Patent Publication Number: US-2021180385-A1

Title: Drive assembly for a closure element of a motor vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase of PCT Application No. PCT/EP2019/061470 filed on May 4, 2019, which claims priority to German Patent Application No. DE 10 2018 110 723.4, filed on May 4, 2018, the disclosures of which are hereby incorporated in their entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a drive assembly for a closure element of a motor vehicle. 
     BACKGROUND 
     The drive assembly under discussion is used in the context of the motorized adjustment of any closure elements of a motor vehicle. Such closure elements can be tailgates, trunk lids, engine hoods, load space floors but also doors, especially sliding doors, of a motor vehicle. In the present case, therefore, the term “closure element” should be interpreted broadly. The important point here is that the closure element usually allows not only motor operation but also manual operation by a user, during which there is no risk to the user. 
     This proven prior art makes it possible to implement large differences between the braking action which opposes a movement introduced on the input side and the braking action which opposes a movement on the output side. If a closure element, e.g. a (tailgate) flap, is in certain intermediate positions, a large part of the weight thereof is often not transmitted into the brake assembly, purely by virtue of the design or of installed dampers of the drive assembly. In the case of a closure element which is fitted with two drive assemblies, it may happen that the drives do not run quite synchronously and one drive introduces a movement on the output side into the brake assembly of the other drive assembly via the flap. This does not result in adjustment of the closure element since this movement introduced on the output side is braked, but the freewheel clutch, which generally exhibits play owing to its design, may rattle. 
     SUMMARY 
     One or more problems addressed by the present disclosure is provide a drive assembly to decrease noise generation. 
     According to one embodiment a drive assembly is provided. The drive assembly may include a freewheel assembly that may be connected to, at least on the output side, an auxiliary braking element with a predetermined permanent braking action which brakes a movement introduced on the output side so that the freewheel assembly is not engaged or disengaged immediately with every small movement. For example, this auxiliary braking element can always oppose a predetermined permanent braking action to all movements which would otherwise be introduced directly into the freewheel assembly. Accordingly, an envisaged main braking action of the brake assembly can be smaller since the permanent braking action is added thereto. Since this auxiliary braking element does not have to be integrated structurally into the freewheel clutch and is preferably also not integrated into the latter, there are more degrees of freedom in the design, and wear can be reduced. 
     According to another embodiment, a clutch element, such as a wrap spring, is provided as part of the freewheel assembly. By virtue of the auxiliary braking element connected thereto, the clutch element can be of radially and/or axially adjustable configuration. A contact surface, which, in the engaged state of the freewheel assembly and thus of the clutch assembly, i.e. when the main braking element is braking the main braking action of a movement introduced on the output side, is connected non-positively to the main braking element. In the disengaged state, it is not connected non-positively to the main braking element, such as not being connected to it at all. As a result, there is preferably no friction between the contact surfaces in the disengaged state, this having the advantage that the wrap spring does not wear in the case of movements introduced on the input side. 
     In one or more embodiments, the brake assembly may be configured in such a way that the main braking action arises between the main braking element and the auxiliary braking element are friction surfaces which may produce the main braking action and the auxiliary braking action. 
     As an example, the friction surfaces which produce the main braking action and the auxiliary braking action are spaced apart radially. 
     The permanent braking action is less than the main braking action. 
     The drive assembly is configured in such a way that, for the purpose of adapting the drive assembly to a different model of motor vehicle for example, a spring is provided which can be interchanged and/or adjusted in order to change the magnitude of the predetermined permanent braking action and of the main braking action. It may be possible to adapt the drive assembly during manufacture by interchanging or preferably adjusting just one part, for which purpose an adjusting screw that adjusts the spring. 
     According to one or more embodiments, a drive assembly having a wrap spring in a freewheel assembly, the contact surface of which, as already described, is not in contact with a contact surface of the main braking element in a disengaged state Reference may be made to all the statements made in relation to the drive assembly according to the proposal in accordance with the first teaching. 
     According to yet another teaching, a drive assembly for a closure element of a motor vehicle is provided. The drive assembly may include a clutch assembly connected into a drivetrain of the drive assembly is provided with an input connection and an output connection, wherein in any case the clutch assembly transmits a movement which is introduced on the input side to the output connection, wherein the clutch assembly has a brake assembly with a main braking element, which produces a main braking action, by means of which the main braking element brakes a movement introduced on the output side, wherein the clutch assembly has a freewheel assembly, wherein the freewheel assembly engages the main braking element by means of the movement introduced on the output side and disengages the main braking element by means of a movement introduced on the input side. 
