Patent Publication Number: US-6986860-B2

Title: Method for producing a throttle valve unit with integrated throttle valve

Description:
BACKGROUND OF THE INVENTION 
   In internal combustion engines, throttle adjusting devices are used in the intake tube section and can regulate the air volume required by the internal combustion engine for the combustion of fuel. As a rule, the throttle adjusting devices include a drive mechanism, the throttle valve supported on a shaft, and a two-part throttle housing, which can be made of cast metal or as an injection-molded plastic part. In addition, the throttle housing is often provided with a separate housing cover, which can be used to seal the housing in order to prevent the intake of outside air. 
   PRIOR ART 
   DE 43 29 522 A1 has disclosed a throttle device, which can be built into the intake conduit of an internal combustion engine. The throttle device is comprised of a housing of a throttle valve control unit, a position sensor, and a throttle valve attached to a throttle valve shaft, the throttle device being disposed between the connection on the clean air side of an air filter and the intake system of the internal combustion engine. The air filter connection and/or the intake system are comprised of a plastic and the individual elements of the throttle device are designed in modular fashion and can be joined to one another by means of slid-together, screwed, or clamped connections. The housing and/or the throttle valve can be made of plastic; the throttle valve shaft is embodied in two pieces: the module for the position sensor can be disposed on one half of the shaft and the module for the throttle valve adjusting unit can be disposed on the other half of the shaft. The adjusting unit, the position sensor, and the throttle valve with the throttle valve shaft constitute a common unit, where the housing can be integrated into the air filter connection fitting or the intake system connection. 
   The subject of WO 95/02493 A1 is a shaped body comprised of plastic. This publication discloses a shaped body made of plastic, preferably produced using an injection molding process, and a throttle valve housing that has a wall whose inner wall surface borders a hollow chamber. An insert part that is covered by the plastic material is disposed inside the wall, at least on the inner wall surface oriented toward the hollow chamber. The insert part is inclined in relation to the normal plane in such a way that a pivotable throttle valve, which is disposed in the hollow chamber and is used to control the output of an internal combustion engine, is flush with this insert part in the idle position of the engine. According to this proposed embodiment, the insert part is made of metal, for example a sheet metal. The insert part includes a section which is bent out from a plane, and can be provided with deformations, in particular with openings that pass through the insert part. 
   DE 195 25 510 A1 relates to a throttle valve adjusting unit. The throttle valve adjusting unit includes a throttle valve fastened to a throttle valve shaft supported so that it can rotate in a throttle valve fitting. In addition, an adjusting motor, which is supported on the throttle valve fitting and is coupled to the throttle valve shaft, is provided for adjusting the throttle valve shaft. This adjusting motor includes at least one slider and at least one potentiometer path for detecting an adjustment position of the throttle valve shaft and an electrical connection to which the adjusting motor and the potentiometer are connected in a connection chamber. Furthermore, a cover is provided, which terminates in the connection chamber. The at least one potentiometer path is affixed to the cover and the cover has a coupling part formed onto it, which is part of the electrical connection. In addition the cover has at least one contact embodied on it, which electrically contacts a reciprocal motor plug contact connected to the adjusting motor when the cover is mounted onto the throttle valve connection. 
   OBJECT AND SUMMARY OF THE INVENTION 
   With the embodiment proposed according to the invention, a throttle valve unit can be produced as an easy-to-use component through the use of multi-component techniques. The actual throttle valve can be manufactured with a frame part running around the edge of the throttle valve surface with a throttle valve shaft embodied as a one-piece component. The ends of the throttle valve shaft between the wings of the throttle valve surface can be produced as bearing pins within the required tolerances so that a throttle valve unit, which is embodied for example as a die-releasing throttle valve component, can be inserted into a throttle valve housing in few handling steps. If a throttle valve unit, which is embodied as die-releasing, i.e. without undercuts, is inserted into a bottom half of a throttle valve housing embodied in the intake tube section, then intermediary assembly steps and machine finishing operations can be eliminated. 
   The bottom housing half of the throttle valve housing can be embodied directly against an intake section tube of an internal combustion engine, which tube is likewise produced as an injection-molded plastic part, thus eliminating the installation step of attaching the throttle valve housing to the intake tube section in an internal combustion engine, which step can be a source of possible defective air intakes. 
