Patent Publication Number: US-8991162-B2

Title: Engine with exhaust gas treatment apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 12/986,290, filed Jan. 7, 2011, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an engine having an exhaust gas treatment apparatus attached thereto and, more particularly, to an engine having an exhaust gas treatment apparatus attached thereto, which is capable of preventing an exhaust pipe from being damaged by a vibration of the main body of the engine. 
     A conventional engine having an exhaust gas treatment apparatus attached thereto includes an engine in which an exhaust gas treatment apparatus is supported by the main body of the engine and the main body of the engine is configured to communicate with the exhaust gas treatment apparatus through an exhaust pipe (for example, refer to Patent Document 1). 
     According to this kind of engine having an exhaust gas treatment apparatus attached thereto, the exhaust gas treatment apparatus is integrated with the main body of the engine. There is an advantage in that the exhaust gas treatment apparatus is easily installed in a machine on which the engine is mounted. 
     However, the prior art is problematic in that the exhaust gas treatment apparatus is supported by the main body of the engine only in the exhaust pipe. 
     Japanese Patent Laid-open Publication No. 2009-12609 (refer to FIGS. 2 and 4) 
     The exhaust pipe is likely to be damaged by a vibration of the main body of the engine. 
     The exhaust gas treatment apparatus is supported by the main body of the engine only in the exhaust pipe. Thus, if the exhaust gas treatment apparatus is shaken by a vibration of the main body of the engine, a heavy load is applied to the exhaust pipe, and thus the exhaust pipe is likely to be damaged. 
     In particular, in case where a Diesel Particulate Filter (DPF) or a catalyst of heavy weight is accommodated in the exhaust gas treatment apparatus, the problem becomes serious. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an engine having an exhaust gas treatment apparatus attached thereto, which is capable of preventing an exhaust pipe from being damaged by a vibration of the main body of the engine. 
     As illustrated in  FIG. 9 , in an engine having an exhaust gas treatment apparatus attached thereto, an exhaust gas treatment apparatus  4  is supported by an engine body  1 , and the engine body  1  and the exhaust gas treatment apparatus  4  are configured to communicate with each other through an exhaust pipe  13 , 
     as illustrated in  FIG. 3 , a casing of the exhaust gas treatment apparatus  4  consists of a plurality of casing units  5 ,  6 , and  7  separable from each other, connection flanges  8 ,  9 ,  10 , and  11  are disposed in respective end portions of the casing units  5 ,  6 , and  7 , and the casing units  5 ,  6 , and  7  are coupled together by a connection of the connection flanges  8 ,  9 ,  10 , and  11 , and 
     as illustrated in  FIGS. 8 ,  14 ,  21 , and  28 , the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the connection flanges  8 ,  9 ,  10 , and  11 . 
     As illustrated in  FIGS. 8 ,  14 ,  21 , and  28 , the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the connection flanges  8 ,  9 ,  10 , and  11 . Accordingly, the exhaust gas treatment apparatus  4  is robustly supported by the engine body  1  through the connection flanges  8 ,  9 ,  10 , and  11  having higher rigidity. Although the exhaust gas treatment apparatus  4  is shaken by a vibration of the engine body  1 , load applied to the exhaust pipe  13  can be reduced and the exhaust pipe  13  can be prevented from being damaged by a vibration of the engine body  1 . 
     The connection flanges of the exhaust gas treatment apparatus can be prevented from being damaged by a vibration of the engine body. 
     As illustrated in  FIGS. 8 ,  14 ,  21 , and  28 , the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the plurality of connection flanges  8 ,  9 ,  10 , and  11  which are spaced apart from each other. Although the exhaust gas treatment apparatus  4  is shaken by a vibration of the engine body  1 , load applied to each of the connection flanges  8 ,  9 ,  10 , and  11  is distributed. Accordingly, the connection flanges  8 ,  9 ,  10 , and  11  of the exhaust gas treatment apparatus  4  can be prevented from being damaged by a vibration of the engine body. 
     A task of installing the support bracket in the support stays can be easily performed. 
     As illustrated in  FIGS. 8 ,  14 , and  21 , the load of the exhaust gas treatment apparatus  4  is supported by the support stays  2  and  3  through the support bracket  12 , and the support bracket  12  is installed in the support stays  2  and  3  using bracket installation fastening members  14 . Accordingly, the support bracket  12  can be easily installed in the support stays  2  and  3  without the need to support the weight of the exhaust gas treatment apparatus  4  using an external support device, such as a crane, during a task of installing the support bracket  12  in the support stays  2  and  3 . 
     The disposition of the exhaust gas treatment apparatus in the forward and backward directions can be freely set up. 
     As illustrated in  FIGS. 8 ,  14 , and  21 , the support stays  2  and  3  consist of the support stays  2  and  3  on the front and back sides, the support stays  2  and  3  on the front and back sides are respectively installed on the front and back sides of the engine body  1 , the support bracket  12  is lengthily formed forward and backward and installed between the support stays  2  and  3  on the front and back sides, and the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the support stays  2  and  3  on the front and back sides in the state in which the exhaust gas treatment apparatus  4  has a long posture in the left and right directions. Thus, the disposition of the exhaust gas treatment apparatus  4  in the forward and backward directions can be freely set up. 
     The connection flanges can be prevented from being damaged by a shake of the exhaust gas treatment apparatus. 
     As illustrated in  FIGS. 1(A) and 21 , the front and back end portions of the support brackets  12   a  and  12   b  on the left and right sides are placed above the support stays  2  and  3  on the front and back sides and installed using bracket installation fastening members  14   a  and  14   b  on the left and right sides. Accordingly, a robust outside structure with high strength can be constructed using the support brackets  12   a  and  12   b  on the left and right sides and the support stays  2  and  3  on the front and back sides. Furthermore, a big shake of the exhaust gas treatment apparatus  4  due to a vibration of the engine body  1  can be suppressed, and thus the connection flanges  8 ,  9 ,  10 , and  11  can be prevented from being damaged by a shake of the exhaust gas treatment apparatus  4 . 
     The maintenance of a DPF can be easily performed. 
     As illustrated in  FIG. 3 , in accommodating a DPF  17  in the exhaust gas treatment apparatus  4 , as illustrated in  FIGS. 10 ,  15 ,  20 , and  22 , the exhaust gas treatment apparatus  4  is disposed on the upper side of a head cover  20  attached to the upper portion of a cylinder head  19 . When the maintenance of the DPF  17  is performed, the exhaust gas treatment apparatus  4  or the DPF  17  can be taken out toward the upper side of the engine body  1  without intervening with the components of the engine body  1 . Accordingly, the maintenance of the DPF  17  can be easily performed. 
     The regeneration efficiency of the DPF can be maintained high. 
     As illustrated in  FIGS. 10 ,  15 ,  20 , and  22 , the exhaust gas treatment apparatus  4  is disposed at a position higher than the upper end portion  21  of the engine cooling fan  18  on the upper side of the head cover  20  attached to the cylinder head  19 . Accordingly, the regeneration efficiency of the DPF  17  can be maintained high because the DPF  17  is difficult to be cooled by engine cooling wind. 
     A task of installing the exhaust inlet flange in the engine exhaust outlet flange can be easily performed. 
     As illustrated in  FIGS. 9 ,  14 , and  26 , the exhaust inlet flange  23  of the exhaust gas treatment apparatus  4  is placed above the engine exhaust outlet flange  22  of the engine body  1 . Accordingly, a task of installing the exhaust inlet flange  23  in the engine exhaust outlet flange  22  can be easily performed without the need to support the load on the side of the exhaust inlet flange  23  using an external support device, such as a crane, during the task of installing the exhaust inlet flange  23  in the engine exhaust outlet flange  22 . 
     The attachment of the support brackets to the connection flanges can be performed without hindrance. 