     The drive assembly according to one or more embodiments may be configured by means of features of the present disclosure. Here, the drive assembly may not need to be fitted with an additional auxiliary braking element as described above. To this extent, reference may be made to all the statements made in relation to the drive assembly according to the proposal in accordance with the above teachings. 
     According to yet another embodiment, which is of independent significance, a closure element assembly as such is claimed which has one or more proposed drive assemblies, the drivetrain of at least one or all the drive assemblies extends between a body of the motor vehicle and the closure element. Reference may be made to all the statements made in relation to the drive assembly according to the proposal in accordance with the above teachings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in greater detail with reference to a drawing, which illustrates only illustrative embodiments. In the drawing: 
         FIG. 1  shows the rear region of a motor vehicle having a drive assembly according to the proposal for the closure element assembly located there, 
         FIG. 2  shows the clutch assembly in the drivetrain of the drive assembly shown in  FIG. 1  in region II, in the case of a movement introduced on the input side, as well as a cross section along section plane A-A, 
         FIG. 3  shows the clutch assembly in the case of a movement introduced on the output side, and 
         FIG. 4  shows three views of an illustrative embodiment of the clutch assembly as a cross section along section plane B-B and as a longitudinal section along section plane C-C. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     A known drive assembly is provided in WO 2013/045099 A1 and includes a clutch assembly that is connected on the input side to a motor and on the output side to the closure element and that has a brake assembly and a freewheel assembly. The freewheel assembly engages the brake assembly when the closure element is adjusted, in particular by manual actuation, and thus an output-side movement is introduced into the clutch assembly. This enables the brake assembly to bear the dead weight of the flap, thus enabling it to be held securely in any positions between the open position and the closed position. In the case of an input-side movement, on the other hand, the main braking element is disengaged, thereby ensuring that the braking force is not opposed by the drive during adjustment. 
     The drive assembly  1  illustrated in  FIG. 1  is used for motorized adjustment of a closure element  2 , which may be a liftgate of a motor vehicle  3 . The drive assembly  1  can also be used for other closure elements, in respect of which attention is drawn to the introductory part of the description. 
     As an example, the drivetrain  4  illustrated on an enlarged scale in the right-hand part of  FIG. 1 , which is part of the drive assembly  1 , has connections  5 ,  6  at both ends, which are connected mechanically to the body  7  and the closure element  2 , with the result that movements of a drive of the drive assembly, which, here and for example, has a motor  8 , such as an electric motor, can be output via the connections  5 ,  6 , thereby adjusting the closure element  2 . Here, “adjust” means that the closure element can be moved in a known manner into an open position ( FIG. 1 ) and a closed position (not shown) and, in between, occupies intermediate positions (not shown). During this process, the axial extent of the drivetrain  4  along a drive axis  9  generally changes. Provision can also be made for the drivetrain  4  to be branched and, for example, for not all the components to be arranged along the drive axis  9 . 
     Furthermore, the drivetrain  4  in this case has a spindle/spindle nut mechanism  10 . In this case, there is a clutch assembly  11  between the spindle/spindle nut mechanism  10  and the drive with the motor  8 , said clutch assembly being connected by means of an input connection  12   a  to the drive, thus enabling the drive to introduce movements into the clutch assembly  11  on the input side, and being connected by means of an output connection  12   b  to the spindle/spindle nut mechanism  10 , which can introduce movements into the clutch assembly  11  on the output side. Provision is furthermore made for these movements, with partial braking, as will be explained, to be transmitted between these two connections  12   a ,  12   b  of the clutch assembly  11 . Here and for example, the output connection  12   b  and the input connection  12   a  form claws of a claw clutch. 
     It is thus possible for the motor  8  to adjust the closure element  2  by motor power. In addition, it is envisaged that the closure element  2  can also introduce a movement, such as a movement by a user, into the drivetrain via one of the connections  6 , this movement then being introduced on the output side into the clutch assembly  11  via the output connection  12   b.    
     Here and for example, therefore, a clutch assembly  11  connected into a drivetrain  4  of the drive assembly  1  is provided with an input connection  12   a  and an output connection  12   b , wherein in any case the clutch assembly  11  transmits a movement which is introduced on the input side to the output connection  12   b.    
