Patent Publication Number: US-8973976-B2

Title: Bulldozer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National stage application of International Application No. PCT/JP2013/059618, filed on Mar. 29, 2013. 
     BACKGROUND 
     The present invention relates to a work vehicle such as a bulldozer. 
     A bulldozer is known which is provided with a cab where a front side has a trapezoidal shape in a top view of the vehicle such that an operator can have sufficient visibility in the vicinity of both edge sides of the front of a working implement (blade) in order to dig and level ground with good accuracy using the bulldozer (refer to Japanese Patent No. 3180925 and Japanese Design Registration No. 1278235). 
     In recent years, there has been demand for cleaning of exhaust in work vehicles such as bulldozers from the viewpoint of the natural environmental protection. As a result, an exhaust treatment apparatus which is more advanced than a muffler in the related art is mounted in the work vehicle. For example, as the exhaust treatment apparatus, there is a diesel particulate filter (DPF) apparatus, a selective catalytic reduction (SCR) apparatus, or the like. The DPF apparatus reduces particulate matter in the exhaust. The SCR apparatus reduces nitrogen oxide (NOx) in the exhaust. The exhaust treatment apparatuses are heavier and have greater capacity than conventional apparatuses. 
     The capacity of an engine compartment is increased by mounting such exhaust treatment apparatuses. For this reason, it is not preferable to increase the width of the engine compartment, because an operator can hardly visually observe the vicinity of both edge sections of the front of a working implement. Alternatively, extension in the front and back length of the engine compartment causes the blade to be arranged away from (the center of gravity of) the vehicle. In this case, when the bulldozer runs across an uneven ground surface, the blade is considerably shaken vertically. Accordingly, the operation by the operator becomes difficult. Thus, extension in the front and back length of the engine compartment is not preferable. Therefore, increasing the height of the engine compartment is one effective means for solving the problem. 
     SUMMARY 
     An upper surface of an engine hood of the bulldozer is often inclined so as to face downward to the front as described in Japanese Design Registration No. 1278235. If an exhaust treatment apparatus is provided in a heightened engine compartment which is covered by such an engine hood, dirt or the like, which falls out from an upper edge of the blade, is likely to damage windshield glass via the upper surface of the engine hood, which leads to obstructing a view from within a cab. 
     The object of the present invention is to provide a bulldozer where dirt is not likely to hit a window of a cab even if the upper surface of an engine hood is heightened due to an increase in loading capacity of the engine compartment. 
     A bulldozer according to a first aspect of the present invention comprises a cab and an engine hood which is arranged in front of the cab. The cab has a foremost surface, a left front surface, and a right front surface. The left front surface is in contact with the left side of the foremost surface and is inclined more obliquely to the left rear than the foremost surface. The right front surface is in contact with the right side of the foremost surface and is inclined more obliquely to the right rear than the foremost surface. The engine hood has an upper surface, a left side surface, a right side surface, a first inclined surface, a second inclined surface, and a third inclined surface. The left side surface is in contact with the left side of the upper surface and is inclined more obliquely downward than the upper surface. The right side surface is in contact with the right side of the upper surface and is inclined more obliquely downward than the upper surface. The first inclined surface is a flat surface in contact with the rear side of the upper surface and the rear side of the left side surface, is inclined more obliquely to the right rear than the left side surface, and is inclined no as to face downward to the rear. The second inclined surface is a flat surface in contact with the rear side of the upper surface and the rear side of the right side surface, is inclined more obliquely to the left rear than the right side surface, and is inclined so as to face downward to the rear. The third inclined surface is a flat surface in contact with the first inclined surface, the second inclined surface, and the upper surface, and is inclined so as to face downward to the rear. A window attached to the foremost surface is arranged above both a first side closest to the foremost surface out of the sides which constitute the first inclined surface and a second side which is closest to the foremost surface out of the sides which constitute the second inclined surface in the vertical direction. 
     The window attached to the foremost surface may be arranged above the rear edge section of the third inclined surface in the vertical direction. 
     An opaque member may be attached to a region under the window in the foremost surface. 
     The upper surface may have a convex section and a base section arranged below the convex section. Then, the upper surface of the convex section may be horizontal and the base section may be inclined toward the front of the vehicle. 
     The convex section may be positioned in the center of the upper surface in the vehicle width direction. 
     The length of the width of the base section in the vehicle width direction may be shortened heading toward the rear of the vehicle in a top view of the vehicle. 
     The first inclined surface may have a pentagonal shape which further has a third side, a fourth side, a fifth side, and a sixth side. The third side is in contact with the left side surface. The fourth side is in contact with the upper surface. The fifth side is in contact with the third inclined surface. The sixth side is a side different from the first side and is not in contact with any of the left side surface, the upper surface, or the third inclined surface. 
     The second inclined surface may have a pentagonal shape which further has a seventh side, an eighth side, a ninth side, and a tenth side. The seventh side is in contact with the right side surface. The eighth side is in contact with the upper surface. The ninth side is in contact with the third inclined surface. The tenth side is a side different from the second side and is not in contact with any of the right side surface, the upper surface, or the third inclined surface. 
     The third inclined surface may have a triangular shape which is enclosed by an eleventh side, a twelfth side, and a thirteenth side. The eleventh side is in contact with the upper surface. The twelfth side is in contact with the first inclined surface. The thirteenth side is in contact with the second inclined surface. 
     The bulldozer may further comprise a side wall section including a fourth inclined surface. The fourth inclined surface is a flat surface in contact with the first inclined surface. The fourth inclined surface has the sixth side as a boundary and is inclined more obliquely downward than the first inclined surface. 
     The side wall section may further include a fifth inclined surface. The fifth inclined surface is a flat surface in contact with the second inclined surface. The fifth inclined surface has the tenth side as a boundary and is inclined more obliquely downward than the second inclined surface. 
