Abstract:
A working vehicle includes an engine, a vehicle body frame on which the engine is mounted, an exhaust gas treatment device for treating exhaust gas of the engine, and a fixing base for fixing the exhaust gas treatment device, and the fixing base is separated from the engine by a gap. Furthermore, a support body for connecting the fixing base to the vehicle body frame is also separated from the engine by a gap. A bellows pipe for absorbing solid-borne sound is provided in an area where a suction pipe of the exhaust gas treatment device is connected to an exhaust manifold of the engine.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Japanese Patent Application No. 2012-213247, filed Sep. 26, 2012, the disclosure of which is hereby incorporated in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a working vehicle in which an exhaust gas treatment device for treating exhaust gas from an engine is disposed in the vicinity of the engine. 
         [0004]    2. Description of the Related Art 
         [0005]    JP 2010-216336A (see  FIG. 8 ) discloses a DPF (Diesel particulate filter: an example of an exhaust gas treatment device) that is disposed above an engine. An exhaust gas inlet pipe of the DPF includes an upper pipe portion that extends horizontally from the DPF and a lower pipe portion that extends vertically from an extended end of the upper pipe portion, and the exhaust gas inlet pipe is an elbow pipe that is bent at a right angle as a whole. The exhaust gas inlet pipe is further connected to an exhaust communicating pipe via a bolt flange coupling. This DPF is coupled to a cylinder head, that is to say, an engine housing via a support block body having a rigid structure. 
         [0006]    US Patent Application Publication No. 2011/0167808 discloses an exhaust gas treatment device that is disposed above an engine and fixed to the engine via two support stays and one support flange. An exhaust pipe connected to the engine is bent at a right angle such that a terminal portion of the exhaust gas pipe is opened upward, and the exhaust pipe is coupled to an exhaust gas introduction pipe that extends downward from the exhaust gas treatment device via a bolt flange coupling. 
         [0007]    US Patent Application Publication No. 2012/0102932 discloses a DPF that is disposed on the side of a flywheel housing coupled to an engine body and fixed to the flywheel housing via a bracket leg. An exhaust gas inlet pipe that extends radially from the DPF is coupled, via a bolt flange coupling, to an exhaust gas discharge pipe that is coupled to an exhaust manifold of the engine. 
         [0008]    As mentioned above, a conventional exhaust gas treatment device, which is fixed to an engine or an engine accessory via a support member, is inconvenient in that vibration of the engine is transmitted directly to the exhaust gas treatment device via a support member. However, the exhaust gas treatment device needs to be disposed in the vicinity of the engine, giving consideration to a limited space of the engine room, and therefore, a structure in which the exhaust gas treatment device is supported by a member other than the engine or the engine accessory has not been employed. 
       SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention is to provide a structure for supporting an exhaust gas treatment device of a working vehicle such that vibration of an engine is not easily transmitted to the exhaust gas treatment device. 
         [0010]    To achieve the above-stated object, a working vehicle according to an aspect of the present invention includes: an engine; a vehicle body frame on which the engine is mounted; an exhaust gas treatment device for treating exhaust gas of the engine; and a fixing base for fixing the exhaust gas treatment device, and the fixing base is separated from the engine by a gap. Furthermore, a support body for connecting the fixing base to the vehicle body frame is also separated from the engine by a gap. A bellows pipe for absorbing solid-borne sound is provided in a connection area where a suction pipe of the exhaust gas treatment device is connected to an exhaust manifold of the engine. 
         [0011]    With this configuration, the exhaust gas treatment device is coupled to the engine serving as a vibration source via the vehicle body frame, the support body, and the fixing base, and accordingly, the vibration from the engine reaches the exhaust gas treatment device only after propagating through these three members. In particular, since the vibration propagation path includes the highly rigid vehicle body frame that is not very likely to resonate, the vibration that ultimately occurs on the exhaust gas treatment device is lower than that in the conventional structure. Furthermore, a passage for sending exhaust gas from the engine to the exhaust gas treatment device necessarily exists between the engine and the exhaust gas treatment device, and therefore, the vibration of the engine reaches the exhaust gas treatment device after passing through this passage. This additional vibration propagation (solid-borne sound) is attenuated due to absorption by the bellows pipe provided in the connection area where the suction pipe of the exhaust gas treatment device is connected to the exhaust manifold of the engine. 
         [0012]    Depending on the working vehicle, the vehicle body frame includes an engine mounting frame and a mission case that is connected to a rear part of the engine mounting frame. In this case, the configuration of the support body may be one selected from the configuration in which it is fixed to the engine mounting frame and the configuration in which it is fixed to the mission case, in accordance with conditions such as an installation space. 
         [0013]    In the case where the exhaust gas treatment device is disposed above the engine, the fixing base will also be located above a rear part of the engine. In this embodiment, the support body formed as a columnar body is convenient. In this case, it is preferable to prepare a first columnar member standing up from the vehicle body frame along one side face of the engine, and a second columnar member standing up from the vehicle body frame along another side face of the engine. With this configuration, a gate-shaped frame is built by the first columnar member, the second columnar member, and the fixing base, and a high rigidity can be expected. 
