Abstract:
A drive arrangement for an aggregate of an internal combustion engine includes a drive element, a housing, and an intermediate element. The housing comprises a static receiving part comprising a stop, and a cover fastened on the static receiving part. The cover is configured to bear axially against the stop. The intermediate element is arranged, in a preloaded state, between the drive element and the housing, radially between the cover and the drive element, and, in an elastically deformed state, axially between the drive element and the cover.

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/EP2014/051139, filed on Jan. 21, 2014 and which claims benefit to German Patent Application No. 10 2013 101 938.2, filed on Feb. 27, 2013. The International Application was published in German on Sep. 4, 2014 as WO 2014/131558 A1 under PCT Article 21(2). 
     FIELD 
     The present invention relates to a drive arrangement for an aggregate of an internal combustion engine, comprising a drive element, a housing and an intermediate element arranged in a preloaded state between the drive element and the housing, and an exhaust gas recirculation valve comprising a housing and an electric motor serving as a drive element and driving a valve via a transmission, the valve controlling a passage between an inlet and an outlet. 
     BACKGROUND 
     Drive arrangements of the above type are used to drive various aggregates in internal combustion engines. A difference is thereby to be made between aggregates which are operated continuously or at least over a longer period of time, such as, for example, pumps for conveying air, exhaust gas, coolant or other hydraulic fluids, and aggregates whose drive is operative only over a defined adjusting range, such as, for example, valves and flaps, particularly exhaust gas recirculation valves, exhaust gas flaps or throttle flaps. 
     All of these drives are exposed to large vibratory and impact loads in the internal combustion engine so that, in order to avoid damage at the drive element, the drive element must be supported to allow for the best possible damping both radially and axially. 
     It has thus become known to use intermediate elements to attach an actuating motor that are intended to improve this damping effect of the bearing support. 
     DE 10 2006 046 451 A1, for example, describes a bearing arrangement of a metal-encapsulated DC electric motor in a housing of synthetic resin for a throttle flap. Due to the differences in the deformability of the synthetic resin and the metal housing of the electric motor, the former must be protected against creeping deformation. An elastic body is therefore provided between the shaftless end of the electric motor and the resin housing, with the abutment face of the elastic body being larger on the resin housing than that abutment face which is in abutment on the metal housing. The elastic body comprises a metallic disk having its front edge provided with trapezoidal rubber cams. A disadvantage of this arrangement, however, resides in the bonding connection between the rubber cams and the metal disk. The radial fixation of the electric motor further takes place merely via the attachment on the A-bearing plate. 
     U.S. Pat. No. 6,860,466 B2 describes radially supporting the free end of the DC motor in the housing of the throttle valve by means of a metallic ring. EP 1 544 428 A2 describes a metallic anti-vibration ring for bracing the electric motor and the housing. It is also known to place an O-ring for vibration damping axially between the housing and the motor. A radial tolerance-insensitive bearing support also provided on the B-bearing is not, however, described in the prior art. 
     DE 10 2004 017 300 A1 describes a two-part intermediate element to support the drive of a secondary air blower on the A-bearing plate and on a support plate in the area of the B-bearing. The intermediate element includes corresponding shapes both for radial and for axial support. Assembly of this bearing support is, however, quite complex. The attachment of the support plate on the housing and the correct positioning of the support plate to obtain the desired effect of the intermediate element are particularly difficult. 
     SUMMARY 
     An aspect of the present invention is to provide a drive arrangement which is durable, which allows the drive to be axially braced in a housing, which is vibration-damping, and which radially supports the drive in a reliable manner. A further aspect of the present invention is to provide a drive arrangement which is as simple as possible so that the components of the housing will be tolerance-insensitive to the highest possible extent. A further aspect of the present invention to provide a drive arrangement which can be inexpensively produced. An aspect of the present invention is also to provide an exhaust gas recirculation valve comprising a drive arrangement having the above advantages. 
