Abstract:
An Exhaust Temperature Reduction Device for Aftertreatment Device is provided useful for lowering the temperature of exhaust gasses exiting the tailpipe of a vehicle having an aftertreatment device. The Exhaust Temperature Reduction Device for Aftertreatment Device may be manufactured from a single piece of formed sheet metal, two pieces of formed sheet metal that have been joined, or a net formed process such as investment cast stainless steel. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72( b ).

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to internal combustion engines, including but not limited to exhaust passages containing after-treatment devices for the internal combustion engine. 
       BACKGROUND 
       [0002]    Internal combustion engines generate exhaust gas during operation that contains various chemical compounds. Many modern engines include after-treatment devices associated therewith for treating some of these chemical compounds in the exhaust gas. Typical after-treatment components may include Oxidation Catalysts (OC) and Particulate Filters (PF). Compression ignition engines in particular, may use such devices for treating their exhaust gas. 
         [0003]    Treatment, or after-treatment as it is commonly known, is a process of treating exhaust gas that is generated during the operation of an engine and before it is released to the environment. In a typical vehicle, for example, an engine might be connected to an exhaust pipe, or tail pipe, that may carry exhaust gases away from the engine. The vehicle tail pipe may include various after-treatment components, along with other components, for example, mufflers, valves, and so forth. 
         [0004]    During operation of an engine, the temperature of the exhaust gases that are generated depends on various factors. During normal engine operation, the temperature of exhaust gas may depend primarily on the speed and load of the engine, and also on other factors, such as barometric pressure, ambient temperature, and so forth. During an idle condition, the temperature of exhaust gas in the tail pipe is expected to be relatively low, for example on some engines about 400 deg. F. (200 deg. C.). During conditions of high loading, for example when the vehicle is traveling at a higher rate of speed under a high load, the temperature of exhaust gas might reach temperatures of 1,500 deg. F. (815 deg. C.). 
         [0005]    PF regeneration, as is known, is a periodic process by which trapped matter in the PF burns off to clean the PF. The addition of after-treatment devices, such as a PF, might increase the temperature of exhaust gas at times when such temperature would otherwise be low. This increase in temperature may be due to a regeneration event of the PF that might be taking place, for example, while the engine is idling. 
         [0006]    Accordingly, there is a need for avoiding exhaust temperature increases in vehicle tailpipes during times when such temperatures are expected to be low. 
       SUMMARY OF THE INVENTION 
       [0007]    Exhaust temperature increases in vehicle tailpipes during times when such temperatures are expected to be low may advantageously be avoided by use of a mixing device as described herein. An engine system includes an internal combustion engine connected to an exhaust system. A portion of the exhaust system is connected to the internal combustion engine, and an additional portion of the exhaust system is connected to the vehicle and includes a tailpipe which opens to the atmosphere. An after-treatment system is connected to the exhaust system located between the internal combustion engine and the tailpipe. The mixing device is located between a first segment of the tailpipe and a second segment of the tailpipe. The mixing device is arranged to mix a flow of exhaust gas from the first segment of the tailpipe with a flow of ambient air to yield a mixture having lowered temperature as compared to the flow of exhaust gas, and to route the mixture into the second segment of the tailpipe. It operates passively, without the need for moving or powered parts. 
         [0008]    The mixing device has several passages through which exhaust gas is directed. Ambient air passages are nested in between the exhaust gas passages. The mixing device is designed so that it may be readily inserted into the first and second segments of the tailpipe, where it may be welded or mechanically fixed in place. It is designed to be manufactured in a net formed process, rather than being constrained to a sheet metal fabrication, though it may be manufactured using sheet metal fabrication if so desired. Preferably, the mixing device may be manufactured of investment cast stainless steel. This provides the shapes and sections required while keeping cost and weight to an acceptable level. 
         [0009]    In the embodiment shown, the hot exhaust stream is divided into five separate passages. Each passage is completely surrounded by the ambient air stream in such a way to maximize contact between the hot exhaust stream and the ambient air stream. This maximizes mixing while minimizing backpressure to the exhaust stream. 
         [0010]    The mixing device may be tuned in order to control the amount of backpressure experienced by the exhaust stream and to control the maximum temperature at the exhaust outlet of the second segment of the tailpipe. This may be done by use of a restriction or plug located in the ambient air passage of the mixing device, where it may be welded or mechanically fixed in place. It may also be done by varying the length of the second segment of the tailpipe. 
         [0011]    As described above, the Exhaust Temperature Reduction Device for Aftertreatment Device and a vehicle made with this device provide a number of advantages, some of which have been described above and others of which are inherent in the invention. Also, modifications may be proposed to the Exhaust Temperature Reduction Device for Aftertreatment Device or a vehicle made with this device without departing from the teachings herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
           [0013]    FIG.  1 —A first embodiment of the invention. 