     It is also possible to provide for the closure element  2  to be adjusted by means of two, preferably identical, drive assemblies  1  according to the proposal or by means of one drive assembly  1  according to the proposal and one drive assembly of a different type, which are preferably situated at two opposite ends of the closure element  2 . 
     Here and for example, the drive assembly  1  is controlled by a control unit  14  which can receive and carry out user instructions to open or close the closure element  2 , for example. 
     In the upper area,  FIG. 2  shows an enlarged detail of the clutch assembly  11 . In general, the clutch assembly  11  has a brake assembly  13  with a main braking element  15 , which produces a main braking action, by means of which the main braking element  15  brakes a movement introduced on the output side. 
     In general, the main braking action is produced by a braking load, which can be a braking force or a braking torque, which can in principle be produced in any desired manner. The essential point here is that the main braking action ensures that a movement introduced on the output side into the clutch assembly  11 , i.e. a movement which is introduced via the output connection  12   b , is slowed or prevented, depending on the strength of the movement. However, the main braking action is produced by a friction torque or a frictional force, wherein static or rolling and/or sliding friction is intended, depending on the state concerned. 
     Moreover, the clutch assembly  11  has a freewheel assembly  16 , wherein the freewheel assembly  16  engages the main braking element  15  by means of the movement introduced on the output side and disengages the main braking element  15  by means of a movement introduced on the input side. Here and for example, the movements introduced into the clutch assembly  11  are transmitted through the freewheel assembly  16 , but it is also sufficient, for example, if these are transmitted only partially into the freewheel assembly  16  as long as engagement and disengagement can thereby be achieved. If not otherwise specified, “the movements introduced on the output side or the input side” always mean those which are introduced into the clutch assembly  11  at the output connection  12   b  and the input connection  12   a  respectively. 
     The main braking action occurs if the movement introduced on the output side has led to engagement of the main braking element  15 . 
     One possible embodiment of the freewheel clutch  16  is furthermore described below. Another illustrative freewheel clutch  16 , which can also be used in accordance with the proposal, is shown in WO 2013/045099 A1, which was originated by the applicant and the contents of which are herewith incorporated into the subject matter of the present application. 
     The situation is very preferably such that all output-side movements, i.e. both opening and closing of the closure element  2 , can lead to engagement of the main braking element  15  and that all input-side movements caused by the motor  8  can lead to disengagement. 
     However, precisely to ensure that not just the slightest movement leads directly to a change in the states or positions of the components of the freewheel clutch  16 , it is envisaged according to the proposal that the brake assembly  13  has an additional auxiliary braking element  17 , which produces a predetermined permanent braking action, by means of which the auxiliary braking element  17  acts at least against the movement introduced on the output side, and the predetermined permanent braking action of the auxiliary braking element  17  has to be overcome to enable the freewheel assembly  16  to disengage. 
     As an example, similarly to the main braking action, the predetermined permanent braking action is produced by a braking force or a braking torque, such as a friction torque. According to the proposal, the predetermined permanent braking action is characterized by the fact that it is produced by a defined auxiliary braking element  17 . It is thus precisely not the internal friction which in general unavoidably occurs in the drive assembly  1  but is preferably at least twice as great, or at least ten times as great. It may be defined locally by the auxiliary braking element  17  and produced directly adjoining the freewheel assembly  16 , as a further example on both sides of the freewheel assembly  16 , wherein the two sides refer to the input connection  12   a  and the output connection  12   b.    
     An illustrative embodiment of the freewheel assembly  16  is shown in  FIG. 4 . For example, the situation is such that the freewheel assembly  16  has a clutch element, such as a wrap spring  18 , the radial and/or axial extent of which can be adjusted by movements introduced into the clutch assembly  11  and which engages and disengages the main braking element  15  as a result. 
     The function of the overall drive assembly, which is explained by way of example below with reference to the illustrative embodiment from  FIG. 4  for the freewheel assembly  16 , will be evident from a joint consideration of  FIGS. 2 to 4 , and the statements apply mutatis mutandis to other freewheel assemblies  16  and other clutch elements. 
     One possible implementation of this function is shown at the bottom right in  FIG. 4  in a cross section along section plane B-B. As shown in  FIG. 2 , an input-side movement, for example every input-side movement, is initiated by the input connection  12   a , whereupon, for example, said connection first of all moves one of the wrap spring ends  19 , which can be seen at the bottom right in  FIG. 4 , thereby reducing the radial extent of the wrap spring  18 . Depending on whether the movement takes place in the opening direction of the closure element  2  or in the closing direction thereof, one wrap spring end  19  or the other is moved. The holding force, indicated by arrows at the bottom left in  FIG. 4 , between the wrap spring  18  and the main braking element  15  is thereby reduced. As an example, the radial extent can also be reduced to such an extent that there is no longer any contact between the wrap spring  18  and the main braking element  15 . 
