Abstract:
A housing has an housing body. An inner pipe is accommodated in the housing body. The inner pipe defines an inner passage internally. The inner pipe defines an annular passage externally with the housing body. The inner pipe has through holes  68  communicating the inner passage with the annular passage. The housing internally defines an EGR channel communicating with the annular passage. The EGR channel accommodates a diffusing device  60  partitioning the EGR channel.

Description:
TECHNICAL FIELD 
     The present disclosure relates to an EGR device having a diffusing device for an internal combustion engine of a vehicle. The present disclosure further relates to an EGR mixer for the EGR device. 
     BACKGROUND 
     A vehicle may be equipped with an exhaust gas recirculation system (EGR system). The EGR system is to reduce emission contained in exhaust gas discharged from an internal combustion engine. The EGR system may recirculate a part of exhaust gas into fresh air to produce mixture gas containing recirculated exhaust gas and fresh air. Recirculated exhaust gas may be unevenly mixed with fresh air to reduce combustion efficiency of the engine consequently. 
     SUMMARY 
     The present disclosure addresses the above-described concerns. 
     According to an aspect of the preset disclosure, an EGR device comprises a housing defining an inner passage internally and having an EGR inlet. The EGR device further comprises a diffusing device extended from the EGR inlet into the inner passage. The diffusing device is a hollow member having at least one wall, a root end, and a tip end defining an interior. The at least one wall has a plurality of through holes communicating the interior with the inner passage. The tip end is twisted relative to the root end. 
     According to another aspect of the preset disclosure, an EGR mixer is configured to be accommodated in a housing of an EGR device. The housing defines an inner passage internally and having an EGR inlet. The EGR mixer comprises a diffusing device body configured to be extended from the EGR inlet into the inner passage. The diffusing device body is a hollow member having a wall, a root end, and a tip end defining an interior. The wall has a plurality of through holes configured to communicate the interior with the inner passage. The tip end is twisted relative to the root end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: 
         FIG. 1  is a block diagram showing an EGR system for an internal combustion engine of a vehicle; 
         FIG. 2  is a partially sectional view showing an EGR device for the EGR system, according to a first embodiment; 
         FIG. 3  is a sectional view showing the EGR device, the sectional view corresponding to a section taken along the line III-III in  FIG. 2 ; 
         FIG. 4  is a view showing the EGR device viewed from a downstream side; 
         FIG. 5  is a view showing a diffusing device of the EGR device; 
         FIG. 6  is a schematic view showing the diffusing device viewed along the arrow VI in  FIG. 5 ; 
         FIG. 7  is a perspective view showing the EGR device; and 
         FIG. 8  is a partially sectional view showing an EGR device according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
     In the following description, a radial direction is along an arrow represented by “RADIAL” in drawing(s). An axial direction is along an arrow represented by “AXIAL” in drawing(s). A circumferential direction is along an arrow represented by “CIRCUMFERENTIAL” in drawing(s). A vertical direction is along an arrow represented by “VERTICAL” in drawing(s). A horizontal direction is along an arrow represented by “HORIZONTAL” in drawing(s). A width direction is along an arrow represented by “WIDTH” in drawing(s). A length direction is along an arrow represented by “LENGTH” in drawing(s). A flow direction is along an arrow represented by “FLOW” in drawing(s). 
     As follows, a first embodiment of the present disclosure will be described with reference to  FIGS. 1 to 7 . As shown  FIG. 1 , according to the present example, an internal combustion engine  150  is connected with an intake manifold  148  and an exhaust manifold  142 . 
     The engine  150  is combined with an intake and exhaust system. The intake and exhaust system includes an intake valve  110 , an intake passage  112 , an EGR device  10 , a mixture passage  122 , a turbocharger including a compressor  130  and a turbine  160 , a charge air passage  142 , and an intercooler  140 . The intake and exhaust system further includes a combustion gas passage  158 , an exhaust passage  162 , an EGR passage  172 , an EGR cooler  180 , and an EGR valve  90 . 