     Effects of the Invention 
     In the bulldozer according to the present invention, the window attached to the foremost surface is arranged above both the first side and the second side in the vertical direction. Accordingly, it is possible to prevent dirt which falls from the first inclined surface, the second inclined surface, and the third inclined surface from hitting the window of a cab. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a left side view of a bulldozer according to an embodiment of the present invention. 
         FIG. 2  is a top view which illustrates a portion of the bulldozer according to an embodiment of the present invention. 
         FIG. 3  is a perspective view where a portion of the rear of an engine hood and a portion of the front of the cab are magnified. 
         FIG. 4  is a planar view which illustrates an inner configuration of an engine compartment. 
         FIG. 5  is a side view which illustrates an inner configuration of the engine compartment. 
         FIG. 6  is a cross-section view of the engine compartment viewed from a cross sectional line VI-VI in  FIG. 2 . 
         FIG. 7  is a diagram for describing a correspondence relationship of a position of each part of the engine hood and a position of each apparatus in the engine compartment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     Overall Configuration 
       FIG. 1  is a side view of a bulldozer  1  according to an embodiment of the present invention.  FIG. 2  is a top view which illustrates a portion of the bulldozer  1  according to an embodiment of the present invention. Here, in the description below, front and back direction means front and back direction of the bulldozer  1 . In other words, the front and back direction means the front and back direction viewed by an operator seated in a cab (operator house)  7 . In addition, left and right direction or to the side mean vehicle width direction of the bulldozer  1 . In other words, left and right direction, the vehicle width direction, or to the side mean the left and right direction viewed by the operator described above. 
     The bulldozer  1  comprises a working implement  2 , a traveling apparatus  3 , and a vehicle body  4 . The working implement  2  has a blade  5  and hydraulic cylinders  6 . The blade  5  is arranged in front of the vehicle body  4 . The hydraulic cylinders  6  are actuated by hydraulic pressure which is generated by a hydraulic pump (which is not shown in the diagram) and moves the blade  5  up and down. The traveling apparatus  3  is an apparatus for running the vehicle, and has a pair of crawler belts  3   a . The bulldozer  1  runs due to the crawler belts  3   a  being driven. The vehicle body  4  has the cab (operator house)  7  and an engine compartment  8 . 
     The cab  7  is arranged behind the engine compartment  8 . A sheet and an operation apparatus which are not shown in the diagram are installed inside the cab  7 . As shown in  FIG. 2 , the cab  7  has a foremost surface  71 , a left front surface  72 , and a right front surface  73 . The foremost surface  71  the left front surface  72  and the right front surface  73  are flat surfaces which are substantially parallel with regard to the vertical direction. The foremost surface  71  is positioned in the center of the cab  7  in the vehicle width direction. The foremost surface  71  is a flat surface which is parallel to the vehicle width direction. The left front surface  72  is in contact with the left side of the foremost surface  71  and is inclined more obliquely to the left rear than the foremost surface  71 . The right front surface  73  is in contact with the right side of the foremost surface  71  and is inclined more obliquely to the right rear than the foremost surface  71 . 
     The engine compartment  8  is arranged in front of the cab  7 . The width of the engine compartment  8  is limited to within the space between the pair of crawler tracks  3   a  since the engine compartment  8  is interposed between the pair of crawler tracks  3   a . The engine compartment  8  has a vehicle body frame which is not shown in the diagram, a roof section  11 , a first side wall section  12 , and a second side wall section  13 . The first side wall section  12  and the second side wall section  13  will be collectively called aside wall section in the description below. 
     The roof section  11  covers the upper part of the engine compartment  8 . A rear section of the roof section  11  has a tapered shape such that the width gets smaller towards the rear side. The rear edge of the roof section  11  faces the foremost surface  71  of the cab  7 . A removable engine hood  14  is provided in the rear section of the roof section  11 . 
     The first side wall section  12  is provided along the front and back direction and covers the left of the engine compartment  8 . The first side wall section  12  has a removable first side cover  15  (refer to  FIGS. 1 and 2 ). The second side wall section  13  is provided along the front and back direction and covers the right of the engine compartment  8 . The second side wall section  13  has a removable second side cover  16 . The first side wall section  12  and the second side wall section  13  have shapes which are left and right symmetrical relative to each other with respect to a center line CL along the front and back direction of the bulldozer  1  and are separated in the vehicle width direction. The center line CL is a reference line which passes through the middle of the first side wall section  12  and the second side wall section  13  in the vehicle width direction. 
     Detailed Configuration of Engine Hood and Vicinity Thereof 
     Next, the detailed configuration of the engine hood  14  will be described. As shown in  FIG. 2 , the engine hood  14  covers the upper part of the engine compartment  8 . That is, the engine hood  14  covers the upper parts of a first exhaust treatment apparatus  41 , a second exhaust treatment apparatus  42 , a second connection pipe  43 , and an engine  31  which will be described later. The engine hood  14  is arranged in front of the cab  7 . In other words, the cab  7  is arranged behind the engine hood  14 . The engine hood  14  has shapes which are left and right symmetrical relative to each other with respect to the center line CL along the front and back direction of the bulldozer  1 . The engine hood  14  has an upper surface  140 , a left side surface  145 , a right side surface  146 , a first inclined surface  147 , a second inclined surface  148 , and a third inclined surface  149 . The left side surface  145  is in contact with the left side of the upper surface  140  and is inclined more obliquely downward than the upper surface  140 . The right side surface  146  is in contact with the right side of the upper surface  140  and is inclined more obliquely downward than the upper surface  140 . The first inclined surface  147  is in contact with the rear side of the upper surface  140  and the rear side of the left side surface  145 . The first inclined surface  147  is inclined more obliquely to the right rear than the left side surface  145  and is inclined so as to face downward to the rear. The second inclined surface  148  is in contact with the rear side of the upper surface  140  and the rear side of the right side surface  146 . The second inclined surface  148  is inclined more obliquely to the left rear than the right side surface  146  and is inclined so as to face downward to the rear. The third inclined surface  149  is in contact with the first inclined surface  147 , the second inclined surface  148 , and the upper surface  140  and is inclined so as to face downward to the rear. All of the first inclined surface  147 , the second inclined surface  148 , and the third inclined surface  149  are flat surfaces. All of the first inclined surface  147 , the second inclined surface  148 , and the third inclined surface  149  are positioned at the rear edge section of the engine hood  14 . 