     As illustrated in  FIGS. 1(A) and 1(B) , support brackets  12   a  and  12   b  are attached to the connection flanges  10  and  11  using bracket installation fastening members  25 , position adjustment holes  26  of the bracket installation fastening members  25  are formed in at least one of the connection flanges  10  and  11  and the support brackets  12   a  and  12   b , and the positions of at least upper and lower directions of the bracket installation fastening members  25  are adjusted using the position adjustment holes  26 . Although the positions of the connection flanges  10  and  11  and the support brackets  12   a  and  12   b  are mutually deviated in the upper and lower directions, the attachment of the support brackets  12   a  and  12   b  to the connection flanges  10  and  11  can be performed without hindrance by up and down adjusting the positions of the bracket installation fastening members  25  using the position adjustment holes  26 . 
     A task of attaching the support brackets to the connection flanges can be easily performed. 
     As illustrated in  FIG. 1(B) , in the state in which the width direction of the engine body  1  is the left and right directions, a large-diameter hole  27  and a small-diameter hole  28  are overlapped with each other left and right, and the bracket installation fastening member  25  is inserted into the overlapped position and configured to pass therethrough. Thus, if the connection flanges  10  and  11  and the support brackets  12   a  and  12   b  are aligned with each other, the bracket installation fastening members  25  are automatically aligned at a proper position. Accordingly, the attachment of the support brackets  12   a  and  12   b  to the connection flanges  10  and  11  can be easily performed without the need to adjust and manipulate the bracket installation fastening members  25 . 
     The support brackets can be installed in the support stays without hindrance. 
     As illustrated in  FIGS. 1(A) and 1(C) , the support brackets  12   a  and  12   b  are installed in the support stays  2  and  3  using respective bracket installation fastening members  14   a  and  14   b , the position adjustment holes  29  of the bracket installation fastening members  14   a  and  14   b  are installed in at least one of the support brackets  12   a  and  12   b  and the support stays  2  and  3 , and the positions of at least the forward and backward directions and the left and right directions of the bracket installation fastening members  14   a  and  14   b  are adjusted using the position adjustment holes  29 . Although the positions of the support stays  2  and  3  and the support brackets  12   a  and  12   b  are mutually deviated in the forward and backward directions or the left and right directions, the positions of the bracket installation fastening members  14   a  and  14   b  can be adjusted using the position adjustment holes  29 , and the installation of the support brackets  12   a  and  12   b  in the support stays  2  and  3  can be performed without hindrance. 
     A task of installing the support brackets in the support stays can become easy. 
     As illustrated in  FIG. 1(C) , the long hole  30  of the forward and backward directions and the long hole  31  of the left and right directions are overlapped with each other up and down in a crossing form, and the bracket installation fastening members  14   a  and  14   b  are inserted into the overlapping position and configured to pass therethrough. When the support brackets  12   a  and  12   b  and the support stays  2  and  3  are aligned with each other, the bracket installation fastening members  14  are automatically aligned at a proper position. Accordingly, a task of installing the support brackets  12   a  and  12   b  in the support stays  2  and  3  is facilitated. 
     The maintenance of the DPF can be performed. 
     As illustrated in  FIGS. 3 ,  14 ,  21 , and  28 , the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7  are detachably coupled to both ends of the DPF accommodation casing unit  5 . If both ends of the DPF  17  are exposed by separating the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7  from the DPF accommodation casing unit  5 , the maintenance of the DPF  17 , such as washing of ashes accumulated in the DPF  17 , can be performed. 
     The maintenance of the DPF can be easily performed. 
     As illustrated in  FIGS. 1(A) and 28 , in the state in which the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7  are supported by the engine body  1 , the DPF accommodation casing unit  5  can be pulled out between the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7 . Accordingly, the maintenance of the DPF  17 , such as washing of ashes accumulated in the DPF  17 , can be easily performed. 
     The maintenance of the DPF can be easily performed. 
     As illustrated in  FIGS. 1(A) and 28 , the pull-up locking units  36  and  37  of the DPF accommodation casing unit  5  are installed in the pull-up protrusions  34  and  35 . Accordingly, the maintenance of the DPF can be easily performed because the DPF accommodation casing unit  5  can be simply pulled up using an external support device, such as a crane. 
     The exhaust gas treatment apparatus and the support bracket can be easily aligned with each other. 
     As illustrated in  FIGS. 2  (A) and (B), a flange-fit concave unit  38   b  having an upper portion opened is installed in the support bracket  12   b , and the lower edge portion of at least one of the connection flanges  9  and  11  where the DPF accommodation casing unit  5  and the exhaust outlet-side casing unit  7  overlap with each other is fitted into the flange-fit concave unit  38   b . Accordingly, the exhaust gas treatment apparatus  4  and the support bracket  12  can be easily aligned with each other. 
     The exhaust gas treatment apparatus can be compacted. 
     As illustrated in  FIG. 3 , a ring-shaped spacer  39  is inserted between the connection flanges  8  and  10  of the DPF accommodation casing unit  5  and the exhaust inlet-side casing unit  6 , and a DPF inlet-side space  40  is formed within the ring-shaped spacer  39 . As illustrated in  FIGS. 4(B) and 28 , a sensor installation hole  41  is formed in the ring-shaped spacer  39 , and an exhaust sensor  42  is inserted from the sensor installation hole  41  toward the DPF inlet-side space  40 . Accordingly, the exhaust gas treatment apparatus  4  can be compacted because the DPF inlet-side space  40  can be narrowed. 
     However, in case where a sensor installation boss is installed on the peripheral wall of a DPF accommodation casing unit using welding, all the peripheral edge portions of the sensor installation boss need to be welded, and space through which a welding torch can enter needs to be secured between the sensor installation boss and the connection flange of a DPF welding casing unit. Accordingly, the distance between the connection flange and a sensor is widened, and an exhaust inlet-side space has to be widened, resulting in an increase of the exhaust gas treatment apparatus in size. 
     The disposition and posture of an exhaust sensor can be freely selected. 
     As illustrated in  FIGS. 1(A) and 28 , the posture of the ring-shaped spacer  39  can be changed in the circumferential direction and thus the position and posture of the sensor installation hole  41  can be changed. Accordingly, the disposition and posture of the exhaust sensor  42  can be freely selected. 
     The erroneous detection of the exhaust pressure sensor can be prevented. 
     As illustrated in  FIGS. 6(C) ,  14 ,  21 , and  28 , a pipe installation boss  46  having the exhaust pressure entrance pipe  45  of an exhaust pressure sensor  44  installed therein is installed in the peripheral wall of the exhaust outlet-side casing unit  7 , and the boss hole  47  of the pipe installation boss  46  is upwardly formed externally. Thus, condensation water remaining in the exhaust outlet-side casing unit  7  can be prevented from entering the exhaust pressure entrance pipe  45  of the exhaust pressure sensor  44 , and thus the erroneous detection of the exhaust pressure sensor  44  can be prevented. 
     The disposition of an exhaust path on the upper stream side of an exhaust inlet pipe can be freely selected. 
     As illustrated in  FIGS. 4(C) ,  14 ,  21 , and  28 , the posture of the exhaust inlet-side casing unit  6  can be changed in the circumferential direction and thus the direction of an inlet  48   a  of the exhaust inlet pipe  48  can be changed. Accordingly, the disposition of an exhaust path on the upper stream side of the exhaust inlet pipe  48  can be freely selected. 
     The disposition of an exhaust path on the lower stream side of an exhaust outlet pipe can be freely selected. 
     As illustrated in  FIGS. 5(A) ,  5 (B),  14 ,  25 , and  28 , the posture of the exhaust outlet-side casing unit  7  can be changed in the circumferential direction and thus the direction of an outlet  49   a  of the exhaust outlet pipe  49  can be changed. Accordingly, the disposition of an exhaust path on the lower stream side of the exhaust outlet pipe  49  can be freely selected. 
     The maintenance of the DPF can be easily performed. 
     As illustrated in  FIGS. 28 and 29 , the exhaust gas treatment apparatus  4  has a long posture in the left and right directions, and the DPF accommodation casing unit  5  is disposed on the upper back side of a flywheel housing  51  immediately after the head cover  20  attached to the upper portion of the cylinder head  19 . When the maintenance of the DPF  17  is performed, the exhaust gas treatment apparatus  4  or the DPF accommodation casing unit  5  can be taken out toward the upper side of the engine body  1  without intervening with the components of the engine body  1 . Accordingly, the maintenance of the DPF  17  can be easily performed. 
