Abstract:
In an adjusting device having a gear, high gear ratios are often demanded. High transverse forces often arise in the gear and must be intercepted by suitably dimensioned bearings. In the adjusting device proposed here, having a basic body and a cap, an embedded device is provided between a shaft, serving to support a gear wheel, and the cap. With the aid of the embedded device, good bearing of the gear wheel on both sides is attained, regardless of component tolerances. The adjusting device is intended especially for vehicles having an internal combustion engine.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based on German Patent Application 10 2005 042 202.0 filed Sep. 6, 2005, upon which priority is claimed.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field Of The Invention  
         [0003]     The invention is directed to an improved adjusting device in which a control motor is employed to adjust a control element via a gear, and to a method of producing the device.  
         [0004]     2. Description of the Prior Art  
         [0005]     Adjusting devices for internal combustion engines exist in which a control motor is meant to adjust a final control element via a gear. Since there is often little installation space available for the adjusting device in a motor vehicle, care must be taken to assure a small structural size. To enable a relatively small control motor to adjust the final control element quickly and precisely, a gear is provided between the control motor and the final control element. Because of the tight space, the gear must be as small as possible.  
         [0006]     German Patent Disclosure DE 195 25 510 A1 and U.S. Pat. No. 5,672,818 show an adjusting device provided in the intake tube of an internal combustion engine. This adjusting device has a throttle valve shaft, which is pivotably supported in a throttle valve housing and on which a throttle valve is secured. A gas conduit extends through the throttle valve housing. By pivoting of the throttle valve shaft, the throttle valve opens and closes the gas conduit. A control motor can adjust the throttle valve via a gear located in a gearbox and having a plurality of gear wheels. A middle gear wheel is supported rotatably on a shaft that is solidly joined to the basic body of the throttle valve housing. The gearbox is covered by a cap. Since among other elements, parts of a position sensor are mounted on the cap, the cap must be positioned very precisely in the region of the position sensor. For this reason, and because manufacturing variations can never be avoided entirely, there must be play in the region between the cap and the cap-side end, toward the cap, of the shaft, especially in the radial direction. The shaft can therefore be firmly held only in the region of the basic body, while in the region of the cap, only loose bearing with a great deal of play can be achieved. This has the disadvantage that particularly at the point where the shaft emerges from the basic body, the shaft is burdened by major bending stresses and shear stresses, and an especially high-strength material must therefore be used for the shaft, or else the shaft would be so thick that the entire device would have to be unnecessarily large.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0007]     The adjusting device and the method of the invention both have the advantage over the prior art that because of the embedded device, an excellent firm hold can be established between the cap and the shaft. A further advantage is that this firm hold can be established regardless of tolerances. This has the advantage that when the cap is being attached to the basic body, care need not be taken to position the cap precisely in the region of the shaft. This has the advantage that the cap can be positioned precisely in the region of other components, for instance in the region of a position sensor or rotary angle sensor. Thus the cap can be secured to the basic body exactly to suit the requirements for the position sensor or rotary angle sensor, without having to take the bearing of the shaft for the gear wheel into account in terms of tolerances. Because of the firm hold of the shaft in the region of the cap, there is the advantage that for a given load on the shaft by the gear wheel, the shaft can be made substantially thinner in comparison to previously known adjusting devices. Another advantage is that for a reasonable diameter of the shaft, the shaft can be manufactured from easily moldable material, making it possible to mold the shaft together with the basic body jointly from a single material.  
         [0008]     If the embedded device is provided on the cap-side end, oriented toward the cap, of the shaft, so that this end of the shaft is well fixed relative to the cap, this has the advantage that the gear wheel supported on the shaft can be supported on both sides in a simple way, which prevents excessive sagging of the shaft and which facilitates the use of readily moldable material, even whenever the shaft has a relatively thin diameter.  