         [0014]    In one preferable embodiment of the present invention, the suction pipe includes an upper pipe portion extending from a portion below a transverse cross-sectional center of the exhaust gas treatment device and being bent obliquely downward at an obtuse angle, and a lower pipe portion forming the connection area, and a depression angle of a pipe axis of the lower pipe portion relative to the exhaust gas treatment device is larger than that of the upper pipe portion. With this configuration, an ample free space between the exhaust gas treatment device and the suction pipe is obtained, compared with a case of employing a right-angle elbow pipe as the suction pipe of the exhaust gas treatment device, and it becomes easy to attach the exhaust gas treatment device itself and to attach other engine devices. 
         [0015]    If the bellows pipe is installed between the upper pipe portion and the lower pipe portion, the bellows pipe can absorb the vibration from the engine, and further absorb a position shift between the exhaust portion and the suction pipe at the time of connecting the suction pipe of the exhaust gas treatment device to the exhaust portion of the exhaust manifold, by means of bellows of the bellows pipe. 
         [0016]    In one preferable embodiment of the present invention, the lower pipe portion is provided with an upper flange, and a terminal of the exhaust manifold is provided with a lower flange connected to the upper flange so as to align a face of the lower flange with a face of the upper flange such that gas can flow. More preferably, a coupling face between the upper flange and the lower flange is an inclined face, and the inclined face is inclined such that a portion thereof close to the exhaust gas treatment device is at a lower position. The flange coupling face formed as an inclined face will function as a guide face during a work of installing the exhaust gas treatment device, which is convenient. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a right side view of a tractor. 
           [0018]      FIG. 2  is a vertical cross-sectional view of the right side of a motor portion. 
           [0019]      FIG. 3  is a plan view of the motor portion. 
           [0020]      FIG. 4  is a perspective view of the motor portion. 
           [0021]      FIG. 5  is a vertical cross-sectional view of the back side of the motor portion. 
           [0022]      FIG. 6  is a vertical cross-sectional view of the back side of a principal part showing a support structure of an exhaust gas treatment device. 
           [0023]      FIG. 7  is a vertical cross-sectional view of the left side of the principal part showing the support structure of the exhaust gas treatment device. 
           [0024]      FIG. 8  is an exploded perspective view of the principal part showing the support structure of the exhaust gas treatment device. 
           [0025]      FIG. 9  is an exploded perspective view of a principal part showing a configuration related to installation of the exhaust gas treatment device using a jig. 
           [0026]      FIG. 10  is an exploded perspective view of a principal part showing a configuration related to installation of the exhaust gas treatment device. 
           [0027]      FIG. 11  is an exploded perspective view of the principal part showing the configuration related to installation of the exhaust gas treatment device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    Embodiments of the present invention will be described below based on the drawings, using a tractor as an exemplary working vehicle according to the present invention. 
         [0029]    As shown in  FIG. 1 , the tractor described as an example in the present embodiment includes a motor portion  2  in the front half of a vehicle body frame  1 , and a driving section  3  is formed in the rear half of the vehicle body frame  1 . This tractor is a four-wheel drive vehicle and provided with front wheels  4  serving as steered wheels that can be driven on the left and right sides of the motor portion  2 , and rear wheels  5  serving as drive wheels that can be controlled on the left and right sides of the driving section  3 . 
         [0030]    The vehicle body frame  1  includes an engine frame  6 , a middle frame  9 , and a transmission case  10 . A water-cooled diesel engine (hereinafter referred to as an “engine”)  7  is mounted at the rear end of the engine frame  6 . A clutch housing  8  is coupled to the lower rear part of the engine  7 , and the transmission case (hereinafter referred to as a “TIM case”)  10  is coupled to the rear part of the clutch housing  8  via the middle frame  9 . The engine frame  6  includes a pair of left and right plate members, one of which will be referred to as a first engine frame  6  and the other will be referred to as a second engine frame  6 . These plate members will be collectively referred to as the engine frame  6  unless they need to be particularly distinguished. 
         [0031]    As shown in  FIGS. 1 to 5 , the motor portion  2  includes an engine room  12  formed by a hood  11  disposed in the front half of the vehicle body frame  1 . In this engine room  12 , a radiator  13 , an air cleaner  14 , and the like, which are peripheral equipment of the engine  7 , are accommodated together with the engine  7 . 
         [0032]    The hood  11  includes a pair of left and right side covers  15  that cover the sides of the engine  7  and the like, and an upper cover  16  that can be opened and closed and covers the engine  7  and the like from above. The left and right side covers  15  are mounted in a detachable manner respectively on the left and right sides of the engine  7  via a first support frame  17  that has an inverted U-shape and is installed on the clutch housing  8  in a standing manner, and the like. The upper cover  16  is coupled to the upper end of the first support frame  17  using a pair of left and right coupling portions  18  and a pair of left and right connecting pins  19  that are provided in the upper part of the rear end of the upper cover  16 . Thus, the upper cover  16  can pivot in the up-down direction so as to be opened and closed between a closed position at which it covers the motor portion  2  from above and an opened position at which it releases the motor portion  2 , around the left and right connecting pins  19  serving as a pivoting fulcrum. 
