Abstract:
A rotation drive, particularly for displacing a moveable part in a motor vehicle, comprising a rotor which is mounted in a housing and which whose front-surface side rests upon a support element which is fixed to the housing in a positive fit. The support element is provided with radial linking elements which can be self-furrowingly rotated into the housing.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention concerns a rotary drive with a supporting member for a rotor according to the class of the independent claim.  
       BACKGROUND  
       [0002]     From the German patent DE 31 505 72 A1 a drive unit was made known, in which the manufacturing tolerances between the armature spindle and the housing which supports it were eliminated by means of an adjusting screw. In so doing, the housing has an internal thread in which the adjusting screw engages by means of an external thread. To compensate for the play in the armature spindle, the adjusting screw with a stop face is turned at a predetermined amount of force against the front (end) face of the rotor shaft.  
         [0003]     In such a device, the forming of a thread on the housing as well as on the adjusting screw is relatively painstaking. Furthermore, after adjusting to a predefined amount of force a further step of work is necessary for a torque proof fixing of the adjusting screw. For example, the screw is glued securely or an additional retaining element is installed.  
       SUMMARY  
       [0004]     The device according to the invention with the characteristics of the independent claim  1  has the advantage, that through the design of self-cutting crosspieces on the supporting member, this member can be fixed in a borehole of the housing in a one-step process. In so doing, the forming of internal threads in the housing section as well as the additional fixing of the supporting member from turning, which requires an additional step of work, are eliminated. Hence by means of a single component part an axial adjustment to the armature is achieved, which is free of play and self-supporting. It is also capable of supporting large axial forces to the armature.  
         [0005]     Advantageous modifications of the device according to the independent claim are possible by means of the measures which are listed in the sub-claims. If the radial crosspieces are arranged on the outer edge of a cylindrical base plate of the supporting member, the crosspieces then form a form closure with the housing section which surrounds the base plate. Through the choice of the radial length of the crosspieces, the area of overlapping diameters between the crosspieces and the borehole of the housing is adjusted to fit the axial forces arising from the armature. The radial crosspieces are thereby advantageously arranged when they approach being vertical to the cylinder axis. In contrast to the threads of an adjusting screw, the crosspieces have no thread lead across their circumference. Therefore, when an axial force acts upon the supporting member, no parts of this force result in a circumferential direction. Thus, these radial crosspieces represent a reliable security against twisting. Moreover, an undesirable axial displacement from turning an adjustment screw in is avoided.  
         [0006]     If the radial crosspieces are designed as angular segments around the base plate, which neither touch nor overlap, these crosspieces during installation of the supporting member can be axially inserted in a simple procedure into corresponding radial recesses of the housing borehole. By turning the supporting member to an angle which corresponds to the amount of angular displacement of the angular segment crosspieces (or somewhat more), the crosspieces cut into the housing material between its radial recesses, whereby an axial support of the armature is achieved.  
         [0007]     Depending upon the diameter of the base plate of the supporting member and the amount of axial forces present acting on the supporting member, two or three crosspieces which respectively lie across from each other—or three or more—can be molded symmetrically across the circumference of the base plate. In so doing, a corresponding number of preferably kidney-shaped radial recesses are formed, in which the respective crosspieces are to be inserted during installation.  
         [0008]     In a further embodiment of the rotary drive according to the invention, the radial crosspieces are arranged on the supporting member in planes which are axially separated from one another and which approximately run vertical to the cylinder axis. Thereby, the two or more radial crosspieces per plane lie respectively in the same angular range as the radial crosspieces of the next plane, so that the radial crosspieces of the various planes upon installation can be respectively inserted axially into the same radial recess of the housing.  
         [0009]     If the housing in the area of the front (end) face of the rotor shaft has a through hole on whose circumference radial recesses have been formed in sections, the supporting member can be axially inserted into the through hole with a predetermined contact pressing force and then pressed against the front face of the rotor shaft. By turning the supporting member around a certain angular range, a form closure occurs between the crosspieces, which create their own chamfers (fluting), and the housing. The supporting member is, thus, stabilized against axial displacement and twisting.  
         [0010]     In addition to this, the housing of the rotary drive is manufactured from plastic or at least soft metal in the area of the borehole. Thereby the radial crosspieces which are preferably manufactured from hard metal—for instance steel—can penetrate into the injection die cast or pressure die cast housing using a relatively minimal turning force.  
         [0011]     In so doing, it is advantageous for the crosspieces to have a sharp, self-chamfering cutting edge along that edge with which they engage the housing section when a twisting of the supporting member occurs. Such a twisting results in the radial crosspieces cutting a corresponding chamfer in the housing section. In order to secure the supporting member against a counter rotation during operation, security areas are formed in an additional edge lying directly across from the initial inner housing wall. These could, for example be designed in the form of a ridge, which would grab into the walls of the carved out chamfers in the housing at the occurrence of a counter rotation of the supporting member.  
         [0012]     In a further embodiment, the front (end) face of the rotor, particularly that of the rotor shaft, is designed spherical, so that this front face has a certain radius. If the rotor supports itself by way of such an arched front face at a flat stop face of the supporting member, the friction in the rotational operation of the rotor can be greatly reduced, whereby the degree of effectiveness is increased.  
         [0013]     For ease in installation, the supporting member has a form-closed entrainment member which positively locks with an installation tool in order to turn the supporting element in the borehole of the housing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     Various examples of embodiment of a device according to the invention are depicted in the drawings and are explained in more detail in the following description. They show:  
         [0015]    
       FIG. 1 
     