     The upper surface  140  has a convex section  141  and a base section  144 . The convex section  141  is positioned at a rear portion of the upper surface  140 . The convex section  141  is positioned in the center of the upper surface  140  in the vehicle width direction. The convex section  141  has a substantially trapezoidal shape in a top view of the vehicle. The convex section  141  is arranged such that the longitudinal direction of the convex section  141  is along the vehicle front and back direction. The convex section  141  is arranged such that two bases thereof which constitute the trapezoidal shape of the convex section  141  extend along the vehicle front and back direction. The convex section  141  has a convex section upper surface  142  and a convex section inclined surface  143 . The convex section upper surface  142  is a horizontal flat surface (refer to  FIG. 5 ). The convex section inclined surface  143  is a flat surface which is inclined toward the base section  144  from the convex section upper surface  142 . The base section  144  is inclined toward the front of the vehicle, so that the width of the convex section inclined surface  143  is widened heading toward the front of the vehicle. 
     The base section  144  is integrally formed with the convex section  141  and is arranged below the convex section  141 . The base section  144  is inclined toward the front of the vehicle (refer to  FIG. 5 ). The length of the base section  144  in the vehicle width direction is shortened heading toward the vehicle rear in a top view of the vehicle. 
       FIG. 3  is a perspective view where a portion of the rear of the engine hood  14  and a portion of the front of the cab  7  are magnified. For convenience of description, a portion of the rear of the engine hood is not displayed in  FIG. 3 . Reference numerals are given to corners which constitute the first inclined surface  147 , the second inclined surface  148 , the third inclined surface  149 , and a portion of the convex section  141  in  FIG. 3 . A side AB is a side of the rear edge of the convex section  141 . The side AB is one of the two bases which constitute the trapezoidal shape of the convex section  141 . Accordingly, the side AB is parallel with regard to the vehicle width direction. That is, the side AB is perpendicular with regard to the center line CL. 
     The first inclined surface  147  is a pentagonal shape with five apexes at points E, F, G, H, and I. The side EF is in contact with the upper surface  140 . The side FG is in contact with the left side surface  145 . The side EI is in contact with the third inclined surface  149 . The side GH is in contact with a fourth inclined surface  121  which will be described later. That is, the side GH is not in contact with any of the left side surface  145 , the upper surface  140 , or the third inclined surface  149 . The side HI is in contact with the rear edge surface  150  (refer to  FIG. 5 ) of the engine hood  14 . The rear edge surface  150  is a flat surface with a triangular shape with three apexes at points H, I, and J. The side HI is also not in contact with any of the left side surface  145 , the upper surface  140 , or the third inclined surface  149 . The side HI is the closest side to the foremost surface  71  among the sides which constitute the first inclined surface  147 . However, as shown in  FIG. 5 , the side HI is separated only by a slight distance from the foremost surface  71 . 
     The second inclined surface  148  is a pentagonal shape with five apexes at points C, D, I, J, and K. The side CD is in contact with the upper surface  140 . The side DI is in contact with the third inclined surface  149 . The side CK is in contact with the right side surface  146 . The side JK is in contact with a fifth inclined surface  131  which will be described later. That is, the side JK is not in contact with any of the right side surface  146 , the upper surface  140 , or the third inclined surface  149 . The side IJ is in contact with the rear edge surface  150  (refer to  FIG. 5 ) of the engine hood  14 . The side IJ is also not in contact with any of the left side surface  145 , the upper surface  140 , or the third inclined surface  149 . The side IJ is the closest side to the foremost surface  71  among the sides which constitute the second inclined surface  148 . However, in a similar manner to the side HI, the side IJ is separated only by a slight distance from the foremost surface  71 . 
     The third inclined surface  149  is a triangular shape with three apexes at points D, E, and I. The side DE is in contact with the upper surface  140 . The side EI is in contact with the first inclined surface  147 . The side DI is in contact with the second inclined surface  148 . The third inclined surface  149  is enclosed by the side DE, the side EI, and the side DI. The side DE comes close to the side AB. That is, the rear edge of the convex section  141  comes close to the third inclined surface  149 . 
     The first side wall section  12  has the fourth inclined surface  121  which is in contact with the first inclined surface  147 , the fourth inclined surface  121  having the side GH as a boundary. That is, the side wall section has the fourth inclined surface  121 . The fourth inclined surface  121  is inclined more obliquely downward than the first inclined surface  147 . The second side wall section  13  has the fifth inclined surface  131  which is in contact with the second inclined surface  148 , the fifth inclined surface  131  having the side JK as a boundary. That is, the side wall section further has the fifth inclined surface  131 . The fifth inclined surface  131  is inclined more obliquely downward than the second inclined surface  148 . 
     A window  74  is attached to the foremost surface  71  of the cab  7 . The window  74  is arranged above all of the side HI at the rear edge section of the first inclined surface  147 , the side IJ at the rear edge section of the second inclined surface  148 , and the point at the rear edge section of the third inclined surface  149  in the vertical direction. In addition, a non-transparent member is attached in a region  75  under the window  74 . For example, the non-transparent member is a metal member. Due to this, it is possible to prevent dirt which falls from any of the first inclined surface  147 , the second inclined surface  148 , or the third inclined surface  149  from hitting the window  74 , i.e. to prevent the windshield glass, which is provided in the window  74  from being damaged due to dirt. 
