Abstract:
The present invention relates to a drive device having an actuating drive for driving a displaceable element, in particular a closing device of a motor vehicle door, by means of a gear wheel that has a ring gear and a hub. The ring gear of the gear wheel can be indirectly or directly driven by the actuating drive and the displaceable element can be impinged indirectly or directly by the hub of the gear wheel. The aid of the invention is to provide a drive device that has particularly small space requirements, which at the same time allows the kinetic energy of the actuating device to be reliably intercepted. To achieve this, the ring gear of the gear wheel and the hub of the gear wheel include a predominantly inflexible material and are interconnected by means of an elastic intermediate element.

Description:
[0001]    The present application is a continuation of International Application WO02/095171A1 filed on 21 May, 2002, which designated the United States and further claims priority to German patent 10125093.2, filed 23 May, 2001, the both of which are herein incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a drive device with an actuating drive for driving a movable element, in particular a locking device of a motor vehicle door, by means of a gear wheel which has a gear ring and a hub, it being possible for the gear ring to be driven directly or indirectly by the actuating drive and for the movable element to be acted on indirectly or directly by the hub of the gear wheel.  
           [0003]    Locking devices of motor vehicle doors are usually driven mechanically or electrically. Electrically driven locking devices are used in particular when a particularly rapid opening and/or locking operation of the motor vehicle door is required. A particularly powerful motor which runs up to particularly high revolutions in a particularly short time is required for a particularly rapid opening and/or locking operation of a motor vehicle door. However, as the opening and/or locking operation takes only a particularly short amount of time, the actuating drive which drives the locking device is usually turned off again, that is to say run down, directly after it has been run up. Even if the actuating drive which activates the locking device is immediately switched off, the kinetic energy of the motor can cause a considerable peak torque to be applied to some elements driven by the motor. This loading can damage components of the drive train and, in extreme cases, even destroy them. However, as an electronically driven locking device of a motor vehicle in a motor vehicle door requires an extremely small amount of space, it is usually not possible to absorb the kinetic energy over a particularly long path when turning off the actuating drive which drives the locking device.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is therefore based on an object of specifying a drive device of the above-mentioned type, which necessitates a particularly small space requirement and in the case of which the kinetic energy of the actuating drive can be reliably absorbed even if the actuating drive is suddenly switched off.  
           [0005]    This and other objects are achieved according to the invention in that the gear ring of the gear wheel and the hub of the gear wheel are composed of predominantly rigid material and are joined to one another by a predominantly elastic intermediate element.  
           [0006]    The invention proceeds from the consideration that the kinetic energy of an actuating drive can produce a considerable peak torque which should be absorbed in order to reliably avoid mechanical damage to the drive device. The kinetic energy could be absorbed by allowing the motion of the respectively moving components to die away. However, space is required in the housing of the drive device to allow the motion of the moving components to die away. This space cannot be provided, as the drive device is provided for installation in particularly narrow elements such as a motor vehicle door. It should therefore be possible to allow the motion of the moving components of the motor of the drive device to die away not over a kinetic path but using components which are already present in the drive device. If the actuating drive and the movable element are now decoupled, then the excess kinetic energy can be absorbed by means of the decoupling element. However, it should be reliably ensured here that it is still possible to activate the movable element in a particularly reliable way. Elastic material, which is arranged within the drive device between the actuating drive and the movable element, is suitable as decoupling medium. However, it should be possible here to dispense with an additional element within the drive device. For this purpose, the gear ring of the gear wheel and the hub of the gear wheel are joined to one another by a predominantly elastic intermediate element. After the actuating drive has been turned off, the elastic intermediate element swings back into its initial position and in this way absorbs kinetic energy of the drive device still present in said drive device after the actuating drive has operated.  
           [0007]    The gear ring of the gear wheel and the hub of the gear wheel are advantageously joined to one another with a material-to-material bond by the elastic intermediate element. In this configuration, the elastic intermediate element is part of the gear wheel. As a result, the drive device has a particularly small overall size. Furthermore, it is possible to dispense with additional fastening means, as the gear ring and the hub of the gear wheel are joined by the elastic intermediate element, for example by means of the two-component technique. All hard/soft combinations which can be joined to one another with a material-to-material bond are suitable for this purpose.  