         [0016]     A section of a rotary drive with a supporting member according to the invention  
         [0017]    
       FIG. 2 
     
         [0018]     A further embodiment example of a rotary drive in the same kind of sectional depiction  
         [0019]    
       FIG. 3 
     
         [0020]     A top view according to III of the rotary drive from  FIG. 2  and  
         [0021]    
       FIG. 4 
     
         [0022]     An additional embodiment of a supporting element in an uninstalled state 
     
    
     DESCRIPTION  
       [0023]     In  FIG. 1  an electromotor  10  is depicted as a rotary drive  10 , that has a rotor  14  positioned with a bearing in a housing  12 . The housing  12  has, for example, a pole pot  16  forming a housing section  13 , in which permanent magnets  18  are located. These magnets work together with electrical coils  20 , which are located on the rotor shaft  22  of the rotor  14 . A collector (commutator)  24  is furthermore located on the rotor shaft  22  for commutation of the electrical coils  20 . The collector  24  is supplied with current via brushes  24  which are located on a housing  12 . Ball and roller bearings  28  are located on the rotor shaft  22 , with which the rotor shaft  22  is at least radially positioned. At one end  30  of the rotor shaft  22  a worm  32  is positioned on it, which engages with a worm wheel  34 . The worm wheel  34  is, for example, positioned on a securely anchored pin and is connected to an output link  38  which, for example, adjusts seat sections of a motor vehicle seat. During the power transfer from the worm  32  on the shaft to the worm wheel  34  via the engagement of the teeth, an axial force acts on the rotor shaft  22 , which (depending upon the direction of rotation of the electromotor  10  in  FIG. 1 ) is directed up or down. The rotor  14  has, therefore, front faces  42  at both ends  30 ,  31  of the rotor shaft  22 , which, for example are formed as one piece on the rotor shaft  22 . These also are, for example, designed through material molding as arched spherical ends with a radius  44 . The rotor  14  supports itself on one end  31  directly on the inside wall of the housing  12  and with the other end  30  on a separate supporting member  50 , which is attached to the housing  12 . After the installation of the drive  10 , the supporting member  50  is pressed through a through hole  52  in the housing  12  axially against the front (end) face  42 , so that this face  42  comes to rest on the stop face  56  of the supporting member  50  at a predetermined contact pressing force  54 . Tolerances due to manufacture can, therefore, be compensated for between the rotor shaft  22  and the housing  12  which is assembled from different housing sections  13 . In order to fix the supporting member  50  axially, it has radial crosspieces  58  formed to a base plate  66 . These mesh as a form closure into a wall  60  of the borehole  52 . The radial crosspieces  58 , which are grouped approximately around a cylindrical axis  62  of the base plate  66 , that is respectively around the rotor shaft  22 , have a self-cutting edge  64  with which the radial crosspieces  58  cut into the material of the housing  12 .  
         [0024]      FIG. 2  shows an enlarged depiction of an additional embodiment example of an electromotor  10 , in which the rotor shaft  22  is positioned in the housing  12  by means of a cup and ball bearing  68 . The collector  24 , which is hereby only schematically depicted, is positioned between the electric coils  22  and the bottom end of the pole housing  16 . In an alternative embodiment the electromotor  10  can also be electrically commutated. A worm  32  designed as a separate component part is fixed in a torque proof manner to the end  30  of the rotor shaft  22 . It in turn meshes with a worm wheel  34 , which is only partially depicted. The worm  32  has a head  33 , on which the axial end  30  of the rotor shaft  22  supports itself, so that the connection between the worm  32  and the rotor shaft  22  must absorb only torsional and no axial forces. At an end  70  of the worm  32 , respectively of the head  33 , a sphere  71  with a radius  44  is located. The rotor  14  supports itself with the sphere  71  on the stop face  56  of the supporting member  50 . Consequently the axial forces  40  which arise from the force transfer between the worm  32  and the worm wheel  34 —analogous with those as in the embodiment according to  FIG. 1 —are supported on the one side by way of the two front (end) faces  42  on the housing  12  (via a washer disc  72 ) and on the other side on the axially adjustable stop face of the supporting member  50 . In this connection the self-chamfering (self-fluting) radial crosspieces are arranged in three planes spaced from each other and running approximately vertical to the cylinder axis  62 . In contrast to the threads of an adjusting screw, the radial crosspieces  58  have no thread lead across their circumference. When the self-cutting radial crosspieces  58  are turned into the inner wall  60  of the housing section  13 , no spiral shaped thread turns emerge, but on the contrary separate ring-shaped chamfers  78 , that respectively lie completely in a plane  74  with a constant surface (face) benchmark (norm). The supporting member  50  has a cylindrical base plate  66 , that closes on one side the through hole  52  in the housing  12 . On an outer circumference  82  of the base plate  66 , the radial crosspieces  58  are preferably formed as one piece. On the side opposite to the stop face  56  the supporting member  50  has an entrainment member  86 , in which, for example, a tool with an outside polyhedron head could positively lock in order to turn the supporting member  50  to a particular angle range during installation.  
