Abstract:
An exhaust system for a motor vehicle includes a housing having an inflow funnel defined by an expanding cross sectional area. Received in the housing is an exhaust-gas treatment device which includes a tubular guide element arranged in the inflow funnel and having a curvature with an outer side formed with at least one embossment. The embossment causes a deflection of the exhaust-gas flow and thereby increases a contact time of the exhaust-gas flow with an insert of the exhaust-gas treatment device.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of German Patent Application, Serial No. 10 2010 006 829.2-13, filed Feb. 3, 2010, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an exhaust system for a motor vehicle. 
         [0003]    It would be desirable and advantageous to provide an improved exhaust system to obviate prior art shortcomings and to also optimize a routing of exhaust gas in a transition zone between an exhaust pipe and an exhaust-gas treatment device in a cost-efficient and yet reliable manner. 
       SUMMARY OF THE INVENTION 
       [0004]    According to one aspect of the present invention, an exhaust system for a motor vehicle includes a housing having an inflow funnel defined by an expanding cross sectional area, and an exhaust-gas treatment device received in the housing and including a tubular guide element arranged in the inflow funnel and having a curvature with an outer side formed with at least one embossment. 
         [0005]    As a result of the curvature of the guide element and the formation of an embossment, exhaust gas routed in the exhaust pipe is deflected by the presence of the embossment to thereby impact on an insert of the exhaust-gas treatment device in an optimum manner. This improves in particular the uniformity index on the surface area of a catalytic converter or particle filter, especially of the exhaust-gas treatment device that is configured as catalytic converter or particle filter, without any significant increase in resistance pressure in the exhaust flow. 
         [0006]    According to another advantageous feature of the present invention, the embossment can be arranged in a direction transversely to a flow direction of exhaust gas. As a result, the exhaust flow is deflected and the flow rate is changed. The deflection of the exhaust-gas flow by the embossment causes turbulences and deflections of the exhaust-gas flow. This deflection causes a slowdown in the flow rate when the exhaust-gas flow impacts the insert arranged in the exhaust-gas treatment device. The embossment results in a targeted flow conduction to thereby attain a better utilization of the entire surface area of the catalytic converter or particle filter. 
         [0007]    According to another advantageous feature of the present invention, the embossment can be arranged on the guide element to point inwardly. In other words, the embossment is directed towards the exhaust-gas flow. As a result of the curvature of the guide element, the exhaust-gas flow is urged radially outwards against the outer side of the curvature. The presence of the inwardly directed embossment causes a deflection of the exhaust-gas flow so that the exhaust-gas flow is prevented from simply flowing undisturbed along the outer surface of the curvature but rather is deflected into the interior of the guide element and thus into the interior of the inflow funnel. As a result, a uniformly distributed and optimized flow pattern is attained when the exhaust-gas flow impacts the exhaust-gas treatment device. 
         [0008]    According to another advantageous feature of the present invention, the embossment may be configured to extend substantially across an entire cross sectional width of the guide element. As a result, the main flow portion of the exhaust-gas flow is deflected within the guide element. 
         [0009]    According to another advantageous feature of the present invention, the outer side of the guide element can be formed with two or more embossments which are arranged successively in flow direction of the exhaust gas. By providing more than one embossment, it is possible to best suit and to improve the flow pattern to the application at hand. For example, an exhaust-gas treatment device in the form of a particle filter requires the exhaust-gas flow to exhibit an impact behavior which is different when the exhaust-gas treatment device is configured in the form of a catalytic converter. The impact behavior can thus be targeted in a desired manner for various flows by appropriately arranging and dimensioning two or more embossments. A catalytic converter requires for example an optimized impact surface already when starting the engine in order to rapidly heat the catalytic converter and render it quickly operational. A diesel particle filter, on the other hand, requires initially a conduction of a relatively cool exhaust-gas flow and is then heated up to operating temperature. Only at that instance is a targeted impact upon the filter insert of a particle filter appropriate. 
         [0010]    According to another advantageous feature of the present invention, the guide element has a cross sectional area which can be configured to change from a round shape to a noncircular shape. The term “noncircular” relates hereby within the scope of the invention to a mixed configuration of a trapezoidal shape and an ellipse, or also to a triangular shape with rounded corners, a hemispherical shape, or a combination of the afore-stated configurations. The cross sectional expansion results in a slowdown of the flow rate so that the flow against an end surface of the insert in the catalytic converter or particle filter is evened out. In addition, the contact time between the exhaust gas and the insert of the exhaust-gas treatment device is advantageously prolonged. 
         [0011]    According to another advantageous feature of the present invention, the cross sectional area of the guide element expands in flow direction of the exhaust gas. The cross sectional increase is continuous like the change in the cross sectional configuration, i.e. without sudden changes, so that pressure loss is kept to a minimum. 
         [0012]    According to another advantageous feature of the present invention, an exhaust pipe can engage an inlet opening of the guide element. In this way, the components can be easily joined. The presence of a gastight coupling can hereby be made possible through a form fit or material joint. An example of a material joint includes a thermal joining process. 