     In an embodiment, the present invention provides a drive arrangement for an aggregate of an internal combustion engine which includes a drive element, a housing, and an intermediate element. The housing comprises a static receiving part comprising a stop, and a cover fastened on the static receiving part. The cover is configured to bear axially against the stop. The intermediate element is arranged, in a preloaded state, between the drive element and the housing, radially between the cover and the drive element, and, in an elastically deformed state, axially between the drive element and the cover. 
    
    
     
       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 partially sectional lateral view of a first drive arrangement for an exhaust gas recirculation valve in accordance with the present invention; 
         FIG. 2  shows a sectional lateral view of the intermediate element according to  FIG. 1 ; 
         FIG. 3  shows a plan view of the intermediate element according to  FIG. 2 ; 
         FIG. 4  shows a schematic lateral view of an alternative drive arrangement in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Because the housing comprises a static receiving part and a cover fastened thereon which is in axial abutment on a stop on the static receiving part, with the intermediate element being arranged radially between the cover and the drive element and, in an elastically deformed state, axially between the drive element and the cover, a vibration-damping decoupling of the electric motor from the housing both axially and radially is achieved. The drive element can be mounted in a simple manner, and the housing components can be produced with large tolerances in an inexpensive manner because differences in size can be compensated by the intermediate element. 
     With regard to the exhaust gas recirculation valve, the fact that the electric motor, under the effect of the spring force of the elastically deformable intermediate element, is axially preloaded against an A-bearing plate formed on the housing and is radially supported in the cover by the intermediate element, it possible to also provide a vibration decoupling on all sides and to brace the electric motor in the housing, thereby providing a safe engagement of the driving toothed wheel in the transmission downstream thereof and a damping the mechanical stresses. The useful life of the electric motor is consequently extended. The tolerances between the size of the electric motor, the accommodation housing, and the cover can be distinctly increased. 
     The embodiment hereinafter described can be advantageously used for various applications of the drive arrangement as well as for the exhaust gas recirculation valve. 
     In an embodiment of the present invention, the intermediate element can, for example, comprise a central opening with an axial end of the drive element extending through or into it. The end of the drive element is thereby encompassed so that, in the mounting process, the intermediate element can be simply shifted into place. 
     In an embodiment of the present invention, the intermediate element can, for example, comprise a disk-shaped portion, with one or a plurality of projections extending therefrom in the axial direction, the projections being arranged in an elastically deformed state between an axial abutment face of the cover and an axial abutment face of the drive element. These projections serve for the axial decoupling, and for an axial tolerance compensation, of the drive element relative to the cover. The abutment area toward the cover or toward the drive element is reduced whereby, with the same degree of hardness, a stronger spring effect and/or elasticity is achieved compared to a full-faced abutment, and the surface area available for heat transmission is reduced. 
     In an embodiment of the present invention, the axially extending projection can, for example, have an annular shape. This contributes to the sealing function of the intermediate element. 
     In an embodiment of the present invention, the axially extending projections can, for example, be formed as a plurality of nubs distributed along the periphery. This results in a particularly good elastic effect of the individual nubs. 
     In an embodiment of the present invention, the intermediate element can, for example, comprise an annular, elastic collar which is abutted radially inwardly by the drive element and is abutted radially outwardly by the cover. In addition to the axial support and preloading of the drive element, the drive element is, in a simple manner, thereby also supported in the cover with a radial damping by use of only one component part. 
     In an embodiment of the present invention, the collar can, for example, surround the central opening and the axial end of the drive element and is radially surrounded by a cup-shaped receiving portion formed on the cover. The bearing support of the drive element is thus effected directly in the area of the B-bearing of the drive element. The cup-shaped receiving portion extending into the B-bearing can be produced with a corresponding large tolerance because a contact between the receiving portion and the B-bearing area is prevented by the collar. 
     In an embodiment of the present invention, the collar on its outer peripheral surface can, for example, comprise raised portions distributed along the outer periphery. This facilitates the assembly process because the raised portions can be radially compressed in a more simple manner. Shift-on attachment can thus be reliably performed by a low force while obtaining good damping properties in the radial direction. 
