Drive unit for an adjustable vehicle flap

Abstract

Drive device, in particular for an adjustable vehicle flap, comprising a housing (2), wherein the housing (2) extends axially along a drive axis (A), a motor (7) to generate a driving force in the direction of the drive axis (A), a first drive element (11), a coupling device (9) arranged between the motor and the first drive element (11), wherein the coupling device (9) comprises a coupling housing (16) and at least one first coupling part (17) with a coupling section (18) for coupling with the first drive element (11), wherein the first drive element (11) is coupled to the coupling device (9) via the coupling section (18) of the first coupling part (17), and a braking device (10) for braking a drive movement of the first drive element (11), characterized by that the brake device (10) is arranged axially completely in the coupling section (18) of the first coupling part (17).

Description

[0001] The invention relates to a drive device, in particular for an adjustable vehicle flap, according to the preamble of claim 1.

[0002] Drive devices, particularly for driven adjustable vehicle flaps, are known from practical experience. These devices extend longitudinally along a drive axis and generate a driving force in the direction of the drive axis. A known drive device for operating a driven adjustable vehicle flap is typically articulated between the vehicle body and the flap to be adjusted, and provides the corresponding driving force by moving its length. Such drive devices are usually designed as spindle drives, as these, due to the spindle-spindle nut drive, can generate sufficient force in the direction of the drive axis and are very reliable and precise.

[0003] To ensure the most precise adjustment possible, known drive devices often incorporate a braking device. This device serves to bring a drive element, particularly a spindle rod and spindle nut, to a stationary position as quickly as possible after the drive unit powering it is switched off, thus rapidly halting the adjustment movement. Furthermore, known drive devices also include coupling devices or torque limiting devices, which serve to enhance operational safety. In particular, these devices are intended to prevent damage to components within the drive train of the drive device from external forces, or to prevent the vehicle flap driven by the drive device from causing significant harm to bystanders, especially through entrapment or similar causes.Due to the arrangement of the additional devices, particularly the braking device in combination with the coupling device, the drive unit typically requires a certain minimum installation space, especially in the direction of the drive axle, to accommodate the corresponding additional braking devices or coupling and / or torque limiting devices. Therefore, a certain minimum length of the drive unit always remains due to its design and cannot be reduced. Depending on the geometry of the vehicle hatch or body, a disadvantage of the drive unit may be that it cannot be optimally connected, as the remaining length may be too great for ideal installation.

[0004] DE 20 2011 106 110 U1 discloses a drive device for a vehicle flap, comprising a housing part, a drive-side coupling element designed for coupling to a drive motor via an intermediate gearbox, and an output-side coupling element designed for coupling to a spindle rod of a spindle-spindle nut drive. The drive device further comprises a motor for generating a drive force in the direction of a drive axis and a first drive element designed as a spindle rod, wherein a coupling device is arranged between the motor and the first drive element. The coupling device comprises a coupling housing and a first coupling part with a coupling section for coupling to the first drive element. The drive device further comprises a braking device for braking a driven movement of the spindle rod.The braking device comprises a first brake element non-rotatably connected to the coupling part and a second brake element non-rotatably arranged relative to the coupling housing. The first brake element includes a pin-shaped section and is hollow cylindrical, while the second brake element is designed as a brake disc. The second brake element is pre-tensioned against the coupling housing by a pre-tensioning element designed as a helical compression spring. A disadvantage of the drive device shown is that the braking device occupies a relatively large axial installation space within the coupling device, and thus the remaining overall length of the drive device may be too great for use in certain vehicle bodies or vehicle hatches.

[0005] DE 10 2017 101 325 A1 discloses a drive device for the motorized adjustment of a vehicle flap, comprising a coupling housing and a coupling device or brake device, wherein the brake device is housed in the coupling housing. The brake device comprises two connection elements, one of which is coupled to a drive motor and the other to a drive element designed as a spindle rod. Friction elements or brake elements are provided between the two connection elements, which effect a frictional coupling of the two connection elements. A disadvantage of the drive device shown is that the coupling device or brake device requires several connection elements and thus occupies a relatively large amount of installation space in the direction of the drive axis, thereby increasing the overall length.

