Patent Publication Number: US-10781740-B2

Title: Exhaust system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. § 119 of German Application 10 2018 104 244.2, filed Feb. 26, 2018, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention pertains to an exhaust system for an internal combustion engine used, for example, in a motor vehicle. 
     BACKGROUND 
     Various sensors, for example, a temperature sensor detecting the exhaust gas temperature or one or more sensors detecting the composition of the exhaust gas, for example, a nitrogen oxide sensor, are provided in modern exhaust systems for providing information that is necessary to reduce the pollutant emission. Such sensors are provided, in general, at, for example, tubular, exhaust gas-carrying elements close to exhaust gas treatment systems, for example, an SCR catalytic converter device. 
     SUMMARY 
     An object of the present invention is to provide an exhaust system, with which it is made possible in a structurally simple manner to provide the information necessary for the operation of an exhaust system or of the internal combustion engine associated therewith. 
     This object is accomplished according to the present invention by an exhaust system, especially for an internal combustion engine in a vehicle, comprising at least one sensor carrier unit carried on an exhaust gas-carrying element, wherein the sensor carrier unit comprises a sensor carrier element fixed to the exhaust gas-carrying element and a sensor carrier element fixed to the exhaust gas-carrying element and, on the sensor carrier element, a plurality of, for example, three or at least three sensor pipe connections that are or can be fitted with sensors, each pipe connection being provided with at least one sensor-mounting/measuring opening formed therein. 
     In an exhaust system configured according to the present invention, it is made possible by the use of a single sensor carrier unit to provide a plurality of sensors on an exhaust system or on an exhaust gas-carrying element. This makes it possible to configure the associated sensor pipe connection with high precision in association with each individual sensor provided and to fix the sensor pipe connection to the exhaust gas-carrying element via the sensor carrier unit. Since the sensor pipe connection is not subject to any action during the fixation of the sensor carrier unit to the exhaust gas-carrying element, there is no risk in any of the plurality of sensor pipe connections to be provided that the sensor pipe connection will be damaged during the connection to the exhaust gas-carrying element or that the sensor pipe connection will be fixed in an unsuitable position especially in relation to other sensor pipe connections. Since it is not necessary to fix each sensor pipe connection individually to an exhaust gas-carrying element, the handling of the components to be connected to one another during the manufacture of an exhaust system is simplified. The time needed to manufacture an exhaust system can also be reduced, because the sensor carrier unit having a plurality of sensor pipe connections is introduced as a prefabricated assembly unit into the manufacturing process and can be connected to the exhaust gas-carrying element in a single operation. 
     To provide a connection between the exhaust gas-carrying element and the sensor carrier unit that is tight against the escape of exhaust gas in a reliable manner, it is proposed that the sensor carrier element have a sensor carrier element contour adapted to an outer circumferential contour of the exhaust gas-carrying element. 
     Provisions may be made in a configuration that can be manufactured in a simple manner for the sensor carrier element to be configured in one piece with at least one and preferably each sensor pipe connection. For example, the sensor carrier unit may be configured as a cast component. 
     In an alternative embodiment, the sensor carrier element has, in association with at least one and preferably each sensor pipe connection, a pipe connection contact plateau for contacting at least one sensor pipe connection formed separately from the sensor carrier element. 
     To make it possible to guarantee a defined positioning of a particular sensor pipe connection in relation to the sensor element, it is proposed that at least one and preferably each sensor pipe connection formed separately from the sensor carrier element comprise a positioning projection positioned such that it meshes with a positioning opening of the sensor carrier element. The positioning projection may surround the sensor-mounting/measuring opening formed in the sensor pipe connection with a ring-shaped configuration. 
     It is proposed for a stable connection of a respective sensor pipe connection to the sensor carrier element that a contact bead be provided for contacting the sensor pipe connection with the associated sensor contact plateau on at least one and preferably each sensor pipe connection formed configured separately from the sensor carrier element. The bead preferably surrounds the positioning projection formed on the sensor pipe connection with a ring-shaped configuration. 
     A connection of a respective sensor pipe connection to the sensor carrier element, which connection is stable under the thermal and mechanical loads occurring, can be obtained by at least one and preferably each sensor pipe connection formed configured separately from the sensor carrier element being connected to the sensor carrier element by welding, preferably by capacitor discharge welding. 
     The sensor carrier element may also be connected to the exhaust gas-carrying element by welding, preferably laser welding, MAG welding or capacitor discharge welding. 
