Patent ID: 12228063

EMBODIMENTS OF THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of a common rail diesel engine5according to this embodiment will be described with reference toFIGS.1to10. In the following description, both sides of an output shaft53(both sides with the output shaft53located in between) will be referred to as left and right, a section where a cooling fan59is located is referred to as a front side, a section where a flywheel61is located is referred to as a rear side, a section where an exhaust manifold57is located is referred to as a left side, and a section where an intake manifold56is located is referred to as a right side. For convenience of description, these are used as a reference for the positional relationship in four directions and the vertical direction in the diesel engine5.

As illustrated inFIGS.1to8, an engine mounted on a work vehicle such as a tractor includes a continuously regenerating exhaust gas purification device (diesel particulate filter (DPF))52. The engine is the diesel engine5in this embodiment. The exhaust gas purification device52removes particulate matter (PM) in exhaust gas discharged from the diesel engine5and reduces carbon monoxide (CO) and hydrocarbon (HC) in the exhaust gas.

The diesel engine5includes a cylinder block54. The cylinder block54embeds an output shaft53(crankshaft) and pistons (not shown). A cylinder head55is mounted on the cylinder block54. The intake manifold56is located on the right side surface of the cylinder head55. The exhaust manifold57is located on the left side surface of the cylinder head55. That is, the intake manifold56and the exhaust manifold57are distributed on both side surfaces of the diesel engine5along the output shaft53. A head cover58is located on the upper surface of the cylinder head55. A cooling fan59is provided on a side surface of the diesel engine5that intersects the output shaft53, more specifically, on the front surface of the cylinder block54. Rotational power is transmitted to the cooling fan59from the front end of the output shaft53via a cooling fan V-belt72a.

A flywheel housing60is provided on the rear surface of the cylinder block54. The flywheel housing60houses a flywheel61. The flywheel61is supported on the rear end of the output shaft53. Motive power of the diesel engine5is transmitted to the operation parts of the work vehicle via the output shaft53. An oil pan62is located on the lower surface of the cylinder block54. Lubricant in the oil pan62is supplied to lubrication parts of the diesel engine5via an oil filter63. The oil filter63is located on the right side surface of the cylinder block54. The oil filter63is secured to the right side surface of the cylinder block54via an oil filter support member88.

A fuel supply pump64for supplying fuel is secured above the oil filter63(below the intake manifold56) on the right side surface of the cylinder block54. The diesel engine5includes injectors65with electromagnetically controlled fuel injection valves for four cylinders. The injectors65are coupled to a fuel tank11via the fuel supply pump64, a cylindrical common rail66, and a fuel filter67. The fuel tank11is mounted on the work vehicle (seeFIGS.19to21). An oil cooler68is located on the right side surface of the cylinder block54at a position vertically sandwiched between the common rail66and the oil filter63.

Fuel in the fuel tank11is fed under pressure from the fuel supply pump64to the common rail66via the fuel filter67, and the pressurized fuel is stored in the common rail66. The pressurized fuel in the common rail66is injected from the injectors65into the cylinders of the diesel engine5by controlling opening and closing of the fuel injection valves of the injectors65. An engine starter69is provided in the flywheel housing60. A pinion gear of the engine starter69is engaged with a ring gear of the flywheel61. When starting the diesel engine5, the ring gear of the flywheel61is rotated by rotational force of the starter69so that the output shaft53starts rotating (or cranked).

A coolant pump71for coolant lubrication is located in front of the cylinder head55(close to the cooling fan59) to be coaxial with a fan axis of the cooling fan59. The coolant pump71is configured to be driven by rotation of the engine output shaft53together with the cooling fan59. The work vehicle includes a radiator235(seeFIGS.22and26). The coolant in the radiator235is supplied to the coolant pump71via a thermostat case70. The thermostat case70is located above the coolant pump71. When the coolant pump71is driven, the coolant is supplied to a water-cooling jacket (not shown) formed in the cylinder head55and the cylinder block54to cool the diesel engine5. The coolant that has contributed to cooling of the diesel engine5is returned to the radiator235. Due to the positional relationship, the coolant pump71opposes the cooling fan59. Thus, the cool air from the cooling fan59contacts the coolant pump71.

A generator that generates electric power by power of the diesel engine5is provided on the left side of the diesel engine5, or more specifically, leftward of the coolant pump71. The generator is an alternator73in this embodiment. Rotational power is transmitted to the cooling fan59and the coolant pump71from the front end of the output shaft53via the cooling fan V-belt72a. Rotational power is also transmitted from the front end of the output shaft53to the alternator73via an alternator V-belt72b. When the coolant pump71is driven, the coolant in the radiator235(FIGS.22and26), which is mounted on the work vehicle, is supplied to the cylinder block54and the cylinder head55to cool the diesel engine5.

An engine mount fitting74is provided on each of left and right side surfaces of the cylinder block54. A front engine mount238(seeFIGS.19and20) can be bolted to each engine mount fitting74. The front engine mount238includes an anti-vibration rubber. The work vehicle includes a pair of left and right engine frames14(FIGS.19to21). In this embodiment, the engine mount fittings74of the cylinder block54are each bolted to the associated engine frame14via the associated engine mount238such that the cylinder block54is sandwiched between the engine frames14. With this configuration, the engine frames14of the work vehicle support the front part of the diesel engine5.