   In order to fulfill the demands placed on the throttle valve unit with regard to imperviousness and ruggedness, a high-quality plastic is selected as the injection molding material for the throttle valve surface and components possibly injection molded onto it, as well as for a frame structure encompassing the throttle valve surface, in order to assure the required closing precision, the maintenance of dimensional stability, and a temperature stability of the throttle valve unit in all operating states of an internal combustion engine. If the throttle valve unit is produced in the course of the plastic injection molding, then it can be molded in one operation as a unit made of high-quality material. The split throttle valve housing, however, can be injection molded of a cheaper plastic, thus minimizing the quantity of high-quality plastic used. 
   During production of the throttle valve unit, not only can its bearing elements, i.e. the bearing pins of the throttle valve shaft, be manufactured in a dimensionally stable fashion within the required tolerances, but also if need be, driving features, driving gears, and receiving surfaces or recesses for sensor components can be produced in a single operation during the manufacture of the throttle valve unit. On the one hand, the above-listed attachments on the throttle valve unit can be directly injection molded onto it and on the other hand, these components can also be subsequently mounted onto a throttle valve unit produced in the plastic injection molding process. 
   With the embodiment proposed according to the invention, the geometry of a frame encompassing the valve surface can be varied in a simple manner, i.e. the material thickness of the frame encompassing the throttle valve surface and the resulting sealing action of the throttle valve unit in the intake tube section of an internal combustion engine can be adapted to the criteria furnished by the client. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which 
       FIG. 1  shows a throttle valve unit with a frame encompassing the valve surface halves and a throttle valve shaft with bearing pins, 
       FIG. 2  shows a throttle valve shaft according to the depiction in  FIG. 1 , with a drive element injection molded onto it, 
       FIG. 3  shows a throttle valve element according to the depiction in  FIG. 2 , inserted into a lower throttle valve housing half, and 
       FIG. 4  shows the upper housing half of a throttle valve housing, which is placed onto the lower throttle valve housing half and fixes the inserted throttle valve unit in place. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The depiction according to  FIG. 1  shows a throttle valve unit with a frame encompassing the valve surface halves and a throttle valve shaft with bearing pins embodied in its end regions. 
   The first embodiment of a throttle valve unit  1  shown in  FIG. 1  is embodied as a die-releasing embodiment without undercuts. A valve surface  4  extends on both sides of a valve shaft  2 . The valve surface  4  is formed symmetrically onto the valve shaft  2  and has a first wing  4 . 1  and a second wing  4 . 2 . The two wings  4 . 1 ,  4 . 2  of the valve surface  4  are encompassed by a frame structure  3 . The frame structure  3  has a first frame part  3 . 1  and a second frame part  3 . 2 , which are embodied with a frame thickness  3 . 3  shown in FIG.  1 . The frame thickness  3 . 3  of the frame structure  3  is dimensioned so that the frame structure  3  protrudes on both sides so that it is raised above the throttle valve surface  4 . The first frame part  3 . 1  and the second frame part  3 . 2  have an approximately half moon shape and have flattened places in the vicinity of where they transition into a first bearing pin  5  and a second bearing pin  7 . 
   In addition to an embodiment of the first frame part  3 . 1  and the second frame part  3 . 2  with a constant frame thickness  3 . 3 , the frame part  3 . 1 ,  3 . 2  can also be embodied with a frame thickness  3 . 3  that changes over the circumferencial surface of the first wing  4 . 1  or of the second wing  4 . 2  of the valve surface  4 . In order to reinforce the valve surface  4 , it can be useful to embody the frame structure  3  at the transition points in the vicinity of the bearing pins  5  and  7  with a greater frame thickness  3 . 3  than the one in  FIG. 1  during production in the injection molding die. It is likewise conceivable to embody the frame thickness  3 . 3 , which is disposed in the region furthest from the valve shaft  2  of the throttle valve unit  1  according to the depiction in  FIG. 1 , with a minimal frame thickness  3 . 3 , which has a favorable influence on the adjusting properties of the throttle valve unit  1  when it is actuated by a drive mechanism, preferably an electric one, which is not shown in FIG.  1 . 