         [0033]    As shown in  FIG. 1 , the driving section  3  includes a passenger space that is demarcated by a cabin  20  mounted on the vehicle body frame  1  in a vibration-proofing manner. In the passenger space, a steering wheel  21  for steering the front wheels, a driver seat  22 , and the like are disposed. A ceiling portion of the cabin  20  is equipped with an indoor unit  23 A of an air-conditioning device  23 . 
         [0034]    In the rear part of the T/M case  10 , a pair of left and right lifting arms  24  that enable an elevating operation of a working machine (not shown), such as a rotary cultivation machine or a plow that is coupled to the rear part of the tractor, a hydraulic lift cylinder  25  that drives the left and right lifting arms  24  in the up-down direction to pivot, a PTO shaft  26 , and the like are disposed. The PTO shaft  26  powers a driven-type working machine, such as a rotary cultivation machine that is coupled to the rear part of the tractor. 
         [0035]    As shown in  FIGS. 2 to 4 , the first support frame  17  supports a resin fuel tank  27  that is disposed in the vicinity of the rear side of the engine  7 , a partition  28  that is disposed between the engine  7  and the fuel tank  27  so as to divide the engine room  12  into an engine side and a fuel tank side, and the like. 
         [0036]    As shown in  FIGS. 1 to 7 , the second support frame  30 , which supports a cylindrical exhaust gas purification device  29  that is disposed above the engine  7  and serves as an exhaust gas treatment device  29 , is installed in the rear part of the engine frame  6  in a standing manner. A third support frame  37 , which supports a compressor  31 , a capacitor  32 , and a receiver  33  that constitute an outdoor unit  23 B of the air-conditioning device  23 , as well as a battery  34 , a reserve tank  35 , an oil cooler  36 , and the like, is installed in the front part of the engine frame  6  in a standing manner. 
         [0037]    As shown in  FIGS. 3 ,  5 , and  6 , the exhaust gas purification device  29  includes a DPF (Diesel Particulate Filter)  38  on the inside thereof, and the DPF  38  collects particulate matter contained in exhaust gas of the engine  7  and removes it from exhaust gas. An oxidation catalyst  39  is disposed on the upstream side in the exhaust direction of the DPF  38  inside the exhaust gas purification device  29 . The oxidization capability of nitrogen dioxide generated by the oxidation catalyst  39  is used to burn the particulate matter collected by the DPF  38  at a relatively low temperature and remove it. With this configuration, the DPF  38  can be continuously regenerated. 
         [0038]    As shown in  FIGS. 2 to 8  and  10 , the exhaust gas purification device  29  is disposed with its longitudinal direction being parallel to the left-right direction (vehicle cross-sectional direction) so as to face the left and right sides, that is to say, such that the oxidation catalyst  39  on the upstream side in the exhaust direction is located on the left side of the vehicle body and the DPF  38  on the downstream side in the exhaust direction is located on the right side of the vehicle body. The exhaust gas purification device  29  is located above the engine  7  and between the air cleaner  14  and the fuel tank  27 . The left end of the exhaust gas purification device  29  is provided with a suction pipe  40  that extends from the rear part of the exhaust gas purification device  29  toward the lower rear side. The suction pipe  40  is connected to an exhaust portion  41 A of an exhaust manifold  41  that is disposed on the upper left part of the engine  7 . The connection between the suction pipe  40  and the exhaust portion  41 A is realized by aligning a face of an upper flange  42  that has an equilateral triangular shape and is provided at an extended end of the suction pipe  40  with a face of a lower flange  43  that has an equilateral triangular shape and is provided as a connecting portion for exhaust of the exhaust portion  41 A, and bolting the upper flange  42  with the lower flange  43 . The bolt-coupling between the flanges  42  and  43  is performed using three round holes  42   a  bored at included-angle portions of the flange  42  of the suction pipe  40 , and three weld bolts  43   a  installed in a standing manner at included-angle portions of the flange  43  of the exhaust portion  41 A. The right end of the exhaust gas purification device  29  is provided with an exhaust pipe connecting portion  29 A that extends frontward from the front end of the exhaust gas purification device  29 , and an exhaust pipe  44  is connected to the exhaust pipe connecting portion  29 A. The exhaust pipe  44  extends from the exhaust pipe connecting portion  29 A toward a part on the right side of the engine frame  6 , and the extended end of the exhaust pipe  44  is located below the third support frame  37 . 
         [0039]    As shown in  FIGS. 2 ,  5 ,  7 ,  8 ,  10 , and  11 , the suction pipe  40  includes an upper pipe portion  40 A, a lower pipe portion  40 B, and a bellows portion  40 Ba. The upper pipe portion  40 A extends at a downward-inclined orientation toward the lower rear side from the rear part of the left end of the exhaust gas purification device  29 . An end of the bellows portion  40 Ba is connected to the upper pipe portion  40 A, and the other end of the bellows portion  40 Ba is connected to the lower pipe portion  40 B. The bellows portion  40 Ba may be formed as a part of the upper pipe portion  40 A and/or the lower pipe portion  40 B. The upper pipe portion  40 A is formed as a bent pipe that extends from a portion below the transverse cross-sectional center of the exhaust gas purification device  29  and is bent obliquely downward at an obtuse angle. In  FIG. 11 , the average angle of its downward inclination relative to the exhaust gas purification device  29  is denoted by θ1. The lower pipe portion  40 B is formed as a straight pipe, and the angle of its downward inclination relative to the exhaust gas purification device  29  is denoted by θ2. In this embodiment, θ2 is set to be larger than θ1, and the suction pipe  40  produces a free space FS between the suction pipe  40  and the exhaust gas purification device  29  while shortening a gap from the exhaust gas purification device  29  in the vehicle longitudinal direction. 