     Configuration of Inner Section of Engine Compartment 
       FIG. 4  is a planar view which illustrates an inner configuration of the engine compartment  8 .  FIG. 5  is a side view which illustrates the inner configuration of the engine compartment  8 .  FIG. 6  is a cross-section view of the engine compartment  8  viewed from a cross sectional line VI-VI in  FIG. 2 .  FIG. 4  displays the engine compartment  8  while omitting a portion of the constitutional elements in  FIG. 2 .  FIG. 5  displays the engine compartment  8  while omitting a portion of the constitutional elements in  FIG. 1 . In addition, the engine hood  14  is displayed by a dotted line in  FIG. 5 . The engine  31 , an air cleaner  32 , a radiator (which is not shown in the diagrams), and an exhaust treatment unit  40  are accommodated in the engine compartment  8 . 
     The engine  31  is, for example, a diesel engine and is a drive source which drives the hydraulic pump and the traveling apparatus  3  which are described above. The engine  31  is arranged below the engine hood  14 . Furthermore, the engine  31  is arranged below the exhaust treatment unit  40  and the air cleaner  32 . As shown in  FIG. 5 , the air cleaner  32  is arranged in front of the exhaust treatment unit  40  in the engine compartment  8 . An air intake pipe  8   b  (refer to  FIG. 1  and  FIG. 2 ) which protrudes from the engine hood  14  is connected to the air cleaner  32 . The radiator which is not shown in the diagrams is arranged in front of the air cleaner  32  in the engine compartment  8 . The radiator is an apparatus for cooling a coolant which circulates between the radiator and the engine  31 . The radiator is configured such that it is possible for air to pass in the front and back direction. 
     As shown in  FIG. 4  and  FIG. 5 , the exhaust treatment unit  40  is arranged below the engine hood  14  and above the engine  31 . The exhaust treatment unit  40  has the first exhaust treatment apparatus  41 , the second exhaust treatment apparatus  42 , the second connection pipe  43 , and a bracket  60 . 
     In the present embodiment, the first exhaust treatment apparatus  41  is, for example, a diesel particulate filter apparatus and processes exhaust from the engine  31 . The first exhaust treatment apparatus  41  captures particulate matter in the exhaust using a filter. The first exhaust treatment apparatus  41  incinerates the captured particulate matter using a heater installed in the filter. 
     The first exhaust treatment apparatus  41  has a substantially cylindrical outer shape. As shown in  FIG. 6 , the first exhaust treatment apparatus  41  is arranged below the engine hood  14  and above the engine  31 . As shown in  FIG. 4 , the first exhaust treatment apparatus  41  is arranged such that a center axis line Ax 1  thereof is along the vehicle front and back direction. That is, the first exhaust treatment apparatus  41  is arranged such that the longitudinal direction thereof is along the vehicle front and back direction. Accordingly, the first exhaust treatment apparatus  41  is arranged such that the center axis line Ax 1  is parallel to the crank shaft of the engine  31 . 
     In the present embodiment, the second exhaust treatment apparatus  42  is, for example, a selective catalytic reduction apparatus and processes exhaust from the engine  31 . The second exhaust treatment apparatus  42  selectively reduces nitrogen oxide (NOx) by urea hydrolysis. 
     The second exhaust treatment apparatus  42  has a substantially cylindrical outer shape. As shown in  FIG. 5  and  FIG. 6 , the second exhaust treatment apparatus  42  is arranged below the engine hood  14  and above the engine  31 . As shown in  FIG. 4 , the second exhaust treatment apparatus  42  is arranged such that a center axis line Ax 2  thereof is along the vehicle front and back direction. That is, the second exhaust treatment apparatus  42  is arranged such that a longitudinal direction thereof is along the vehicle front and back direction. Accordingly, the second exhaust treatment apparatus  42  is arranged such that the center axis line Ax 2  is parallel to the crank shaft of the engine  31 . In addition, the second exhaust treatment apparatus  42  is arranged such that the center axis line Ax 2  is parallel to the center axis line Ax 1  of the first exhaust treatment apparatus  41 . Furthermore, as shown in  FIG. 6 , the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are arranged to come close to each other. 
     As shown in  FIG. 4 , the first exhaust treatment apparatus  41  has a first connection port  44 . As shown in  FIG. 4  and  FIG. 5 , the bulldozer  1  is provided with a first connection pipe  51 . The first connection pipe  51  links the engine  31  and the first exhaust treatment apparatus  41 . 
     The first connection pipe  51  has a first curved section  53  and a bellows section  54 . As shown in  FIG. 5 , the first curved section  53  links the bellows section  54  and the first connection port  44 . The first connection pipe  51  is connected to the engine  31  in the edge section other than the edge section connected to the connection port  44 . The bellows section  54  is in a bellows shape and can extend and contract. The bellows section  54  is linked to a plurality of bellows expansion and contraction joints. The bellows section  54  is arranged substantially along the vertical direction. 
     As shown in  FIG. 4  and  FIG. 5 , the first exhaust treatment apparatus  41  has a second connection port  45 . The second connection port  45  protrudes obliquely upward and towards a side of the second exhaust treatment apparatus  42 . The second exhaust treatment apparatus  42  has a third connection port  46 . The third connection port  46  protrudes obliquely upward and towards a side of the first exhaust treatment apparatus  41 . 