         [0009]     If the embedded device has a relatively hard impressed body, which is attached to the shaft and formingly engages the cap as the cap is being joined to the basic body, this has the advantage that the embedded device on the cap molds integrally only when the cap is attached to the basic body, so that the cap can be produced with conventional, easily achieved tolerances.  
         [0010]     If the impressed body is embodied in the form of a sleeve, this has the advantage that the adjusting device can be produced very simply, because of the circumstance of the very simple, economical capability of producing a sleeve, even in large mass-production numbers.  
         [0011]     If the sleeve has a reduced diameter toward the cap, then this has the advantage that in the longitudinal direction to the shaft the sleeve can be positioned very simply on the shaft, and it has the further advantage that because of the reduced diameter, the forces for impressing it into the cap are reduced.  
         [0012]     If a rib is provided on the cap, this has the advantage that this rib can serve as material for the impressing by the impressed body, and on the far side of the rib, material can be cut out, which reduces the force for impressing into the cap to a readily manageable amount. If a plurality of ribs are provided, into which the impressed body must impress as the cap is being attached to the basic body, this has the advantage that the volume to be positively displaced per penetration point is slight, so that for the cap, even a material that is not so readily deformable can be used.  
         [0013]     The rib has a further advantage in that it can be oriented such that it extends along the direction of the force with which the gear wheel acts on the shaft, so that with little use of material and with only slight required impressing forces, good fixation of the shaft relative to the cap can be achieved.  
         [0014]     If the sleeve is used for supporting the gear wheel on the shaft, then without additional effort or expense, a good improvement to the bearing of the gear wheel on the shaft is obtained. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment, taken in conjunction with the drawings, in which:  
         [0016]      FIG. 1  shows a top view on an adjusting device according to the invention;  
         [0017]      FIG. 2  is a side view of the adjusting device shown in  FIG. 1 ;  
         [0018]      FIG. 3  is an enlarged, fragmentary section through a portion of section through the adjusting device;  
         [0019]      FIG. 4  shows a further enlarged detail designated IV in from  FIG. 3 ;  
         [0020]      FIG. 5  is an enlarged section taken along line V-V of  FIG. 2  the adjusting device;  
         [0021]      FIG. 6  is a further enlarged detail designated VI in  FIG. 5 ;  
         [0022]      FIG. 7  shows a further section, taken along line VII-VII in  FIG. 2 , through the adjusting device;  
         [0023]      FIG. 8  shows a further enlarged detail designated VIII in  FIG. 7 ;  
         [0024]      FIG. 9  is a section through the gear wheel transversely to the shaft; and  
         [0025]      FIG. 10  shows a further enlarged detail designated X in  FIG. 9 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     The adjusting device of the invention can be used in various places in internal combustion engines, in particular for controlling a passage through a gas conduit. The gas conduit is intended for instance for a flow of air or a fuel-air mixture or for controlling exhaust gas, and so forth. Depending on the pivoted position of the throttle valve, the flow of gas is throttled to a greater or lesser degree. Normally, the throttle valve can be pivoted by up to 90°. However, embodiments also exist in which the throttle valve can be pivoted by only less than 90° or by more than 90°, for instance by up to 180°. The throttle valve shaft with the throttle valve can be pivoted with the aid of a control motor, for instance. The control motor engages the throttle valve shaft, for instance by way of at least one gear wheel.  
         [0027]     In all the drawings, elements that are the same or function the same are provided with the same reference numerals. Unless otherwise mentioned or shown in the drawing, what is said and shown for one of the drawings applies to the others as well. As long as nothing else is said in the explanations, the various details can be combined with one another.  
         [0028]      FIG. 1  shows an adjusting device  2  with a basic body  4 , a throttle valve shaft  6 , a throttle valve  8 , and a cap  10 . Inside the adjusting device  2 , there is a gearbox  12 . The gearbox  12  is enclosed by the basic body  4 , side walls of the basic body  4 , and the cap  10 . Inside the basic body  4 , there is also a control motor  14 . Since in  FIG. 1  the gearbox  12  and the control motor  14  are covered by the basic body  4  and the cap  10 , respectively, and are thus not directly visible, the reference lines for reference numerals  12  and  14  are shown as dashed lines.  