         [0040]    With this configuration, the extension of the bent portion of the suction pipe  40  toward the upper rear side can be further suppressed without bringing the flange  42  provided at the extended end of the suction pipe  40  close to the exhaust gas purification device  29 , in comparison with in a case where, for example, the suction pipe  40  is formed so as to be bent at a right angle and thus have a horizontal upper pipe portion and a vertical lower pipe portion. Therefore, owing to the suppression of the extension of the suction pipe  40 , it is possible in this tractor to cause the fuel tank  27  disposed on the rear side of the engine  7  and the exhaust gas purification device  29  to protrude, at its upper side located on the rear side of the exhaust gas purification device  29 , toward the exhaust gas purification device  29 , and is possible to dispose the fuel tank  27  close to the exhaust gas purification device  29 . 
         [0041]    As a result, the fuel tank  27 , which is part of the peripheral equipment of the engine  7 , is installed in a compact state in which the fuel tank  27  is brought close to the rear side of the engine  7  while an increase in the capacity of the fuel tank  27  is achieved, without causing inconveniences such as difficulty in connecting the flange  43  on the exhaust manifold side to the flange  42  on the exhaust gas purification device side due to the flange  42  provided at the extended end of the suction pipe  40  being disposed close to the exhaust gas purification device  29 , and without causing inconveniences such as a higher installation height of the exhaust gas purification device  29  installed above the engine  7  and a higher height of the hood  11  covering the engine  7  and the exhaust gas purification device  29  due to extending length of downward extension of the suction pipe  40  for facilitating this connection. 
         [0042]    Further, the overall length of the suction pipe  40  can be shortened by forming the suction pipe  40  so as to be bent at an obtuse angle, compared with a case where, for example, the suction pipe  40  is formed so as to be bent at a right angle. With this configuration, heat energy loss can be suppressed when exhaust gas is supplied from the exhaust manifold  41  to the DPF  38  of the exhaust gas purification device  29 , and removal of particulate matter collected by the DPF  38  by combustion is facilitated. 
         [0043]    As a result, the DPF  38  can be desirably regenerated, and particulate matter contained in exhaust gas of the diesel engine can be efficiently removed. 
         [0044]    As shown in  FIGS. 5 ,  6 , and  8  to  10 , the upper flange  42  on the exhaust gas purification device side and the lower flange  43  on the exhaust manifold side, which are each formed in an equilateral triangular shape, are provided on the suction pipe  40  of the exhaust gas purification device  29  or the exhaust portion  41 A of the exhaust manifold  41  in a state where the orientation of one side of the upper and lower flanges  42  and  43  is set to form their front end on the exhaust gas purification device side. 
         [0045]    With this configuration, bolt-coupling between the upper flange  42  and the lower flange  43  is facilitated. 
         [0046]    As shown in  FIGS. 2 and 7 , the coupling face of the upper flange  42  and the lower flange  43  is set at a rear-raised orientation at which the coupling face is inclined toward the exhaust gas purification device side so as to extend toward the exhaust gas purification device  29 . 
         [0047]    That is to say, the coupling face of the upper flange  42  and the lower flange  43  is an inclined face, and this inclined face is inclined such that a portion close to the exhaust gas purification device  29  is at a lower position. 
         [0048]    This configuration further facilitates bolt-coupling between the upper flange  42  and the lower flange  43 . 
         [0049]    As shown in  FIGS. 2 to 5 ,  7 , and  8  to  10 , the suction pipe  40  includes the bellows portion  40 Ba. With this configuration, a position shift between the flange  42  on the suction pipe side and the flange  43  on the exhaust manifold side at the time of connecting the flange  42  on the suction pipe side to the flange  43  on the exhaust manifold side can be absorbed by the bellows portion  40 Ba. Further, vibration of the engine  7  is absorbed by the bellows portion  40 Ba, propagation of the vibration to the exhaust gas purification device  29  reduces, and vibrating movement of the exhaust gas purification device  29  caused by the vibration of the engine  7  is suppressed. 
         [0050]    As shown in  FIGS. 2 to 10 , the second support frame  30  includes a stage unit  45  on which the exhaust gas purification device  29  is placed, and a support body  46  for receiving and supporting the stage unit  45  from below. In this embodiment, the support body  46  includes a first column  461  and a second column  462  that are fixed respectively to the rear parts of the first engine frame  6  and the second engine frame  6  that constitute the engine frame  6 . The stage unit  45  is installed so as to span from the upper end of the first column  461  to the upper end of the second column  462 . That is to say, the second support frame  30  is formed as an overall gate-shaped frame that spans across the engine  7  in the left-right direction. Note that the first column  461  and the second column  462  have substantially the same shape and the same function, and will be referred to simply as the column  46  unless they need to be particularly distinguished. 