         [0025]     The rotary drive is depicted in  FIG. 3  according to a view in accordance with III. The housing  12  has in this instance, for example, a gear assembly housing  13 , that is manufactured from plastic by an injection die casting process. A borehole  52  is located in the housing section  13  in the direction of the cylinder axis  62 , which has additional auxiliary radial recesses  88  in the housing section  13 . In the embodiment example both of the radial recesses  88  extend over an angular range  90  of approximately ninety degrees and lie across from each other in such a fashion, that between both of the recesses  88  corresponding angular ranges  92  are arranged in a circumferential direction that form the inside wall  60  of the borehole  52 . When installing the supporting member  50  into the borehole  52  with the radial recesses  88 , it is inserted with its radial crosspieces  58  axially into the borehole  52  and is pressed with a contact pressing force  54  against the front face  42  of the rotor  14 . During the installation, the rotor shaft  22  is preferably aligned vertically, so that due to its own weight, the rotor  14  rests with its one end  31  on the wall  46  of the housing  12  lying across from the supporting member  50 . If a predetermined contact pressing force  54  of the supporting member  50  is reached, it  50  is turned around a certain angle using an installation tool that positively locks in the entrainment member  86 —for example into an inside polyhedron. In so doing, the radial crosspieces  58  cut into the housing wall  60  with their self-cutting edge  64 . The radial crosspieces  58  extend here over an angular range  94  that is smaller than the angular range  90  of the radial recesses  88 , so that upon installation the supporting member  50  can be axially inserted into the borehole  52 . Furthermore the angular range  94  of the radial crosspieces  58  is smaller than the angular range  92  of the inner wall  60 , so that the radial crosspieces  58  are located after installation completely within the inner wall  60 . So that the radial crosspieces  58  are not thereby turned entirely to the next recess  88 , a section of the inner wall  60  forms a security area  96 , which forms a limit stop above the crosspieces  58 . This prevents a further twisting of the output link  50 .  
         [0026]     A supporting member  50  of an additional embodiment example is depicted in  FIG. 4  before its installation into the housing  12 . The supporting member  50  has three angular ranges  94  with radial crosspieces  58 , between which angular ranges without axial crosspieces  58  are arranged across the circumference  82  of the base plate  60 , which are at least exactly as large as those with radial crosspieces. In order to install the supporting member  50 , it is turned in the direction of rotation of installation around an angular range, that approximately corresponds to the angular range  94  of the crosspieces  58 . In order that the radial crosspieces  58  cut lightly into the inner wall  60 , the radial crosspieces  58  have a self-chamfering (self-fluting) edge  64 , which during installation comes to rest in the inner wall  60  in the direction of rotation  98 . On the edge of the radial crosspieces  58  opposite to the above mentioned self-chamfering edge as seen in a circumferential direction (against the direction of rotation  98 ), the crosspieces  58  have locking mechanisms  102 . The locking mechanisms  102  are, for example, designed as sharp edged ridges  102 , which grab tightly into the housing material  12  if the supporting member  50  rotates backwards during operation. The supporting member  50  has a cross slit  86  as an entrainment member in which the corresponding installation tool engages as a form-closure in order to turn it in the direction of rotation. The number of radial crosspieces  58  in a plane  74  is not limited to two or three but can amount to four or more. Likewise the formation of the edges  64  and  102  can be varied especially to accommodate the combination of materials between the radial crosspieces  58  and the housing wall  60  (for example kidney shaped). In so doing, it is extremely important, that the crosspieces  58  in a plane  74  are arranged approximately vertical to the cylinder axis  62  and especially parallel to the stop face  56  (without an upward slope to their circumference  76 ), as then the axial force acting on the supporting member does not lead to a rotational movement of the supporting element  50 . The supporting member  50  is preferably manufactured from metal, whereby the stop face  56  is hardened to increase its service life.  
         [0027]     It should be noted, that when considering the many examples of embodiment in all of the depicted figures and accompanying descriptions, many combinations are possible among them. Especially the number and form of the radial crosspieces  58  as well as those of the corresponding recesses  88  can be varied. Furthermore, the number of planes  74  needed to correspond to the axial forces  40  which arise can be varied. Additionally, the front faces  42  are not limited to spherical, arched surfaces, but any desirable stop faces of the rotor  14 , respectively the rotor shaft  22  can be formed. In place of the worm  32  other gear assembly components can be positioned on the rotor shaft  22  (as for example a spur gear with straight or slanted outer gearing), which have likewise a head  33  to provide for rotor shaft support. The supporting member  50  can be placed as desired at the gear assembly housing  12  or at the end of the pole pot  16 . Such an axial adjustment of the armature according to the invention, which is both self-supporting and free of play, adapts itself especially well for use in regulating drives in the motor vehicle; however, is not limited to this application alone.