     The total height of the engine can be suppressed low. 
     As illustrated in  FIGS. 28 and 29 , in the state in which the exhaust gas treatment apparatus  4  has a long posture in the left and right directions, the DPF accommodation casing unit  5  of the exhaust gas treatment apparatus  4  is disposed on the upper back side of the flywheel housing  51  immediately after the head cover  20  attached to the upper portion of the cylinder head  19 . Accordingly, the total height of the engine can be suppressed low. 
     The regeneration efficiency of the DPF can be maintained high. 
     As illustrated in  FIG. 8 , the engine cooling fan  21  is disposed in the front part of the engine body  1 . As illustrated in  FIGS. 28 and 29 , in the state in which the exhaust gas treatment apparatus  4  has a long posture in the left and right directions, the DPF accommodation casing unit  5  of the exhaust gas treatment apparatus  4  is disposed on the upper back side of the flywheel housing  51  immediately after the head cover  20  attached to the upper portion of the cylinder head  19 . Accordingly, the regeneration efficiency of the DPF can be maintained high because the DPF  17  is difficult to be cooled by engine cooling wind. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
       In the drawings: 
         FIGS. 1(A) to 1(C)  are diagrams illustrating an engine having an exhaust gas treatment apparatus attached thereto according to a first embodiment of the present invention.  FIG. 1(A)  is a perspective view of the exhaust gas treatment apparatus and peripherals thereof seen from the upper side on the front right side.  FIG. 1(B)  is an exploded view of a portion indicated by an arrow B in  FIG. 1(A) .  FIG. 1(C)  is an exploded view of a portion indicated by an arrow C in  FIG. 1(A) . 
         FIG. 2(A)  is a lateral view of the exhaust gas treatment apparatus of  FIG. 1(A)  and peripherals thereof, seen from the right side, and  FIG. 2(B)  is a cross-sectional view of  FIG. 2(A)  taken along line B-B. 
         FIG. 3  is a cross-sectional view of  FIG. 2(A)  taken along line 
         FIGS. 4(A) ,  4 (B), and  4 (C) are diagrams illustrating the exhaust gas treatment apparatus of  FIG. 1(A) .  FIG. 4(A)  is a longitudinal side view of a DPF accommodation casing unit seen from the right side,  FIG. 4(B)  is a lateral view of a ring-shaped spacer seen from the right side, and  FIG. 4(C)  is a lateral view of an exhaust inlet-side casing unit seen from the right side. 
         FIGS. 5(A) and 5(B)  are diagrams illustrating the exhaust gas treatment apparatus of  FIG. 1(A) .  FIG. 5(A)  is a lateral side view of an exhaust outlet-side casing unit seen from the right side, and  FIG. 5(B)  is a lateral view of the DPF accommodation casing unit seen from the right side. 
         FIGS. 6(A) to 6(C)  are diagrams illustrating the exhaust gas treatment apparatus of  FIG. 1(A) .  FIG. 6(A)  is a front view of the exhaust outlet-side casing unit,  FIG. 6(B)  is a cross-sectional view of  FIG. 6(A)  taken along line B-B, and  FIG. 6(C)  is an enlarged view of a portion indicated by an arrow C of  FIG. 6(B) . 
         FIG. 7  is a front view of the exhaust gas treatment apparatus of  FIG. 1(A) . 
         FIG. 8  is a perspective view of the engine having the exhaust gas treatment apparatus attached thereto relating to the first embodiment of the present invention, which is seen from the upper side on the front right side. 
         FIG. 9  is a perspective view of the engine, seen from the upper side on the front left side. 
         FIG. 10  is a lateral view of the engine of  FIG. 8 , seen from the right side. 
         FIG. 11  is a lateral view of the engine of  FIG. 8 , seen from the left side. 
         FIG. 12  is a front view of the engine of  FIG. 8 . 
         FIG. 13  is a plan view of the engine of  FIG. 8 . 
         FIG. 14  is a perspective view of an engine having an exhaust gas treatment apparatus attached thereto according to a second embodiment of the present invention, which is seen from the upper side on the front right side. 
         FIG. 15  is a lateral view of the engine of  FIG. 14 , seen from the left side. 
         FIG. 16  is a front view the engine of  FIG. 14 . 
         FIG. 17  is a plan view of the engine of  FIG. 14 . 
         FIG. 18  is a lateral view of the engine of  FIG. 14 , seen from the right side. 
         FIG. 19  is a rear view of the engine of  FIG. 14 . 
         FIG. 20  is a diagram showing a tractor with the engine of  FIG. 14 . 
         FIG. 21  is a perspective view of an engine having an exhaust gas treatment apparatus attached thereto according to a third embodiment of the present invention, which is seen from the upper side on the front right side. 
         FIG. 22  is a lateral view of the engine of  FIG. 21 , seen from the left side. 
         FIG. 23  is a front view of the engine of  FIG. 21 . 
         FIG. 24  is a plan view of the engine of  FIG. 21 . 
         FIG. 25  is a lateral view of the engine of  FIG. 21 , seen from the right side. 
         FIG. 26  is a rear view of the engine of  FIG. 21 . 
         FIG. 27  is a lateral view showing a modification example of a support bracket used in the engine of  FIG. 21 . 
         FIG. 28  is a perspective view of the back part of an engine having an exhaust gas treatment apparatus attached thereto according to a fourth embodiment of the present invention, which is seen from the upper side on the front right side. 
         FIG. 29  is a lateral view of the back part of the engine of  FIG. 28 , seen from the right side. 
         FIG. 30  is a rear view of the engine of  FIG. 28 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 to 30  are diagrams illustrating an engine having an exhaust gas treatment apparatus attached thereto relating to embodiments of the present invention.  FIGS. 1 to 13  are diagrams illustrating a first embodiment,  FIGS. 14 to 20  are diagrams illustrating a second embodiment,  FIGS. 21 to 27  are diagrams illustrating a third embodiment, and  FIGS. 28 to 30  are diagrams illustrating a fourth embodiment. 
     In each of the embodiments, a water-cooled vertical in-line multi-cylinder diesel engine having a DPF muffler attached thereto is described. 
     The construction of the first embodiment is described below. 
     As shown in  FIG. 8 , in the state in which a direction along which a crank shaft center line  16  extends is forward and backward directions and the width direction of an engine body  1  orthogonal to the crank shaft center line  16  is left and right directions, the engine body  1  has a cylinder head  19  attached above a cylinder block  52 , a head cover  20  attached above the cylinder head  19 , an oil pan  53  attached under the cylinder block  52 , a coolant pump  54  attached in front of the cylinder block  52 , an engine cooling fan  18  disposed in front of the coolant pump  54 , a gear casing  15  disposed in the rear of the cylinder block  52 , a flywheel housing  51  disposed in the rear of the gear casing  15 , a suction manifold  56  attached on the right side of the cylinder head  19 , and an exhaust manifold  55  attached on the left side of the cylinder head  19  as shown in  FIG. 9 . 
     As shown in  FIG. 8 , the engine cooling fan  18  is disposed in the input axis of the coolant pump  54 , and the coolant pump  54  and the engine cooling fan  18  are driven by a belt transmission device from the crank shaft. 
     The engine body  1  is equipped with an EGR apparatus (i.e., exhaust gas recirculation system) and a common rail fuel injection system. The EGR apparatus reduces some of an exhaust gas into a suction gas. The common rail fuel injection system accumulates fuel, boosted by the fuel supply pump  57 , in a common rail  58  and controls a fuel injection time or a fuel injection amount of each cylinder by opening or closing the electromagnetic valve of an injector through electronic control. 
