Abstract:
A flap device for an internal combustion engine or an electric vehicle includes a flap body comprising a receiving opening, a duct housing configured to rotate arranged in the flap body, an actuator, a first bearing, a stub shaft arranged to project from the actuator through the duct housing to the flap body, a slide bearing arranged in the receiving opening of the flap body, and an axial pin arranged so as to be fixed in the duct housing on a side of the flap body opposite to the stub shaft. The stub shaft is supported in the duct housing via the first bearing. The axial pin supports the flap body via the slide bearing and projects into the receiving opening.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/EP2013/068158, filed on Sep. 3, 2013 and which claims benefit to German Patent Application No. 10 2012 110 763.7, filed on Nov. 9, 2012. The International Application was published in German on May 15, 2014 as WO 2014/072094 A1 under PCT Article 21(2). 
     FIELD 
     The present invention relates to a flap device for an internal combustion engine or an electric vehicle, comprising a flap body, a duct housing in which the flap body is arranged in a rotatable manner, an actuator, and a stub shaft which projects from the actuator through the duct housing to the flap body and is supported in the duct housing via a first bearing. 
     BACKGROUND 
     Flap devices of the above type are known in particular as throttle flaps for controlling the air supply to the internal combustion engine. In the process, the flap will be rotated in the duct housing, whereby the available flow cross section will be changed. Other applications for control of a gas flow, particularly of an air or exhaust gas flow, are also, however, known. 
     Various types of supports and designs of these flaps have been disclosed. In most cases, such flaps, which can be produced from plastic or metal, comprise a throughgoing shaft which is supported on both sides of the flap body in the duct housing. Primarily rolling bearings and, in this case, ball bearings are used for support. While the first shaft end is mostly supported in a blind hole of the duct housing, the opposite end passes through the duct housing. On this shaft end, a toothed wheel of a transmission is normally supported via which a connection to an electric motor is established, the electric motor serving as an actuator to drive the flap body and being connected to the control unit of the internal combustion engine. 
     Such a throttle body is described, for example, in DE 10 2007 013 937 A1. The rotary shaft, connected to the electric motor via the transmission, is supported in the duct housing by means of two needle bearings which include sealing rings. 
     DE 44 23 370 A1 describes a throttle flap made of plastic which comprises two opposite receiving openings for two shaft ends which are held in the openings in a form-locking manner. The flap body comprises rotary-bearing sites which are surrounded by a soft plastic sealing. DE 44 23 370 A1 does not disclose how the bearing support in the stub is actually realized. 
     The known designs have the disadvantage that the assembly process is relatively bothersome and that a high dimensional accuracy or additional measures are required in order the provide an exact position of the flap body when mounting the flap body in the duct in the direction of the axis of rotation. These designs are further vulnerable towards corrosive condensates. 
     SUMMARY 
     An aspect of the present invention is to provide a flap device which can be produced and assembled at a favorable cost and which can be precisely located in the duct in a convenient manner without requiring additional measures. An additional aspect of the present invention is that the bearings should be protected from corrosive condensates in the best possible manner. 
     In an embodiment, the present invention provides a flap device for an internal combustion engine or an electric vehicle which includes a flap body comprising a receiving opening, a duct housing configured to rotate arranged in the flap body, an actuator, a first bearing, a stub shaft arranged to project from the actuator through the duct housing to the flap body, a slide bearing arranged in the receiving opening of the flap body, and an axial pin arranged so as to be fixed in the duct housing on a side of the flap body opposite to the stub shaft. The stub shaft is supported in the duct housing via the first bearing. The axial pin is configured to support the flap body via the slide bearing and to project into the receiving opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described in greater detail below on the basis of embodiments and of the drawings in which: 
         FIG. 1  shows a three-dimensional representation of a flap device according to the present invention depicting the duct housing in a sectional view at the level of the axis of rotation, and depicting the flap body in a lateral view; and 
         FIG. 2  shows a plan view onto the flap device in a fully sectional representation. 
     
    
    
     DETAILED DESCRIPTION 
     Because an axial pin is fixedly arranged in the duct housing on the side of the flap body opposite the stub shaft, on which pin the flap body is supported via a slide bearing arranged in a receiving opening of the flap body, with the axial pin extending into the receiving opening, there is achieved a particularly simple assembly process because the axial pin and the stub shaft can be inserted into the duct housing from axially opposite sides. The entire arrangement can thus be assembled from the outside in a simple manner. In addition thereto, ingress of condensate in the area of the slide bearing in case of inclined mounting positions is reliably prevented. With this design, the slide bearing cannot only be pressed in at a later time, as has already been common practice, but can also be produced by surrounding injection or be directly formed from the plastic used. 