[0006] DE 10 2020 105 716 B3 discloses a drive device for an adjustable vehicle flap. The drive device comprises a housing that extends axially along a drive axis. The drive device further comprises a coupling device arranged between a motor and a first drive element designed as a spindle rod. The coupling device includes at least one first coupling part designed as an adapter sleeve with a coupling section designed as an internal toothing for coupling to the first drive element, wherein the first drive element is coupled to the coupling device via the coupling section of the first coupling part. The drive device further comprises a braking device designed as a multi-disc brake for braking the first drive element. The braking device and the coupling section or the coupling device partially overlap.A disadvantage of providing both a braking device and a coupling device is an increase in the axial extension or the remaining overall length of the drive device.

[0007] The object of the present invention is to create a drive device, in particular for an adjustable vehicle flap, which has a shorter remaining length and can therefore be used more flexibly in different installation space situations.

[0008] According to one aspect of the invention, a drive device, particularly for an adjustable vehicle flap, is provided, comprising a housing, the housing extending axially along a drive axis. The drive device further comprises a motor for generating a drive force in the direction of the drive axis, a first drive element, and a coupling device arranged between the motor and the first drive element. The coupling device includes a coupling housing and at least one first coupling part with a coupling section for coupling to the first drive element. The first drive element is coupled to the coupling device via the coupling section of the first coupling part. The drive device further comprises a braking device for braking a drive movement of the first drive element.The drive device is characterized by the fact that the braking device is arranged axially entirely within the coupling section of the first coupling part. Advantageously, the remaining overall length of the drive device is not increased by the additional braking device, so that, in addition to a torque limiting function or transmission function provided by the coupling device, a braking function can also be provided without increasing the axial dimensions of the drive device.

[0009] In a particularly preferred embodiment, the braking device radially surrounds the coupling section. Advantageously, the radial extent of the braking device is not too small, so that sufficient braking torques are achieved and the components within the braking device can be easily replaced.

[0010] Advantageously, the braking device comprises a first braking element, wherein the first braking element is rotatably mounted in the coupling housing about the drive axis. In a further advantageous embodiment, the braking device comprises a second braking element, wherein the second braking element is arranged in the coupling housing in a rotationally fixed manner and is positively coupled to the first braking element to generate a braking force. Advantageously, the frictional forces required for the braking force are provided by the two braking elements, so that only the brake elements need to be replaced over time, while the coupling housing is not subject to significant wear during the generation of the braking forces.

[0011] In a further advantageous embodiment, the braking device includes a preloading element that axially preloads the first and second braking elements against each other. The preloading element is particularly preferably designed as a disc spring. Advantageously, the braking force exerted by the braking device can be adjusted with particular precision by adjusting the preload exerted on the first and second braking elements by the preloading element.

[0012] Preferably, the first brake element is rotationally fixed to the first coupling part within the coupling section. In a suitably advantageous embodiment, the first brake element and the first coupling part are rotatably mounted about the drive axis within the coupling housing. Advantageously, the first brake element does not occupy any additional installation space in the axial direction of the drive device. The first brake element is driven rotatably about the drive axis together with the first drive element, which is also rotationally fixed to the first coupling part. When the motor is switched off, thus terminating any driven movement of the first drive element, the first brake element or the braking device acts directly on any remaining residual movement of the first drive element, causing rapid braking of any residual drive movement of the drive device caused by inertia.

[0013] Furthermore, the braking device also ensures that the vehicle flap remains in its current position and does not move unintentionally.

[0014] In a particularly preferred embodiment, the first brake element is designed as a brake disc. Advantageously, the first brake element has an annular braking surface, which is particularly advantageously oriented perpendicular to the drive axis. This results in particularly effective braking of the first drive element or the first coupling part. Furthermore, the first brake element can be manufactured with high reliability and cost-effectively in large quantities and can also be easily replaced.

[0015] The coupling section of the first coupling part is preferably designed as a hollow cylinder. This advantageously creates the possibility that, within a limited axial section, both the coupling of the first coupling part with the first drive element and the coupling of the first coupling part with the braking device or brake elements, which are to be moved or rotated together with the first drive element, can be carried out simultaneously in the coupling section.

[0016] In an advantageous embodiment, the coupling section of the first coupling part features an internal spline for coupling with the first drive element and an external spline for coupling with the brake device. Preferably, the internal spline is located on an inner circumference of the hollow cylindrical first coupling part, and the external spline is located on an outer circumference. This advantageously allows the first drive element to engage with the internal spline of the first coupling part via a corresponding feedback section, while the external spline engages with the brake device or brake elements, which, together with the first coupling part, are rotatably mounted in the coupling housing.