     As shown in  FIG. 8 , in the EGR apparatus, an EGR valve casing  59  is attached above the suction manifold  56  and configured to communicate with the exhaust manifold  55  through an EGR cooler  60 . As shown in  FIG. 10 , the EGR cooler  60  is disposed immediately after the cylinder head  19  and immediately above a flywheel housing  51 . 
     As shown in  FIG. 8 , the common rail fuel injection system is configured to have the common rail  58  disposed under the suction manifold  56  and to pump fuel from a fuel supply pump  57  to the common rail  58  and supply fuel, compressed by the common rail  58 , to the injector through the high pressure pipe  61 . The fuel supply pump  57  is disposed on the front side of the gear casing  15  in the right direction of the cylinder block  52 . 
     As shown in  FIG. 9 , an exhaust gas treatment apparatus  4  is supported by the engine body  1 , and the engine body  1  and the exhaust gas treatment apparatus  4  are configured to communicate with each other through an exhaust pipe  13 . 
     A super charger  62  is attached above the exhaust manifold  55 , and the exhaust pipe  13  of an elbow form is coupled to the exhaust outlet of an exhaust turbine  63  of the super charger  62 . 
     As shown in  FIG. 3 , a DOC  64  and a DPF  17  are accommodated in the exhaust gas treatment apparatus  4 . The DOC  64  is disposed on the upper stream side of the exhaust gas treatment apparatus  4 , and the DPF  17  is disposed on the lower stream side thereof. 
     The DOC is an abbreviation of a diesel oxidization catalyst, and the DPF is an abbreviation of a diesel particulate filter. 
     In the exhaust gas treatment apparatus  4 , the DPF  17  is configured to capture PM (particle materials) included in an exhaust gas, oxidize non-combustion fuel, drained out from a combustion chamber or sprayed to an exhaust path, using the DOC  64 , raise temperature of the exhaust gas using oxidization heat, and incinerate the PM accumulated in the DPF  17  using the raised temperature, thereby contriving the regeneration of the DPF  17 . 
     The DPF muffler is used in the exhaust gas treatment apparatus  4  in the present embodiment, but an exhaust muffler or a catalyst converter which does not include the DPF may be used as the exhaust gas treatment apparatus  4 . 
     As shown in  FIG. 3 , the casing of the exhaust gas treatment apparatus  4  consists of a plurality of casing units  5 ,  6 , and  7  which can be separated from each other. Connection flanges  8 ,  9 ,  10 , and  11  are installed at the end of each of the casing units  5 ,  6 , and  7 . The casing units  5 ,  6 , and  7  are coupled by a connection of the connection flanges  8 ,  9 ,  10 , and  11 . 
     As shown in  FIG. 8 , the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the connection flanges  8 ,  9 ,  10 , and  11 . 
     As shown in  FIG. 3 , the casing of the exhaust gas treatment apparatus  4  consists of three casing units; the DPF accommodation casing unit  5 , the exhaust inlet-side casing unit  6 , and the exhaust outlet-side casing unit  7 . 
     The DPF accommodation casing unit  5  accommodates the DPF  17 , and the exhaust inlet-side casing unit  6  accommodates the DOC  64 . 
     The DPF inlet-side connection flange  8  and the DPF outlet-side connection flange  9  are disposed on both ends of the DPF accommodation casing unit  5 . The exhaust inlet-side connection flange  10  is disposed at the end of the DPF inlet side of the exhaust inlet-side casing unit  6 , and the exhaust outlet-side connection flanges  11  is disposed at the end of the DPF outlet side of the exhaust outlet-side casing unit  7 . 
     Between the DPF inlet-side connection flange  8  and the exhaust inlet-side connection flange  10 , a ring-shaped spacer  39  is inserted, and the connection flanges  8  and  10  and the ring-shaped spacer  39  are overlapped with each other and fastened by flange connection fastening members  43  on the DPF inlet side. 
     Furthermore, the DPF outlet-side connection flange  9  and the exhaust outlet-side connection flange  11  are overlapped with each other and fastened by flange connection fastening members  50  on the DPF outlet side. 
     All the flange connection fastening members  43  and  50  are bolts and nuts. 
     As shown in  FIG. 8 , the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the plurality of connection flanges  8 ,  9 ,  10 , and  11  which are spaced apart from each other. 
     The plurality of connection flanges  8 ,  9 ,  10 , and  11  includes the DPF inlet-side connection flange  8  and the DPF outlet-side connection flange  9  of the DPF accommodation casing unit  5 , the exhaust inlet-side connection flange  10  of the exhaust inlet-side casing unit  6 , and the exhaust outlet-side connection flange  11  of the exhaust outlet-side casing unit  7 . 
     As shown in  FIG. 8 , support stays  2  and  3  are installed in the engine body  1 , a support bracket  12  is attached to the connection flanges  10  and  11 , and the support bracket  12  is disposed above the support stays  2  and  3 . 
     The load of the exhaust gas treatment apparatus  4  is supported by the support stays  2  and  3  through the support bracket  12 , and the support bracket  12  is installed in the support stays  2  and  3  using bracket installation fastening members  14 . 
     As shown in  FIG. 8 , the support stays  2  and  3  consist of the front and rear support stays  2  and  3 , the front and rear support stays  2  and  3  are installed on the front and back sides of the engine body  1 , the support bracket  12  is lengthily formed forward and backward, the support bracket  12  is disposed between the front and rear support stays  2  and  3 , and the exhaust gas treatment apparatus  4  is supported by the engine body  1  through the front and rear support stays  2  and  3  in a long posture in the left and right directions. 
     As shown in  FIG. 1(A) , the support bracket  12  consists of support brackets  12   a  and  12   b  on the left and right sides, and the support brackets  12   a  and  12   b  are respectively attached to the connection flanges  8 ,  10  and  9 ,  11  on the left and right sides. 
     The front and rear ends of the support brackets  12   a  and  12   b  are disposed on the front and rear support stays  2  and  3  and fastened by bracket installation fastening members  14   a  and  14   b  on the left and right sides. 
     As shown in  FIG. 2(A) , the front support stay  2  is formed by bending a horizontal placement unit  2   b  from the upper end of a vertical stay installation unit  2   a  toward the back side. Furthermore, the rear support stay  3  is formed by bending a horizontal placement unit  3   b  from the upper end of a vertical stay installation unit  3   a  toward the back side. 
     As shown in  FIG. 10 , the stay installation units  2   a  and  3   a  of the respective front and rear support stays  2  and  3  are installed in the front and rear end faces of the cylinder head  19 . 
     As shown in  FIG. 2(B) , the support bracket  12   a  on the left side is formed by bending a vertical support unit  12   d  from the left edge of a horizontal bracket installation unit  12   c  toward an upper side. The right support bracket  12   b  is formed by bending a vertical support unit  12   d  from the right edge of a horizontal bracket installation unit  12   c  toward an upper side. 
     As shown in  FIGS. 1(A) and 1(C) , the front end portions of the bracket installation units  12   c  and  12   c  of the support brackets  12   a  and  12   b  on the left and right sides are placed on the placement unit  2   b  of the front support stay  2 . The front end portions are fastened by the bracket installation fastening members  14   a  and  14   b  on the left and right sides. 
     As shown in  FIGS. 2(A) and 2(B) , the rear end portions of the bracket installation units  12   c  and  12   c  of the support brackets  12   a  and  12   b  on the left and right sides are placed on the placement unit  3   b  of the rear support stay  3 . The rear end portions are fastened by the bracket installation fastening members  14   a  and  14   b  on the left and right sides. 
     The bracket installation fastening members  14   a  and  14   b  are bolts and nuts. 
     As shown in  FIG. 10 , on the upper side of the head cover  20  attached above the cylinder head  19 , the exhaust gas treatment apparatus  4  is disposed in a place higher than the upper end portion  21  of the engine cooling fan  18 . 
     As shown in  FIG. 9 , the exhaust inlet flange  23  of the exhaust gas treatment apparatus  4  is placed on the engine exhaust outlet flange  22  on the side of the engine body  1 . 