           [0008]    The predominantly rigid material of the gear ring of the gear wheel and of the hub of the gear wheel is advantageously predominantly rigid plastic, the elastic intermediate element being composed of a predominantly elastic plastic. Plastics can be joined to one another with a material-to-material bond in a particularly easy manner, for example chemically, as a result of which the expenditure on manufacture of the drive device is particularly small.  
           [0009]    The hub of the gear wheel advantageously engages in a gear ring of a control disk, the control disk in turn releasing or locking the movable element directly or indirectly. Here, the gear wheel represents the connecting element between the actuating drive and the control disk. Particular requirements made on the loading of the movable element can be allowed for by means of the control disk.  
           [0010]    The hub of the gear wheel advantageously has a stop which releases or locks the movable element as a function of the position of the gear wheel. The hub, which is provided with a stop, can act, directly or indirectly, on a movable element, in particular a locking device of a motor vehicle door, as a result of which a drive device, in particular for a locking device of a motor vehicle door, is realized particularly effectively with a particularly small number of elements.  
           [0011]    The actuating drive of the drive device is advantageously an electric motor. It can be a commercially available electric motor, as a result of which the financial expenditure of the drive device is particularly small.  
           [0012]    The advantages achieved with the invention lie in particular in the fact that the drive device has a particularly small overall height, which recommends it in particular as the drive for a locking device of a motor vehicle door. At the same time, it is possible here to ensure particularly low wear of the drive device, as long as the elastic intermediate element is made from material which withstands loading for a prolonged time. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0013]    An exemplary embodiment of the invention is explained in greater detail using a drawing, in which:  
         [0014]    [0014]FIG. 1 schematically shows a drive device for a locking device of a motor vehicle door from the side,  
         [0015]    [0015]FIG. 2 schematically shows a drive device for a locking device of a motor vehicle door from the front, and  
         [0016]    [0016]FIG. 3 schematically shows a bottom view of the drive device according to FIGS. 1 and 2. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    Mutually corresponding parts are provided with the same designations in all figures.  
         [0018]    The drive device  10  according to FIGS. 1 and 2 is provided for an electrically operated lock of a door of a motor vehicle. The door and the motor vehicle are not shown in greater detail in the drawing.  
         [0019]    The drive device  10  is arranged in a housing  11  and comprises an actuating drive  12 , which is a commercially available electric motor. The actuating drive  12  can be supplied with electricity externally (not shown in greater detail in the drawing). The actuating drive  12  has an actuating drive housing  14 , from which a shaft  16  protrudes. A worm  18  is arranged on the shaft  16 . The shaft  16  and the worm  18  according to the drawing are of one-piece design, as an alternative they can also be of two-piece design, however. The worm  18  meshes a gear wheel  20 , which has a gear ring  22  and a hub  24 .  
         [0020]    The hub  24  of the gear wheel  20  meshes in turn with a gear ring  26  of a control disk  28 . This meshing connection takes place below the gear ring  20  and can therefore not be seen in FIGS. 1 and 2. The control disk  28  has a stop  29 , by means of which it is possible to set a starting and a rest position of the drive device  10 . Furthermore, the stop  29  serves for fixing a position of maximum deflection of the drive device  10  by means of a stop  30  fixed to the housing.  
         [0021]    The gear ring  22  of the gear wheel  20  and the hub  24  of the gear wheel  20  are composed of predominantly rigid material  31 , which is plastic in this exemplary embodiment. The gear ring  22  of the gear wheel  20  and the hub  24  of the gear wheel  20  are joined to one another by an elastic intermediate element  32 . The elastic intermediate element  32  is composed of a predominantly elastic plastic  33 . The gear ring  22  of the gear wheel  20  and the hub  24  of the gear wheel  20  are joined to one another with a material-to-material bond by what is known as a two-component technique.  
         [0022]    A first arm  36  of a two-armed lever  38  engages in a depression  35 , arranged on the upper side  34  of the control disk  28 , by means of a lug, which is arranged at the end region of the first arm  36  of the lever  38  so as to extend approximately parallel to the rotational axis  41  of the control disk  28  (not shown in greater detail in the drawing). The depression  35  is configured as an approximately circular channel which extends asymmetrically to the rotational axis  41  of the control disk  28  at least one location. A lug (not shown in greater detail in the drawing) of a second arm  40  of the two-armed lever  38  likewise engages in the underside  44  of the control disk  28 . The two arms  36  and  40  of the two-armed lever  38  are prestressed against the control disk  28  by means of a spiral spring  46 . The spiral spring  46  is arranged on a projection  48  of the housing  11 . The spiral spring  46  is of one-piece design, but it can alternatively also be of two-piece design. The two-armed lever  38  is connected via a shaft  50  to a first movable element  52 A and a second movable element  52 B which is configured as locking elements for a motor vehicle door.  