         [0051]    With this configuration, the exhaust gas purification device  29  that is large and heavy due to provision of the DPF  38 , the oxidation catalyst  39 , and the like can be stably supported in a state of being separate from the engine  7  by the firm second support frame  30  that substantially has a gate-shape. 
         [0052]    Since the exhaust gas purification device  29  is not supported by the engine  7 , inconveniences such as the weight of the heavy exhaust gas purification device  29  being applied to the engine  7 , the large and heavy exhaust gas purification device  29  vibrating integrally with the engine  7 , and the like are eliminated. As a result, it is possible to reduce the possibility of causing damage to the exhaust gas purification device  29  or the like caused by the vibration of the engine  7 , loosening of the coupling portions involved in support of the engine  7  and the exhaust gas purification device  29 , or the like. 
         [0053]    As shown in  FIGS. 2 to 8  and  10 , the stage unit  45  has a two-division structure, that is to say, the stage unit  45  can be divided into a fixing base  47  to which the exhaust gas purification device  29  is coupled with bolts, and a coupling portion  48  that is made of a metal plate and couples the right end of the fixing base  47  to the upper end of the second column  462  on the right side. The fixing base  47  includes a base plate  47 A that is made of a metal plate and formed to be bent in a U-shape as viewed from the side, and this base plate  47 A has left and right coupling members  47 B and  47 C for bolt-coupling to the exhaust gas purification device  29 , and the like. The base plate  47 A has, in two (front and rear) parts of its left end, bolt-coupling portions  47   a , each of which includes weld nuts that enable bolt-coupling to the upper end of the left column  46 , and the like. In two (front and rear) parts of the right end of the base plate  47 A, round holes  47   b  serving as engaging portions A to engage with the coupling portion  48  are bored. In two (front and rear) parts of the right end of the coupling portion  48 , elongated holes  48   a  that are elongated in the left-right direction and enable bolt-coupling to the upper end of the left column  46  are bored. Further, in two (front and rear) parts of the left end of the coupling portion  48 , weld bolts  48   b  serving as engaged portions B to engage with the fixing base  47  are provided in a standing manner. 
         [0054]    The two (front and rear) round holes  47   b  bored in the fixing base  47  and the two (front and rear) weld bolts  48   b  installed on the coupling portion  48  in a standing manner are configured such that the positioning of the fixing base  47  in the lateral direction (horizontal direction) relative to the coupling portion  48  is performed by means of engagement therebetween. After the positioning, the fixing base  47  is fixed to the coupling portion  48  by the nuts  49  being screwed onto the respective weld bolts  48   b.    
         [0055]    That is to say, a coupling mechanism C for fixing the fixing base  47  to the coupling portion  48  includes the two (front and rear) round holes  47   b  of the fixing base  47 , the front and rear weld bolts  48   b  of the coupling portion  48 , and the two nuts  49  that are screwed with the weld bolts  48   b.    
         [0056]    As shown in  FIGS. 2 and 4  to  10 , a support plate  46 A for receiving and supporting the stage unit  45  from below is welded at the upper end of each column  46  at an orientation at which the longitudinal direction of the support plate  46 A is parallel to the front-rear direction. Elongated holes  46   a  that are elongated in the left-right direction and enable bolt-coupling to the fixing base  47  are bored in two (front and rear) parts of the left support plate  46 A. Each elongated hole  46   a  has a larger diameter than that of a screw hole of the corresponding bolt-coupling portion  47   a  of the fixing base  47 . The right support plate  46 A has, in two (front and rear) parts thereof, bolt-coupling portions  46   b  each including a weld nut that enables bolt-coupling to the coupling portion  48 , and the like. The elongated holes  48   a  of the coupling portion  48  that correspond to each bolt-coupling portion  46   b  have a larger diameter than that of a screw hole of the bolt-coupling portion  46   b.    
         [0057]    That is to say, in the second support frame  30 , the two (front and rear) elongated holes  46   a  bored in the support plate  46 A of the left column  46 , and the two (front and rear) elongated holes  48   a  provided in the coupling portion  48  of the stage unit  45  constitute, due to having leeway with respect to the screw holes of the corresponding bolt-coupling portions  47   a  and  46   b , a lateral adjustment mechanism D that enables position adjustment of the exhaust gas purification device  29  in the lateral direction (horizontal direction) relative to the engine  7 , between the stage unit  45  and the left and right columns  46 . 
         [0058]    On the other hand, coupling plates  46 B, which are coupled with bolts to left and right brackets  50  installed so as to project outward in the lateral direction in the rear part of the engine frame  6 , are welded onto the lower end of the respective columns  46 . Elongated holes  46   c  that are elongated in the up-down direction and enable bolt-coupling to the corresponding brackets  50  are bored in two (front and rear) parts of each coupling plate  46 B. Each bracket  50  has, in two (front and rear) parts thereof, bolt-coupling portions  50   a  each including a weld nut that enables bolt-coupling to the corresponding coupling plate  46 B, and the like. A tool insertion hole  46   d  having a circular shape with a large diameter is bored in a part of each column  46  facing the elongated hole  46   c.    