[0017] In a particularly preferred embodiment, the first brake element has an internal toothed ring, the internal toothed ring meshing with the external serrations of the first coupling part. Advantageously, this connects the first brake element to the first coupling part in a rotationally fixed manner, so that when the coupling part is driven by the motor, the first brake element also rotates. Furthermore, it is advantageous that the first brake element is simultaneously axially displaceable relative to the first coupling part, so that the first brake element can be displaced, in particular by a preloading device, towards a second brake element, thus allowing a braking force to be set that counteracts an unintentional rotational movement of the coupling part or of the first drive element, which is rotationally fixed to the coupling part.

[0018] In a further advantageous embodiment, the first drive element has a feedback section. Advantageously, the feedback section is coupled to the coupling section of the first coupling part. Particularly preferred is an external knurling in the feedback section of the first drive element. Advantageously, the external knurling of the feedback section of the first drive element engages with an internal serration of the coupling section of the first coupling part. The feedback section is particularly advantageously arranged at a first end of the first drive element. Advantageously, a rotationally fixed connection between the first drive element and the first coupling part can be established by inserting the first end of the first drive element or the feedback section into the coupling section of the first coupling part.

[0019] The first drive element is preferably designed as a spindle rod. Advantageously, the drive device comprises a second drive element which engages with the first drive element. Preferably, the second drive element is designed as a spindle nut, so that a sufficiently large driving force can be generated in the direction of the drive axis by a driven rotation of the spindle rod and spindle nut.

[0020] In an advantageous embodiment, a cover element is arranged at an open end of the coupling housing. The cover element preferably serves as a stop for the brake device, which is limited on one side by the cover element in the direction of the drive axis. The cover element is particularly preferably injection-molded from a laser-transparent plastic. Advantageously, the cover element has a smaller outer diameter than the hollow cylindrical coupling housing, so that the cover element can be inserted into the open end of the coupling housing and subsequently fixed by laser welding. Alternatively, instead of laser welding, the cover element can also be connected to the coupling housing by alternative material-bonded connections, such as adhesive bonding. A further alternative is a positive-locking connection between the cover element and the coupling housing.

[0021] The braking device is preferably clamped axially between the cover element and a base surface of the coupling housing. The base surface is preferably ring-shaped and is radially bounded inwards by a central opening in the coupling housing. Advantageously, the preloading element, the first braking element, and the second braking element are clamped axially between the cover element and the base surface of the coupling housing. Advantageously, the components of the braking device can be inserted into the coupling housing, with the braking device being aligned concentrically around the drive axis in the coupling section of the first coupling part. The braking force exerted by the braking device can then be fixed by finally inserting the cover element, since the preload of the braking elements relative to each other is achieved by the clamping between the cover element and the base surface of the coupling housing.

[0022] The coupling device is preferably designed as an intermediate gearbox. Advantageously, the intermediate gearbox comprises several gear components that mesh with one another to translate a primary torque generated by a drive shaft of the motor into an output torque. The first coupling component is designed as a gear wheel, which is arranged on the side of the intermediate gearbox facing the first drive element, so that the output torque can be transmitted to the first drive element by coupling the first coupling component to the first drive element. Alternatively, the coupling device is designed as a torque limiting device.

[0023] Further advantages, developments and features of the invention will become apparent from the following description of a preferred embodiment and from the dependent claims.

[0024] The invention is explained in more detail below with reference to the accompanying drawings and a preferred embodiment of the invention. Fig. Figure 1 shows a preferred embodiment of a drive device according to the invention in a cross-sectional view. Fig. 2 shows a detailed view of the drive device. Fig. 1 in the area of ​​the braking device.

[0025] Fig. Figure 1 shows a preferred embodiment of a drive device 1 according to the invention in a cross-sectional view. The drive device 1 comprises a telescopic drive housing 2 with a first housing part 3 and a second housing part 4, which are hollow cylindrical and are nested within each other, so that they can be axially displaced relative to each other along a drive axis A of the drive device 1, thus making the length of the drive housing 2 adjustable. The drive device 1 further comprises a first connecting element 5, which is attached at one end to the first housing part 3. The first connecting element 5 is designed as a ball socket and is attached in an open end of the first housing part 3, so that the first end 2a of the drive housing 2 can be pivotally connected to a vehicle body and vehicle hatch.The drive device further comprises a second connection element 6 arranged opposite the first connection element 5. The second connection element 6 is also designed as a ball socket and is fastened in an open end of the second housing part 4, so that a second end 2b of the drive housing 2 can be articulated to the other end of the vehicle body and vehicle flap.