         [0029]     Inside the gearbox  12  is a gear train  16  ( FIG. 2 ), with a motor pinion  18 , a gear wheel  20 , and a power takeoff wheel  22 . Since in the viewing direction selected for  FIG. 2  the motor pinion  18 , gear wheel  20  and power takeoff wheel  22  are covered by the cap  10 , these parts are represented by dashed lines in  FIG. 2 .  
         [0030]     In the manufacture of the adjusting device  2 , once the control motor  14  and the gear  16  have been built in, the cap  10  is mounted on the basic body  14 . In the finished state, the circumference of the cap  10  is solidly welded, glued, or firmly held with clamps to the basic body  4 .  
         [0031]     On the cap  10 , a first rib  24   a  and a second rib  24   b  are provided ( FIG. 2 ). Since the ribs  24   a  and  24   b  are located on the cap  10  on the side of the cap  10  facing away from the observer, the ribs  24   a  and  24   b  in  FIG. 2  are represented by dashed lines.  
         [0032]     A shaft  28  is integrally molded onto the basic body  4  ( FIGS. 3, 5 ,  7 ). In the especially advantageous exemplary embodiment that is preferably selected, the basic body  4  and the shaft  28  are molded from the same plastic, for instance by injection molding. However, the shaft  28  may also be a separate material, which is joined to the basic body  4  for instance via a press fit. Because of the invention proposed here, in which the load on the shaft  28  is reduced markedly compared to known adjusting devices, it is easily possible to make the shaft  28  and the basic body  4  from the same plastic.  
         [0033]     The shaft  28  has different diameters, viewed along its axial direction. Beginning at the basic body  4 , the shaft  28  first has a larger shaft diameter  28   a , and with increasing distance from the basic body  4 , it has a smaller shaft diameter  28   c . In a transition region  28   b , the larger shaft diameter  28   a  merges with the smaller shaft diameter  28   c . On the side facing away from the basic body  4 , the shaft  28  has a cap-side end  28   d  on its face end.  
         [0034]     The gear wheel  20  is rotatably supported on the shaft  28 . The gear wheel  20  has one region with a larger inside diameter  20   a  and another region with a smaller inside diameter  20   c  ( FIGS. 3,5  and  7 ).  
         [0035]     The gear wheel  20  is rotatably supported on the larger shaft diameter  28   a  via the larger inside diameter  20   a  and on the smaller shaft diameter  28   c  via the smaller inside diameter  20   c . It is also possible to provide more than two different diameter steps, so that the shaft  28 , beginning at the basic body  4 , becomes increasingly thinner in a plurality of stages in a more or less finely graduated way, and the inside diameters of the gear wheel  20  are adapted to suit the diameters of the shaft  28 .  
         [0036]     A sleeve  30  is located on the shaft  28 . The sleeve  30  surrounds the smaller shaft diameter  28   c  of the shaft  28 . The sleeve  30  is pressed onto the shaft  28 . The sleeve  30  protrudes in the axial direction past the cap-side end  28   d  of the shaft  28 . The sleeve  30  has a first region  30   c  which is pressed onto the smaller shaft diameter  28   c  of the shaft  28 . At the place where the sleeve  30  protrudes past the cap-side end  28   d , the sleeve  30  has a diameter step  30   d  ( FIG. 8 ). This is adjoined, with reduced diameter, by a second region  30   e . The second region  30   e  of the sleeve  30 , beginning at the diameter step  30   d , extends axially in the direction of the cap  10 . The sleeve  30 , or at least the second region  30   e  of the sleeve  30 , or at least the axially protruding edge of the second region  30   e  of the sleeve  30 , comprises relatively hard or hardened material, and the wall thickness of the second region  30   e  is relatively thin and preferably tapers to a point or to a knife edge at the end. When the cap  10  is joined to the basic body  4 , the second region  30   e  of the sleeve  30  presses into the ribs  24   a  and  24   b  provided on the cap  10 . As a result, the sleeve  30  together with the cap  10  form an embedded device  33  as best seen in  FIG. 4 . The second region  30   e  of the sleeve  30  acts as an impressed body  33   e  of the embedded device  33 , and the ribs  24   a  and  24   b  of the cap  10  act as a receptacle region  33   b  for the impressed body  33   e  of the embedded device  33 . It is pointed out that  FIG. 3  shows a section through the adjusting device along the sectional plane marked III-III in  FIG. 2 . The sectional plane is stepped in the region of the pivot axis  26  of the gear wheel  20 . In the region above the pivot axis  26 , the sectional plane III-III extends through the rib  24   b , and below the pivot axis  26 , the sectional plane III-III extends to the right of the rib  24   b . The viewing direction of the sectional plane III-III shown is marked with arrows III in  FIG. 2 .  