     The wrap spring ends  19  that can be seen in  FIG. 4  are not situated in the same plane there, one being the lower end of the wrap spring  18 , the other being the upper end, which is situated approximately at the level of section plane B-B in  FIG. 4 , and the cross section thus represents a plan view that combines several planes. 
     The movement introduced on the input side is then transmitted from the input connection  12   a , via one of the wrap spring ends  19 , to the output connection  12   b , while the wrap spring  18  moves freely within the braking element  15 . In contrast to the following description of the engaged state, the braking element  15  is not co-rotated, consequently being disengaged. 
     As shown in  FIG. 3  and  FIG. 4 , a movement, for example every movement, introduced on the output side by the output connection  12   b  is also transmitted from the output connection  12   b  to the wrap spring ends  19 , but in each case from the other side of the respective wrap spring end  19 . There too, there is a directional dependence as regards the wrap spring end  19  to which the movement is transmitted. Similarly, for example, this movement is transmitted to the input connection  12   a , with the difference that the axial extent of the wrap spring  18  increases, thereby increasing the force between the wrap spring  18  and the main braking element  15 . A nonpositive connection is thereby formed between the two. The wrap spring  18  cannot move freely and takes the main braking element  15  along in its rotation. For example, the contact between the two occurs via a contact surface  20  of the wrap spring  18  and a contact surface  21  of the main braking element  15 . 
     In each case, the movements can also be transmitted indirectly via transmission elements, for example, but this is not shown here. 
     As an example therefore, the situation is such that a contact surface of the clutch element, such as a contact surface  20  of the wrap spring  18 , is connected non-positively, such as for conjoint rotation, to a contact surface  21  of the main braking element  15  in a state in which the main braking element  15  is engaged, and the two contact surfaces  20 ,  21  are rotatable relative to one another, such as without contact, in a state in which the main braking element  15  is disengaged. 
     As an example, the situation is furthermore such that the auxiliary braking element  17  has a main friction surface  22 , which produces the main braking action in the engaged state of the main braking element  15  by friction with a mating friction surface  22   a  of the main braking element  15  and in this way brakes the movement introduced on the output side. As an example, in the case of a movement introduced on the output side the main braking element  15  is taken along by the freewheel assembly  16  and rubs against the main friction surface  22  of the auxiliary braking element  17 , which is in turn nonrotatable relative to the outer shell of the clutch assembly  11 . The non-rotatability can be achieved by means of projections  23  of the auxiliary braking element in recesses of an outer shell of the clutch assembly  11 , as shown in  FIGS. 2 and 4 , for example. 
     The situation is such that the auxiliary braking element  17  and/or the main braking element  15  have/has at least one, preferably at least two, permanent friction surface(s)  24  that is/are spaced apart axially and each have a defined friction lining, which produces the predetermined permanent braking action of the auxiliary braking element  17 , in each case by friction against an associated mating friction surface  24   a  of the input connection  12   a  and/or output connection  12   b . The situation may be that two or at least two permanent friction surfaces  24  are provided, of which one is on the auxiliary braking element  17  and one is on the main braking element  15  and the respective mating friction surfaces  24   a  of which are on the input connection  12   a  and on the output connection  12   b  and brake any movement that is introduced into the freewheel assembly  16 . As a result, any movement which is to be transmitted by the clutch assembly  11  must first overcome the static friction of the permanent friction surfaces  24 , with the result that the freewheel assembly  16  is also adjusted only when this static friction has been overcome. As an example, the situation in this case is such that the permanent friction surfaces  24  have defined friction linings by which the permanent braking action can be influenced in the design process. As an example, one of the permanent friction surfaces  24   a  is taken along by the main braking element  15  when the latter is engaged, with the result that this permanent braking surface  24  is deactivated. 
     In order to obtain further degrees of freedom in the design process, the respective permanent friction surface  24  has a mean friction radius R P , in relation to a drive axis  9  of the drivetrain, which is smaller than a mean friction radius R H  of the main friction surface  22 . This means that the permanent friction surfaces  24  and the main friction surface  22  can be arranged over a circular area, coaxially around the drive axis  9 , wherein the mean radii of the surfaces  22 ,  24  differ. By this means, it is possible to advantageously configure a braking torque of the respective surfaces  22 ,  24 . If different permanent friction surfaces  24  are provided on the input side and the output side, the friction radii thereof can also differ in order, for example, to brake output-side movements more powerfully. 