     The engine exhaust outlet flange  22  is formed toward the upper side of the end of the exhaust pipe  13 . The exhaust inlet flange  23  is formed toward the lower side of the leading end of the exhaust inlet pipe  48  of the exhaust gas treatment apparatus  4 . 
     As shown in  FIGS. 1(A) and 1(B) , the support brackets  12   a  and  12   b  on the left and right sides are attached to the connection flanges  10  and  11  using bracket installation fastening members  25 . The position adjustment holes  26  of the bracket installation fastening members  25  are formed in at least one of the connection flanges  10  and  11  and the support brackets  12   a  and  12   b . The positions of at least upper and lower directions of the bracket installation fastening members  25  are adjusted by the position adjustment holes  26 . 
     As shown in  FIG. 2(B) , in the present embodiment, the support brackets  12   a  and  12   b  on the left and right sides are respectively attached to the exhaust inlet-side connection flange  10  of the exhaust inlet-side casing unit  6  and the exhaust outlet-side connection flange  11  of the exhaust outlet-side casing unit  7 . The position adjustment holes  26  of the bracket installation fastening members  25  are formed in the support brackets  12   a  and  12   b.    
     As shown in  FIG. 1(B) , the position adjustment hole  26  of the bracket installation fastening member  25  is a large-diameter hole  27 . The large-diameter holes  27  are formed in one of the connection flanges  10  and  11  and the support bracket  12 , and small-diameter holes  28  are formed in the other of the connection flanges  10  and  11  and the support bracket  12 . The inside diameter of the large-diameter hole  27  is set to a size in which a portion through which the bracket installation fastening member  25  inserted therein passes can be moved and adjusted in a direction orthogonal to the direction in which the bracket installation fastening member  25  passes. The inside diameter of the small-diameter hole  28  is set to a size in which a portion through which the bracket installation fastening member  25  inserted therein passes cannot be moved and adjusted in a direction orthogonal to the direction in which the bracket installation fastening member  25  passes. 
     In the state in which the width direction of the engine body  1  is left and right directions, the large-diameter hole  27  and the small-diameter hole  28  overlap with each other left and right, and the bracket installation fastening member  25  is inserted into the overlapping position and passes through the overlapping position. 
     As shown in  FIGS. 1(A) and 1(C) , the support brackets  12   a  and  12   b  are attached to the support stays  2  and  3  using the bracket installation fastening members  14   a  and  14   b . The position adjustment holes  29  of the bracket installation fastening members  14   a  and  14   b  are formed in at least one of the support brackets  12   a  and  12   b  and the support stays  2  and  3 . The positions of at least the forward and backward directions and left and right directions of the bracket installation fastening members  14   a  and  14   b  are adjusted through the position adjustment holes  29 . 
     As shown in  FIG. 1(C) , in the present embodiment, the position adjustment holes  29  are formed in the front end portion of the support bracket  12   a  on the left side and in the front support stay  2  on both sides of the left side. The positions of the forward and backward directions and the left and right directions of the bracket installation fastening members  14   a  on the left side are adjusted through the position adjustment holes  29 . The rear end portion of the support bracket  12   a  on the left side, the front and rear end portions of the support bracket  12   b  of the left and right sides of the rear support stay  3 , and the right side of the pair of front and rear support stays  2  and  3  have the same construction. The positions of the forward and backward directions and the left and right directions of the bracket installation fastening members  14   a  and  14   b  are adjusted through the position adjustment holes  29 . 
     As shown in  FIG. 1(C) , the position adjustment holes  29  of the bracket installation fastening members  14   a  and  14   b  consist of a long hole  30  in the forward and backward directions and a long hole  31  in the left and right directions. The long holes  30  of the forward and backward directions are formed in one of the support stays  2  and  3  and the support brackets  12   a  and  12   b , and the long holes  31  of the left and right directions are formed in the other of the support stays  2  and  3  and the support brackets  12   a  and  12   b.    
     The long holes  30  of the forward and backward directions and the long holes  31  of the left and right directions overlap with each other up and down in a crossing form. The bracket installation fastening members  14   a  and  14   b  are inserted into the overlapping positions and configured to pass therethrough. 
     As shown in  FIG. 1(C) , in the present embodiment, the long holes  30  of the forward and backward directions are formed in the support stays  2  and  3  on the front and back sides, and the long holes  31  of the left and right directions are formed in the support brackets  12   a  and  12   b  on the left and right sides. 
     As shown in  FIG. 3 , the DPF  17  is accommodated in the exhaust gas treatment apparatus  4 . The casing of the exhaust gas treatment apparatus  4  is formed of the DPF accommodation casing unit  5 , the exhaust inlet-side casing unit  6 , and the exhaust outlet-side casing unit  7 . 
     The exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7  are connected to both ends of the DPF accommodation casing unit  5  so that they can be separated from each other. 
     As shown in  FIG. 2(B) , the connection flanges  8  and  9  of the DPF accommodation casing unit  5  overlap with the respective connection flanges  10  and  11  of the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7 . Support protrusions  32  and  33  are outwardly more protruded than the respective connection flanges  8  and  9  of the DPF accommodation casing unit  5  in the diameter direction and formed in the respective connection flanges  10  and  11  of the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7 . The exhaust gas treatment apparatus  4  is supported by the engine body  1  through the support protrusions  32  and  33 . 
     As shown in  FIG. 1(A) , in the state in which the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7  are supported by the engine body  1 , the DPF accommodation casing unit  5  can be pulled out between the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7 . 
     As shown in  FIGS. 4(B) and 4(C) , the ring-shaped spacer  39  is detachably installed in the exhaust inlet-side connection flange  10  of the exhaust inlet-side casing unit  6  using an installation bolt  69 . However, the ring-shaped spacer  39  is not detached from the exhaust inlet-side connection flange  10  when the DPF accommodation casing unit  5  is pulled out between the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7 . 
     As shown in  FIG. 1(A) , pull-up protrusions  34  and  35  are outwardly more protruded than the connection flanges  10  and  11  of the exhaust inlet-side casing unit  6  and the exhaust outlet-side casing unit  7  in the diameter direction and installed in the respective connection flanges  8  and  9  of the DPF accommodation casing unit  5 . The pull-up locking units  36  and  37  of the DPF accommodation casing unit  5  are installed in the respective pull-up protrusions  34  and  35 . 
     As shown in  FIGS. 2(A) and 2(B) , a flange-fit concave unit  38   b  having an upper portion opened is formed in the support bracket  12   b  on the right side. The lower edge portion of at least one of the connection flanges  9  and  11  at which the DPF accommodation casing unit  5  and the exhaust outlet-side casing unit  7  overlap with each other is fitted into the flange-fit concave unit  38   b.    
     As shown in  FIG. 3 , in the present embodiment, the lower edge portions of both sides of the connection flanges  9  and  11  of the DPF accommodation casing unit  5  and the exhaust outlet-side casing unit  7  are fitted into the flange-fit concave unit  38   b.    
     As shown in  FIG. 2(B) , a flange-fit concave unit  38   a  having an upper portion opened is also formed in the support bracket  12   a  on the left side. The lower edge portion of at least one of the connection flange  10  of the exhaust inlet-side casing unit  6  and the ring-shaped spacer  39  which overlap with each other is fitted into the flange-fit concave unit  38   a.    
     The inner peripheral edges of the flange-fit concave units  38   a  and  38   b  are formed in a curved shape along the connection flanges  9 ,  10 , and  11  of a polygon or the intersecting corner of a lower edge portion of the ring-shaped spacer  39 . Since the lower edge portions are fitted into the flange-fit concave units  38   a  and  38   b  as described above, the position of the exhaust gas treatment apparatus  4  in the forward and backward directions and the rotation and posture of the exhaust gas treatment apparatus  4  are determined. 
     As shown in  FIG. 3 , the ring-shaped spacer  39  is inserted between the connection flanges  8  and  10  of the DPF accommodation casing unit  5  and the exhaust inlet-side casing unit  6 , and DPF inlet-side space  40  is formed in the ring-shaped spacer  39 . 