     It is advantageous if the axial pin is pressed in internally of the duct housing so that no further sealings need to be provided on the side of the axial pin to provide a sealing tightness toward the outside. By being fastened in the duct housing, the axial pin is not subjected to any alternating bending. 
     In an embodiment of the present invention, the first bearing can, for example, be a rolling bearing with its axial end extending into the duct and being in abutment on an abutment face of the flap body, said abutment face delimiting a receiving ring having the stub shaft extending through it. During assembly of the stub shaft and the axial pin with the flap, it can thus be avoided that the flap might drop down before insertion of the stub shaft. A high sealing tightness toward the outside is at the same time also provided on the side of the stub shaft. The axial play of the flap in the duct can be adapted through the insertion of the rolling bearing by shifting the rolling bearing to a position which is spaced from the disk, while various disk thicknesses can be used. 
     It can be advantageous if the rolling bearing is a needle bearing since such a bearing has a particularly high load-bearing capacity and thus has a long operating life at high stress. 
     In an embodiment of the present invention, a disk can, for example, be arranged between the flap body and the duct housing, the disk radially surrounding the axial pin and being in axial abutment against an abutment face surrounding the receiving opening and against the duct housing. This disk thereby creates a planar abutment face toward the flap body in spite of the cylindrical shape of the duct housing. The flap body can be pressed against this disk by a shift-in of the rolling bearing during the assembly process. The disk serves as a washer disk in the axial direction. The arrangement of the disk around the pin of the bearing arranged in the flap will also lead to a reduction of leakage in the closed position of the flap. 
     In an embodiment of the present invention, a first axial section of the disk can, for example, be arranged in a recess of the duct housing, and a second axial section can, for example, extend into the duct. This provides the positioning of the disk in the duct and the functioning of the disk as a planar abutment face. 
     For further simplification of the assembly process and for further enhancement of the sealing tightness of the flap, a respective annular projection extends from the abutment faces to the duct housing. Prior to insertion of the axis and of the stub shaft, the flap body can thus be supported on the disk and the rolling bearing via these projections. 
     In correspondence thereto, the first annular projection surrounds the section of the rolling bearing extending into the duct, and the second annular projection surrounds the section of the disk extending into the duct. This will also effect an increased resistance against ingress of corrosive liquid into the region of the bearing. 
     In an embodiment of the present invention, the stub shaft can, for example, comprise a step which is arranged in the receiving ring of the flap body, wherein the section having a smaller diameter faces toward the flap body, thus reliably preventing damage of the seals when passing the stub shaft through the housing. 
     In an embodiment of the present invention, the flap body can, for example, be made of plastic and can comprise a metal plate having the plastic molded partially around it, and the stub shaft can comprise an axial slot having the metal plate of the flap body extending into it. This makes it possible to obtain a durable fastening of the flap body on the stub shaft. The contour of the flap follows the contour of the shaft in order to prevent leakage within the range of the differences of diameter. 
     In an embodiment of the present invention, the metal plate can, for example, be formed with a hole in which, for fastening the flap body to the first stub shaft, a screw is attached which extends through the first stub shaft into the hole of the metal plate and engages a thread in the stub shaft beyond the slot. 
     A further simplification of the assembly process is achieved if, at the end of the stub shaft facing toward the actuator, a tooth segment is attached by molding, which tooth segment is then connected to the further transmission and thus to the actuator. 
     In an embodiment of the present invention, the slide bearing can, for example, be formed in the flap body geodetically below the rolling bearing, thus excluding ingress of generated condensate into the slide bearing. 
     It is advantageous if the needle bearing comprises integrated sealing rings. This prevents the ingress of liquid without requiring additional assembly steps. 
     A flap device is thereby created which allows for a particularly simple assembly process. Possible batch variations during production of the flap body can be compensated by simple means. An exact positioning of the flap body in the duct housing is thus obtained, which leads to a relatively good sealing tightness in the closed state, and to a reduced number of rejected products in the assembly process. The flap device can further be produced at favorable costs and is not sensitive to occurring corrosive liquids. 
     An embodiment of the flap device of the present invention is illustrated in the drawings and will be described hereunder. 
     The flap device of the present invention comprises a flap body  12  which is arranged to rotate in a duct housing  10 , wherein the radial dimension of the flap body  12  substantially corresponds to the free diameter of a duct  14  formed in the duct housing  10 . Flap body  12  is fastened in a slot  16  of a stub shaft  18  which on its opposite end has a tooth segment (not shown) molded to it, the tooth segment being connected to a continuing transmission arranged in a transmission housing  20 , while the transmission together with an electric motor forms an actuator  22  driving the flap body  12 . 