         [0059]    With this configuration, on the second support frame  30 , the two (front and rear) elongated holes  46   c  bored in the brackets  50  constitute a vertical adjustment mechanism E that enables position adjustment of the exhaust gas purification device  29  in the vertical direction relative to the engine  7 , between the engine frame  6  and the left and right columns  46 . 
         [0060]    That is to say, since the second support frame  30  in this tractor includes the lateral adjustment mechanism D and the vertical adjustment mechanism E, the positioning of the exhaust gas purification device  29  relative to the engine  7  can be easily performed, even though it is supported by the second support frame  30  in a state of being separate from the engine  7 , as described above. In other words, when the exhaust gas purification device  29  is installed, even if a position shift occurs between the flange  43  serving as a connecting portion for exhaust provided on the engine  7  and the flange  42  provided on the suction pipe  40  serving as a suctioning portion of the exhaust gas purification device  29 , the positioning in the lateral direction (horizontal direction) and in the vertical direction between the flange  43  on the engine side and the flange  42  on the exhaust gas purification device side can be easily performed by the lateral adjustment mechanism D and the vertical adjustment mechanism E. 
         [0061]    Since the flange  43  on the engine side and the flange  42  on the exhaust gas purification device side can be easily and appropriately connected, it is possible to avoid possible damage to the bellows portion  40 Ba or the like due to a stress concentrating on the bellows portion  40 Ba provided on the suction pipe  40  of the exhaust gas purification device  29 , for example, resulting from inappropriate connection between the flange  43  on the engine side and the flange  42  on the exhaust gas purification device side. 
         [0062]    As shown in  FIG. 9 , when the exhaust gas purification device  29  is installed, position adjustment of the exhaust gas purification device  29  relative to the engine  7  is performed using a jig  51  in place of the fixing base  47  on which the exhaust gas purification device  29  is mounted. 
         [0063]    This jig  51  has a positioning flange  51 C in an equilateral triangular shape, which corresponds to the flange  42  on the exhaust gas purification device side, in the left rear part of a metal plate member  51 A, which corresponds to the fixing base  47  of the stage unit  45 , via a support arm  51 B. Positioning round holes  51   a , in which the weld bolts  43   a  installed on the flange  43  on the engine side in a standing manner are allowed to be inserted, are bored at included-angle portions of the positioning flange  51 C. Further, positioning round holes  51   b , which serve in place of the bolt-coupling portions  47   a  of the fixing base  47 , are bored in two (front and rear) parts of the left end of the metal plate member  51 A. Furthermore, positioning round holes  51   c , which can engage with the two weld bolts  48   b  of the coupling portion  48  similarly to the round holes  47   b  of the fixing base  47 , are bored in two (front and rear) parts of the right end of the metal plate member  51 A. The positional relationship between the three round holes  51   a  of the positioning flange  51 C and the four round holes  51   b  and  51   c  of the metal plate member  51 A is the same as the positional relationship between the two bolt-coupling portions  47   a  and two round holes  47   b  of the fixing base  47  and the three round holes  42   a  of the flange  42  on the exhaust gas purification device side of the fixing base  47  on which the exhaust gas purification device  29  is mounted in a fixed manner. 
         [0064]    That is to say, the positioning flange  51 C of the jig  51  functions as a positioning mechanism F for exhaust that can perform positioning relative to the flange  43  serving as the connecting portion for exhaust provided on the engine  7 . The two (front and rear) round holes  51   c  on the right side function as an engaging mechanism G for performing positioning in the lateral direction (horizontal direction) relative to the coupling portion  48  by engaging with the two weld bolts  48   b  serving as the engaged portions B of the coupling portion  48 . 
         [0065]    Installation of the exhaust gas purification device  29  will now be described based on  FIGS. 6 and 8  to  10 . Initially, the left and right columns  46  are temporarily installed on the engine frame  6  using the two (front and rear) bolt-coupling portions  50   a  provided on the left and right brackets  50  of the engine frame  6 , the two (front and rear) elongated holes  46   c  (vertical adjustment mechanism E) that are provided in the coupling plates  46 B of the columns  46  and extend in the up-down direction, and the like. Next, the coupling portion  48  of the stage unit  45  is temporarily installed on the support plate  46 A provided at the upper end of the right column  46  using the two (front and rear) bolt-coupling portions  46   b  provided in the support plate  46 A and the two (front and rear) elongated holes  48   a  (lateral adjustment mechanism D) that are provided in the coupling portion  48  and extend in the left-right direction. 
         [0066]    After the above temporal installation, the jig  51  is used in place of the fixing base  47  on which the exhaust gas purification device  29  is mounted. The two (front and rear) round holes  51   c  (engaging mechanism G) provided at the right end of the jig  51  engage with the two (front and rear) weld bolts  48   b  provided on the coupling portion  48 , and the three round holes  51   a  provided in the positioning flange  51 C engage with the three weld bolts  43   a  provided on the flange  43  (connecting portion for exhaust) on the engine side. Furthermore, the jig  51  is fixed to the coupling portion  48  and the support plate  46 A of the left column  46  such that the two (front and rear) round holes  51   b  provided at the left end of the jig  51  face the two (front and rear) elongated holes  46   a  provided in the support plate  46 A of the left column  46 , using the two (front and rear) elongated holes  48   a  of the coupling portion  48  and the two (front and rear) elongated holes  46   a  provided in the support plate  46 A of the left column  46 . 