           [0014]    FIG.  2 —A second embodiment of the invention. 
           [0015]    FIG.  3 —A third embodiment of the invention. 
           [0016]    FIG.  4 —A fourth embodiment of the invention. 
           [0017]    FIG.  5 —A fifth embodiment of the invention. 
           [0018]    FIG.  6 —A sixth embodiment of the invention. 
           [0019]    FIG.  7 —A seventh embodiment of the invention. 
           [0020]    FIG.  8 —A eighth embodiment of the invention. 
           [0021]    FIG.  9 —A ninth embodiment of the invention. 
           [0022]    FIG.  10 —A tenth embodiment of the invention. 
           [0023]    FIG.  11 —A eleventh embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 1  shows a mixing device  101  for use in an exhaust system of a vehicle having an internal combustion engine, particularly for an exhaust system having an aftertreatment system, which aftertreatment system results in the generation of very high temperature exhaust gasses. The mixing device  101  in the embodiment shown in  FIG. 1  is provided with five exhaust passages  102  spaced regularly between four ambient air passages  103 . High temperature exhaust gasses  112  enter the mixing device  101  at the inlet end  106 , and are channeled through the five exhaust passages  102  at the outlet end  107 . The inlet end  106  is sized such that the engine side exhaust pipe mating surface  108  will slide into and be clamped upon, welded to, or mechanically attached to the engine side exhaust pipe (not shown). The outer exhaust passages  102  of the outlet end  107  are shaped such that the outer surfaces thereof are partially concentrically cylindrical, forming a tailpipe side exhaust pipe mating surface  109 . 
         [0025]      FIG. 2  shows a mixing device  101  for use in an exhaust system of a vehicle having an internal combustion engine, similar to the mixing device  101  shown in  FIG. 1 . The mixing device  101  in the embodiment shown in  FIG. 2  is again provided with five exhaust passages  102 , four ambient air passages  103 , an inlet end  106 , and an outlet end  107 . Ambient air  113  enters the mixing device  101  through the four ambient air passages  103 , drawn by a venturi effect created by the high temperature exhaust gasses  112  (not shown) exiting the five exhaust passages  102 . The inlet end  106  is again sized such that the engine side exhaust pipe mating surface  108  will slide into and be clamped upon, welded to, or mechanically attached to the engine side exhaust pipe (not shown). The outer exhaust passages  102  of the outlet end  107  are again shaped such that the outer surfaces thereof are partially concentrically cylindrical, forming a tailpipe side exhaust pipe mating surface  109 . In this way, a tailpipe (not shown) that is slid over and clamped upon, welded to, or mechanically attached to the outlet end  107  of the mixing device  101  forms the outer wall of the four ambient air passages  103 . Ambient air  113  is thereby drawn into and mixed with the high temperature exhaust gasses  112  (not shown) as they enter the tailpipe (not shown). 
         [0026]      FIG. 3  shows a mixing device  101  installed, such that the inlet end  106  is inserted into the engine side exhaust pipe  110 , and the outlet end  107  is inserted into a tailpipe  111 . The ambient air passages  103  remain exposed, such that ambient air is drawn into the tailpipe  111  by the venturi effect of the exhaust gasses exiting the exhaust passages  102  (not visible). 
         [0027]      FIG. 4  shows an end view of the outlet end  107  of a mixing device  101 , similar to the mixing device  101  shown in  FIG. 1 . The mixing device  101  shown in  FIG. 4  is again provided with five exhaust passages  102  and four ambient air passages  103 . Four of the five exhaust passages  102  are so shaped that they form segments of a tailpipe side exhaust pipe mating surface  109 . 
         [0028]      FIG. 5  shows a side view of a mixing device  101 , similar to the mixing device  101  shown in  FIG. 1 . The mixing device  101  shown in  FIG. 5  is again provided with exhaust passages  102 , ambient air passages  103 , an inlet end  106 , and an outlet end  107 . The inlet end  106  is again provided with an engine side exhaust pipe mating surface  108 . The outlet end  107  is again provided with a tailpipe side exhaust pipe mating surface  109 . 
         [0029]      FIG. 6  shows the inner portion  105  of a mixing device  101 , in order to clarify the form thereof. The mixing device  101  has an inlet end  106  and an outlet end  107 . The exhaust passages  102  and ambient air passages  103  are formed from an essentially contiguous piece of metal. The outer portion (not shown) may be of the same contiguous piece of metal, so that the mixing device  101  is deep drawn and pierced from a single piece of metal. Alternately, the inner portion  105  of the mixing device  101  and the outer portion (not shown) of the mixing device  101  may be formed from separate pieces of metal and subsequently joined. Further, the inner portion  105  and the outer portion (not shown) of the mixing device  101  may be separately cast, or the mixing device  101  may be a single piece casting. Preferably, the mixing device  101  may be a single piece investment casting of stainless steel. 
