Abstract:
An adjustment drive includes a drive motor, and a drive train in driving relationship with the drive motor for reducing a motor speed of the drive motor. The drive train includes a plurality of gear wheels operated by the drive motor and intermeshing with one another to form a chain to define at least one gear stage, whereby at least the plurality of gear wheels is supported by a carrier that defines thereby a separate drive unit.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of prior filed copending PCT International application no. PCT/EP02/03832, filed Apr. 6, 2002, on which priority is claimed under 35 U.S.C. §120, the disclosure of which is hereby incorporated by reference.  
         [0002]    This application claims the priority of German Patent Application, Serial No. DE 201 07 324.2, filed Apr. 27, 2001, pursuant to 35 U.S.C.  119 ( a )-(d), the disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0003]    The present invention relates to an adjustment drive, in particular for use with adjustable flap valves.  
           [0004]    An adjustment drive of a type involved here finds application especially in heating, air-conditioning and ventilation systems for opening and closing a control element of a flap valve. Hereby, the normal basic position may also be an intermediate position. Associated to the electromotive adjustment drive is a control unit. Some applications involve opening or closing of the control element in case of a danger, e.g. adjustment of the flap valve in case of fire. Conventional adjustment drives have wheels to form a chain of wheels which are normally supported on bolts received with their end surfaces in bores of a housing. These types of construction are labor-intensive to assemble and complicated when individual wheels have to be replaced.  
           [0005]    It would therefore be desirable and advantageous to provide an improved adjustment drive which obviates prior art shortcomings and which is compact in structure, while yet being reliable in operation.  
         SUMMARY OF THE INVENTION  
         [0006]    According to one aspect of the present invention, an adjustment drive includes a drive motor, a drive train in driving relationship with the drive motor for reducing a motor speed of the drive motor, wherein the drive train includes a plurality of gear wheels operated by the drive motor and intermeshing with one another to form a chain to define at least one gear stage, and a carrier defining a separate drive unit and at least supporting the plurality of wheels.  
           [0007]    The present invention resolves prior art shortcomings by including the carrier as a separate drive unit which can be attached to a housing of the adjustment drive so that in conjunction with the drive components mounted to the carrier, a structural unit or functional unit is realized which in its entirety can be inserted into the housing or a housing portion. Installation is very simple in view of the easy accessibility. Moreover, it is possible to execute the installation with handling systems or assembly robots. Also, there is no need to support the bolts that carry the gear wheels in the walls of the housing so that the housing walls can be dimensioned relatively thin, as its primary function is to provide protection.  
           [0008]    According to another feature of the present invention, the drive motor may also be connected, e.g. flange-mounted, to the carrier. An advantage of such an arrangement is the formation of a separate functional unit comprised of the drive motor and the chain(s) of gear wheels, so that the housing may be omitted altogether, when the output member of the drive train is suitably configured, for adjusting the attached components. Then, only the relevant safety regulations need to be observed. Suitably, the output member of the drive train receives a hollow shaft in fixed rotative engagement. The output member may be configured as a tooth segment. The configuration of a tooth segment is sufficient because the control element to be adjusted is normally moved by a maximum of 90°. Therefore, the tooth segment can also be configured about an angle of 90°.  
           [0009]    According to another feature of the present invention, the hollow shaft may have internal teeth for connection in a rotationally fixed manner to the control element to be adjusted. Suitably, the connection of the hollow shaft with the tooth segment is realized by a form-fitting engagement.  
           [0010]    According to another feature of the present invention, the gear wheels may be disposed on both sides of the carrier. Suitably, the carrier has a plate-shaped configuration. In this way, the adjustment drive is very compact. The intermeshing gear wheels on each side of the carrier suitably define a gear stage.  
           [0011]    According to another feature of the present invention, the housing may be made of two housing portions which are connectable to one another at a partition plane which extends in an area of the carrier.  
           [0012]    According to another feature of the present invention, the carrier may be formed with a projecting centering pin so that the carrier can be better secured in place.  
           [0013]    According to another feature of the present invention, the drive motor may be a brushless motor with an external rotor.  
           [0014]    According to another feature of the present invention, at least the carrier and the plurality of wheels are made of metal, e.g. steel or non-ferrous heavy metal.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0015]    Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:  
         [0016]    [0016]FIG. 1 shows an exploded view of an adjustment drive according to the present invention;  
         [0017]    [0017]FIG. 2 shows a top view of the adjustment drive; and  
         [0018]    [0018]FIG. 3 shows a bottom view of the adjustment drive. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]    The depicted embodiment is to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.  