         [0067]    The positioning in the lateral direction (horizontal direction) of the jig  51  (positioning flange  51 C) relative to the engine  7  (flange  43 ) is thereby performed easily and appropriately. 
         [0068]    Next, the position adjustment in the vertical direction of the jig  51  relative to the engine  7  is performed by adjusting the position of the columns  46  in the vertical direction relative to the engine frame  6  using the two (front and rear) elongated holes  46   c  of the columns  46  such that the flange  43  on the engine side and the positioning flange  51 C (positioning mechanism F) of the jig  51  are in a joined state. At the stage where the joined state is achieved, the left and right columns  46  are ultimately fixed to the engine frame  6 . 
         [0069]    It is thereby possible to appropriately install the left and right columns  46  on the engine frame  6  in a standing manner. 
         [0070]    Thereafter, the coupling portion  48  of the stage unit  45  is ultimately fixed to the support plate  46 A of the right column  46 . It is thereby possible to appropriately install the coupling portion  48  of the stage unit  45  on the right column  46 . 
         [0071]    Consequently, the jig  51  is disposed at an appropriate position relative to the engine  7  by the left and right columns  46  installed on the engine frame  6  in a standing manner and the coupling portion  48  installed on the right column  46 . 
         [0072]    Next, the engagement between the three weld bolts  43   a  provided on the flange  43  on the engine side and the three round holes  51   a  provided in the positioning flange  51 C of the jig  51  is released, and the engagement between the two (front and rear) weld bolts  48   b  provided on the coupling portion  48  and the two (front and rear) round holes  51   c  provided at the right end of the jig  51  is released, thus removing the jig  51  from the coupling portion  48 . Thereafter, the fixing base  47  on which the exhaust gas purification device  29  is mounted in a fixed manner is fixed to the coupling portion  48  and the support plate  46 A of the left column  46 . At this time, the two (front and rear) round holes  47   b  provided at the right end of the fixing base  47  engage with the two (front and rear) weld bolts  48   b  provided on the coupling portion  48 , and the three round holes  42   a  provided in the flange  42  of the exhaust gas purification device  29  engage with the three weld bolts  43   a  provided on the flange  43  on the engine side. 
         [0073]    Thus, the stage unit  45  on which the exhaust gas purification device  29  is mounted in a fixed manner is appropriately installed so as to span between the left and right columns  46 , and the exhaust gas purification device  29  is located at an appropriate position relative to the engine  7 . As a result, the flange  42  of the exhaust gas purification device  29  can be accurately joined to the flange  43  on the engine side. 
         [0074]    Thereafter, the flange  42  of the exhaust gas purification device  29  is coupled with bolts to the flange  43  on the engine side using the three weld bolts  43   a  provided on the flange  43  on the engine side. The left end of the fixing base  47  is coupled with bolts to the support plate  46 A of the left column  46  using the two (front and rear) elongated holes  46   a  provided in the support plate  46 A of the left column  46  and the two (front and rear) round holes  51   b  provided at the left end of the fixing base  47 . Furthermore, the right end of the fixing base  47  is coupled with the bolts to the coupling portion  48  fixed to the right column  46  using the two (front and rear) weld bolts  48   b  provided on the coupling portion  48 . 
         [0075]    It is thereby possible to appropriately install the second support frame  30  for supporting the exhaust gas purification device  29  on the engine frame  6  in a standing manner. With the second support frame  30 , the exhaust gas purification device  29  can be supported at an appropriate position relative to the engine  7 . 
         [0076]    That is to say, it is possible to more easily and appropriately install the second support frame  30  to be installed on the engine frame  6  in a standing manner, support the exhaust gas purification device  29  with the second support frame  30  installed on the engine frame  6  in a standing manner, and connect the flange  43  on the engine side to the flange  42  of the exhaust gas purification device  29 , while achieving a reduction in effort needed for these tasks, by using the jig  51  that is more compact, lighter, and easier to handle than the fixing base  47  on which the exhaust gas purification device  29  is mounted in a fixed manner. 
         [0077]    The structure of the left and right columns  46  will now be described using  FIGS. 2 and 4  to  10 . An upper column member  46 C and a lower column member  46 D are welded in a state of being connected vertically via a relay member  46 E. In a state of being fixed to the engine frame  6 , the lower column member  46 D coupled to the engine frame  6  is at an inclined orientation at which it is inclined outward in the lateral direction of the vehicle, and the upper column member  46 C is at a vertical orientation. That is to say, the upper column member  46 C is bent inward of the vehicle relative to the lower column member  46 D. 
         [0078]    Thus, the horizontal width of the space that is secured above the engine frame  6  and where the engine  7  and the exhaust gas purification device  29  are disposed becomes longer. It is thereby possible to dispose a large exhaust gas purification device  29 . 
         [0079]    As shown in  FIGS. 2 and 4  to  10 , the column members  46 C and  46 D are each made of groove-shaped steel material having a first vertical wall portion  46   e  and a second vertical wall portion  46   f , and this groove faces the engine  7 . 