     In an embodiment of the present invention, the collar of the intermediate element can, for example, be arranged on the outer periphery of the disk so that the radial bearing support is effected via the outer periphery of the drive element. 
     In an embodiment of the present invention, the intermediate element can, for example, be formed in one piece from an elastomer or from another elastic non-metallic material. This allows for a simple manufacture and assembly, and good elastic properties will be provided, wherein, by changing the Shore hardness, the damping can also be changed and self-resonances can be shifted. 
     In an embodiment of the present invention, the cover with its cup-shaped receiving portion can, for example, be formed as a deep-drawn component. This allows for a particularly inexpensive manufacturing process. Too narrow tolerances are no longer required so that, compared to known bearing supports, the radii generated in deep-drawing can be tolerated without disadvantages. 
     The drive arrangement of the present invention and the exhaust gas recirculation valve of the present invention are thus distinguished by a long useful life as a result of vibration decoupling on all sides, and by particularly inexpensive manufacture and assembly processes, because it is possible to use easily manufactured component parts and because of the existing high insensitivity to tolerances. 
     Further advantages and features of the present invention will hereafter be explained via the Figures and by way of several exemplary embodiments. 
     Identical features are marked by identical reference numerals throughout the Figures. 
       FIG. 1  shows a drive arrangement comprising a housing  10  accommodating a drive element  12  in the form of an electric motor. In the shown embodiment, a drive shaft  14  of the electric motor  12  has a drive pinion  16  arranged on it for common rotation therewith, the drive pinion  16  serving to operate an exhaust gas recirculation valve  18  via a transmission  20 . The exhaust gas recirculation valve  18  comprises a valve plate  24  arranged on a valve shaft  22  and controlling a passage  26  between an inlet  28  and an outlet  30  in a known manner. However, the drive arrangement can also be used to operate or to drive pumps or flaps. 
     The illustrating housing  10  is of a multi-part design and comprises a static receiving part  32 , shown in sectional view, which, with interposition of an intermediate seal  34 , is fastened on a transmission housing member  36 , and a cover  38  fastened to the static receiving part  32 . The static receiving part  32  comprises a cover portion  40  in which the intermediate seal  34  is arranged and by which the transmission housing member  36  is closed. In its radially inner area relative to intermediate seal  34 , the cover portion  40  comprises an A-bearing plate  42  having a circuit board  44  arranged therein to control and contact the electric motor  12 , and having an annular abutment portion  46  formed on it which is axially abutted by the electric motor  12 . Internally of the abutment portion  46 , an opening  48  is formed through which the drive pinion  16  extends and which radially surrounds the first radial bearing  50  of electric motor  12 . 
     On the side opposite to the transmission housing member  36 , there extends a hollow cylindrical portion  52  radially surrounding the electric motor  12  and having an annular widened portion  54  formed on its end. After insertion of the electric motor  12  into the hollow cylindrical portion  52  of static receiving part  32 , the cover  38  will be shifted onto the electric motor  12 . The cover  38  is a sheet-metal component produced by deep-drawing, likewise surrounding the electric motor  12  via the portion not covered by the hollow cylindrical portion  52 . 
     Cover  38  is substantially shaped in the manner of a cup having three diameters decreasing in steps. The largest diameter encloses the annular widened portion  54  at the static receiving part  32 , while the intermediate portion radially surrounds the electric motor  12  at a small distance. The rear portion, closed in the rearward direction, surrounds a B-bearing portion  56  of electric motor  12  forming an axial end  59  of electric motor  12 . 
     In the assembly process, the largest diameter will be shifted over the annular widened portion  54  until a first step  58  will have come to abut, between the largest two diameters of cover  38 , against an abutment portion  60  formed by the axial end of annular widened portion  54 . The annular widened portion  54  comprises an annular recess facing toward the first step  58  and having an O-ring  62  arranged in it, thus effecting a tight connection. The end of cover  38  will then be crimped behind the annular widened portion  54  and thereby be fastened to the static receiving part  32 . 