         [0037]     The embedded device  33  is designed such that the relatively hard impressed body  33   e  presses into the receptacle  33   b  while the cap  10  is being mounted on the basic body  4 . Since the receptacle  33   b  is not integrally molded on until during the mounting of the cap  10  onto the basic body  4 , an exact positioning is obtained between the shaft  28  and the cap  10 , regardless of dimensional tolerances of the cap  10  and/or of the basic body  4 .  
         [0038]     The gear wheel  20  has one larger ring gear  20   g  and one smaller ring gear  20   k  ( FIGS. 2 and 7 ). The larger ring gear  20   g  meshes with the motor pinion  18  ( FIG. 2 ), and the smaller ring gear  20   k  meshes with the power takeoff wheel  22 . Depending on the torque to be transmitted, the gear wheel  20  loads the shaft  28 , transversely to the pivot axis  26 , with a transverse force indicated by the arrow  35 . The direction of this transverse force  35  onto the shaft  28  is substantially perpendicular to the connecting line between the pivot axis  26  of the gear wheel  20  and the pivot axis of the power takeoff wheel  22 . The direction of the transverse force  35  also depends somewhat on the pivot axis of the motor pinion  18 , but this influence is relatively slight. In  FIG. 2 , the arrow  35  is meant to roughly symbolize the direction of the transverse force  35 . Depending on the rotational direction of the torque, the direction of the transverse force  35  may also be oriented counter to the arrow. The transverse force  35  is especially great if, when the throttle valve  8  is being adjusted rapidly ( FIG. 1 ), the throttle valve  8  strikes an end stop.  
         [0039]     The ribs  24   a  and  24   b  on the cap  10  offer the advantage that the impressed body  33   e  of the embedded device  33  need not dig into the cap  10  over the entire circumference of the second region  30   e  of the sleeve  30 , but instead has to dig into only parts of the circumference of the second region  30   e  of the sleeve  30 .  
         [0040]     Instead of the two ribs  24   a  and  24   b , it is also possible for only one rib  24   a  to be provided. It is equally possible to provide three or more ribs, however. It is also possible to make the cap  10  without ribs and to design it such that the impressed body  33   e  on the shaft  28  presses directly into the inside of the cap  10 , oriented toward the gearbox  12 , and the receptacle  33   b  of the embedded device  33  is formed there on the cap  10 .  
         [0041]     The at least one rib  24   a , or the ribs  24   a  and  24   b , are preferably oriented such that they extend parallel to the direction of the transverse force  35  acting from the gear wheel  20  onto the shaft  28  ( FIG. 2 ). The lengths of the ribs  24   a  and  24   b  are dimensioned such that the impressed body  33   e , formed by the second region  30   e  of the sleeve  30 , penetrates each of the ribs  24   a ,  24   b  at two points each spaced apart from one another. As a result, the receptacle  33   b  extends in the ribs  24   a  and  24   b  transversely to the direction of the transverse force  35 , so that when the transverse force  35  occurs, this transverse force  35  can be optimally absorbed by the cap  10 . As a result, a good hold between the cap  10  and the shaft  28  is achieved with a relatively short receptacle  33   b . The short receptacle  33   b  has the advantage that the impressed body  33   e  of the embedded device  33  can be impressed into the receptacle  33   b  with relatively little force.  