     The sensor carrier element may be configured as a shaped sheet metal part in an embodiment that is also advantageous on the basis of the manufacturing costs. 
     Further, the present invention pertains to a sensor carrier unit, especially for an exhaust system configured according to the present invention, comprising a sensor carrier element to be fixed to an exhaust gas-carrying element and, on the sensor carrier element, a plurality of sensor pipe connections, which can be fitted with sensors and which have each at least one sensor-mounting/measuring opening formed in it. Such a sensor carrier unit may be configured with the individual features explained above or with any desired combination of the features explained above, which are specific for the sensor carrier unit. 
     The present invention will be described in detail below with reference to the attached figures. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a plan view of an exhaust system for an internal combustion engine of a vehicle; 
         FIG. 2  is a perspective view showing a sensor carrier unit of the exhaust system according to  FIG. 1 ; 
         FIG. 3  is a longitudinal sectional view of the sensor carrier unit according to  FIG. 2 ; 
         FIG. 4  is a lateral view of the sensor carrier unit according to  FIG. 2 ; 
         FIG. 5  is a top view of the sensor carrier unit according to  FIG. 2 ; 
         FIG. 6  is an end view of the sensor carrier unit according to  FIG. 2  in the direction of view VI in  FIG. 2 ; and 
         FIG. 7  is a cross-sectional view of the sensor carrier unit according to  FIG. 2 , cut along a line VII-VII in  FIG. 5 . 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the drawings, an exhaust system for an internal combustion engine of a motor vehicle is generally designated by  10  in  FIG. 1 . The exhaust system  10  comprises in an upstream area an exhaust gas aftertreatment unit  12 , for example, an SCR catalytic converter unit, into which the exhaust gas A discharged by an internal combustion engine is introduced. A tubular exhaust gas-carrying element  14  guides the exhaust gas discharged from the exhaust gas aftertreatment unit  12  to a muffler unit  16 , which is arranged, for example, in a downstream end area of the exhaust system  10 . The exhaust gas is discharged into the environment via tail pipes  18 . 
     A sensor carrier unit  20 , which will be described in detail below with reference to  FIGS. 2 through 7 , is provided in an area of the tubular exhaust gas guide element  14 , which area adjoins, for example, the exhaust gas aftertreatment unit  12 . The sensor carrier unit  20  comprises in the example being shown a sensor carrier element  22  configured, for example, as a shaped sheet metal part. The contour or shape of the sensor carrier element  22  is adapted to the contour of the exhaust gas guide element  14  in the area accommodating the sensor carrying unit  20 . In the example shown, the elongated sensor carrier element  22  has a curved shape adapted to the, for example, circularly curved outer contour of the exhaust gas-carrying element  14 . 
     Three sensor pipe connections  24 ,  26 ,  28 , which are arranged such that they follow each other in a line, are provided on the elongated sensor carrier element  22  in the example being shown. Each sensor pipe connection  24 ,  26 ,  28  provides a sensor-mounting/measuring opening  30 , into which a sensor can be inserted and through which the sensor can have a measuring interaction with the exhaust gas flowing in the exhaust gas-carrying element  14 . The sensor-mounting/measuring opening  30  may be configured, for example, in at least some areas, with an internal thread  31 , into which a corresponding external thread of the sensor to be mounted therein can be screwed, for a stable and gas-tight mounting of a sensor in a respective sensor-mounting/measuring opening  30 . Adjacent to this internal thread area, a respective sensor-mounting/measuring opening  30  may have a ring-shaped bottom area  32 , at which the sensor mounted therein can be supported via a, for example, O-ring-like sealing element or the like. To make it possible to provide the sensor-mounting pipe connections  24 ,  26 ,  28  with the required precision, these may be configured, for example, as metal components manufacturing, for example, by machining. 
     In association with each of the sensor pipe connections  24 ,  26 ,  28 , a pipe connection contact plateau  34  is provided at the sensor carrier element  22 . A positioning opening  36  is provided in each pipe connection contact plateau  34 , which provides an essentially uncurved, flat contact area for a respective associated sensor pipe connection  24 ,  26 ,  28 , for receiving a positioning projection  38 , which is provided at the respective sensor pipe connections  24 ,  26 ,  28  and which surrounds the sensor-mounting/measuring opening in a ring-shaped or an essentially cylindrical configuration. The internal dimension of the positioning opening  36  and the outer dimensions of the positioning projection  38  may be coordinated with one another such that a nearly clearance-free meshing interaction, which thus predefines a defined positioning for a respective sensor pipe connection  24 ,  26 ,  28 , is obtained. 