         [0013]    According to another advantageous feature of the present invention, the guide element can be secured in an entry (or receiving) region of the inflow funnel. This simplifies manufacture. The guide element can be coupled with the inflow funnel by a gastight material joint and/or formfit. 
         [0014]    According to another advantageous feature of the present invention, the insert of the exhaust-gas treatment device and the inflow funnel can jointly define an interior space, with the guide element having an outlet opening positioned within the interior space at a distance to the insert. In addition, the outlet opening of the guide element may extend in a plane at an angle to a plane of an attachment zone of the exhaust-gas treatment device to the inflow funnel (end face of the insert). As a result, the exhaust-gas treatment device can be best suited in the area of the guide element to the respective flow demands of the internal combustion engine being used and to the downstream exhaust-gas treatment device, even when the installation space is limited. 
         [0015]    According to another advantageous feature of the present invention, the guide element and the inflow funnel can define a gap there between, with a distance between the inflow funnel and the guide element on the outer side of the curvature increasing in flow direction of exhaust gas. The presence of the gap keeps thermal stress away from the outer side of the inflow funnel to a certain extent. The thermal stress between the exhaust pipe ad the exhaust-gas treatment device can thus be minimized in the area of the inflow funnel. This extends service life of the overall system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0016]    Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which: 
           [0017]      FIG. 1  is a cross sectional view of an exhaust-system tract according to the present invention with a guide element; and 
           [0018]      FIG. 2  is a plan view of an exhaust-system tract according to the present invention with inserted guide element. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. 
         [0020]    Turning now to the drawing, and in particular to  FIG. 1 , there is shown a cross sectional view of an exhaust-system tract according to the present invention, generally designated by reference numeral  1 . The exhaust tract  1  has an exhaust pipe  2 , an inflow funnel  3 , and a guide element  4 . The exhaust pipe  2  has a circular tubular cross section and includes in flow direction S of the exhaust gas a coupling zone  5  which is embraced by the guide element  4  in a gastight manner, as indicated by reference numeral  6 . The gastight coupling  6  may be realized by a material joint or by a form fit. 
         [0021]    As viewed in the flow direction S, the inflow funnel  3  has an entry region A which is coupled in the coupling zone  5  with the guide element  4  in a gastight manner, e.g. by a material joint or form fit. The entry region A of the inflow funnel  3  overlaps hereby the guide element  4 . 
         [0022]    In the illustration of  FIG. 1 , the guide element  4  is curved downwards and has an outer side  7  which is formed with two embossments  8 ,  8 ′. The embossments  8 ,  8 ′ point inwards in a direction of the exhaust flow. The embossments  8 ,  8 ′ have a wavy configuration, as shown in  FIG. 1 . Although not shown here, the embossments may be configured also more sharp-edged with tighter bending radii. The leading embossment  8 , as viewed in flow direction S, has a more pronounced curvature than the trailing embossment  8 ′. 
         [0023]    Defined between the guide element  4  and the inflow funnel  3  is a circumferential gap  9  which increases substantially steadily in flow direction S in relation to the outer side  7  of the guide element  4 . The main stream of the exhaust gas flows along the outer side  7  of the curvature, i.e. this region is subject to particularly high thermal stress. As a result of a distance  10  as defined by the gap  9  between the guide element  4  and the inflow funnel  3 , a thermal barrier is established for the inflow funnel  3 . 
         [0024]    The guide element  4  has an outlet opening  11  which is oriented in a plane which lies within an interior space I defined by the inflow funnel  3  and an insert (not shown) of the exhaust-gas treatment device. The plane of the outlet opening  11  extends, as shown in  FIG. 1 , at an angle α in relation to a plane  12  in which the outlet opening of the inflow funnel  3  lies, with the angle α ranging between 0° and 45°, preferably between 0° and 30°. Currently preferred is a range between 0° and 20°. 
         [0025]    As shown in  FIG. 1 , the guide element  4  and the inflow funnel  3  have each a cross sectional area which widens in the flow direction S. The increase of the cross sectional area may be continuous, as shown with reference to the inflow funnel  3 , or discontinuously, as shown with reference to the guide element  4 . The cross sectional area of the guide element  4  is hereby smaller in the coupling zone  5  than the cross sectional area of the outlet opening  11 . 
         [0026]      FIG. 2  shows a plan view of the inflow funnel  3 , with the outlet opening  11  of the guide element  14  shown by way of a plan view. As can be seen from  FIG. 2 , the embossment  8 ′ extends essentially over the entire width of the guide element  4  transversely to the flow direction S. The outlet opening  11  has a substantially trapezoidal shape with rounded corners. The cross sectional area of the outlet opening  11  is greater than the cross sectional area of the exhaust pipe  2  but smaller by more than 50% than the outlet opening of the inflow funnel  3  in the plane  12  ( FIG. 1 ). As a result, the flow rate is slowed down so as to realize an evening of the flow upon the exhaust-gas treatment device. 
         [0027]    While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. 
         [0028]    What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: