Abstract:
The present invention relates to a compressor-cooler module, having a housing, a compressor contained in the housing and an air cooler disposed within the housing and positioned in the flow path of the compressor. The present invention also includes an intake in fluid communication with the housing, a cooler bypass valve operably associated with the air cooler and the compressor, and a low-pressure exhaust gas recirculation passage operably associated with the cooler bypass valve, and the cooler by pass valve selectively directs exhaust gas to bypass the air cooler.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/844,248 filed Sep. 13, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to an engine assembly having an exhaust air cooler integrated into a turbocharger. 
       BACKGROUND OF THE INVENTION 
       [0003]    Current and future emissions requirements for diesel engines in Europe, the United States and most foreign markets will require engine concepts capable of achieving low Oxides of Nitrogen (NOx) and low Particulate Matter (PM) emissions while at the same time having a high integration of components and functions with lowered costs. Emissions reduction systems, like low-pressure exhaust gas recirculation (EGR) are required while cooling of the intake air becomes more and more important in order to reduce unwanted emissions. Integration of the different intake gas coolers like a charge air cooler or a low-pressure EGR cooler into one casting including a compressor of a turbocharger can provide improved compressor efficiency, reduced overall costs and smaller packaging. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention relates to a compressor-cooler module, having a housing, a compressor contained in the housing, and an air cooler disposed within the housing and positioned in the flow path of the compressor. The present invention also includes an intake in fluid communication with the housing, a cooler bypass valve operably associated with the air cooler and the compressor, and a low-pressure exhaust gas recirculation passage operably associated with the cooler bypass valve. The cooler by pass valve selectively directs exhaust gas to bypass the air cooler. 
         [0005]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0007]      FIG. 1  is a sectional side view of a prior art turbocharger unit; 
           [0008]      FIG. 2  is a schematic view of an exhaust air cooler integrated into a turbocharger, according to the present invention; 
           [0009]      FIG. 3  is a schematic view of an alternate embodiment of an exhaust air cooler integrated into a turbocharger, according to the present invention; 
           [0010]      FIG. 4  is a schematic view of an alternate embodiment incorporating a separator unit upstream of a compressor, according to the present invention; 
           [0011]      FIG. 5  is a schematic view of an alternate embodiment incorporating a separator unit downstream of a compressor, according to the present invention; 
           [0012]      FIG. 6  is an exploded view of a separator unit, according to the present invention; and 
           [0013]      FIG. 7  is a sectional side view of a compressor having a silencer, according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0015]      FIG. 2  is a schematic view of a system  10  according to the present invention. The system has a high-pressure EGR loop  12  and a low-pressure EGR loop  14 . The low-pressure EGR loop  14  is downstream of a turbine  16 , which is part of a turbocharger unit  18  having a compressor  20 . The low-pressure EGR loop  14  is upstream of the compressor  20 . The turbine  16  and compressor  20  are connected through the use of a shaft  22 . The high-pressure EGR loop  12  is located downstream of the compressor  20 , and upstream of the turbine  16 . 
         [0016]    Exhaust gas is generated by an engine  24 , and exits through an exhaust gas manifold  26 . Connected to the exhaust gas manifold  26  is an exhaust gas conduit  28 , which is used for delivering the exhaust gas to either the high-pressure EGR loop  12 , or the turbine  16 . If the exhaust gas passes through the turbine  16 , the exhaust gas will flow into an exhaust pipe  30 , where the exhaust gas will then flow through either the low-pressure EGR loop  14 , or out of the exhaust pipe  30  into atmosphere. 
         [0017]    If exhaust gas is recirculated through the high-pressure EGR loop  12 , the exhaust gas will pass through an EGR valve  32 , an EGR cooler  34  and is then introduced to an intake pipe  36  that leads to an intake manifold  38 . To create enough EGR-flow through, the EGR valve  32  can be adjusted accordingly. If the valve  32  is fully open and more flow through is required, the intake pipe  36  also includes an intake throttle valve  40  which can be adjusted to create more flow down stream of the valve  32 , thereby increasing flow the high-pressure EGR loop  12  into the intake pipe  36 . 
         [0018]    If exhaust from the engine  24  is recirculated in the low-pressure EGR loop  14 , the exhaust gas passes through the variable turbine  16 , and into the exhaust pipe  30 . Disposed in the exhaust pipe  30  is a diesel particulate filter (DPF)  42 , where the exhaust gas is cleaned of soot and carbon monoxide and hydrocarbons. After going through the DPF  42 , an EGR valve  44  in the low-pressure loop  14  is opened to allow the exhaust gas to flow through the low-pressure EGR loop  14  into a compressor-cooler module, generally shown at  46 . 
         [0019]    The compressor-cooler module  46  contains the compressor  20  and a cooler  48  integrated into a single housing  50 . The cooler  48  can be positioned upstream of the compressor  20  as shown in  FIG. 2 , or in an alternate embodiment shown in  FIG. 3 , the cooler  48  can be positioned downstream of the compressor  20 . It is also possible to have two coolers  48 , one upstream and one downstream of the compressor  20 . In applications where the cooler  48  is positioned upstream of the compressor  20 , an EGR cooler bypass valve  52  is used to bypass incoming exhaust gas around the cooler  48  so the exhaust gas selectively flows through a bypass conduit  54  and is introduced directly into the compressor  20 , instead of flowing through the cooler  48 . Fresh air is introduced through an intake, or intake duct  56 , mixed with exhaust gas from the low-pressure EGR loop  14 , if present, and is compressed by the compressor  20 , cooled by a second charge-air cooler  58 , and flows through the throttle valve  40 . The gas mixture then mixes with EGR flowing through the high-pressure EGR loop  12  before flowing into the intake manifold  38 . Other engine layouts may include only one EGR loop or multiple turbo chargers. As shown in  FIG. 3 , the second charge-air cooler  58  is located downstream of the compressor  20  and cooler  48 , which allows the charge-air cooler  58  to further reduce the temperature of the compressed air. 
         [0020]    The low-pressure EGR cooler  48  is typically located in the path of the low-pressure EGR loop  14 . The low-pressure EGR valve  44  is a stand alone valve bolted into the low-pressure EGR path  14  or the cooler  48 . The low-pressure EGR valve  44  can be positioned either before (i.e., functioning as a “hot side valve”) or after the cooler  48  (i.e., functioning as a “cold side valve”). The EGR valve  44  can be a poppet type, a flapper type valve, or other similar valve type. If the cooler  48  is located downstream of the compressor  20 , the exhaust gas and air mixture will flow into the charge-air cooler  58 . 
         [0021]    As shown in  FIGS. 2 and 3 , an exhaust throttle valve  60  is located in the exhaust pipe  30  somewhere downstream of the low-pressure EGR loop  14  to control the flow and pressure of exhaust gas downstream of the turbine  16 . The low-pressure EGR valve  44  and the exhaust throttle  60  can also be integrated into a combined module (using either one or two actuators). This module can be located either on the exhaust side or on the intake side at the junction of the low-pressure EGR loop  14 . 
         [0022]      FIG. 3  also depicts an alternate embodiment of the invention where the high-pressure EGR loop  12  passes through the module  46 . The EGR valve  32  is contained in the module  46  and controls the flow of exhaust gas from the engine  24  into the module  46 . In this embodiment, the particulate filter  42  is located upstream of the variable turbine  16 , and filters the exhaust gas before the exhaust gas enters the module  46  through either the low-pressure or high-pressure EGR loops  12 , 14 . In addition to the EGR valve  32  being located in the module  46 , there is also a charge-air cooler bypass valve  62  that can direct the flow of exhaust gas flowing through the EGR valve  32  around the compressor-cooler module  46  components. 