     The exhaust treatment unit  40  has the second connection pipe  43 . One end of the second connection pipe  43  is connected to the second connection port  45  of the first exhaust treatment apparatus  41 . The other end of the second connection pipe  43  is connected to the third connection port  46  of the second exhaust treatment apparatus  42 . That is, the second connection pipe  43  is a relay connection pipe which connects the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . As shown in  FIG. 6 , the second connection pipe  43  is arranged above the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . In addition, as shown in  FIG. 4 , the second connection pipe  43  is arranged so as to overlap with the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  in a top view of the vehicle. 
     As shown in  FIG. 4 , the second connection pipe  43  has a main pipe section  57 , a first connection section  58 , and a second connection section  59 . The main pipe section  57  has a substantially cylindrical shape. As shown in  FIG. 6 , the main pipe section  57  is positioned above the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . In detail, a lower end of the main pipe section  57  is positioned above an upper end of the cylindrical shape of the first exhaust treatment apparatus  41  and an upper end of the cylindrical shape of the second exhaust treatment apparatus  42 . Accordingly, a center axis line Ax 3  of the main pipe section  57  is positioned above the upper end of the cylindrical shape of the first exhaust treatment apparatus  41  and the upper end of the cylindrical shape of the second exhaust treatment apparatus  42 . In addition, the upper end of the main pipe section  57  is positioned above the upper end of the cylindrical shape of the first exhaust treatment apparatus  41  and the upper end of the cylindrical shape of the second exhaust treatment apparatus  42 . 
     The main pipe section  57  is arranged such that the center axis line Ax 3  thereof is along the vehicle front and back direction. That is, the main pipe section  57  is arranged such that the longitudinal direction thereof is along the vehicle front and back direction. Accordingly, the main pipe section  57  is arranged such that the center axis line Ax 3  is parallel to the crank shaft of the engine  31 . In addition, the main pipe section  57  is arranged such that the center axis line Ax 3  is parallel with regard to the center axis line Ax 1  of the first exhaust treatment apparatus  41  and the center axis line Ax 2  of the second exhaust treatment apparatus  42 . The length of the second connection pipe  43  in the direction of the center axis line Ax 3  is substantially the same as the length of the first exhaust treatment apparatus  41  or the length of the second exhaust treatment apparatus  42 . 
     The first connection section  58  links the main pipe section  57  and the second connection port  45 . That is, the first connection section  58  is connected to the main pipe section  57  and the first exhaust treatment apparatus  41 . The second connection section  59  links the main pipe section  57  and the third connection port  46 . That is, the second connection section  59  is connected to the main pipe section  57  and the second exhaust treatment apparatus  42 . An aqueous urea ejection apparatus  49  is attached in the first connection section  58 . The aqueous urea ejection apparatus  49  ejects aqueous urea into the second connection pipe  43 . 
     As shown in  FIG. 4  and  FIG. 5 , the second exhaust treatment apparatus  42  has a fourth connection port  47 . The fourth connection port  47  protrudes obliquely upwards. The bulldozer  1  is provided with an exhaust pipe  8   a . The exhaust pipe  8   a  is connected to the fourth connection port  47 . As shown in  FIG. 1 , an upper section of the exhaust pipe  8   a  protrudes upwards from the engine hood  14 . As shown in  FIG. 2 , the exhaust pipe  8   a  and the air intake pipe  8   b  are eccentric to a side of the first side wall section  12  with respect to the center line CL along the front and back direction of the bulldozer  1 . 
     The engine  31 , the first connection pipe  51 , the first exhaust treatment apparatus  41 , the second connection pipe  43 , the second exhaust treatment apparatus  42 , and the exhaust pipe  8   a  are sequentially connected in series. Accordingly, the exhaust from the engine  31  passes through the first connection pipe  51  and is fed into the first exhaust treatment apparatus  41 . Particulate matter is mostly reduced from the exhaust in the first exhaust treatment apparatus  41 . Next, the exhaust passes through the second connection pipe  43  and is fed into the second exhaust treatment apparatus  42 . NOx is mostly reduced in the second exhaust treatment apparatus  42 . After this, the cleaned exhaust passes through the exhaust pipe  8   a  and is discharged to the outside. 
     As shown in  FIG. 5  and  FIG. 6 , the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are attached to the bracket  60 . As shown in  FIG. 6 , the bracket  60  has a first support section  61  which supports the first exhaust treatment apparatus  41  and a second support section  62  which supports the second exhaust treatment apparatus  42 . 
     The first exhaust treatment apparatus  41  is fixed onto the bracket  60  by a U-bolt being attached to the first support section  61 . In a similar manner, the second exhaust treatment apparatus  42  is fixed onto the bracket  60  by a U-bolt being attached to the second support section  62 . The bracket  60  is supported by the engine  31  via a plurality of support members which are not shown in the diagrams. That is, the first exhaust treatment apparatus  41 , the second exhaust treatment apparatus  42 , and the second connection pipe  43  are supported by the engine  31  via the bracket  60 . 
     Positional Relationship Between Each Part of Engine Hood  14  and Apparatuses Inside Engine Compartment 
       FIG. 7  is a diagram for describing a correspondence relationship of a position of each part of the engine hood and a position of each apparatus in the engine compartment.  FIG. 7  illustrates the magnified vicinity of the engine hood  14  in  FIG. 2  and shows a boundary line of surfaces constituting the engine hood  14  with two-dot chain lines. In addition, reference numerals are given as shown in  FIG. 3  at points where multiple boundary lines of the engine hood  14  intersect. Furthermore, edge points (corner points) of the boundary line which is the front edge of the convex section upper surface  142  in the vehicle front and back direction are set as points L and M and edge points (corner points) of the boundary line which is the front edge of the convex section inclined surface  143  in the vehicle front and back direction are set as points T and U. Here, as shown in  FIG. 2 , a part of the corner at the front edge of the convex section upper surface  142  and the convex section inclined surface  143  is actually rounded, but for convenience of description, the corner will be described as angular in the contents below. 