         [0023]    [0023]FIG. 3 shows the actuating drive  12 , the gear wheel  20  and the control disk  28  from below. It can be clearly seen that the hub  24  of the gear wheel  20  and the gear ring  26  of the gear wheel  20  are joined to one another by the elastic intermediate element  32 . FIG. 3 also shows how the hub  24  of the gear wheel  20  meshes the gear ring  26  of the control disk  28 . It is also possible to see the stop  29  by means of which it is possible to fix a defined position of the drive device  10  using the stop  30  which is fixed to the housing. Furthermore, FIG. 3 contains a depression  54  which is provided for a lug of the arm  40  of the two-armed lever  38  and designed for a 360 degree rotational movement of the lug. Here, the depression  54  is delimited by three projections  56  at the edge  58  of the control disk  28  and by an elevation  60  extending asymmetrically to the rotational axis  41  of the control disk  28 . Alternatively, it is also possible to provide more or less than three projections. Furthermore, it is also possible to configure the depression  54  to be approximately in the shape of a channel.  
         [0024]    During the operation of the drive device  10 , the actuating drive  12 , configured as an electric motor, is supplied with electricity in a manner not shown in greater detail. The shaft  16  of the actuating drive  12  rotates when electricity is supplied. The rotational movement of the shaft  16  is transmitted to the hub  24  of the gear wheel  20  via the worm  18  and the gear ring  22  of the gear wheel  20 . The rotational movement of the actuating drive  12  is transmitted in turn from the hub  24  to the control disk  28  via the gear ring  26  of the control disk  28 . The rotational movement of the control disk  28  in turn moves the two arms  36  and  40  of the two-armed lever  38  as a function of the position of the respective arm  36  or  40  in the respective depression  35  and  54 , respectively.  
         [0025]    If the arm  36  is situated in the region of the depression  35  which runs approximately symmetrically to the rotational axis  41  of the control disk  28 , then neither the arm  36  nor the movable elements  52 A and  52 B move. If, however, the arm  36  is situated in the region of the depression  35  which runs asymmetrically to the rotational axis  41  of the control disk  28 , then the arm  36  of the two-armed lever  38  is initially deflected in the direction of the rotational axis  41  and then away from the rotational axis  41 . This deflection of the arm  36  of the two-armed lever  38  causes, via the shaft  50 , an up and down or to and fro movement of the movable elements  52 A and  52 B. In an analogous manner, the movable elements  52 A and  52 B are also moved by the second arm  40  of the two-armed lever  38 . Here, the two arms  36  and  40  of the two-armed lever  38  can activate the movable elements  52 A and  52 B in arbitrary combinations, such as simultaneously, sequentially or individually.  
         [0026]    In order for it to be possible for the actuating drive  12  to run up in a particularly short time and drive the movable elements  52 A and  52 B, the actuating drive  12  is is of particularly powerful design. The actuating drive  12  can displace the movable elements  52 A and  52 B in such a way that the stop  29  of the control disk  12  comes into contact with the stop  30 . The situation can therefore arise in which the stop  29  of the control disk  28  rests on the stop  30  fixed to the housing and the actuating drive  12  continues to be supplied with electricity. The kinetic energy still present in the drive device  10  on account of the high power of the actuating drive  12 , both when the stop  29  of the control disk  28  reaches the stop  30  and when the actuating drive  12  is turned off, is absorbed by the elastic intermediate element  32 , which will be described in more detail in the following text.  
         [0027]    When the actuating drive  12  is supplied with electricity, the rotational movement of the shaft  16  is transmitted to the gear ring  22  of the gear wheel  20  via the worm  18 . The hub  24  of the gear wheel  20  follows the rotational movement of the gear ring  20 , as the elastic intermediate element  32  is of sufficiently rigid configuration. The hub  24  of the gear wheel  20  meshes the gear ring  26  of the control disk  28 .  