     As shown in  FIG. 4(B) , a sensor installation hole  41  is formed in the ring-shaped spacer  39 . An exhaust sensor  42  is inserted from the sensor installation hole  41  toward the DPF inlet-side space  40 . 
     The exhaust sensor  42  is an exhaust temperature sensor on the DPF inlet side. 
     As shown in  FIG. 4(B) , a pipe installation hole  66  in which the DPF inlet-side exhaust pressure entrance pipe  65  of an exhaust pressure sensor  44  shown in  FIG. 1(A)  is installed is formed in the ring-shaped spacer  39 . The pipe installation hole  66  is upwardly formed externally so that condensation water within the DPF inlet-side space  40  does not flow into the DPF inlet-side exhaust pressure entrance pipe  65 . 
     As shown in  FIGS. 4(A) and 4(C) , a plurality of locked units  8   a  and  10   a  is disposed in the respective connection flanges  8  and  10  where the DPF accommodation casing unit  5  and the exhaust inlet-side casing unit  6  overlap with each other and arranged in their circumferential direction at equally spaced angles. 
     As shown in  FIG. 4(B) , a plurality of locked units  39   a  is disposed in the ring-shaped spacer  39  and arranged in their circumferential direction at equally spaced angles. The posture of the ring-shaped spacer  39  is moved in the circumferential direction in the unit of the equally spaced angle, and the locked units  39   a  of the ring-shaped spacer  39  are aligned with the respective locked units  8   a  and  10   a  of the connection flanges  8  and  10 . In this state, if the locked units  8   a  and  10   a  of the connection flanges  8  and  10  are locked into the locked units  39   a  of the ring-shaped spacer  39  using the flange connection fastening members  43 , the posture of the ring-shaped spacer  39  can be changed in the circumferential direction and thus the position and posture of the sensor installation hole  41  can be changed. 
     As shown in  FIG. 6(C) , a pipe installation boss  46 , in which the exhaust pressure entrance pipe  45  of the exhaust pressure sensor  44  is installed, is disposed in the peripheral wall of the exhaust outlet-side casing unit  7 . The boss hole  47  of the pipe installation boss  46  is upwardly formed externally. 
     As shown in  FIG. 1(A) , the exhaust pressure entrance pipe  45  is disposed on the DPF outlet side and configured to communicate with the exhaust pressure entrance pipe  65  on the DPF inlet side and the exhaust pressure sensor  44 . The exhaust pressure sensor  44  detects a difference in the pressure between the inlet side and the outlet side of the DPF  17 . An engine ECU estimates the amount of PM accumulated in the DPF  17  on the basis of the detection value. The ECU is an abbreviation of an electronic control unit. 
     As shown in  FIG. 4(C) , an exhaust inlet pipe  48  is installed in the exhaust inlet-side casing unit  6 . 
     The plurality of locked units  8   a  and  10   a  is disposed in the connection flanges  8  and  10  where the DPF accommodation casing unit  5  and the exhaust inlet-side casing unit  6  overlap with each other and arranged in their circumferential direction at equally spaced angles. 
     The exhaust inlet-side casing unit  6  is moved in the circumferential direction in the unit of the equally spaced angle. The locked units  10   a  of the connection flange  10  of the exhaust inlet-side casing unit  6  are aligned with the respective locked units  8   a  of the connection flange  8  of the DPF accommodation casing unit  5  and then fastened using the flange connection fastening members  43 . Accordingly, the posture of the exhaust inlet-side casing unit  6  can be changed in the circumferential direction, and thus the direction of an inlet  48   a  of the exhaust inlet pipe  48  can be changed. 
     As shown in  FIGS. 4(A) and 4(C) , the bolt insertion through holes of the flange connection fastening members  43  are formed in the locked units  8   a  and  10   a . The bolt insertion through holes of the flange connection fastening members  43  are spaced apart from each other at equal angles of 36° and formed at 10 places in the circumferential direction. 
     As shown in  FIG. 1(A) , the sensor installation hole  67  for an exhaust sensor is formed in the peripheral wall of the exhaust inlet-side casing unit  6 . An exhaust gas temperature sensor for detecting the temperature of an exhaust gas on the upper stream side of the DOC is disposed in the sensor installation hole  67 . 
     As shown in  FIGS. 5(A) and 5(B) , an exhaust outlet pipe  49  is installed in the exhaust outlet-side casing unit  7 . A plurality of locked units  11   a  and  9   a  is disposed in each of the connection flanges  11  and  9  where the exhaust outlet-side casing unit  7  and the DPF accommodation casing unit  5  overlap with each other and arranged in their circumferential direction at equally spaced angles. 
     The exhaust outlet-side casing unit  7  is moved in the circumferential direction in the unit of the equally spaced angle, and the locked units  11   a  of the connection flange  11  of the exhaust outlet-side casing unit  7  are aligned with the respective locked units  9   a  of the connection flange  9  of the DPF accommodation casing unit  5  and then fastened using respective flange connection fastening members  50 . Accordingly, the posture of the exhaust outlet-side casing unit  7  can be changed in the circumferential direction, and the direction of an outlet  49   a  of the exhaust outlet pipe  49  can be changed. 
     As shown in  FIGS. 5(A) and 5(B) , the bolt insertion through holes of the flange connection fastening members  50  are formed in the locked units  11   a  and  9   a . The bolt insertion through holes of the flange connection fastening members  50  are spaced apart from each other at equal angles of 36° and formed at 10 places in the circumferential direction. 
     As shown in  FIG. 1(A) , a sensor installation hole  68  for an exhaust sensor is formed in the peripheral wall of the exhaust outlet-side casing unit  7 . An exhaust gas temperature sensor for detecting the temperature of an exhaust gas on the lower stream side of the DPF can be disposed in the sensor installation hole  68 . 
     Second and third embodiments shown in  FIGS. 14 to 27  relate to a diesel engine having an exhaust gas treatment apparatus attached thereto, which is specialized for a tractor. The diesel engine is mounted on the following tractor vehicle  102 . 
     As shown in  FIG. 20 , the tractor vehicle  102  includes an engine body  1 , a clutch housing, a transmission casing, a front axle frame  105 , and so on which are coupled in series. A bonnet  107  is formed to generally surround various equipments attached to its peripherals, engine auxiliary equipments, etc. starting from the engine body  1 . The ceiling unit  107   a  of the bonnet  107  is configured to be the highest in its back part and lowered in its front part. That is, the ceiling unit  107   a  is disposed in a tilt fashion in which the back part becomes gradually high from the front part to the back part. 
     Furthermore, as shown in  FIG. 20 , a cabin  108  is disposed above the tractor vehicle  102  in the back side of the engine body  1 , and a cockpit having a handle and a driver&#39;s seat disposed therein is formed in the cabin  108 . 
     The engine body  1  has a crank shaft center line  16  disposed in the forward and backward directions. An engine cooling fan  18 , a radiator  112 , a battery  113 , and the like are disposed above the front axle frame  105  in front of the engine body  1 . 
     As shown in  FIG. 20 , a shroud  115  of a cylindrical shape is backwardly protruded in the radiator  112 . The front part of the engine cooling fan  18  is disposed within the shroud  115 . Furthermore, an air cleaner  116  is disposed above the battery  113 . A clean air suction pipe  118  led out from the air cleaner  116  is coupled to the suction manifold  56  of the engine body  1  shown in  FIG. 18  so that it communicates therewith. 
     The construction of the second embodiment shown in  FIGS. 14 to 20  is described below. 
     As shown in  FIG. 15 , the EGR apparatus has an EGR cooler  60  and an EGR gas lead-out pipe  135  disposed in an EGR gas lead-out passage  133  and an EGR valve casing  59  disposed on the down stream side of the EGR gas lead-out pipe  135 . As shown in  FIG. 18 , an EGR gas inlet pipe  137  is led out from the suction manifold  56 . 