     As described above, the convex section  141  has a substantially trapezoidal shape in top view of the vehicle. In detail, the convex section  141  has a substantially isosceles trapezoid shape with the side AB and side TU as the two bases. The side AB and the side TU extend in the vehicle width direction. That is, the side AB and the side TU are perpendicular to the center line CL. In addition, the convex section  141  is arranged such that the longitudinal direction of the convex section  141  is along the vehicle front and back direction. In detail, the side TU of the front edge of the convex section  141  is positioned in front of the first connection section  58  of the second connection pipe  43  in the vehicle front and back direction. The side AB on the rear edge of the convex section  141  is positioned close to the side DE at the front edge of the third inclined surface  149 . 
     As shown in  FIG. 5  and  FIG. 7 , a line segment UL at the upper edge of the main pipe section  57  of the second connection pipe  43  is shown with a dashed line. As shown in  FIG. 7 , the line segment UL overlaps with the center axis line Ax 3  of the second connection pipe  43  in a top view of the vehicle. As shown in  FIG. 7 , the height of the trapezoid ABTU is longer than the length of the main pipe section  57 . That is, the length of the convex section  141  in the vehicle front and back direction is longer than the length of the main pipe section  57 . In addition, at least a portion of the line segment UL which extends along the upper edge of the main pipe section  57  overlaps with the convex section upper surface  142  and a portion of the base section  144  behind the convex section upper surface  142  within the engine hood  14  in a top view of the vehicle. In detail, the line segment UL which extends along the upper edge of the main pipe section  57  overlaps with both the convex section upper surface  142  within the engine hood  14  in a top view of the vehicle. Here, the line segment UL which extends along the upper edge of the main pipe section  57  may further overlap with the third inclined surface  149 . According to the above description, it is clear that the convex section  141  protrudes above the second connection pipe  43 . 
     As shown in  FIG. 7 , a point F located at the front edge of the first inclined surface  147  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  and is positioned in front of the rear edge of the second exhaust treatment apparatus  42  in the vehicle front and back direction. Furthermore, the side EF of the first inclined surface  147  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  and is positioned in front of the rear edge of the second exhaust treatment apparatus  42 . In particular, the side EF of the first inclined surface  147  is positioned in front of the rear edge of the second exhaust treatment apparatus  42  which is positioned at the left side in the vehicle width direction out of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . 
     Furthermore, both the side GH and the side HI of the first inclined surface  147  are positioned behind the rear edge of the first exhaust treatment apparatus  41  and are positioned behind the rear edge of the second exhaust treatment apparatus  42 . In particular, both the side GH and the side HI of the first inclined surface  147  are positioned behind the rear edge of the second exhaust treatment apparatus  42  which is positioned at the left side in the vehicle width direction out of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . In addition, the side FG of the first inclined surface  147  is positioned to the left of the second exhaust treatment apparatus  42  which is positioned at the left side in the vehicle width direction. 
     In addition, a point C located at the front edge of the second inclined surface  148  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  and is positioned in front of the rear edge of the second exhaust treatment apparatus  42  in the vehicle front and back direction. Furthermore, the side CD of the second inclined surface  148  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  and is positioned in front of the rear edge of the second exhaust treatment apparatus  42 . In particular, the side CD of the second inclined surface  148  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  which is positioned at the right side in the vehicle width direction out of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . 
     Furthermore, both the side IJ and the side JK of the second inclined surface  148  are positioned behind the rear edge of the first exhaust treatment apparatus  41  and are positioned behind the rear edge of the second exhaust treatment apparatus  42 . In particular, both the side IJ and the side JK of the second inclined surface  148  are positioned behind the rear edge of the first exhaust treatment apparatus  41  which is positioned at the right side in the vehicle width direction out of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . In addition, the side CK of the second inclined surface  148  is positioned to the right of the first exhaust treatment apparatus  41  which is positioned at the right side in the vehicle width direction. 
     In addition, the side DE of the third inclined surface  149  is positioned in front of the rear edge of the second connection pipe  43 . In more detail, the side DE of the third inclined surface  149  is positioned in front of the rear edge of the second connection section  59 . Furthermore, the side DE of the third inclined surface  149  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  and is positioned in front of the rear edge of the second exhaust treatment apparatus  42 . 
     Next, an inclination degree of the first inclined surface  147  and the second inclined surface  148  will be described. The cross sectional line VI-VI in  FIG. 2  overlaps with the side AB. A straight line which is the same as the cross sectional line VI-VI is displayed with a dashed line in  FIG. 7 . Here, intersection points of the side CD, the side EF, the side CK, the side FG, and the cross section defined by the cross sectional line VI-VI are respectively set as points P, Q, R, and S. The points which correspond to points P, Q, R, and S are also shown in  FIG. 6 . Here, the cross section defined by the cross sectional line VI-VI is a cross section which passes through the first inclined surface  147 , the second inclined surface  148 , and the second connection pipe  43  and is perpendicular to the vehicle front and back direction. The point R is a bottom edge point of the nodal line PR of such a cross section and the first inclined surface  147 . The point S is a bottom edge point of the nodal line QS of such a cross section and the second inclined surface  148 . As shown in  FIG. 6 , the point R and the point S are below the position of the center axis line Ax 3  of the main pipe section  57  in the second connection pipe  43 . That is, there is a the cross section which passes through the first inclined surface  147 , the second inclined surface  148 , and the second connection pipe  43  and is perpendicular to the vehicle front and back direction, such that the bottom edge point of the nodal line of the cross section and the first inclined surface  147  is below the position of the center axis line Ax 3  of the main pipe section  57 , and that the bottom edge point of the nodal line of the cross section and the second inclined surface  148  is below the position of the center axis line Ax 3  of the main pipe section  57 . 