     The intake passage  112  is equipped with the intake valve  110 . The intake passage  112  is connected with the EGR device  10 . The EGR device  10  is connected with the compressor  130  through the mixture passage  122 . The compressor  130  is connected with the intake manifold  148  through the charge air passage  142 . The charge air passage  142  is equipped with the intercooler  140 . The exhaust manifold  142  is connected with the turbine  160  through the combustion gas passage  158 . The turbine  160  is connected with the exhaust passage  162 . The EGR passage  172  is branched from the exhaust passage  162  and connected with the EGR device  10 . The EGR passage  172  is equipped with the EGR cooler  180  and the EGR valve  90 . 
     The intake passage  112  conducts fresh air from the outside of the vehicle through the intake valve  110  into the EGR device  10 . The intake valve  110  regulates a quantity of fresh air flowing through the intake passage  112  into the EGR device  10 . The EGR device  10  draws fresh air from the intake passage  112  and draws exhaust gas from the exhaust passage  162  through the EGR passage  172 . The EGR device  10  includes an EGR mixer to blend the drawn fresh air with the drawn exhaust gas to produce mixture gas. The mixture passage  122  conducts the mixture gas from the EGR device  10  into the compressor  130 . 
     The compressor  130  is rotatably connected with the turbine  160  via a common axis. The compressor  130  is driven by the turbine  160  to compress the mixture gas. The charge air passage  142  conducts the compressed mixture gas to the intake manifold  148 . The intercooler  140  is a heat exchanger to cool the compressed mixture gas conducted through the charge air passage  142 . 
     The engine  150  draws the cooled mixture gas. The engine  150  forms air-fuel mixture with the drawn mixture gas and injected fuel in each cylinder and burns the air-fuel mixture in the cylinder to drive a piston in the cylinder. The engine  150  emits combustion gas (exhaust gas) through the exhaust manifold  142  into the combustion gas passage  158 . The combustion gas passage  158  conducts the combustion gas into the turbine  160 . The turbine  160  is driven by the exhaust gas to drive the compressor  130  thereby to cause the compressor  130  to compress mixture gas and to press-feed the compressed mixture gas through the charge air passage  142  and the intercooler  140  into the engine  150 . 
     The exhaust passage  162  conducts exhaust gas (combustion gas) from the turbine  160  to the outside of the vehicle. The EGR passage  172  is branched from the exhaust passage  162  at the downstream side of the turbine  160  to recirculate a part of exhaust gas from the exhaust passage  162  into the EGR device  10 . The EGR cooler  180  is a heat exchanger to cool exhaust gas flowing though the EGR passage  172  into the EGR device  10 . The EGR device  10  is located at a connection among the intake passage  112 , the EGR passage  172 , and the mixture passage  122 . The EGR passage  172  is merged with the intake passage  112  in the EGR device  10 . The EGR valve  90  regulates a quantity of EGR gas recirculated through the EGR passage  172  into the EGR mixer. 
     As described above, the EGR system is configured to recirculate a part of exhaust gas from the exhaust passage  162  into the intake passage  112 . The circulated exhaust gas may contain oxygen at a lower percentage compared with oxygen contained in fresh air. Therefore, circulated exhaust gas may dilute mixture of exhaust gas and fresh air thereby to reduce peak temperature of combustion gas when burned in the combustion chamber of the engine  150 . In this way, the EGR system may reduce oxidization of nitrogen, which is caused under high temperature, thereby to reduce nitrogen oxide (NOx) occurring in the combustion chamber. 
     Subsequently, the configuration of the EGR device  10  will be described in detail. As shown in  FIGS. 2 to 4 , the EGR device  10  includes a housing  20  accommodating a diffusing device (diffusing device body)  60 . The diffusing device  60  may function as an EGR mixer. The housing  20  and the diffusing device  60  are formed of a metallic material such as stainless steel and/or an aluminum alloy. 