     A shown in  FIG. 15 , an exhaust gas treatment apparatus  4  is coupled to a super charger  62 , attached to an exhaust manifold  55 , through a flange. The exhaust gas treatment apparatus  4  is a DPF muffler, but it has a larger external size and heavier weight than a conventional muffler. The weight of the exhaust gas treatment apparatus  4  is 20 to 30 Kg which is 4 to 6 times greater than that of the conventional muffler. 
     As shown in  FIG. 15 , the exhaust gas treatment apparatus  4  is disposed above the back part of the engine body  1  covering the bonnet  107  so that the length direction of the exhaust gas treatment apparatus  4  is oriented left and right. The exhaust gas treatment apparatus  4  is disposed in the space having the largest gap in the upper and lower directions between the engine body  1  and the ceiling unit  107   a  of the bonnet  107 . 
     As shown in  FIG. 16 , as in the first embodiment, the casing of the exhaust gas treatment apparatus  4  is divided into three parts; a DPF accommodation casing unit  5 , an exhaust inlet-side casing unit  6  on the left side, and an exhaust outlet-side casing unit  7  on the right side. Connection flanges  8  and  9  are formed in the DPF accommodation casing unit  5  placed in a central portion and configured to flange-couple the casing units  6  and  7  on the left and right sides. Connection flanges  10  and  11  corresponding to the connection flanges  8  and  9  are formed at the respective end portions of the casing units  6  and  7  on the left and right sides. The casing units  6  and  7  on the left and right sides are coupled to the DPF accommodation casing unit  5  placed in a central portion by means of the connection flanges  8  and  10  and the connection flanges  9  and  11 . 
     As shown in  FIG. 19 , an exhaust inlet pipe  48  is downwardly protruded from the exhaust inlet-side casing unit  6  on the left side and coupled to the exhaust manifold  55  of the engine body  1  through the super charger  62 . An exhaust outlet pipe  49  is downwardly led out from the exhaust outlet-side casing unit  7  on the right side and coupled to an exhaust pipe  150 . A longitudinal pipe  149  shown in  FIGS. 14 and 17  is coupled to the exhaust pipe  150 . The longitudinal pipe  149  is disposed on the side of a back part of the engine body  1 . As shown in  FIG. 16 , a muffler element  151 , such as a DPF  17 , is accommodated in the casing of the exhaust gas treatment apparatus  4 . 
     The sizes of the engine body  1  and the exhaust gas treatment apparatus  4  are compared below. Assuming that, in case of the engine body  1  having 3800 cc, for example, the front and rear width L 1  of the engine body  1  is 600 mm, the front and rear width L 2  of the engine body  1  including a flywheel housing  51  is 738 mm, and the height H of the engine body  1  is 826 mm as shown in  FIG. 15 , the diameter R 1  of the exhaust gas treatment apparatus  4  is 300 mm as shown in  FIG. 15 , the diameter R 2  of the connection flanges  9  and  11  of the exhaust gas treatment apparatus  4  is 340 mm and the left and right width W of the exhaust gas treatment apparatus  4  is 560 mm as shown in  FIG. 16 , and the diameter R 1  of the exhaust gas treatment apparatus  4  is about ⅓ of the height H of the engine body  1 . 
     As shown in  FIG. 14 , a single support bracket  12  which is long in the forward and backward directions is disposed at the lower side of the middle part of the exhaust gas treatment apparatus  4  in the left and right directions. The exhaust gas treatment apparatus  4  is placed on the back side of the support bracket  12 . The front and back parts of the support bracket  12  are detachably coupled to respective support stays  2  and  3  attached to the front and back sides of the engine body  1 . The support stays  2  and  3  are attached to respective connection flanges  8  and  9  on the left and right sides of a DPF accommodation casing  5  placed in a central portion through respective installation members  155  and  156  disposed on the left and right sides and configured to have a ‘ ’ shape. 
     As shown in  FIG. 19 , the installation members  155  and  156  on the left and right sides include respective lower wall portions  155   a  and  156   a  of a horizontal shape, respective fixed wall portions  155   b  and  156   b  raised from the external ends of the lower wall portions  155   a  and  156   a  in the left and right directions, and respective installation wall portions  155   c  and  156   c  raised from the internal ends of the lower plate units  155   a  and  156   a  in the left and right directions. 
     As shown in  FIG. 19 , the fixed wall portions  155   b  and  156   b  of the installation members  155  and  156  on the left and right sides are assembled with the respective lower portions of the connection flanges  8  and  9  on the left and side of the DPF accommodation casing unit  5  placed in a central portion and then fastened by bracket installation fastening members  25  and  25 . The installation wall portions  155   c  and  156   c  of the pair of installation members  155  and  156  have the support unit  12   d  of the support bracket  12  inserted therebetween on both sides left and right, and they are then fastened by the bracket installation fastening members  25 . Accordingly, the support bracket  12  is attached to the connection flanges  8  and  9  on the left and right sides of the DPF accommodation casing unit  5  placed in a central portion through the installation members  155  and  156 . 
     The bracket installation fastening members  25  and  25  which fix the installation members  155  and  156  on the left and right sides to the connection flanges  8  and  9  on the left and right sides also serve as the flange connection fastening members  43  and  50 . 
     As shown in  FIGS. 15 and 18 , the locked units  10   a  and  11   a , such as the connection flanges  10  and  11  locked by the flange connection fastening members  43  and  50 , are spaced apart from each other at equal angles of 60° and placed at 6 places in the circumferential direction of the connection flanges  10  and  11 . 
     As shown in  FIG. 19 , the lower plate units  155   a  and  156   a , the fixed wall portions  155   b  and  156   b , and the installation wall portions  155   c  and  156   c  of the installation members  155  and  156  on the left and right sides are coupled by connection plates  159  and  160 . 
     As shown in  FIG. 14 , the front support stay  2  installed in the front part of the engine body  1  has a placement unit  2   b  of a horizontal form. The placement unit  2   b  couples the upper end portions of a pair of support legs  163  and  164  and a pair of support legs  163  and  164  on the left and right sides. 
     The lower portion of the support leg  163  on the left side is fixed to the left face of a cylinder head  19  of the front part of the engine body  1 , and the lower portion of the support leg  164  on the right side is fixed to the upper right portion of the front part of the engine body  1 . 
     As shown in  FIG. 15 , in a support stay  3  on the back side, the lower portion of a stay installation unit  3   a  having an upper and lower long belt form is fixed to the back side of the engine body  1 . A placement unit  3   b  forwardly curved in an ‘L’ form is formed at the top of the stay installation unit  3   a.    
     According to the second embodiment, in case where the exhaust gas treatment apparatus  4  is installed within the bonnet  107  as shown in  FIG. 15 , the support bracket  12  long in the forward and backward directions is previously attached to the lower side of a middle portion of the exhaust gas treatment apparatus  4  in the left and right directions, the support stays  2  and  3  on the front and back sides are previously installed in the front and rear portions of the engine body  1 , the front part of the support bracket  12  is placed in the placement unit  2   b  of the front stay  2 , the back part of the support bracket  12  is placed on the placement unit  3   b  of the rear support stay  3 , and the front and back parts of the support bracket  12  are fixed to the placement units  2   b  and  3   b  using bracket installation fastening members  14 , such as bolts. Accordingly, although the exhaust gas treatment apparatus  4  has a large size and heavy weight, the exhaust gas treatment apparatus  4  can be simply installed in the engine body  1 . 
     Furthermore, after the exhaust gas treatment apparatus  4  is installed, the front and back parts of the support bracket  12  supporting the weight of the exhaust gas treatment apparatus  4  are detachably coupled to the support stays  2  and  3  on the front and back sides which are installed in the front and back parts of the engine body  1 . Accordingly, although the exhaust gas treatment apparatus  4  has a large size and heavy weight, it can sufficiently stand self weight and a vibration of the tractor vehicle  102 , and the deformation and damage of the support bracket  12  can be prevented. Furthermore, the length direction of the exhaust gas treatment apparatus  4  is disposed in the left and right directions. Accordingly, more empty space can be secured as compared with a case in which the length direction of the exhaust gas treatment apparatus  4  is disposed in the forward and backward directions. Furthermore, since the longitudinal pipe  149  is disposed on the side of the back part of the engine body  1 , the front and rear distance from the front part of the exhaust gas treatment apparatus  4  to the longitudinal pipe  149  can be reduced, and thus space above the engine body  1  can be efficiently used. 