   In the end regions of the valve shaft  2 , bearing pins  5  and  7  are formed onto the throttle valve unit  1 , which is a one-piece component, preferably produced in a two-component injection molding process and injection molded of a high-quality plastic material. Ideally, the injection molding die exerts adjusting forces that are powerful enough to permit the die-releasing throttle valve unit  1  according to the depiction of  FIG. 1  to be produced so as to be free of defects. This eliminates the need for a machine finishing of the bearing pins  5  and  7 ; receiving surfaces  6  can be formed onto the first bearing pin  5 . On the one hand, the receiving surfaces  6  can be used to support sensor elements, which can detect the rotary position of the throttle valve unit. The receiving surfaces  6  can also be used as slide-on surfaces for separately installed drive elements not shown in  FIG. 1 , for example gears or driving features. 
     FIG. 2  shows another embodiment of a one-piece throttle valve unit according to  FIG. 1 , with drive elements injection molded onto it. 
   The throttle valve unit  1  according to  FIG. 2 , which corresponds essentially to the depiction according to  FIG. 1 , includes a drive element  10  in the vicinity of the second bearing pin  7 . 
   The drive element  10  can be formed directly onto the valve shaft  2  during the production of the throttle valve unit  1  in the course of the two-component injection molding process, i.e. injection molded onto it. The drive element  10  shown in  FIG. 2  is embodied as a disc  11 . The disc  11  has a first side  13  oriented away from, valve surface  4  and a second side  14  oriented toward the valve surface  4 . Individual projections  15  spaced apart from one another are embodied on the first side  13 . The projections  15  serve as supports for restoring springs, which can restore the throttle valve unit  1  into its starting position. In lieu of the projections  15  injection molded onto the drive element  10  shown in  FIG. 2 , an external gearing can also be injection molded onto the circumference surface  12  of the drive element embodied in the form of a disc  11 . In addition to the embodiment shown in  FIG. 2 , with the drive element  10  injection molded onto it, other components, e.g. driving features or the like, can be injection molded onto the valve shaft  2  of the throttle valve unit  1 . 
   The throttle valve unit  1 , which is shown by way of example in  FIG. 2  as a one-piece component produced in the course of the two-component injection molding process, has a frame structure  3 , which encompasses the first wing  4 . 1  and the second wing  4 . 2  of the valve surface  4  in an approximately half moon shape. The frame thickness  3 . 3  of the first frame part  3 . 1  and the second frame part  3 . 2  of the frame structure  3  can, as shown in  FIG. 2 , be produced so that it is constant over the radius of the first wing  4 . 1  and the second wing  4 . 2  of the valve surface  4 . In addition, analogous to the depiction according to  FIG. 1 , a frame thickness  3 . 3  can be provided, which varies over the circumference of the first wing  4 . 1  and the second wing  4 . 2 . 
   A receiving surface  6  in the form of a flattened area is formed onto the region of the first bearing pin  5  of the valve shaft  2  and can be used to attach sensor elements or slip-on drive elements to the valve shaft  2  or throttle valve unit  1  according to FIG.  2 . 
     FIG. 3  shows the throttle valve unit according to the depiction in  FIG. 2 , with a drive element injection molded onto it, inserted into a lower housing half of a throttle device. 
   The lower housing half  20  shown in a perspective top view in  FIG. 3  can be embodied as a fitting to be separately installed into the intake section of an internal combustion engine; it is also possible to embody the lower housing half  20  as a lower housing half of a throttle device that is integrated into the intake section of an internal combustion engine. The first housing half  20  includes a first bearing point  21  and a second bearing point  22 , into which are inserted the first bearing pin  5  and the second bearing pin  7  of the one-piece throttle valve unit  1  according to  FIGS. 1 and 2 . A drive housing  23 , which in this case is embodied as cylindrical, is injection molded onto the first housing half  20 . The drive housing  23  encloses a hollow chamber  24 , which can accommodate a preferably electrical drive mechanism that is not shown here. The drive housing  23  is connected by means of a bridge  25  to a first receptacle half  26 . The first receptacle half  26  encloses a hollow chamber in the first throttle valve housing half, which in turn provides external protection to the drive element  10  that is injection molded onto the valve shaft  2 . The drive element  10  according to the depiction in  FIG. 3  has a first side  13  and a second side  14 ; projections  15  for supporting restoring springs are embodied on the first side  13 , spaced apart from one another evenly over the circumference of the drive element  10 . 