[0026] In the first housing part 3, a motor 7, designed as an electric motor, is arranged, which is intended for driving a linear adjustment movement of the drive housing 2 along the drive axis A. A protruding drive shaft 8 of the motor 7 is coupled at one end, facing away from the first connecting element 5, to a coupling device 9. In the embodiment shown here, the coupling device 9 is designed as an intermediate gear, so that a torque transmission of the drive shaft 8 is possible.

[0027] The drive device 1 further comprises a braking device 10, which is designed to brake an adjustment movement driven by the drive shaft 8. The drive device 1 also comprises a first drive element 11 designed as a spindle rod and a second drive element 12 designed as a spindle nut, which are threaded together so that a rotary movement of the first drive element 11, driven by the drive shaft 8 and mediated via the coupling device, is converted into a linear movement along the drive axis A. The coupling device 9 is advantageously arranged between the drive shaft 8 and the spindle rod 11. Advantageously, the spindle rod 11 is coupled to the drive shaft 8 of the motor 7 via the coupling device 9, with the spindle rod 11 rotatably mounted in a rotary bearing 13 designed as a ball bearing. The rotary bearing 13 itself is fixedly mounted in the first housing part 3.

[0028] The spindle nut 12 is arranged in a rotationally fixed manner in a guide tube 14 connected to the second housing part 4. A spring element 15, designed as a helical compression spring, is arranged radially between the guide tube 14 and the second housing part 4. This spring element 15 is designed to preload the housing 2, or the first housing part 3 and the second housing part 4, into the extended position. For this purpose, the spring element 15 is axially clamped between the first housing part 3 and the second housing part 4, so that the spring element 15 exerts a force parallel to the drive axis A.

[0029] Fig. 2 shows a detailed view of the drive device. Fig.1 in the area of ​​the brake device 10. In this view, it is clearly visible that the coupling device 9 comprises a coupling housing 16 and a first coupling part 17, which is arranged facing the spindle rod 11. The first coupling part 17 is rotatably mounted in the coupling housing 16 and comprises an end coupling section 18. In the embodiment shown here, the coupling section 18 is designed as a hollow cylindrical extension of the first coupling part 17. The coupling section 18 passes through a central inner bore 16a of the coupling housing 16, thereby guiding the first coupling part 17 radially within the coupling housing 16.

[0030] The first coupling element 17 is rotationally fixed to the spindle rod 11 in the coupling section 18 via a counter-coupling section 11a, which is provided at the end of the spindle rod 11. For the rotationally fixed coupling of the spindle rod 11 with the first coupling element 17, the coupling section 18 of the first coupling element 17 has an internal serration 19 along its inner diameter, which engages with an external knurling 20 provided in the counter-coupling section 11a of the spindle rod 11. Advantageously, the spindle rod 11 can simply be inserted into the coupling section 18 of the first coupling element 17, thus achieving a reliable rotationally fixed coupling between the spindle rod 11 and the first coupling element 17.

[0031] The braking device 10 comprises a first braking element 21 rotatable relative to the coupling housing 16, which is arranged on the first coupling part 17 in a rotationally fixed but axially displaceable manner. The braking device 10 further comprises a second braking element 22, which is rotationally fixed relative to the coupling housing 16 but axially displaceable, and a third braking element 23, which is rotationally fixed relative to the coupling housing 16 but axially displaceable. The first braking element 21, the second braking element 22, and the third braking element 23 are designed as brake discs. In the embodiment shown here, the first braking element 21 is arranged axially between the second braking element 22 and the third braking element 23.

[0032] An external serration 24 is provided on the outer circumference of the coupling section 18, which is designed for the rotationally fixed coupling of the first brake element 21 of the brake assembly 10 with the first coupling part 17. The first brake element 21, designed as a brake disc, has an internal toothed ring 21a that matches the external serration 21 and engages with the external serration 24 of the coupling section 18. Advantageously, the first brake element 21 is thus arranged on the coupling section 18 of the first coupling part 17 in a rotationally fixed but axially displaceable manner.

[0033] The second brake element 22 and the third brake element 23 are arranged on the coupling section 18 of the first coupling part 17 in a rotationally fixed manner, but axially displaceable relative to the coupling housing 16. The first brake element 21 is arranged between the second brake element 22 and the third brake element 23. The braking device 10 further comprises a preloading device 25, which preloads the brake elements 21, 22, 23 against each other and thus determines the braking force on the first coupling part 17 or the spindle rod 11. The preloading device 25 is designed as a disc spring. Advantageously, this is very compact and sufficiently reliable for setting the required preload force.