         [0080]    Each relay member  46 E is made of groove-shaped steel material, and this groove faces outward in the lateral direction of the vehicle and extends in the front-rear direction. The groove of the relay member  46 E is covered with a vertical wall member  46 G that is made of a metal plate and formed in a bent shape. Thus, a through-hole  46 F is produced that passes through a vertically intermediate portion of each column  46  in the front-rear direction. 
         [0081]    The vertical wall member  46 G is fixed with bolts to the first vertical wall portion  46   e  in a detachable manner. 
         [0082]    It is thereby possible to easily dispose utility pipes, which were disposed between the lateral sides of the engine  7  and the hood  11 , by passing the utility pipes through the through-hole  46 F even in a case where, for example, the left and right columns  46  are fixed to the engine frame  6  in a state of being close to the lateral sides of the engine in order to prevent the horizontal width of the hood  11  from unnecessarily increasing in size. Note that examples of the utility pipes include a wiring harness  52  that extends to electric parts such as the battery  34  and the indoor unit  23 A of the air-conditioning device  23 , a hot water hose  53  for circulating a cooling water (hot water) after cooling the engine as a heat medium through the motor portion  2  and the indoor unit  23 A of the air-conditioning device  23 , a refrigerant pipe  54  for circulating a coolant through the indoor unit  23 A and the outdoor unit  23 B of the air-conditioning device  23 , and the like. 
         [0083]    Upper and lower wall portions  46   h  and  46   i  that are provided in each relay member  46 E and border the through-hole  46 F function as a face for guiding or supporting the utility pipes. If the utility pipes are made of a material that absorbs vibration, such as elastic hoses, vibration that propagates through the wall face of the through-hole  46 F can be absorbed as a result of the utility pipes coming in close contact with the wall face. 
         [0084]    Moreover, the vertical wall member  46 G covering each through-hole  46 F is detachable from the column  46 , which is convenient for tasks of installation and maintenance of the utility pipe. 
         [0085]    As shown in  FIGS. 2 and 5  to  8 , the lower end portion of each second vertical wall portion  46   f  partially protrudes outward of the coupling plate  46 B. With this configuration, when the coupling plates  46 B provided at the lower end of the columns  46  are coupled to the left and right brackets  50  of the engine frame  6 , the positioning in the front-rear direction is realized as a result of the lower end portions of the front and rear second vertical wall portions  46   f  of the columns  46  coming in contact with the front end and the lower end of the corresponding brackets  50 . 
         [0086]    As shown in  FIGS. 1 to 5 , in a state where the left and right columns  46  are fixed, the through-holes  46 F are located upward of a lower edge  11   a  of the hood  11  covering the engine  7 , the exhaust gas purification device  29 , and the like. The utility pipes that are passed through the through-holes  46 F are thereby covered with the hood  11 . 
       Other Embodiments 
       [0087]    [1] The engine  7  may be a gasoline engine. Alternatively, it may be a diesel engine including a common-rail fuel injection system.
 
[2] The exhaust gas treatment device  29  may be a muffler, an exhaust gas purification device that only includes an oxidation catalyst, an exhaust gas purification device including the DPF  38  that carries a catalyst, or the like. Furthermore, the exhaust gas purification device including the DPF  38  may increase the temperature of exhaust gas that passes through the DPF  38  with post-injection after main injection by a fuel injection system, or include a heater for increasing the temperature of exhaust gas that passes through the DPF  38 . The orientation at which the exhaust gas treatment device  29  is installed may be modified in various manners. For example, the exhaust gas treatment device  29  may be disposed at an orientation in the front-rear direction of the vehicle.
 
[3] The suction pipe  40  of the exhaust gas treatment device  29  may be one in which the lower pipe portion  40 B thereof is formed in a bent state where it is vertically suspended at a vertical orientation toward the exhaust portion  41 A from the extended end of the upper pipe portion  40 A, which extends at a rear-lowered inclined orientation toward the lower rear side from the rear part of the exhaust gas purification device  29 . Alternatively, the suction pipe  40  may be constituted by an upper pipe portion  40 A that extends at a front-lowered inclined orientation toward the lower front side from the front part of the exhaust gas purification device  29 , and a lower pipe portion  40 B that extends at a larger depression angle than that of the upper pipe portion  40 A from the extended end of the upper pipe portion  40 A toward the exhaust portion  41 A. Furthermore, the suction pipe  40  may be constituted by an upper pipe portion  40 A that extends at a left-lowered or right-lowered inclined orientation from the left end or right end of the exhaust gas purification device  29  toward the lower left side or lower right side, and a lower pipe portion  40 B that extends at a larger depression angle than that of the upper pipe portion  40 A from the extended end of the upper pipe portion  40 A toward the exhaust portion  41 A.
 
         [0088]    The flange  42  on the exhaust gas purification device side and the flange  43  on the exhaust manifold side may be formed in a circular shape or in a square shape. Further, the joint face therebetween may be set to be horizontal. 
         [0089]    The working vehicle according to the present invention is applicable to various working vehicles including an exhaust gas treatment device, such as, for example, a tractor, a mowing machine, a combine harvester, a rice planting machine, a wheel loader, and a backhoe.