     As an example, the situation is that the predetermined permanent braking action is smaller in magnitude than the main braking action, preferably that the predetermined permanent braking action is overcome during each adjustment of the closure element. As an example, as already explained above, any movement introduced into the clutch assembly  11  will first have to overcome the static friction of the permanent friction surfaces  24  before it can have an effect on the freewheel assembly  16 . Noise generation can thereby be avoided in a particularly simple manner. 
     The control unit  14  which adjusts the closure element is frequently fitted with a rotational speed sensor system on the motor  8 . By means of the auxiliary braking element  17 , which to this extent forms a kind of mechanical low-pass filter for movements introduced into the clutch assembly  11 , control of the movement by the control unit  14  is simplified, which represents a further advantage of the drive assembly  1  in accordance with the proposal. 
     The situation is furthermore such that the auxiliary braking element  17  has a spring  25 , for example a wave spring, which can be interchanged and/or adjusted, thus changing the magnitude of the predetermined permanent braking action of the auxiliary braking element  17  and/or the magnitude of the main braking action. As an example, the situation is such that two permanent friction surfaces  24  are provided on the input side and the output side of the freewheel assembly  16 , and one main friction surface  22  is provided. As an example, these are part of the auxiliary braking element  17  and can all be influenced by a single wave spring, with the result that their contact pressure against the respective mating friction surfaces  22   a ,  24   a  and thus also their respective main/auxiliary braking action change. This represents a structure of particularly simple design. 
     As an alternative or in addition to the simple interchangeability of the spring  25 , the situation is such that, for adjustment, such as adjustment of the axial extent, of the spring  25 , an adjusting element, such as an adjusting screw  26 , is provided, which preferably extends along the drive axis of the drivetrain. As an example, the adjusting element is arranged coaxially with the drive axis  9  and, for example centrally in the clutch assembly  11  as regards the radial extent, whereby the overall design can be of compact configuration. However, an adjusting element that extends orthogonally with respect to the drive axis  9  is also conceivable, for example. As an example, the adjusting screw  26  acts in such a way that it can be tightened and loosened in a thread and thereby moves an upper part  27  and a lower part  28  of the auxiliary braking element  17  closer together or further apart in the axial direction (parallel to the drive axis  9 ) and, in the process, compresses or extends the spring  25  between these parts  27 ,  28 . 
     According to another teaching, which is of independent significance, a drive assembly  1  for a closure element  2  of a motor vehicle  3  is claimed, wherein a clutch assembly  11  connected into a drivetrain  4  of the drive assembly  1  is provided with an input connection  12   a  and an output connection  12   b , wherein in any case the clutch assembly  11  transmits a movement which is introduced on the input side to the output connection  12   b , wherein the clutch assembly  11  has a brake assembly  13  having a main braking element  15 , which brakes a movement introduced on the output side by means of a main braking action, wherein the clutch assembly  11  has a freewheel assembly  16 , wherein the freewheel assembly  16  engages the main braking element  15  by means of the movement introduced on the output side and disengages the main braking element  15  by means of a movement introduced on the input side. Reference may be made to all the statements made in relation to the drive assembly  1  according to the proposal in accordance with the first teaching. It is essential here that the freewheel assembly  16  has a wrap spring  18 , the radial and/or axial extent of which can be adjusted by movements introduced into the clutch assembly  11  via the output connection  12   b  and the input connection  12   a  and which engages and disengages the main braking element  15  as a result, and that a contact surface  20  of the wrap spring  18 , is connected non-positively to a contact surface  21  of the main braking element  18  in a state in which the main braking element  15  is engaged, and the two contact surfaces  20 ,  21  are not in contact with one another in a state in which the main braking element  15  is disengaged. 
     The situation is such that no friction arises between the two contact surfaces  20 ,  21  during all the movements introduced on the input side. The situation is furthermore such that there is then a gap between the two contact surfaces  20 ,  21 . 