     The housing  20  includes an air inlet  22 , a housing body  40 , an outlet  26 , and an EGR inlet  28 . The air inlet  22  is connected with the intake passage  112 . The outlet  26  is connected with the mixture passage  122 . The housing body  40  is located between the air inlet  22  and the outlet  26 . In the present example, the air inlet  22 , the housing body  40 , and the EGR inlet  28  are integrally formed with each other, and the outlet  26  is affixed to the housing body  40  by, for example, welding. The housing body  40  has an inner periphery, which defines an inner passage  42  communicated with the intake passage  112  and the mixture passage  122 . 
     The EGR inlet  28  is connected with the EGR passage  172 . The EGR inlet  28  defines an EGR channel  46  internally. The EGR channel  46  extends along the radial direction through the EGR inlet  28 . The EGR channel  46  is directed substantially at 90 degrees relative to a center axis  40 AX of the housing body  40 . The EGR channel  46  is defined with a curvature surface, which is in a funnel shape gradually reducing in cross section toward the inner passage  42 . 
     The diffusing device  60  is inserted through the EGR channel  46  into the inner passage  42 . The diffusing device  60  is affixed to the housing  20  at a root end  62  (one end) by, for example, welding or crimping, such that an opening  62 A of the diffusing device  60  is communicated with the EGR channel  46 . The diffusing device  60  may be in contact with the inner periphery of the housing body  40  at a tip end  66  (other end). In this case, the diffusing device  60  may be supported at the root end  62  and the tip end  66 . 
     The diffusing device  60  is projected from the EGR channel  46  radially inward into the inner passage  42 . The diffusing device  60  is extended into the inner passage  42  and inclined from the EGR inlet  28  toward the downstream side. That is, the diffusing device  60  is inclined relative to a center axis  46  AX of the EGR channel  46 . 
     The diffusing device  60  is a twisted hollow object having multiple through holes  68 . The diffusing device  60  may be formed by, for example, deep-drawing a metallic plate into a bottomed hollow case, forming the through holes  68  on walls, and twisting the bottomed hollow case. Alternatively, the diffusing device  60  may be formed by, for example, forming twisted metallic plates, forming through holes  68  in the twisted plates, and combining the twisted plates by, for example, welding into the twisted hollow object. The diffusing device  60  may be formed by various methods such as injection molding or 3D-printing of a resin or metallic material. 
     The diffusing device  60  has an intermediate portion  64  between the root end  62  and the tip end  66 . The intermediate portion  64  is formed with an upstream wall  52 , lateral walls  54  and  56 , and a downstream wall  58 . The upstream wall  52  is located on the upstream side of the lateral walls  54  and  56  relative to the fresh air flow. The downstream wall  58  is located on the downstream side of the lateral walls  54  and  56  relative to the mixture gas flow. The root end  62 , the intermediate portion  64 , and the tip end  66  define an interior  60 A inside the diffusing device  60 . The interior  60 A of the diffusing device  60  communicates with the EGR channel  46  through the opening  62 A of the root end  62 . The tip end  66  forms the bottomed end of the diffusing device  60 . The tip end  66  has a convex cross section projected toward the inner periphery of the housing body  40 . The tip end  66  may have a curvature along the inner periphery of the housing body  40  to enable the tip end  66  to be fitted to the housing body  40 . The inner periphery of the housing body  40  may be equipped with a bracket and/or a dent to retain the tip end  66 . 
     In  FIG. 4 , the housing body  40  has a cross section having a vertical center  40 V, a horizontal center  40 H, and a center point  40 C, which is an intersection between the vertical center  40 V and the horizontal center  40 H. The downstream wall  58  has through holes  68  arranged in one row along an imaginary line  58 B. The imaginary line  58 B may be substantially in parallel with sidelines  58 A of the downstream wall  58 . The imaginary line  58 B may be a centerline of the downstream wall  58  and may extend along the vertical center  40 V at the root end  62  to be veered from the vertical center  40 V toward the tip end  66 . 