     The sensor pipe connections  24 ,  26 ,  28  are in contact with these respectively associated pipe connection contact plateaus  34  of the sensor carrier element  22  preferably via a contact bead  40  surrounding the positioning projection  38  or the sensor-mounting/measuring opening  30  in a ring-shaped configuration. A linear contact interaction, which extends over the entire circumference around the sensor-mounting/measuring opening, is thus obtained between a respective sensor pipe connection  24 ,  26 ,  28  and a respective pipe connection contact plateau  34 . This is especially advantageous if the sensor pipe connections  24 ,  26 ,  28  with the sensor carrier element are to be connected to one another by capacitor discharge welding. Such a welding process is therefore especially advantageous because a connection of the sensor pipe connections  24 ,  26 ,  28  to the sensor carrier element  22 , which is also very stable under the thermal loads and mechanical stresses to be expected during the operation of an internal combustion engine, is guaranteed. The sensor carrier unit  20  can be manufactured very easily with the use of such a welding process, because the components to be welded together, namely, the sensor pipe connections  24 ,  26 ,  28 , on the one hand, and the sensor carrier element  22 , on the other hand, can easily be pressed against each other with the use of corresponding tools in order to guarantee the contact pressure necessary for carrying out a capacitor discharge welding operation. Further, the use of such a capacitor discharge welding process leads to a nearly complete absence of weld warpage on the components to be connected to one another, so that these are available with the shape provided with high precision, which shape arises from the particular manufacturing process and is provided for the connection to the exhaust gas-carrying element  14 , on the one hand, and for the mounting of sensors, on the other hand, even after the capacitor discharge welding process has been carried out. 
     The sensor carrier unit  20  having a plurality of sensor pipe connections  24 ,  26 ,  28  can be introduced in its entirety into the exhaust system manufacturing process, so that only a single connection operation is to be carried out during this manufacturing process in order to fix a plurality of sensor pipe connections  24 ,  26 ,  28  to the exhaust gas-carrying component  14  of the exhaust system  10 . A connection by substance is preferably established by welding in this case as well. For example, a laser welding operation or a MAG welding operation, i.e., a protective gas welding operation, is preferably carried out to fix the plurality of sensor pipe connections  24 ,  26 ,  28  to the exhaust gas-carrying component  14  of the exhaust system  10 . A comparatively high pressing pressure, as this is necessary in case of a capacitor discharge welding operation, is not necessary between the components to be welded together in such welding processes. Thus, there is no risk that the tabularly configured exhaust gas guide component  14  will be additionally weakened, in the area in which the sensor carrier unit  20  is to be fixed, due to an excessively high pressure or otherwise associated with the creation of an opening to be covered by the sensor carrier unit  20 . A capacitor discharge welding operation may, of course, also be used to connect the sensor carrier unit  20  to the exhaust gas-carrying component  14 , especially if there is access for corresponding supporting tools in the area of the exhaust gas-carrying component  14  or this exhaust gas-carrying component  14  is correspondingly stable because of its structural configuration. 
     As is shown clearly above all in  FIGS. 2 through 4 , sensor pipe connections of various constructions may be provided on a sensor carrier unit  20  built according to the present invention in order to make it possible to correspondingly provide sensors of different configurations in an exhaust system. It should be noted that it is also possible, of course, to provide sensor pipe connections of identical configuration on a sensor carrier unit or/and that it is also possible, for example, to provide more than three sensor pipe connections or even only two sensor pipe connections on a sensor carrier unit. It would also be possible, in principle, to create the possibility of fixing a plurality of sensors in a single sensor pipe connection. A corresponding number of sensor-mounting/measuring openings associated with the sensors to be fixed to the sensor pipe connection could be provided for this in a single sensor pipe connection. 
     In another alternative embodiment, the sensor carrier unit could be provided as a one-piece structure, in which at least one of the sensor pipe connections is provided integrally with the sensor carrier element, i.e., as a material block, and is not fixed thereto as a separate component. For example, the sensor carrier unit with the sensor carrier element and with at least one of the sensor pipe connections can be provided in case of such a configuration as a cast component or possibly also as a shaped sheet metal part, on which the sensor pipe connections provided with an internal thread can be prepared by non-cutting shaping and possibly subsequent machining. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.