     As described above, it is possible to downsize the engine compartment  8  and increase the space filling ratio of the inside of the engine compartment  8  if the shapes of the first inclined surface  147 , the second inclined surface  148 , and the third inclined surface  149  are determined, and the positions of the first exhaust treatment apparatus  41 , the second exhaust treatment apparatus  42 , and the second connection pipe  43  are determined. 
     Features 
     The bulldozer  1  according to the present embodiment has the following features. 
     The first inclined surface  147  and the second inclined surface  148  which are inclined so as to face downward to the rear are provided at the rear edge of the engine hood  14  while the height of the engine hood  14  is increased in order to increase the capacity of the engine compartment  8 . Furthermore, the window  74  attached to the foremost surface  71  of the cab  7  is arranged above both the side HI of the first inclined surface  147  and the side IJ of the second inclined surface  148  in the vertical direction. Due to this, it is possible to prevent dirt which falls from either of the first inclined surface  147  or the second inclined surface  148  from hitting the window  74 , which prevents the windshield glass provided in the window  74  from being damaged. 
     The engine hood  14  has, in the rear edge section of the engine hood  14 , the first inclined surface  147  which is inclined more obliquely to the right rear than the left side surface  145  and which is inclined so as to face downward to the rear, and the second inclined surface  148  which is inclined more obliquely to the left rear than the right side surface  146  and which is inclined so as to face downward to the rear. Accordingly, it is possible to widen the view of the operator in the vicinity of both edge sections of the blade  5  which is most important to the operator due to the first inclined surface  147  and the second inclined surface  148  in the bulldozer  1 . 
     Furthermore, the engine hood  14  has the third inclined surface  149  between the first inclined surface  147  and the second inclined surface  148 . If the third inclined surface  149  is not provided, the side EF of the first inclined surface  147  and the side CD of the second inclined surface  148  extend to a point which overlaps with the center line CL (refer to  FIG. 2 ) in a top view and intersect at this point. Furthermore, a boundary line between the first inclined surface  147  and the second inclined surface  148  overlaps with the center line CL in a top view. In an engine hood with such a shape, the base section  144  protrudes to the rear and an oppressive feeling is imparted to the operator. The third inclined surface  149  provided for the engine hood  14  prevents the operator from feeling oppressed by the presence of the engine hood  14 . 
     (2) The window  74  attached to the foremost surface  71  of the cab  7  is arranged above the point I at the rear edge section of the third inclined surface  149  in the vertical direction. Due to this, it is possible to prevent dirt which falls from the third inclined surface  149  from hitting the window  74 , which prevents the windshield glass provided in the window  74  from being damaged. 
     (3) An opaque metal member is attached in the region  75  under the window  74 . Due to this, the height of the lower edges of the first inclined surface  147 , the second inclined surface  148 , and the third inclined surface  149  are within the range of the height of the region  75 . Due to this, it is possible to prevent the windshield glass in the window  74  from being damaged due to spattering of dirt which has collided with the engine hood  14 . 
     (4) The upper surface  140  of the engine hood  14  has the convex section  141  and the base section  144  arranged below the convex section  141 . Then, the upper surface  142  of the convex section  141  is horizontal and the base section  144  is inclined toward the front of the vehicle. Therefore, it is possible for the bulldozer  1  to drop, in front of the vehicle, the dirt which has fallen onto the base section  144 . In addition, it is possible to arrange a member which needs to be arranged horizontally, such as the second connection pipe  43  at the upper section of the engine compartment  8  below the convex section. Due to this, the entire engine hood is not heightened as shown by the two-dot chain lines in  FIG. 5  and only a necessary portion is heightened as the convex section. This prevents imparting an oppressive feeling to the operator. 
     (5) The convex section  141  is positioned at the center of the upper surface  140  in the vehicle width direction. As a result, the convex section  141  does not obstruct the view of the operator in the vicinity of both edge sections of the blade  5  which is most important to the operator. 
     (6) The length of the base section  144  in the vehicle width direction is shortened heading toward the rear of the vehicle in a top view of the vehicle. Accordingly, the engine hood  14  does not obstruct the view of the operator in the vicinity of both edge sections of the blade  5  which is most important to the operator. In addition, it is possible to arrange the exhaust treatment apparatuses in the rear section space in the engine compartment  8  even with this shape since the installation width of the exhaust treatment apparatuses is short. This allows shortening of the length of the engine compartment  8  in the front and back direction. 
     (7) The first side wall section  12  (that is, the side wall section) has the fourth inclined surface  121  which is inclined more obliquely downward than the first inclined surface  147 . Then, the first inclined surface  147  is in contact with the fourth inclined surface  121  at the side GH. Accordingly, it is possible to discharge dirt which falls onto the first inclined surface  147  to the side of the bulldozer  1  via the fourth inclined surface  121 . 
     (8) The second side wall section  13  (that is, the side wall section) has the fifth inclined surface  131  which is inclined more obliquely downward than the second inclined surface  148 . Then, the second inclined surface  148  is in contact with the fifth inclined surface  131  at the side JK. Accordingly, it is possible to discharge dirt which falls onto the second inclined surface  148  to the side of the bulldozer  1  via the fifth inclined surface  131 . 
     (9) The first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are arranged such that the respective longitudinal directions are along the vehicle front and back direction. Furthermore, the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are arranged to be close to each other. As a result, even though the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are accommodated in the engine compartment  8 , it is possible to prevent the width of the engine compartment  8  from being increased due to the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . 