[0034] The preloading device 25 is arranged axially between an annular base 16b of the coupling housing 16, located in the region of the opening 16a, and the brake elements 21, 22, 23. A cover element 26 is arranged at an open end of the coupling housing 16 facing the rotary bearing 13. The brake elements 21, 22, 23 are arranged axially between the cover element 26 and the preloading device. Advantageously, the cover element 26 acts as a stop surface, which is inserted into the open end of the coupling housing 16 during assembly of the drive device and is pressed into the coupling housing 16 until the desired preload of the brake elements 21, 22, 23 is achieved under the force exerted by the preloading device 25.

[0035] The cover element 26 is radially enclosed by the coupling housing 16. The cover element 26 is made of a laser-opaque plastic, and the coupling housing 16 is made of a laser-transparent plastic. Advantageously, the cover element 26 is connected to the coupling housing 16 by laser welding. Advantageously, the preload of the preloading device 25, and thus the friction between the brake elements 21, 22, 23 that determines the braking force, can be set very precisely by inserting the cover element 26 into the open end of the coupling housing 16 and permanently fixed by laser welding from the outside through the coupling housing 16.

[0036] The advantage of the above embodiment of a drive device according to the invention, besides the reduction of the remaining overall length or technical length, is that the spindle rod 11 experiences less modulation, since the distance between the coupling section 18, in which the spindle rod 11 is supported at its ends, and the ball bearing 13 is also reduced. Furthermore, the overall tolerances of the coupling device and the braking device can be adjusted together, thus reducing the overall tolerances.

[0037] The invention has been explained above with reference to an exemplary embodiment in which the brake device 10 is designed as a multi-disc brake with three brake discs, the preload being applied mechanically via a disc spring 25. It is understood that the brake device can also be designed as an electromechanical brake. In any case, the brake device is arranged axially completely within the coupling section of the coupling device for coupling with the first drive element, so that no additional installation space is required for the brake device in the direction of the drive axis and the remaining overall length is as short as possible.

Claims

[1] Drive device, in particular for an adjustable vehicle flap, comprising a housing (2), wherein the housing (2) extends axially along a drive axis (A), a motor (7) to generate a driving force in the direction of the drive axis (A), a first drive element (11), a coupling device (9) arranged between the motor and the first drive element (11), wherein the coupling device (9) comprises a coupling housing (16) and at least one first coupling part (17) with a coupling section (18) for coupling with the first drive element (11), wherein the first drive element (11) is coupled to the coupling device (9) via the coupling section (18) of the first coupling part (17), and a braking device (10) for braking a drive movement of the first drive element (11), characterized by , that the brake device (10) is arranged axially completely in the coupling section (18) of the first coupling part (17). [2] Drive device according to claim 1, characterized by , that the brake device (10) radially surrounds the coupling section (18). [3] Drive device according to claim 1 or 2, characterized by , that the braking device (10) comprises a first braking element (21), wherein the first braking element (21) is rotatably mounted in the coupling housing (16) about the drive axis (A). [4] Drive device according to claim 3, characterized by , that the braking device (10) comprises a second braking element (22), wherein the second braking element (22) is arranged in the coupling housing (16) in a rotationally fixed manner and is positively coupled to the first braking element (21) to generate a braking force. [5] Drive device according to claim 4, characterized by, that the braking device (10) comprises a pretensioning means (25) which axially pretensions the first braking element (21) and the second braking element (22) against each other. [6] Drive device according to any one of claims 2 to 5, characterized by , that the first brake element (21) in the coupling section (18) is coupled to the first coupling part (17) in a rotationally fixed manner. [7] Drive device according to claim 6, characterized by , that the first brake element (21) together with the first coupling part (17) is rotatably mounted about the drive axis (A) in the coupling housing (16). [8] Drive device according to any one of claims 2 to 7, characterized by , that the first brake element (21) is designed as a brake disc. [9] Drive device according to any one of claims 2 to 8, characterized by , that the coupling section (18) of the first coupling part (17) is hollow cylindrical. [10] Drive device according to claim 9, characterized by, that in the coupling section (18) of the first coupling part (17) an internal serration (19) for coupling with the first drive element (11) and an external serration (24) for coupling with the brake device (10), preferably with the first brake element (21), is provided.

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