24. In case an increased braking force is required during pivoting of the door, the electromagnet 24 is switched off, so that the first friction surface 20a of the first brake element 20 and the second friction surface 22a of the second brake element 22 are brought into contact. Due to the frictional forces generated in this case, the rotational movement of the spindle shaft 12, which is connected in a rotationally fixed manner to the first brake element 20, is decelerated. If the braking force must be increased further, the electromagnet 24 is energized in the opposite orientation so that the magnetic flux generated by the electromagnet 24 provides an increased attractive force that causes the first brake element 20 to be attracted toward the second brake element 22.

Fig. 3 shows a vehicle door 80 which is pivotably arranged on a vehicle body part 70 and comprises a drive device 101. In this case, the drive device 101 is hinged to the vehicle body member 70 by the first end 103a and to the vehicle door 80 by the second end 105d, so that the vehicle door 80 pivots when the first end 103a is displaced relative to the second end 105 d. For this purpose, the first end 103a of the drive device 101 is guided through the recess 71 of the vehicle door 80.

Above, a drive device has been disclosed with reference to embodiments, in which only the first braking element is displaceable in the axial direction. It will be appreciated that additionally or alternatively the second brake element may be floatingly mounted, the second brake element still being fixed against rotation relative to the housing, and the first brake element rotating with the spindle shaft.

Above, a drive device has been disclosed with reference to an embodiment, in which the housing parts at least partially protrude one into the other and are sealed to one another. The housing part is correspondingly elongated, so that the housing made up of the housing parts encloses almost the entire length of the drive. It should be understood that the housing parts can also have a compact design, so that they only enclose the spindle shaft and the spindle nut. The housing parts do not have to be sealed to each other. Therefore, the self weight and material cost of the driving device can be reduced.