         [0028]    After the actuating drive  12  has been supplied with electricity and the stop  29  of the control disk  28  has reached the stop  30 , the control disk  28  barely moves any more, as its stop  29  rests on the stop  30  fixed to the housing. However, the actuating drive  12  continues to run and still continues to drive the shaft  16 , the worm  18 , arranged on the shaft  16  of the actuating drive  12 , and the gear ring  22  of the gear wheel  20  in the direction predefined by the actuating drive  12 , on account of the fact that the actuating drive  12  continues to run. After the stop  29  of the control disk  28  has reached the stop  30 , this movement of the shaft  16  of the actuating drive  12 , is transmitted to the gear ring  22  of the gear wheel  20  via the shaft  16  and the worm  18 . On account of the elastic properties of the elastic intermediate element  32 , the elastic intermediate element  32  now twists without rotating the hub  24  of the gear ring  20  with it. Therefore, a first virtual fixed point on the gear ring  22  of the gear wheel  20  is displaced relative to a second virtual fixed point on the hub  24  of the gear wheel  20 . The extent of the displacement is dependent here on the elasticity of the elastic intermediate element  32 . Therefore, the second virtual fixed point on the hub  24  of the gear wheel  20  lags behind the first virtual fixed point on the gear ring  22  of the gear wheel  20  in the direction of rotation. The actuating drive  12  is of such dimensions that the actuating drive  12  cannot effect a further rotational movement of the gear wheel  20  given a maximum deflection of the elastic intermediate element  32 . Therefore, the twisting of the elastic intermediate element  32  reliably absorbs excess kinetic energy of the actuating drive  12 .  
         [0029]    Alternatively, the actuating drive  12  can be turned off by a control device (not shown in greater detail) when the stop  29  of the control disk  28  reaches the stop  30 . The shaft  16  then comes to rest only after the actuating drive  12  has been switched off. Once the shaft  16  is at a standstill, the elastic intermediate element  32  initially continues to swing in the previous direction. The two virtual fixed points on the gear ring  22  of the gear wheel  20  and on the hub  24  of the gear wheel  20  are arranged approximately opposite one another until the shaft  16  comes to a standstill. Once the shaft  16  is stationary, the first virtual fixed point arranged on the gear ring  22  of the gear wheel  20  overtakes, as it were, the second virtual fixed point arranged on the hub  24  of the gear wheel  20 . The extent of the deflection of the first virtual fixed point compared with the second virtual fixed point is dependent here on the elastic properties of the elastic intermediate element  32 .  
         [0030]    After a point of maximum deflection, defined by the elastic properties of the elastic intermediate element  32 , has been reached, the elastic intermediate element  32  then swings back in the opposite direction and once again changes its swing direction as soon as it has reached a further point of maximu=deflection. The elastic intermediate element  32  swings to and fro here in a damped manner, as no further energy is supplied to the elastic intermediate element  32 . The elastic intermediate element  32  swings until it has reached its position of rest. The elastic intermediate element  32  therefore has the effect of allowing the motion of the control wheel  28  to die away slowly when the actuating drive  12  is turned off. As a result, the rotational movement of the control disk  28  is slowly braked in a damped manner. If the control disk  28  were not braked, the dying-out of the motion of the control disk  28  could cause teeth of the control disk  28 , of the hub  24  of the gear wheel  20  and of the gear ring  22  of the gear wheel  20  to be destroyed in an undamped manner on account of the kinetic energy of the actuating drive.  
         [0031]    The motion of the elastic intermediate element  32  dies away in a comparable manner if the actuating drive  12  is turned off without the stop  30  of the control disk  28  coming into contact with the stop  30 .  
         [0032]    The elastic intermediate element  32 , which connects the hub  24  of the gear wheel  20  to the gear ring  22  of the gear wheel  20 , ensures that, when the actuating drive  12  is turned off, the excess kinetic energy of the actuating drive  12  and the associated peak torque are absorbed by the drive device, without components of the drive device being damaged or, in an extreme case, even destroyed in the process. At the same time, the drive device  10  has a particularly small space requirement which recommends it in particular as the drive of a locking device for a door of a motor vehicle.  
         [0033]    The invention being thus described, it will be obvious that the same may be varied in many ways. The variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.