   In  FIG. 3 , the one-piece throttle valve unit  1 , which is preferably produced using a two-component injection molding technique, is inserted into the bearings  21 ,  22 , which are embodied on the first throttle valve housing half. A dimensionally stable production of the first bearing pin  5  and second bearing pin  7  renders a subsequent machine finishing of the circumference surfaces of the bearing pins  5  and  7  superfluous so that the throttle valve unit  1  can be inserted into the first housing half  20  immediately after being removed from the injection molding die. 
   For the sake of completeness, it should be noted that the drive housing  23  of the first housing half  20  is provided with locking elements  27  in which a locking element can lock in detent fashion after a drive mechanism, not shown here, is inserted into the hollow chamber  24  of the drive housing  23 . 
   The depiction according to  FIG. 4  shows the second housing half of the throttle valve housing, which is placed onto the first housing half and fixes the inserted throttle valve unit in place. 
   The second housing half  30  of the throttle device has an upper receptacle half  33  formed onto it, which closes the lower receptacle half  26  formed onto the first housing half  20  shown in  FIG. 3  so that the drive element  10  enclosed by the receptacle halves  26 ,  33  is sealed off from the environment. When assembling the first housing half and when installing the second housing half  30  onto the first housing half  20 , a sealing element or gasket, (not shown) can be disposed in the vicinity of the gap at the joint between the two housing halves  20 ,  30  and can seal the two housing halves  20 ,  30  against each other, thus preventing the intake of outside air. 
   A form-fitting element  31  is embodied on the second housing half  30 . The form-fitting element  31  is disposed on the outer circumference surface of a fitting  34 . An air hose leading from the air filter housing can be snapped on over the form fitting element  31 . The wall  35  of the fitting  34  has an inner diameter  36 , which corresponds to the cross section, which in the position of the one-piece throttle valve unit  1  shown in  FIG. 4 , is closed by the first wing  4 . 1  and the second wing  4 . 2  of the valve surface  4  of the throttle valve unit  1 . An appropriate through flow of air required for combustion in the combustion chambers of an internal combustion engine is set as a function of the rotary position of the throttle valve unit  1 , which is dictated by a drive mechanism that can be accommodated in the drive housing  23 . Fastening elements are injection molded onto the second throttle valve housing half  30 , each of which encompasses a through bore  32 . Slide-in screws can be inserted through the through bore  32 , with which the housing halves  20 ,  30  of the throttle device are fixed in relation to each other in a sealed fashion. In the perspective top view of a throttle valve unit  1  shown in  FIG. 4 , which is mounted in a two-part housing that includes the two housing halves  20  and  30 , the first bearing pin  5  formed onto the valve shaft  2 , with the receiving surface  6  embodied as a flattened area, protrudes laterally from the housing. Sensor elements can be placed on the receiving surface  6  on the first bearing pin  5  and can detect the rotary position of the throttle valve unit  1  in relation to the inner diameter  36  of the fitting  34 . Since the one-piece throttle valve unit  1  represents a single component, a sensor element to be provided on the receiving surface  6  can detect the rotary position of the valve surface  4  or of the first wing  4 . 1  and second wing  4 . 2  inside the inner diameter  36  of the fitting  34  with a high degree of precision. 
   Through the one-piece embodiment of the throttle valve unit  1 , whether as a die-releasing component according to the depiction in  FIG. 1  or as a throttle valve unit  1  with attachments according to the depiction in  FIG. 2 , this component can be produced continually in a separate operation from a higher-quality plastic than the plastic material used to produce the first housing half  20  and the second housing half  30 . This permits materials cost savings to be realized. In addition, the one-piece, dimensionally stable manufacture of the throttle valve unit  1  permits the elimination of intermediary assembly steps as well as finishing, e.g. burr removal. The die-releasing throttle valve unit  1  can be immediately inserted into the first housing half  20 , in which it is fixed in its insertion position and permanently held in place by the mounting of the second housing half  30 . 
   The foregoing relates to preferred exemplary embodiments 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.