     Duct housing  10  comprises a first bore  24  through which the stub shaft  18  extends from transmission housing  20  into the duct  14 . Arranged in the first bore  24  is a rolling bearing designed as a needle bearing  26 , with sealing rings  28  integrated into it on both sides. 
     The needle bearing  26  extends by its axial end  30  into duct  14  where it is in axial abutment against an abutment face  32  axially delimiting the flap body  12 . The abutment face  32  forms the axial delimitation of flap body  12 . This axial end  30  of needle bearing  26  is radially surrounded by a first annular projection  36  extending from abutment face  32  of flap body  12  in the direction of duct housing  10 . 
     In a receiving ring  34 , the stub shaft  18  is arranged which in this region comprises a step  38  so that a slotted section  40 , comprising the slot  16 , of stub shaft  18  facing into the interior of duct  14  has a smaller diameter than the section  42  of stub shaft  18  arranged in first bore  24 . 
     The thinner slotted section  40  is formed with a hole  44  in which a head  46  of a screw  48  is arranged, the screw  48  clamping a metal plate  52  via the shaft slot and an opposite thread. The metal plate  52  is a part of flap body  12  and, prior to molding, will be inserted in the tool for forming the flap body  12  and then will be enclosed by molding material. The slotted section  40  of stub shaft  18  is arranged in abutment against this metal plate  52  on both sides and thus establishes the fixed connection between flap body  12  and stub shaft  18 . 
     On the side axially opposite to the receiving ring  34 , the flap body  12  comprises a receiving opening  54  in which a slide bearing  56  is arranged. This slide bearing  56  can either be inserted into the tool prior to the molding of flap body  12  or can be formed by the material itself, or be molded in at a later time. The slide bearing  56  radially surrounds an axial pin  58  whose opposite end is fastened in a second bore  59 , arranged opposite to the first bore  24 , within the duct housing  10 . 
     A disk  60  is arranged between duct housing  10  and slide bearing  56 , as viewed in the direction of the axis of rotation, whose first axial section  62  is located in a correspondingly shaped recess  64  in the wall of duct housing  10  and whose second axial section  66  extends into duct  14  and is in axial abutment against an abutment face  68  which radially delimits the receiving opening  54 . This second axial section  66  is radially surrounded by a second annular projection  70  extending from the abutment face  68  in the direction of duct housing  10 . 
     The special advantages of this flap device become clear in the assembly process, particularly if the part of the flap body  12  with the slide bearing  56  is arranged geodetically below the part supported via the needle bearing  26 . After producing the duct housing  10  with the bores  24 ,  59  and the molding of the flap body  12  with the metal plate  52 , the slide bearing  56  is first pressed into the receiving opening  54  unless it was already produced along with the molding process for the flap body  12 . 
     The disk  60  will subsequently be placed in the recess  64  of duct housing  10 , which, due to the geodetic position, is particularly simple. The flap body  12  will be placed in the duct  14  in so that the second annular projection  70  will surround the disk  60  and the abutment surface  68  will be in abutment on disk  60 . The needle bearing  26  will be pressed in at a distance from disk  60 . This distance corresponds to the flap thickness and the temperature-dependent minimum play. The axial pin  58  will then be inserted through the second bore  59  into the receiving opening  54  and through the slide bearing  56 , wherein, by press fit of axial pin  58  within second bore  59 , a sealing effect toward the outside can be generated. From the opposite side, the stub shaft  18  will be shifted through the first bore  24 , and respectively the needle bearing  26 , as well as through the receiving ring  34 , notably so that the metal plate  52  will come to rest in the slot  16  of stub shaft  18 . 
     The flap body  12  with metal plate  52  as well as the stub shaft  18  can be rotated for this purpose. The flap body  12  will subsequently be screwed by the screw  48  through the hole  44  of the stub shaft  18  and thereby be clamped with the aid of the shaft slot. 
     By use of favorably priced component parts, there is thus created a flap device which can be assembled with low expenditure. The position of the flap can be optimized in the duct so that batch variations can be compensated for. Particularly in case of an inclined installation position, no condensate will intrude into the slide bearing so that the operating life of the bearings is distinctly increased because, under the effect of gravity, the condensate will run out of both slide bearings. 
     It should be evident that the scope of protection of the main claim is not delimited to the above described exemplary embodiment but that various constructional modifications can be envisioned; reference should also be had to the appended claims. Connections may in particular be realized in a detachable or non-detachable manner. The design of the individual component parts can of course be adapted to the respective purpose.