       FIG. 5  is a side view showing the diffusing device  60 . In  FIG. 5 , the upstream wall  52  and the lateral walls  54  and  56  form sidelines  52 A therebetween. The lateral walls  54  and  56  and the downstream wall  58  form the sidelines  58 A therebetween. Each of the sidelines  52 A and  58 A is defined by, for example, a combination of two or more arcs. In the present example, the sideline  52 A includes an upper sideline  52 A 1  and a lower sideline  52 A 2 , and the sideline  58 A includes an upper sideline  58 A 1  and a lower sideline  58 A 2 . Each of the upper sidelines  52 A 1  and  58 A 1  is in an arc shape convex downward (in one direction) in the drawing. Each of the lower sidelines  52 A 2  and  58 A 2  is in an arc shape convex upward (in another direction) in the drawing. The diffusing device  60  having the upper sidelines  52 A 1  and  58 A 1  and the lower sidelines  52 A 2  and  58 A 2  may form the interior  60 A, which is bent twice from the root end  62  toward the tip end  66  while being twisted. 
     The lateral wall  54  has the through holes  68  arranged in two rows along imaginary lines  54 A and  54 B respectively. The lateral wall  56  has the through holes  68  arranged in two rows along imaginary lines (not shown) respectively, similarly to the lateral wall  54 . That is, the through holes  68  are arranged substantially along the length direction of the diffusing device  60 . Each of the imaginary lines  54 A and  54 B may be in parallel with the sidelines  52 A and  58 A. The through holes  68  adjacent to each other in the width direction are arranged alternately. That is, the through holes  68  are arranged in a zigzag form from the root end  62  toward the tip end  66 . 
       FIG. 6  is a schematic top view showing the diffusing device  60 . In  FIG. 6 , the tip end  66  is hidden by the lateral walls  54  and  56  and the downstream wall  58  and is shown by dotted lines. In  FIG. 6 , through holes  68  are omitted. In the present example, the shape of the tip end  66  is substantially identical to the shape of the root end  62 . The upstream wall  52  has a convex cross section projected toward the upstream side of fresh air. Each of the downstream wall  58  and the lateral walls  54  and  56  substantially has a flat cross section. In  FIG. 6 , the root end  62  has a centerline (root center)  62 C shown by a chain line, and the tip end  66  has a centerline (tip center)  66 C shown by a chain line. The tip center  66 C is inclined relative to the root center  62 C by a twisted angle A. The twisted angle A may be, for example, about 30 degrees. The twisted angle A may be in a range between 0 degree and 45 degree or may be in a range between 15 degree and 40 degree. The twisted angle A may be determined in consideration of a mixing effect of fresh air and EGR gas and blockage of the inner passage  42  caused by the lateral wall  54  faced to the upstream side of the mixture gas flow. 
     In  FIG. 7 , the EGR inlet  28  may have screw holes  28 A screwed with the EGR passage  172 . The present configuration enables to flow EGR gas from the EGR passage  172  ( FIG. 1 ) to pass through the EGR channel  46  into the interior  60 A of the diffusing device  60 . The diffusing device  60  enables EGR gas to further flow from the interior  60 A through the through holes  68  into the inner passage  42 . The through holes  68  extend through the lateral walls  54  and  56  and the downstream wall  58  ( FIG. 5 ). The present configuration enables to flow EGR gas from the interior  60 A of the diffusing device  60  through the through holes  68  into the inner passage  42 . After passing through the through holes  68 , EGR gas may be expanded and diffused into fresh air passing through the inner passage  42 . Thus, the present configuration may enable EGR gas to be homogeneously and evenly blended with fresh air in the inner passage  42  to produce uniform mixture gas. 
     The diffusing device  60  has the twisted configuration to form the interior  60 A twisted from the upstream to the downstream in the flow direction. The present configuration may cause turbulence in the EGR gas flow through the interior  60 A of the diffusing device  60  and through holes  68 . In addition, the lateral walls  54  and  56  being twisted may deflect fresh air to cause turbulence in the fresh air. 
     In the present example, the upstream wall  52  does not have a through hole. Therefore, the upstream wall  52  may baffle EGR gas flow incoming from the opening  62 A, thereby to reflect the EGR gas flow toward the lateral walls  54  and  56  and the downstream wall  58 . In this way, the diffusing device  60  may rectify the EGR gas flow toward the downstream side lengthwise in the diffusing device  60 . Thus, the diffusing device  60  may rectify the EGR gas flow and to diffuse EGR gas through the through holes  68 . The diffusing device  60  may enable to lead EGR gas beyond the center of the inner passage  42  to the radially opposite side of the EGR channel  46 . That is, the diffusing device  60  may enable EGR gas to access the opposite side of the diffusing device  60  from the EGR channel  46 . 
     Second Embodiment 
     As shown in  FIG. 8 , according to the present second embodiment, a diffusing device  260  is shorter than the diffusing device  60  in the first embodiment. The housing  20  is substantially identical to that of the first embodiment. 
     The diffusing device  260  according to the present second embodiment extends to the center of the inner passage  42 . The diffusing device  260  has a tip end  266  distant from the inner periphery of the housing body  40 . The diffusing device  260  is cantilevered at a root end  262 . The tip end  266  is located around the center axis  40 AX of the housing body  40 . 
     Similarly to the first embodiment, the diffusing device  260  has an intermediate portion  264  between the root end  262  and the tip end  266 , and the intermediate portion  264  is formed with an upstream wall  252 , lateral walls  254  and  256 , and a downstream wall  258 . The diffusing device  260  has a twisted configuration. 
     In the present example, the diffusing device  260  has through holes  68  selectively around the tip end  266 . More specifically, the through holes  68  form an array centered around the center axis  40 AX of the housing body  40 . That is, the diffusing device  260  does not have the through holes  68  at the side of the root end  262 . According to the present embodiment, the through holes  68  are selectively (mainly) formed around the tip end  66  located close to the center of the inner passage  42 . The present configuration may concentrate the EGR gas flow around the center of the inner passage  42  to diffuse EGR gas radially from the center of the inner passage  42 . 
     The through holes  68  are located selectively on the downstream side in the lateral walls  254  and  256 . For example, in the lateral walls  254  and  256 , the number of the through holes  68  on the downstream side may be larger than the number of the through holes  68  on the upstream side. For example, in the lateral walls  254  and  256 , the through holes  68  may be located only on the downstream side relative to a center of the diffusing device  260  in the width direction. 
     Other Embodiment 
     The shape of the diffusing device is not limited to the above examples, and may be in various forms. The upper sideline and the lower sideline may not be arc lines and may be in various shapes. 
     The tip end may be different in shape from the root end. The tip end may be reduced in cross section relative to the root end. 
     Various combinations of the features such as the arrangement of the through holes and the twisted angle according to the above-described embodiments may be arbitrary employed. 
     The through holes may employ various forms. For example, the through holes may employ various numbers, various sizes, various arrangements, and/or various shapes. For example, the through holes may employ various shapes such as an oval shape, a polygonal shape, or a star shape. Various combinations of the through holes of the above-described embodiments may be arbitrary employed. The through holes may be unevenly arranged. 
     It should be appreciated that while the processes of the embodiments of the present disclosure have been described herein as including a specific sequence of steps, further alternative embodiments including various other sequences of these steps and/or additional steps not disclosed herein are intended to be within the steps of the present disclosure. 
     While the present disclosure has been described with reference to preferred embodiments thereof, it is to be understood that the disclosure is not limited to the preferred embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.