         [0042]     At the place where the sleeve  30  is pressed on, or in other words in the exemplary embodiment shown at the smaller shaft diameter  28   c , the shaft  28  has a basic diameter  28   g  ( FIGS. 8 and 10 ). On the circumference of the basic diameter  28   g , it has a protuberance  28   h , or a plurality of protuberances  28   h  distributed more or less uniformly over the circumference. The basic diameter  28   g  with the protuberances  28   h  has a circular outline. The circular outline is the smallest possible circle into which the basic diameter  28   g  would fit, including the protuberances  28   h , without being pressed. It is proposed that the circular outline of the basic diameter  28   g  with the protuberances  28   h  be selected as larger than the inside diameter of the region  30   c  of the sleeve  30 , yet the basic diameter  28   g , without taking the protuberances  28   h  into account, is smaller than the inside diameter of the region  30   c  of the sleeve  30 . As a result, the region  30   c  of the sleeve  30  can be pressed onto the shaft  28  with relatively little force and with relatively little deformation of the material comprising the shaft  28 .  
         [0043]     As the sleeve  30  is being pressed onto the shaft  28 , only the tips in the region of the protuberances  28   h  have to be deformed slightly. This offers the advantage that for the shaft  28 , a material that is relatively difficult to deform later can be used. A further advantage is that because of the protuberances  28   h , the sleeve  30  is somewhat deformed elastically, creating an initial tension that reliably holds the sleeve  30  firmly on the shaft  28 .  
         [0044]     The gear wheel  20  is seated, in the region of the large ring gear  20   g  having the larger inside diameter  20   a , on the larger shaft diameter  28   a  of the shaft  28  ( FIGS. 5 and 7 ). The large ring gear  20   g  is rather large, so that the larger shaft diameter  28   a  can also be dimensioned as relatively large. This offers the advantage that the load acting on the shaft  28  because of the transverse force  35  can be absorbed relatively easily by the shaft  28 .  
         [0045]     The gear wheel  20  is seated, in the region of the small ring gear  20   k  having the smaller inside diameter  20   c , on the first region  30   c  of the sleeve  30  and thus indirectly on the smaller shaft diameter  28   c  of the shaft  28 . Because of the reduction in the diameter of the shaft  28  in the transitional region  28   b , the advantage is obtained that the small ring gear  20   k  can be selected to be rather small, which makes a high gear ratio possible between the gear wheel  20  and the power takeoff wheel  22  ( FIG. 2 ).  
         [0046]     To obtain as high a gear ratio as possible between the gear wheel  20  and the power takeoff wheel  22 , the small ring gear  20   k  of the gear wheel  20  should be relatively small. Since with greater distance from the basic body  4  the shaft  28  has the smaller shaft diameter  28   c , the small ring gear  20   k  of the gear wheel  20  can be kept rather small, as desired.  
         [0047]     By means of the embedded device  33  between the shaft  28  and the cap  10 , the advantage is obtained that the shaft  28  is held directly by the basic body  4  on one end and by the cap  10  in an excellent way on the other end. Since the cap  10  is firmly held by the basic body  4  in a highly nondisplaceable manner, the result is good bearing on both sides of the gear wheel  20  on the shaft  28  and as a result on the basic body  4 .  
         [0048]     If the sleeve  30  surrounds only the smaller shaft diameter  28   c  of the shaft  28 , then this offers advantages because of reduced tolerance problems and reduced forces required for pressing the sleeve on, and where the load between the gear wheel  20  and the shaft  28  is especially great, or in other words at the smaller shaft diameter  28   c , a distribution of the load per unit of surface area on the shaft  28  is obtained.  
         [0049]     The foregoing relates to a preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.