         [0030]      FIG. 7  shows the inner portion  105  of a mixing device  101 , similar to the inner portion  105  shown in  FIG. 6 . The inner portion  105  shown in  FIG. 7  again has an inlet end  106 , an outlet end  107 , exhaust passages  102 , and ambient air passages  103 . The inner portion  105  may again be formed of a single contiguous piece of stamped metal, and subsequently joined to a separate formed outer portion (not shown), or the inner portion  105  and the outer portion (not shown) may be deep drawn and pierced from a single piece of metal. Similar to the inner portion  105  of the mixing device  101  of  FIG. 6 , the inner portion  105  of the mixing device  101  of  FIG. 7  may be cast, either separately or integrally with the outer portion (not shown). 
         [0031]      FIG. 8  shows the inner portion  105  of a mixing device  101 , similar to the inner portion  105  shown in  FIGS. 6 and 7 . The inner portion  105  shown in  FIG. 8  again has an inlet end  106 , an outlet end  107 , exhaust passages  102 , and ambient air passages  103 . Ambient air  113  is drawn into the mixing device  101  by the venturi effect caused by the flow of the high temperature exhaust gases  112  (not shown) as the high temperature exhaust gases  112  exit the exhaust passages  102  and enter the tailpipe  111  (not shown). The flow of ambient air  113  is represented by ambient air flow velocity vectors  117 . Generally regions of low velocity ambient air flow are indicated at points  118 . Generally regions of medium velocity ambient air flow are indicated at points  119 . Generally regions of high velocity ambient air flow are indicated at points  120 . 
         [0032]      FIG. 9  shows the inner portion  105  of a mixing device  101 , similar to the inner portion  105  shown in  FIGS. 6-8 . The inner portion  105  shown in  FIG. 9  again has an inlet end  106 , an outlet end  107 , exhaust passages  102 , and ambient air passages  103 . High temperature exhaust gases  112  enter the mixing device  101  at the inlet end  106 , pass through the exhaust passages  102 , and enter the tailpipe  111 . Ambient air  113  enters through the ambient air passages  103 . The ambient air  113  is shown entering at about 40° Celsius or about 100° Fahrenheit. The high temperature exhaust gases  112  are shown entering at about 650° Celsius or about 1200° Fahrenheit. There is an area of initial contact  114  between the high temperature exhaust gas  112  and the ambient air  113 , followed by a mixing volume  115  within the tailpipe  111 . The length of the tailpipe  111  and thus the mixing volume  115  may be varied, in order to accomplish optimum mixing and while maximizing the volume of ambient air that is drawn into the mixing device  101 . Finally, lowered temperature mixed air and exhaust gasses  116  exits the tailpipe  111 . 
         [0033]      FIG. 10  shows the inner portion  105  of a mixing device  101 , similar to the inner portion  105  shown in  FIGS. 6-9 . The inner portion  105  shown in  FIG. 10  again has an inlet end  106 , an outlet end  107 , exhaust passages  102 , and ambient air passages  103 . High temperature exhaust gases  112  and ambient air  113  are again shown entering the mixing device  101  and flowing into the tailpipe  111 . The ambient air  113  is again shown entering at about 40° Celsius or about 100° Fahrenheit, and the high temperature exhaust gases  112  are shown entering at about 650° Celsius or about 1200° Fahrenheit. There is again an area of initial contact  114  between the high temperature exhaust gas  112  and the ambient air  113 , followed by a mixing volume  115  within the tailpipe  111 , and lowered temperature mixed air and exhaust gasses  116  exiting the tailpipe  111 . The lowered temperature mixed air and exhaust gasses  116  exit the tailpipe  111  at about 340° Celsius or about 640° Fahrenheit. 
         [0034]      FIG. 11  shows a mixing device  101  for use in an exhaust system of a vehicle having an internal combustion engine, similar to the mixing device  101  shown in  FIG. 1 . The mixing device  101  in the embodiment shown in  FIG. 11  is again provided with five exhaust passages  102 , four ambient air passages  103 , an inlet end  106 , an engine side exhaust pipe mating surface  108 , an outlet end  107 , and tailpipe side exhaust pipe mating surface  109 . A plug  104  is shown inserted into one of the four ambient air passages  103 , which plug may be geometrically locked into place, force fit, or welded into place. The plug  104  is useful for tuning the backpressure of the exhaust system and the amount of ambient air drawn into the exhaust stream. 
         [0035]    While specific embodiments have been described in detail in the foregoing detailed description and illustrated in the accompanying drawings, those with ordinary skill in the art will appreciate that various permutations of the invention are possible without departing from the teachings disclosed herein. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof. Other advantages to a vehicle equipped with an Exhaust Temperature Reduction Device for Aftertreatment Device may also be inherent in the invention, without having been described above.