     Furthermore, both the point F which is the front edge of the first inclined surface  147  and the point C which is the front edge of the second inclined surface  148  are positioned in front of the rear edge of the first exhaust treatment apparatus  41  and positioned in front of the rear edge of the second exhaust treatment apparatus  42 . Accordingly, a considerable portion of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  is arranged in the rear section space of the engine compartment  8  which is below the first to third inclined surfaces, so that the front and back length of the engine compartment can be shortened. While the bulldozer  1  runs across an uneven ground surface, the bulldozer  1  pitches up (inclined upward) and pitches down (inclined downward). If the blade  5  is arranged to be separated from (the center of gravity of) the vehicle, the blade is considerably shaken vertically. Accordingly, the operation of the blade  5  becomes difficult for the operator. Shortening the front and back length of the engine compartment allows the blade  5  to be arranged close to (the center of gravity of) the vehicle. This reduces the vertical shaking of the blade  5 , and makes it easier to work with the blade  5 . 
     (10) The side EF of the first inclined surface  147  is positioned in front of the rear edge of an exhaust treatment apparatus which is positioned at the left side in the vehicle width direction out of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . As a result, it is possible to arrange the exhaust treatment apparatus, which is positioned at the left side in the vehicle width direction, closer to the rear end of the rear section space of the engine compartment  8 . This allows further shortening of the front and back length of the engine compartment. 
     (11) The side CD of the second inclined surface  148  is positioned in front of the rear edge of an exhaust treatment apparatus which is positioned at the right side in the vehicle width direction out of the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42 . As a result, it is possible to arrange the exhaust treatment apparatus, which is positioned at the right side in the vehicle width direction, closer to the rear end of the rear section space of the engine compartment  8 . This allows further shortening of the front and back length of the engine compartment. 
     (12) The side DE of the third inclined surface  149  is positioned in front of the rear edge of the first exhaust treatment apparatus  41  and is positioned in front of the rear edge of the second exhaust treatment apparatus  42 . As a result, it is possible to arrange the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  closer to the rear end of the rear section space of the engine compartment  8 . This allows further shortening of the front and back length of the engine compartment. 
     (13) The main pipe section  57  of the second connection pipe  43  is arranged such that the longitudinal direction thereof is along the front and back direction. Furthermore, the second connection pipe  43  is arranged so as to overlap with both the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  in a top view of the vehicle. Accordingly, it is possible to prevent the width of the engine compartment  8  from being increased while the height of the second connection pipe  43  can be lowered. As a result, it is possible to suppress elevation of the engine hood  14 . Accordingly, it is also possible to prevent the operator from feeling oppressed. 
     (14) The side DE of the third inclined surface  149  is positioned in front of the rear edge of the second connection pipe  43 . As a result, it is possible to arrange the second connection pipe  43  in the rear side space of the engine compartment  8 . This allows in further shortening of the front and back length of the engine compartment. 
     (15) There is a cross section which passes through the first inclined surface  147 , the second inclined surface  148 , and the second connection pipe  43  and is perpendicular to the vehicle front and back direction, such that the bottom edge point R of the nodal line of the cross section and the first inclined surface  147  is below the position of the center axis line Ax 3  of the main pipe section  57 , and that the bottom edge point S of the nodal line of the cross section and the second inclined surface  148  is below the position of the center axis line Ax 3  of the main pipe section  57 . Accordingly, the first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are arranged in a confined space close to the rear of the engine compartment  8 . Accordingly, this allows still further shortening of the front and back length of the engine compartment. 
     (16) The convex section  141  protrudes above the second connection pipe  43 . Accordingly the second connection pipe  43  is provided below the convex section  141 . Therefore, the entire engine hood is not heightened as shown by the two-dot chain lines in  FIG. 5  and only a necessary portion is heightened as the convex section. This prevents imparting an oppressive feeling to the operator. 
     Modified Examples 
     An embodiment of the present invention is described above but the present invention is not limited thereto and various modifications are possible within a gist of the invention. 
       FIG. 5  illustrates an example where the second connection pipe  43  is not included in an inner space of the convex section  141 , but a portion of the second connection pipe  43  may be included in the inner space of the convex section  141 . If the second connection pipe  43  is arranged in this manner, it is possible to further lower the base section  144  of the engine hood  14  and it is possible to further widen the view of the operator in the anterior direction and particularly the view in the left and right edge direction of the blade  5 . 
     In the present embodiment, the third inclined surface  149  is illustrated as a triangular shape, but the shape may be a rectangular shape such as a trapezoid. Even in this case, the window  74  of the cab  7  is arranged above the side which is the rear edge section of the third inclined surface (in other words, the side which is closest to the foremost surface  71  of the cab  7  out of the sides which constitute the third inclined surface) in the vertical direction. In addition, the first inclined surface  147  and the second inclined surface  148  may be a different rectangular shape. 
     The configuration of the exhaust treatment unit  40  is not limited to the configuration described above. For example, the first exhaust treatment apparatus  41  may be a treatment apparatus other than the diesel particulate filter apparatus. The second exhaust treatment apparatus  42  may be a treatment apparatus other than the selective catalytic reduction apparatus. The first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  may be arranged at different positions from the positions described above. The shapes of first exhaust treatment apparatus  41  and the second exhaust treatment apparatus  42  are not limited to a cylindrical shape or the like and may be another shape such as a rectangular shape or an elliptical shape. The positions of the first connection pipe  51 , the exhaust pipe  8   a , the air intake pipe  8   b , and the air cleaner  32  may be arranged at different positions from the positions described above. 
     The layout of the inside of the engine compartment  8  may be reversed in terms of the left and right of the layout described above. For example, the first exhaust treatment apparatus  41  may be arranged at the left side and the second exhaust treatment apparatus  42  may be arranged at the right side in the vehicle width direction. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, it is possible to provide a bulldozer where dirt is not likely to hit the window of the cab even if the upper surface of the engine hood is heightened due to an increase in loading capacity of the engine compartment.