         [0023]    Other embodiments of the present invention are shown in  FIGS. 4-7 , wherein like numbers refer to like elements. In  FIGS. 4 ,  6 , and  7 , a separator unit, generally shown at  64 , is integrated into the compressor-cooler module  46 . The separator unit  64  includes a cover  66  which is connected to the intake duct  56  and the low-pressure EGR loop  14 . The cover  66  is connected to the intake duct  56  through the use of a circular flange  68  having an aperture  70 , and is connected to the low-pressure EGR loop  14  through the use of a square-shaped flange  72 , which extends from the cover  66  in a perpendicular manner relative to the circular flange  68 . The cover  66  is hollow, and receives a mixer  74 . The mixer  74  is a generally cylindrical-shaped member which includes a series of apertures  76 ; the mixer  74  is surrounded by a separator  78 . The separator  78  is made of a wire mesh which traps and retains debris from the exhaust gas flowing through the low-pressure EGR loop  14 . The mixer  74  can be formed as part of the housing  50 , or the mixer  74  can be formed as a separate component. The mixer  74  and separator  76  as described herein reduces the velocity of the air flowing which will also reduce the pressure drop of the air flow going into the compressor  20 , thereby improving the efficiency of the compressor  20 . 
         [0024]    When the mixer  74  is disposed within the cover  66 , the mixer  74  will abut a shoulder  80  formed as a portion of the cover  66 . This will ensure that any exhaust gas flowing into the cover  66  will be forced to flow through the separator  78 , and then the apertures  76  of the mixer  74 . After the exhaust gas has passed through the apertures  76 , the exhaust gas will mix with the fresh air flowing into the aperture  70 . The mixture of fresh air and exhaust gas will then flow into the compressor  20 , or the cooler  48 , depending on whether the bypass valve  52  is open or closed. 
         [0025]    The separator unit  64  also includes a swirler  82  having a plurality of vanes  84 . As air enters the separator unit  64 , the vanes  84  will act to create turbulence in the flow of the air, which allows the air to mix with the exhaust gas more effectively when flowing through the mixer  74 . 
         [0026]    The separator unit  64  described in  FIG. 4  is incorporated to be used with the low-pressure EGR loop  14 . However,  FIG. 4  shows the separator unit  64  incorporated for use with the high-pressure EGR loop  12 . In this embodiment, fresh air, which has already been compressed by the compressor  20 , flows through the intake pipe  36  and into the aperture  70 . The compressed fresh air then mixes with exhaust gas flowing into the separator unit  64  from the high-pressure EGR loop  12 , and flows into the intake manifold  38 . The high-pressure EGR loop  12  is connected to the square-shaped flange  72 , and feeds exhaust gas into the cover  66 . 
         [0027]    Another embodiment of the present invention is shown in  FIGS. 4 ,  5 , and  7 . In this embodiment, a silencer, generally shown at  86 , is incorporated as a portion of the compressor-cooler module  46 . The silencer  86  is formed as part of the housing  50 . This is in contrast to  FIG. 1 , which shows a turbocharger unit which does not have a silencer  86 . A cross-sectional view of the compressor  20  according to this embodiment is shown in  FIG. 7 . The compressor  20  includes a compressor wheel  88  which is mounted on the shaft  22 . Surrounding the compressor wheel  88  is a volute  90 . In operation, as the compressor wheel  88  rotates, fins  92  compress air flowing into the compressor  20 , and force the air into the volute  90 , where the compressed air is then forced into the intake duct  36 . The silencer  86  includes a series of chambers  94  formed in the housing  50 . The chambers  94  are circular in cross-section, and circumscribe the volute  90 . The chambers  94  are hollow, and have different diameters for reducing noise generated by the compressor  20 . The different diameter chambers  94  will each have a different natural frequency, and thereby offset the various frequencies generated by the compressor  20  as the compressor wheel  88  rotates at various speeds. 
         [0028]    In another embodiment, the chambers  94  are all of the same diameter, and include a filler (not shown). The filler is a rubber or silicone based filler, which absorbs vibration. Other cross-sectional shapes may be used as well, such as square, rectangular, triangular, trapezoidal, or other shapes which would reduce noise in the compressor  20 . 
         [0029]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.