         [0020]    This is one of four applications all filed on the same day. These applications deal with related inventions. They are commonly owned and have same inventive entity. These applications are unique, but incorporate the other by reference. Accordingly, the following U.S. patent applications are hereby expressly incorporated by reference: “Electromotive Adjustment Device”, “Adjustment Device”, and “Electromotive Servo Drive”, respectively.  
         [0021]    Turning now to FIG. 1, there is shown an exploded view of an adjustment drive according to the present invention, generally designated by reference numeral  1 . The adjustment drive  1  includes a carrier  10  which has a plate-shaped configuration. Flange-mounted to the carrier  10  is a drive motor  11  as drive for a drive train comprised of gear wheels. The drive motor  11  is a brushless motor with an external rotor. Of course, other types of motors which generally follow the concepts outlined here are applicable as well. A flat cable  12  having several wires is used for power supply to the drive motor  11 . The drive motor  11  has a splined output journal  11  for engagement with a gear wheel  13  which is disposed on the underside of the carrier  10 , as shown in FIG. 3. Although not shown in the drawing for sake of simplicity, the drive train may also have an output journal for connection to a pinion that is in engagement with the gearwheel  13 .  
         [0022]    The gear wheel  13  is operatively connected to a double spur gear wheel assembly  14  with two gear wheels  14   a ,  14   b  having tooth systems of significantly different number of teeth and also positioned on the underside of the carrier  10 . The gear wheel  13  is hereby in mesh with the gear wheel  14   a , while the gear wheel  14   b  extends through the carrier  10  and is in mesh with a double spur gear wheel assembly  15  placed on the top side of the carrier  10 , as shown in FIG. 2. The gear wheel assembly  15  has two gear wheels  15   a ,  15   b  with tooth systems of significantly different number of teeth. Hereby, the gear wheel  14   b  of the double spur gear wheel assembly  14  is in mesh with the gear wheel  15   a  having a greater number of tooth for reducing the motor speed of the drive motor  11  and provided with a pin (not shown) for insertion in an anchoring bore  20  on the carrier  10 . The gear wheel  15   b  with a smaller number of teeth is in mesh with a tooth segment  16  which is mounted on a hollow shaft  17  in fixed rotative engagement, e.g. via complementary profiles. The tooth segment  16  is rotatably supported on the carrier  10 .  
         [0023]    The hollow shaft  17  includes internal teeth  17   a  for providing a driving connection through form-fitting engagement with a control element (not shown). A bearing ring  18  is provided for placement in a respective bore or recess  21  of the carrier  10 .  
         [0024]    The adjustment drive further includes an operating shaft  19  which is actuated by hand and is connected to a spring element  22  so as to allow a tensioning thereof by hand. Thus, the control element may be moved by the drive motor  11  in one direction, while the return movement of the control element is realized by the restoring force of the spring element  22 . Adjustment drives of this type are also labeled as spring-return mechanisms.  
         [0025]    As can be seen from FIG. 1, the drive components connected to the carrier  10  form a fully operational unitary structure which may assume a driving function, without provision of a housing. The provision of a housing (not shown) may, however, be suitable for protection and safety considerations. In this case, the housing is so configured that the carrier  10 , at least partially, contacts the inner surfaces of the housing. Moreover, the provision of the housing may afford also advantages as far as a support of the carrier is concerned because the carrier can be supported in suitably designed bearings. The housing may be configured to have housing portions which are screwed together at their corners by suitable screw fasteners, whereby the partition plane of both housing portions extends approximately in an area of the carrier.  
         [0026]    For ease of illustration, the required parts for securing the components of the adjustment drive are not shown in detail. Suitably, the carrier  10  is provided with centering pins  23  (FIG. 1).  
         [0027]    The adjustment drive according to the present invention may also be used for adjusting control elements in case of fire. In order to ensure the operation of the adjustment drive even at elevated temperatures, the mentioned components are made of metal, for example, steel or non-ferrous heavy metal.  
         [0028]    While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. For example, it is, of course, conceivable to place the drive motor laterally to the carrier, instead of mounting it onto the carrier, as shown in FIG. 2. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.  
         [0029]    What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: