Patent Publication Number: US-2023145865-A1

Title: Engine

Description:
TECHNICAL FIELD 
     The present invention relates to an engine. 
     BACKGROUND ART 
     A conventional engines is known to be equipped with an engine body, a turbocharger connected to the engine body, an after-treatment unit that purifies exhaust gas discharged from the turbocharger, and an exhaust communication pipe connecting the turbocharger with the after-treatment unit (see, for example, Patent Document 1). Patent Document 1 describes a harvester equipped with an engine body, a turbocharger, an exhaust gas purifier that purifies exhaust gas discharged from the turbocharger, and an exhaust pipe connecting the turbocharger with the exhaust gas purifier. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-000002 
     SUMMARY OF INVENTION 
     Technical Problem 
     By the way, the turbocharger described in Patent Document 1 has an exhaust pipe connection portion that is connected to an exhaust pipe. Typically, a gas flow path at the exhaust pipe connection portion is circular in shape. In other words, the exhaust pipe connection portion has an inner peripheral face having a cross-section in a circular shape. 
     However, the exhaust pipe connection portion, as the case may be, has the inner peripheral face having an abnormally shaped cross-section that is different from the circular shape. In this case, forming the gas flow path of the exhaust pipe in the abnormal shape increases a pressure loss seen when the exhaust gas passes through the gas flow path of the exhaust pipe. 
     In view of the above issue, the present invention has been made; therefore, it is an object of the present invention to provide an engine capable of suppressing a larger pressure loss in an exhaust communication pipe connecting a turbocharger with an after-treatment unit. 
     Solution to Problem 
     An engine according to an aspect of the present invention includes: an engine body, a turbocharger, an exhaust gas purifier, an exhaust communication pipe. The turbocharger is connected to the engine body. The exhaust gas purifier purifies exhaust gas discharged from the turbocharger. The exhaust communication pipe connects the turbocharger with the exhaust gas purifier. The exhaust communication pipe includes: a first connection member that is connected to the turbocharger, and a second connection member that connects the first connection member with the exhaust gas purifier. A downstream end portion of the first connection member has an inner peripheral face having a cross-section of a circular shape. An upstream end portion of the first connection member has an inner peripheral face having a cross-section of an abnormal-shape that is different from the inner peripheral face of the downstream end portion. 
     Advantageous Effects of Invention 
     The present invention can provide an engine capable of suppressing a larger pressure loss in an exhaust communication pipe connecting a turbocharger with an after-treatment unit. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view showing, from the front, a configuration of an engine of one embodiment of the present invention. 
         FIG.  2    is a perspective view showing, from the rear, the configuration of the engine of the one embodiment of the present invention. 
         FIG.  3    is a perspective view showing configurations of a turbocharger, exhaust communication pipe, and exhaust gas purifier of the engine of the one embodiment of the present invention. 
         FIG.  4    is a perspective view showing the configuration of the turbocharger of the engine according to the one embodiment of the present invention. 
         FIG.  5    is a side view showing the configuration of the exhaust communication pipe of the engine of the one embodiment of the present invention. 
         FIG.  6    shows, from the front, a configuration of a first connection member of the engine of the one embodiment of the present invention. 
         FIG.  7    is a cross-sectional view along the line VII-VII in  FIG.  5   . 
         FIG.  8    is a cross-sectional view along the line VIII-VIII in  FIG.  6   . 
         FIG.  9    shows, from the rear, the configurations of the turbocharger and exhaust communication pipe of the engine of the one embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following is a description of an embodiment of an engine according to the present invention, referring to the drawings. Note that, in the drawings, the same reference signs are used for the same or equivalent components, and repeated descriptions are omitted. In the present specification, for ease of understanding, a first direction X, a second direction Y, and a third direction Z, which intersect each other, are used as appropriate. The first and second directions X and Y are substantially parallel to the horizontal direction, and the third direction Z is substantially parallel to the vertical direction. In the present specification, the first direction X, second direction Y, and third direction Z are orthogonal to each other, but may not be orthogonal. Hereinafter, one side X 1  in the first direction X indicates the left side of the engine, and another side X 2  in the first direction X indicates the right side face of the engine. Further, one side Y 1  in the second direction Y indicates the front side of the engine, and another side Y 2  in the second direction Y indicates the rear side of the engine. Further, one side Z 1  in the third direction Z indicates the upper side, and another side Z 2  in the third direction Z indicates the lower side. However, the left-right, front-rear, and up-down directions are defined only for convenience of description, and do not limit the orientation of the engine in use and assembly. 
     Referring to  FIGS.  1  through  9   , an engine  1  according to one embodiment of the present invention is described.  FIG.  1    is a perspective view showing, from the front, a configuration of the engine  1  of the one embodiment of the present invention.  FIG.  2    is a perspective view showing, from the rear, the configuration of the engine  1  of the one embodiment of the present invention. The engine  1  is installed on a work machine such as agricultural machine, construction machine, and civil engineering machine, for example. 
     As shown in  FIGS.  1  and  2   , the engine  1  has an engine body  2 , an oil pan  6 , a cooling fan  7 , a crankshaft  10 . The engine body  2  includes a left side portion  2   a.  The left side portion  2   a  is an example of the “first side portion” of the present invention. The engine body  2  includes a combustion chamber (not shown), a cylinder block  3 , a cylinder head  4 , and a head cover  5 . 
     The crankshaft  10  is placed inside the cylinder block  3 . The crankshaft  10  is an output shaft. The crankshaft  10  is placed along the front-rear direction. Both end portions of the crankshaft  10  protrude externally from the cylinder block  3 . 
     The cylinder block  3  includes a right side face (not shown), a left side face  3   a,  and a mounting portion  3   b.  The mounting portions  3   b  are placed on the front and rear portions on each of the right and left side faces  3   a  of the cylinder block  3 . With a bolt, the mounting portion  3   b  is fixed to a chassis (not shown) of a work machine through a vibration-proof member such as rubber. 
     The cylinder head  4  is placed above the cylinder block  3 . The engine  1  is further equipped with an intake manifold (not shown) and an exhaust manifold  11 . The intake manifold is placed on the right side face (not shown) of the cylinder head  4 . The intake manifold supplies air to each cylinder (not shown) of the engine body  2 . The exhaust manifold  11  is placed on a left side face  4   a  (see  FIG.  2   ) of the cylinder head  4 . The exhaust manifold  11  is connected to the cylinder head  4 . Exhaust gas is discharged from cylinder head  4  to the exhaust manifold  11 . 
     The head cover  5  is placed above the cylinder head  4 , covering the top of the cylinder head  4 . 
     The oil pan  6  is placed below the engine body  2 . That is, the oil pan  6  is placed below the cylinder block  3 . The oil pan  6  stores a lubricating oil. After being supplied to each part of the engine  1 , the lubricating oil in the oil pan  6  returns to the oil pan  6 . 
     The cooling fan  7  is placed in front of the engine body  2 . The engine  1  is further equipped with a belt  12  placed in front of the engine body  2 . To the cooling fan  7 , a rotational drive power is transmitted from the front end portion of the crankshaft  10  via the belt  12 . 
     The engine  1  is further equipped with a flywheel  13  and a flywheel housing  13   a.  The flywheel housing  13   a  is placed at the rear of the engine body  2 . The flywheel housing  13   a  houses the flywheel  13 . The flywheel  13  is mounted to the rear end portion of the crankshaft  10 . The rotational drive power of the crankshaft  10  is transmitted to an actuator of the work machine via the flywheel  13 . 
     Referring to  FIGS.  1  and  2   , the configuration around the engine body  2  will be described. The engine  1  is further equipped with a turbocharger  20 , an intake pipe  23 , a turbocharger pipe (not shown), and an exhaust communication pipe  25 . The turbocharger  20  increases the pressure of the air supplied to the engine body  2 . The turbocharger  20  is placed on the left side of the head cover  5 . In other words, the turbocharger  20  is placed on the left side portion  2   a  of the engine body  2 . The turbocharger  20  includes a compressor case  21  and a turbine case  22 . The compressor case  21  incorporates a blower wheel (not shown). The turbine case  22  houses a turbine wheel (not shown). 
     The intake pipe  23  is connected to an intake air inlet of compressor case  21 . The turbocharger pipe is connected to an intake air outlet of the compressor case  21 . 
     In the left side face  4   a  of the cylinder head  4 , the exhaust manifold  11  extends from the front portion to the rear. The exhaust manifold  11  is connected to an exhaust inlet of the turbine case  22 . The exhaust communication pipe  25  is connected to an exhaust outlet of the turbine case  22 . The exhaust communication pipe  25  is connected to a tail pipe (not shown) via an exhaust gas purifier  40  described below. Accordingly, the exhaust gas discharged from each cylinder (not shown) of the engine body  2  to the exhaust manifold  11  is discharged via the turbocharger  20 &#39;s turbine case  22 , the exhaust communication pipe  25 , the exhaust gas purifier  40 , and the tail pipe, etc. to the outside. The detailed configuration around the exhaust communication pipe  25  is to be described below. 
     The engine  1  is further equipped with the exhaust gas purifier  40  and a support member  50 . The exhaust gas purifier  40  is an example of an “after-treatment unit” of the present invention. The exhaust gas purifier  40  collects a particulate matter and the like in the exhaust gas. The exhaust gas purifier  40  is fixed to the engine body  2 . In the present embodiment, the exhaust gas purifier  40  is fixed to the engine body  2  via the support member  50 . The exhaust gas purifier  40  is placed above the engine body  2 . Specifically, a pair of support members  50  is provided, for example. The support members  50  are placed at the front and rear portions of the engine  1 , respectively. With a screw, the support member  50  is fixed to the cylinder head  4 . The support member  50  supports the exhaust gas purifier  40 . 
     In the present embodiment, the exhaust gas purifier  40  is fixed to the engine body  2 , as described above. Thus, with the exhaust gas purifier  40  fixed to the engine body  2 , the engine  1  can be fixed to the chassis (not shown) of the work machine. Thus, compared with the case of fixing the engine body  2  and the exhaust gas purifier  40  to the chassis (not shown) of the work machine in a separated manner, for example, the installation work of the engine  1  can be simplified. 
     Removing NOx, CO, HC, and a particulate matter, for example, included in the exhaust gas, the exhaust gas purifier  40  purifies the exhaust gas. The exhaust gas purifier  40  has a DPF (Diesel Particulate Filter) unit  41 , an SCR (Selective Catalytic Reduction) unit  42 , and a connecting pipe  43 . The DPF unit  41  has, for example, a substantially cylindrical case  41   a,  and an oxidation catalyst and a filter which are housed in the case  41   a.  The oxidation catalyst and the filter reduce the NOx, HC, CO, and the particulate matter which are included in the exhaust gas. 
     The SCR unit  42  has, for example, a substantially cylindrical case  42   a,  and an SCR catalyst and an oxidation catalyst which are housed in the case  42   a.  The SCR catalyst and the oxidation catalyst reduce NOx included in the exhaust gas. 
     The DPF unit  41  is placed on the left side above the engine body  2 , and the SCR unit  42  is placed on the right side above the engine body  2 . The connecting pipe  43  connects the DPF unit  41  with the SCR unit  42 . In the present embodiment, the connecting pipe  43  connects the rear portion of the DPF unit  41  with the front portion of the SCR unit  42 . The exhaust gas flows from the front portion to rear portion of the DPF unit  41 , then flows through the connecting pipe  43  into the SCR unit  42 , and flows from the front portion toward the rear portion of the SCR unit  42 . Then, the exhaust gas is discharged to the outside through an exhaust pipe (not shown) connected to the SCR unit  42 . 
     The engine  1  is further equipped with an EGR (Exhaust Gas Recirculation) cooler  30  and a cooling water outlet pipe  31 . The exhaust manifold  11  extends to the rear end portion of the left side face  4   a  of the cylinder head  4 . A rear end portion  11   a  of the exhaust manifold  11  is connected to the EGR cooler  30 . The exhaust gas&#39;s part in the exhaust manifold  11  is sent to the EGR cooler  30 . The cooling water outlet pipe  31  is connected to the left side face  3   a  of the cylinder block  3 . To the cooling water outlet pipe  31 , the cooling water that has cooled the cylinder block  3  is discharged. The cooling water outlet pipe  31  is connected to the EGR cooler  30 . The exhaust gas in the EGR cooler  30  is cooled by the cooling water passing through in the cooling water outlet pipe  31 . 
     Next, referring to  FIGS.  3  to  9   , the configuration around the exhaust communication pipe  25  of the engine  1  of the present embodiment will be described. Referring to  FIG.  3    and  FIG.  4   , the configuration of the turbocharger  20  will be described.  FIG.  3    is a perspective view showing configurations of the turbocharger  20 , exhaust communication pipe  25 , and exhaust gas purifier  40  of the engine  1  of the present embodiment.  FIG.  4    is a perspective view showing the configuration of the turbocharger  20  of the engine  1  according to the present embodiment. 
     As shown in  FIGS.  3  and  4   , the turbocharger  20  has a communication pipe connection portion  221  that is connected to the exhaust communication pipe  25 . The communication pipe connection portion  221  is placed at the turbine case  22 . As shown in  FIG.  4   , the turbocharger  20  further has an opening portion  222 , a waste gate port (also referred to as a bypass path)  223 , and a waste gate valve  224 . The opening portion  222  is placed inside the communication pipe connection portion  221 . The opening portion  222  is a discharge port that allows exhaust gas to be discharged from inside the turbine case  22  to the exhaust communication pipe  25 . The opening portion  222  is circular in shape. In the present embodiment, “circular shape” means a substantially true circular shape. 
     The waste gate port  223  is placed adjacent to the opening portion  222 . In the present embodiment, the opening portion  222  and waste gate port  223  are formed in a same wall portion  222   a.  The waste gate port  223  is opened and closed by the waste gate valve  224 . With an actuating unit  26  having a link mechanism  26   a,  the waste gate valve  224  opens and closes the waste gate port  223 . The waste gate valve  224  opens the waste gate port  223 , thereby to prevent the gas pressure in the turbine case  22  from becoming too high. 
     The communication pipe connection portion  221  has a side wall portion  225  to surround the waste gate port  223  and waste gate valve  224 . The side wall portion  225  has an inner peripheral face  225   a.  The inner peripheral face  225   a  surrounds the opening portion  222 , the waste gate port  223 , and the waste gate valve  224 . Therefore, the inner peripheral face  225   a  has a shape that is different from the circular shape. Viewed from the front-rear direction, the inner peripheral face  225   a  may be a substantially oval or a substantially rectangular shape, for example, but in the present embodiment, has a shape with no symmetrical axis. 
     Next, the configuration of the exhaust communication pipe  25  is described referring to  FIG.  3    and  FIGS.  5  to  8   .  FIG.  5    is a side view showing the configuration of the exhaust communication pipe  25  of the engine  1  of the present embodiment.  FIG.  6    shows, from the front (one side Y 1  in the second direction Y), the configuration of a first connection member  60  of the engine  1  of the present embodiment. 
     As shown in  FIGS.  3  and  5   , the exhaust communication pipe  25  has the first connection member  60  and a second connection member  70 . The first connection member  60  is connected to the turbocharger  20 . The second connection member  70  connects the first connection member  60  with the exhaust gas purifier  40 . In the present embodiment, the second connection member  70  has a bellows portion  71  and a downstream connection portion  72 . The bellows portion  71  and the downstream connection portion  72  are each formed of metal, such as stainless steel. The exhaust communication pipe  25  further has metal connecting bands (also referred to as V-clamps)  75   a,    75   b  and  75   c  (see  FIG.  3   ). The connecting band  75   a  connects the first connection member  60  with the bellows portion  71 . The connecting band  75   b  connects the bellows portion  71  with the downstream connection portion  72 . The connecting band  75   c  connects the downstream connection portion  72  with the DPF unit  41  of the exhaust gas purifier  40 . 
     The first connection member  60  is formed by casting, for example. The first connection member  60  has an upstream end portion  61  connected to the turbocharger  20  and a downstream end portion  62  connected to the second connection member  70 . 
     As shown in  FIG.  6   , the downstream end portion  62  has an inner peripheral face  62   a  with a circular cross-section. Meanwhile, the upstream end portion  61  has an abnormal shaped inner peripheral face different from that of the inner peripheral face  62   a  of the downstream end portion  62   61   a.  Viewed from the front and rear directions, the inner peripheral face  61   a  is substantially the same in shape as the inner peripheral face  225   a  (see  FIG.  4   ) of the communication pipe connection portion  221  of the turbocharger  20 . Thus, the inner peripheral face of a part of the first connection member  60  has an abnormal shape that is different from a circular shape, while for the inner peripheral face of the second connection member  70  may have a circular shape. Therefore, compared with the case where, for example, the inner peripheral face of the second connection member  70  has the abnormal shape, the pressure loss seen when the exhaust gas passes through the interior of the exhaust communication pipe  25  can be suppressed. The flow path cross-sectional area of the upstream end portion  61  (the area of the region surrounded by the inner peripheral face  61   a ) is larger than the flow path cross-sectional area (the area of the region surrounded by the inner peripheral face  62   a ) of the downstream end portion  62 . 
       FIG.  7    is a cross-sectional view along the line VII-VII in  FIG.  5   . As shown in  FIG.  7   , the first connection member  60  has a right side portion  601  opposing the left side portion  2   a  of the engine body  2 . In the present embodiment, the outer face of the right side portion  601  has a flat portion  601   a  along the left side portion  2   a  of the engine body  2 . Therefore, the first connection member  60  can be placed closer to the engine body  2 , making it possible to prevent the entire engine  1  from becoming larger in the width direction (first direction X). The right side portion  601  is one example of the “second side portion” of the present invention. 
     Further, the first connection member  60  has a left side portion  602  opposing the right side portion  601 . In the present embodiment, the outer face of the left side portion  602  has a flat portion  602   a  along a flat portion  601   a  of the right side portion  601 . In other words, the outer face of the left side portion  602  has the flat portion  602   a  along the left side portion  2   a  of the engine body  2 . Thus, the entire engine  1  can be more suppressed from becoming larger in the width direction (first direction X). 
     In the present embodiment, the right side portion  601  and the left side portion  602  are formed to have a substantially constant thickness. Then, the right side portion  601  and the left side portion  602  include portions  601   b  and  602   b  along the left side portion  2   a  of the engine body  2 , respectively. 
     As shown in  FIGS.  5  to  7   , in the present embodiment, the first connection member  60  has a curved portion  63  that is placed between the upstream end portion  61  and the downstream end portion  62 . The curved portion  63  has an inner portion  631  positioned inside a bend and an outer portion  632  positioned outside the bend. As shown in  FIG.  7   , an inner face  631   a  of the inner portion  631  has a cross-section with a linear portion  631   b.  Therefore, unlike the case where the inner face  631   a  of the inner portion  631  is formed to protrude inside the bend, for example, as indicated by the two-chained line in  FIG.  7   , the curvature radius seen when the exhaust gas passes through the curved portion  63  can be prevented from becoming too small. Thus, the exhaust gas flows more smoothly. 
     An outer face  632   a  of the outer portion  632  has a cross-section with a linear portion  632   b.  Thus, unlike the case where the outer face  632   a  of the outer portion  632  is formed to protrude outside the bend, for example, the length of the first connection member  60  in the second direction Y can be prevented from becoming longer. 
     In the present embodiment, the inner portion  631  and the outer portion  632  are formed to have a substantially constant thickness. The curved portion  63  has a substantially rectangular cross-section. 
       FIG.  8    shows a cross-sectional view along the line VIII-VIII in  FIG.  6   . As shown in  FIGS.  5  and  8   , the upstream end portion  61  of the first connection member  60  is open in one direction (one side Y 1  in the second direction Y). Further, the downstream end portion  62  opens in one direction (one side Y 1  in the second direction Y). That is, the first connection member  60  is approximately 180° curved. Thus, when the first connection member  60  expands due to the heat of the exhaust gas when the engine  1  is driven, the upstream portion (here the upper portion) of the first connection member  60  extends rearward (the other side Y 2  in the second direction Y) relative to the turbocharger  20 , while the downstream portion (here the lower portion) of the first connection member  60  extends forward (one side Y 1  in the second direction Y) relative to the curved portion  63 . Therefore, an end face  62   b  of the downstream end portion  62  is suppressed from being displaced in the front-rear direction (second direction Y) relative to an end face  61   b  of the upstream end portion  61 . As a result, the position of the end face  62   b  of the downstream end portion  62  can be suppressed from moving in the front-rear direction (second direction Y). 
     In addition, the end face  61   b  of the upstream end portion  61  and the end face  62   b  of the downstream end portion  62  are placed on substantially a same plane S 60 . Therefore, when manufacturing the first connection member  60 , the end faces  61   b  and  62   b  can be machined at the same time. Further, positional accuracy (manufacturing error) of the end face  62   b  relative to the end face  61   b  can be improved. Therefore, when assembling the engine  1 , the positional accuracy of the end face  62   b  relative to the exhaust gas purifier  40  can be improved, thus making it possible to prevent the second connection member  70  from becoming difficult to mount to the exhaust gas purifier  40 . This means that the engine  1  is easier to assemble. 
     In addition, placing, on the same plane S 60 , the end face  61   b  of the upstream end portion  61  and the end face  62   b  of the downstream end portion  62 , can more suppress the position of the end face  62   b  of the downstream end portion  62  from moving in the front-rear direction (in the second direction Y), even when the first connection member  60  expands due to the heat of the exhaust gas at the driving of the engine  1 . Therefore, a force applied to the second connection member  70  can be suppressed. 
     Further, in the present embodiment, as described above, the second connection member  70  has the bellows portion  71  connected to the first connection member  60 . The bellows portion  71  is a pipe having a bellows shape. Therefore, the exhaust communication pipe  25 &#39;s thermal expansion due to hot exhaust gas can be absorbed by the bellows portion  71 , thus making it possible to easily prevent the exhaust communication pipe  25  from being damaged. 
       FIG.  9    shows, from the rear (the other side Y 2  in the second direction Y), the configurations of the turbocharger  20  and exhaust communication pipe  25  of the engine  1  of the present embodiment. As shown in  FIGS.  3  and  9   , the second connection member  70  is placed above or below (here below) the turbocharger  20 . Thus, compared with the case where the second connection member  70  is placed on the side (one side X 1  in the first direction X) of the turbocharger  20 , for example, the second connection member  70  can be placed closer to the engine body  2 . Thus, the entire engine  1  can be prevented from becoming larger in the width direction (first direction X). In the present embodiment, the entire bellows portion  71  of the second connection member  70  and a part of the downstream connection portion  72  are placed below the turbocharger  20 . 
     The embodiment of the present disclosure has been described hereinabove referring to the drawings. However, the present invention is not limited to the embodiment described above, and can be embodied in various modes within the range not departing from the gist of the present invention. Further, combining a plurality of components disclosed in the above embodiment can form various inventions. For example, some of the components may be removed from all the components shown in the embodiment. In addition, any component across different embodiments may be combined as appropriate. The drawings are schematically shown with each component as a main subject as to facilitate understanding, and the thickness, length, number, space, and the like of each of the shown components may be different from actual ones due to convenience of making the drawings. Further, the material, shape, size, and the like of each of the components shown in the above embodiment are merely examples and are not particularly limited, and various modifications may be made without substantially departing from the effect of the present invention. 
     For example, the above embodiment shows the example that the upstream end portion  61  of the first connection member  60  opens in the one direction and the downstream end portion  62  opens in the one direction. That is, the example has been shown in which the first connection member  60  is approximately 180° curved, but the present invention is not limited to this. The first connection member  60  may be curved only less than 180° or may be curved more than 180°. 
     In the above embodiment, the end face  61   b  of the upstream end portion  61  of the first connection member  60  and the end face  62   b  of the downstream end portion  62  of the first connection member  60  are placed on substantially the same plane S 60 , but the present invention is not limited to this. The end face  61   b  of the upstream end portion  61  of the first connection member  60  and the end face  62   b  of the downstream end portion  62  of the first connection member  60  may not be placed on the same plane S 60 . 
     In the above embodiment, the example has been shown in which the second connection member  70  includes two pipes (bellows portion  71  and downstream connection portion  72 ), but the present invention is not limited to this. The second connection member  70  may include one pipe, or three or more pipes. 
     In the above embodiment, the pipes (first connection member  60 , bellows portion  71 , and downstream connection portion part  72 ) included in the exhaust communication pipe  25  are connected using the connecting bands  75   a  and  75   b,  but the present invention is not limited to this. For example, the pipes may be connected by being welded together. 
     In the above embodiment, the example of fixing the exhaust gas purifier  40  to the engine body  2  has been shown, but the present invention is not limited to this. The engine body  2  and the exhaust gas purifier  40  may be separately fixed to the chassis. 
     INDUSTRIAL APPLICABILITY 
     The present invention is useful in the field of an engine. 
     REFERENCE SIGNS LIST 
       1 : engine 
       2 : engine body 
       2   a:  left side portion (first side portion) 
       20 : turbocharger 
       25 : exhaust communication pipe 
       40 : exhaust gas purifier (after-treatment unit) 
       60 : first connection member 
       61 : upstream end portion 
       61   a:  inner peripheral face 
       61   b:  end face 
       62 : downstream end portion 
       62   a:  inner peripheral face 
       62   b:  end face 
       63 : curved portion 
       70 : second connection member 
       71 : bellows portion 
       221 : communication pipe connection portion 
       222 : opening portion 
       223 : waste gate port 
       224 : waste gate valve 
       225   a:  inner peripheral face 
       601 : right side portion (second side portion) 
       601   a:  flat portion 
       631 : inner side portion 
       631   a:  inner face 
       631   b:  linear portion 
     S 60 : same plane