     According to the present invention, however, in this process of shifting the cover  38  against the abutment portion  60 , an intermediate element  64  previously shifted into place via the B-bearing portion  56  will also be elastically deformed, while, in this condition, the intermediate element  64  is clamped, in a preloaded state, between a rear wall  66  of electric motor  12  serving as an axial abutment face  67  of the electric motor  12 , and a second step of cover  38  forming the transition between the smallest and the intermediate diameter of cover  38  and serving as an axial abutment face  69  of cover  38 . At the same time, an annular collar  68  of intermediate element  64  which surrounds the B-bearing portion  56  and thus the axial end  59  of electric motor  12 , will be received and radially braced in a cup-shaped receiving portion  70  of the cover  38  formed by the portion of the cover  38  having the smallest diameter. 
     The intermediate element  64  is made of an elastomer and, as can be seen in  FIGS. 2 and 3 , consists of a disk-shaped portion  72  comprising a central opening  74 . In the radially outer area of the disk-shaped portion  72 , eight projections in the form of nubs  76  extend from the disk-shaped portion  72  in the axial direction, the projections being distributed along the periphery. During assembly, these nubs  76  will be axially compressed between the axial abutment faces  67 ,  69  of electric motor  12  and cover  38 . They are arranged to face in the direction of the cover  38  so that the disk-shaped portion  72  is in abutment on the rear wall  66  of electric motor  12 . From the radial inner area of the disk-shaped portion  72 , the annular collar  68 , while surrounding the central opening  74 , extends in the axial direction. This annular collar  68  also comprises, on its outer side, eight raised portions  78  so that an undulated surface is generated, each of the raised portions  78  extending from the disk-shaped portion  72  to a position shortly before the axial end of annular collar  68 . At the outer periphery of the annular collar  68 , the end of the annular collar  68  is provided with a bevel  80  whereby, while the cover  38  is being shifted via the bevel  80  onto the intermediate element  64 , there will occur a gradual centering of the B-bearing portion  56  in the cup-shaped receiving portion  70 . The assembly process is thus distinctly facilitated because a radial pressure will be generated only after the bevel  80  has been passed during the shifting movement onto the annular collar  68 . 
     By the elasticity of the intermediate element  64 , there is thus achieved an accommodation of the electric motor  12  in the cover  38  that is vibration-damped in the axial and radial directions. The cover  38  can be produced with large tolerances and radii because these are compensated by the intermediate element  64 . 
     In the embodiment according to  FIG. 4 , the disk-shaped portion  72  is provided with an annular projection  82  extending in the direction of the rear wall  66  of electric motor  12  and being elastically deformed during assembly. In this embodiment, however, the radial support of the electric motor  12  in the cover  38  is achieved via the outer diameter of electric motor  12  and thus at the intermediate diameter of cover  38 . The disk-shaped portion  72  of the intermediate element  64  has a larger diameter than the electric motor  12 . In correspondence thereto, when the cover  38  is shifted into place, the radially outer projecting area of the disk-shaped portion  72  will be folded inwardly and be clamped between the outer diameter of electric motor  12  and the intermediate portion of cover  38 . In this state, the area forms the annular collar  68  but, in the assembled state, extends in the direction of the static receiving part  32 . 
     This embodiment also makes it possible, by use of component parts which can be produced in an inexpensive manner and by way of a facilitated assembly process, to realize a drive arrangement which has a long useful life because the impact and vibration stresses acting on the drive element are distinctly reduced both axially and radially. This drive is particularly suited for an exhaust gas recirculation valve. 
     It should be evident that the scope of protection of the main claim is not restricted to the described embodiments. There can in particular be used mixed forms of the two embodiments, or other drive elements. This arrangement is also suited for other uses. Other constructional changes of the housing, the cover, or the drive elements are also conceivable without leaving the scope of protection of the main claims. Reference should also be had to the appended claims.