     Furthermore, as shown in  FIG. 19 , the connection flanges  8  and  9  are configured to flange-couple the casing units  6  and  7  on the left and right sides and formed in the DPF accommodation casing unit  5  placed in a central portion, and the support bracket  12  is installed on both sides of the connection flanges  8  and  9  on the left and right sides of the DPF casing unit  5  placed in a central portion through the installation members  155  and  156 . Accordingly, the support bracket  12  and the connection flanges  8  and  9  on the left and right sides can be easily coupled. Furthermore, the support bracket  12  can be robustly fixed and installed in the middle portion of the exhaust gas treatment apparatus  4  using the connection flanges  8  and  9  of the casing unit  5 . Accordingly, the deformation and damage of the support bracket  12  can be prevented. 
     Furthermore, as shown in  FIG. 15 , the bonnet  107  is formed with the ceiling unit  107   a  downwardly inclined, and the exhaust gas treatment apparatus  4  is disposed left and right at a position having the greatest gap between the engine body  1  and the back part of the bonnet  107 . Accordingly, the exhaust gas treatment apparatus  4  of a large size can be disposed in small space, and the weight of the tractor  102  itself can be well balanced on the front and back sides. 
     Other constructions or functions of the second embodiment are the same as those of the first embodiment, and the same elements as those of the first embodiment in  FIGS. 14 to 20  are assigned the same reference numerals as  FIGS. 1 to 13 . 
       FIGS. 21 to 27  show a third embodiment. A pair of support brackets  12   a  and  12   b  on the left and right sides are disposed in response to respective connection flanges  8  and  9  on the left and right sides of a DPF casing unit  5  placed in a central portion. The front parts of the pair of support brackets  12   a  and  12   b  are detachably coupled to the upper portion of a front support stay  2 . The back parts of the pair of support brackets  12   a  and  12   b  are detachably coupled to the upper portion of the rear support stay  3 . 
     As shown in  FIG. 26 , the support unit  12   d  of the support bracket  12   a  on the left side is assembled with the lower portion of the connection flange  8  on the left side of the DPF casing unit  5  placed in a central portion and fastened by bracket installation fastening members  25  and  25 . The support unit  12   d  of the support bracket  12   b  on the right side is assembled with the lower portion of the connection flange  9  on the right side of the DPF casing unit  5  placed in a central portion and fastened by bracket installation fastening members  25  and  25 . 
     The bracket installation fastening members  25  and  25  also serve as flange connection fastening members  43  and  50  and attach the support brackets  12   a  and  12   b  on the left and right sides to the connection flanges  8  and  9  on the left and right sides. 
     As shown in  FIGS. 22 and 25 , locked units  10   a  and  11   a , such as connection flanges  10  and  11  fastened by respective flange connection fastening members  43  and  50 , are spaced apart from each other at equal angles of 45° and placed at 8 places in the circumferential direction of the connection flanges  10  and  11 . 
     The back side of the front support stay  2  is reinforced by a reinforcement plate  76 . 
     The rear support stay  3  has an installation unit  3   a  and a placement unit  3   b  coupled by a reinforcement plate  80 . 
     According to the third embodiment, as in the second embodiment, although the exhaust gas treatment apparatus  4  has a large size and heavy weight, the exhaust gas treatment apparatus  4  can stand its weight and a vibration of the tractor vehicle  102 . Furthermore, the pair of support brackets  12   a  and  12   b  installed in the exhaust gas treatment apparatus  4  can detachably coupled to the support stays  2  and  3  on the front and back sides of the front and back parts of the engine body  1 . Accordingly, the exhaust gas treatment apparatus  4  can be easily installed in the engine body  1 . 
     Moreover, in the third embodiment, the pair of support brackets  12   a  and  12   b  on the left and right sides are disposed in response to the respective connection flanges  8  and  9  on the left and right sides of the DPF casing unit  5  placed in a central portion. The front parts of the pair of support brackets  12   a  and  12   b  on the left and right sides are detachably coupled to the upper portion of the front support stay  2 . The back parts of the pair of support brackets  12   a  and  12   b  on the left and right sides are detachably coupled to the upper portion of the rear support stay  3 , and the pair of support brackets  12   a  and  12   b  on the left and right sides are used. Accordingly, the exhaust gas treatment apparatus  4  can be easily and robustly installed through the pair of support brackets  12   a  and  12   b  on the left and right sides by using the connection flanges  8  and  9  on the left and right sides of the DPF casing unit  5  placed in a central portion. 
       FIG. 27  shows a modification example of the support bracket. The support unit  12   d  of support brackets  12   a  and  12   b  is divided into a support member body  81  and a fixing plate body  82  which is fixed to connection flanges  8  and  9  on the left and right sides of a DPF casing unit  5  placed in a central portion. The support member body  81  and the fixing plate body  82  are detachably fastened by a fixture, such as bolts. In the modification example, although the support member body  81  and the fixing plate body  82  are detached, the exhaust gas treatment apparatus  4  can be detached from the engine body  1 . Accordingly, periodic inspection can be easily performed on the exhaust gas treatment apparatus  4 . 
     Other constructions or functions of the third embodiment are the same as those of the first and second embodiments, and the same elements as those of the first and second embodiments in  FIGS. 21 to 27  are assigned the same reference numerals as those of  FIGS. 1 to 20 . 
     In the second embodiment of  FIGS. 14 to 20 , a single support bracket  12  is installed in the connection flanges  8  and  9  on the left and right sides of the DPF casing unit  5 , placed in a central portion, of the exhaust gas treatment apparatus  4  through the pair of installation members  155  and  156 . Furthermore, in the third embodiment of  FIGS. 21 to 26 , the support brackets  12   a  and  12   b  on the left and right sides are installed in the respective connection flanges  8  and  9  on the left and right sides of the casing unit  5  placed in a central portion of the exhaust gas treatment apparatus  4 . However, the support brackets  12 ,  12   a , and  12   b  may be installed only in one of the connection flanges  8  and  9  on the left and right sides of the casing unit  5  placed in a central portion of the exhaust gas treatment apparatus  4 . 
     The construction of a fourth embodiment shown in  FIGS. 28 to 30  is described below. 
     As shown in  FIGS. 28 and 29 , an exhaust gas treatment apparatus  4  is placed at a long posture in the left and right directions, and the DPF accommodation casing unit  5  of the exhaust gas treatment apparatus  4  is disposed on the upper back side of a flywheel housing  51  immediately after a head cover  20  attached to the upper portion of a cylinder head  19 . 
     A pair of support stays  71  and  72  on the left and right sides are installed in the rear portion of the engine body  1 . The support protrusions  32  and  33  of the connection flange  10  of an exhaust inlet-side casing unit  6  and of the connection flange  11  of an exhaust outlet-side casing unit  7  are installed in the pair of left and right support stays  71  and  72  using flange installation locking units  73  without using support brackets on the left and right sides. The flange installation locking units  73  are inserted into position adjustment holes, like the position adjustment holes  26  of the bracket installation fastening members  25 , and configured to pass therethrough. Furthermore, the positions of the flange installation locking units  73  can be adjusted in the upper and lower directions and the forward and backward directions. In addition, like the flange-fit concave units  38   a  and  38   b , flange fitting units  74  are installed in a pair of stays on the left and right sides. Lower edge portions, such as the connection flange  11 , are fitted into the fitting units  74 . 
     In the fourth embodiment, like the first embodiment, the DPF  17  is accommodated in the exhaust gas treatment apparatus  4 , and the engine cooling fan  21  is disposed in the front part of the engine body  1 . 
     Other constructions or functions of the fourth embodiment are the same as those of the first embodiment, and the same elements as those of the first embodiment in  FIGS. 28 to 30  are assigned the same reference numerals as those of  FIGS. 1 to 13 . 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.