     According to another teaching, which is of independent significance, a drive assembly for a closure element  2  of a motor vehicle  3 , including a clutch assembly  11  connected into a drivetrain  4  of the drive assembly  1  is provided with an input connection  12   a  and an output connection  12   b , wherein in any case the clutch assembly  11  transmits a movement which is introduced on the input side to the output connection  12   b , wherein the clutch assembly  11  has a brake assembly  13  with a main braking element  15 , which produces a main braking action, by means of which the main braking element  15  brakes a movement introduced on the output side, wherein the clutch assembly  11  has a freewheel assembly  16 , wherein the freewheel assembly  16  engages the main braking element  15  by means of the movement introduced on the output side and disengages the main braking element  15  by means of a movement introduced on the input side. 
     Here, the drive assembly  1  according to the proposal in accordance with the last-mentioned teaching is not fitted with an additional auxiliary braking element as described above. Irrespective of this, the drive assembly  1  according to the proposal can have one or more of the further features described above. To this extent, reference may be made to all the statements made in relation to the drive assembly  1  according to the proposal in accordance with the first and the second teaching. 
     The drive assembly  1  according to the proposal in accordance with the last-mentioned teaching, just like that in accordance with the first or the second teaching, has a sleeve-shaped main braking element  15 , wherein a clutch element, for example a wrap spring  18 , of the freewheel assembly  16  is arranged in the radial interior of said main braking element, the clutch element or spring being adjustable in its radial and/or axial extent by means of movements introduced into the clutch assembly  11  and engaging and disengaging the main braking element  15  as a result. 
     The sleeve-shaped main braking element  15  can be held axially between the input connection  12   a  and the output connection  12   b  and/or between the input connection  12   a  and the outer shell, i.e. the housing, of the clutch assembly  11  by means of a defined axial clamping force. As an example, the clamping force can be adjusted by means of the adjusting screw  26  by tightening or loosening the adjusting screw  26  in the thread. 
     The main braking element  15  can be coupled for conjoint rotation to a brake disk, for example a brake disk which is mounted in an axially movable or floating manner and interacts with a braking effect with one or more braking elements that are nonrotatable relative to the outer shell or housing of the clutch assembly  11 . The braking element or elements can likewise be mounted in an axially movable or floating manner on the outer shell or housing of the clutch assembly  11 . Furthermore, the brake disk and the braking element or elements can be preloaded axially against one another by means of a spring  25  of the kind described above, for example a wave spring. As an example, the spring  25  is preloaded by means of two parts of the outer shell or housing of the clutch assembly  11  which can be adjusted axially relative to one another. As stated, the spring  25  can preferably be interchanged and/or adjusted, thus enabling the magnitude of the braking action between the brake disk and the braking element or braking elements to be changed. 
     The braking element or elements jointly form the main friction surface  22 , which produces the main braking action by means of friction with a mating friction surface  22   a , formed by the brake disk, of the main braking element  15  in the engaged state of the main braking element  15 , and thus brakes the movement introduced on the output side. 
     According to a further teaching, which is of independent significance, a closure element assembly having a closure element  2 , preferably a flap, and at least one drive assembly  1  in accordance with the proposal is claimed. Reference may be made to all the statements made in relation to the drive assembly  1  according to the proposal in accordance with the above teachings. 
     The drivetrain  4  extends between a body  7  of the motor vehicle  3  and the closure element  2 , and the brake assembly  13  is designed in such a way that it holds the closure element  2  in an intermediate position, preferably in any intermediate position, for example against weight forces and against any spring forces that may be present. 
     The following is a list of reference numbers shown in the Figures. However, it should be understood that the use of these terms is for illustrative purposes only with respect to one embodiment. And, use of reference numbers correlating a certain term that is both illustrated in the Figures and present in the claims is not intended to limit the claims to only cover the illustrated embodiment. 
     LIST OF REFERENCE NUMBERS 
     
         
         
           
               1  drive assembly 
               2  closure element 
               3  motor vehicle 
               4  drivetrain 
               5  connections 
               6  connections 
               7  body 
               8  motor 
               9  drive axis 
               10  spindle/spindle nut mechanism 
               11  clutch assembly 
               13  brake assembly 
               14  control unit 
               15  main braking element 
               16  freewheel assembly 
               17  auxiliary braking element 
               18  spring 
               19  spring end 
               20  contact surface 
               21  contact surface 
               22  main friction surface 
               23  projections 
               24  permanent friction surface 
               25  spring 
               26  screw 
               27  upperpart 
               28  part 
               12   a  input connection 
               12   b  output connection 
               22   a  mating friction surface 
               24   a  permanent friction surfaces 
           
         
       
    
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.