An intake connecting pipe76is coupled to the right side inlet portion of the intake manifold56. Fresh air (external air) is supplied to the intake connecting pipe76. An intake throttle member77is provided at the intake-air inlet side (upstream side) of the intake connecting pipe76. A recirculation exhaust gas pipe78is coupled to the top inlet portion of the intake manifold56via an EGR valve member79. Some of exhaust gas (EGR gas) of the diesel engine5is supplied to the recirculation exhaust gas pipe78. In the intake manifold56, the intake-air outlet side (downstream side) of the intake connecting pipe76and the coupling portion (rear portion) between the intake manifold56and an EGR valve member79configure a body case of an exhaust gas recirculation (EGR) apparatus75. That is, the intake-air introduction side of the intake manifold56configures the EGR body case.

The EGR apparatus (exhaust gas recirculation apparatus)75is located mainly on the right side of the diesel engine5, and more specifically, rightward of the cylinder head55and mixes some of the exhaust gas of the diesel engine5(EGR gas) with fresh air to supply the mixture to the intake manifold56. The apparatus (exhaust gas recirculation apparatus)75includes the EGR body case configured by part of the intake manifold56, the intake connecting pipe76, which communicates with the intake manifold56, the intake throttle member77, which is located in the intake connecting pipe76, the recirculation exhaust gas pipe78, which is coupled to the exhaust manifold57via an EGR cooler80, and the EGR valve member79, which connects the intake manifold56to the recirculation exhaust gas pipe80.

The intake throttle member77is coupled to the intake-air introduction side of the intake manifold56via the intake connecting pipe76. The outlet of the recirculation exhaust gas pipe78is also coupled to the intake-air introduction side of the intake manifold56via the EGR valve member79. The inlet of the recirculation exhaust gas pipe78is coupled to the exhaust manifold57via the EGR cooler80. The amount of EGR gas supplied to the intake-air introduction side of the intake manifold56is adjusted by adjusting the opening degree of the EGR valve in the EGR valve member79.

With the above-described configuration, while fresh air is supplied to the intake-air introduction side of the intake manifold56via the intake connecting pipe76and the intake throttle member77, the EGR gas is supplied to the intake-air introduction side of the intake manifold56from the exhaust manifold57. The fresh air from the outside and the EGR gas from the exhaust manifold57are mixed in the intake-air introduction side of the intake manifold56. Some of the exhaust gas discharged to the exhaust manifold57from the diesel engine5is circulated from the intake manifold56to the diesel engine5. This reduces the highest combustion temperature during high load operation and the discharge amount of NOx (nitrogen oxides) from the diesel engine5.

A turbocharger81is located leftward of the cylinder head55above the exhaust manifold57. The turbocharger81includes a turbine case82and a compressor case83. The turbine case82embeds a turbine wheel. The compressor case83embeds a blower wheel. The exhaust introduction side of the turbine case82is coupled to the outlet of the exhaust manifold57. The exhaust discharge side of the turbine case82is coupled to the exhaust introduction side of the exhaust gas purification device52via an exhaust connecting pipe84. That is, the exhaust gas that has been discharged from the cylinders of the diesel engine5to the exhaust manifold7is released to the outside via, for example, the turbocharger81and the exhaust gas purification device52.

The intake-air introduction side of the compressor case83is coupled to the intake-air discharge side of an air cleaner221(seeFIGS.22and26) via a supply pipe222(seeFIGS.22and26). The intake-air discharge side of the compressor case83is coupled to the intake-air introduction side of an intercooler224(seeFIGS.22and26) via an upstream relay pipe223(seeFIGS.22and26). The intake-air discharge side of the intercooler224(seeFIGS.22and27) is coupled to the intake throttle member77via a downstream relay pipe225(seeFIGS.22and27). That is, the fresh air (external air) from which dust has been removed by the air cleaner221is sent from the compressor case83to the EGR apparatus75via the intercooler224and then supplied to the cylinders of the diesel engine5.

The exhaust gas purification device52is located on the top side of the diesel engine5above the exhaust manifold57and the turbocharger81, that is, leftward of the cylinder head55and above the exhaust manifold57and the turbocharger81. In this case, the position of the exhaust gas purification device52is set such that the longitudinal direction of the exhaust gas purification device52extends parallel to the output shaft53of the diesel engine5.

Next, a configuration of the exhaust gas purification device (diesel particulate filter (DPF))52will be described with reference to the previous drawings andFIGS.9to16. The DPF52is for collecting, for example, particulate matter (PM) in exhaust gas. The DPF52is configured to be approximately cylindrical and to extend parallel to the output shaft (crankshaft)53of the diesel engine5in the fore-and-aft direction. The DPF52is located above the cylinder head55of the diesel engine5. An exhaust gas inlet pipe161(exhaust gas introduction side) and an exhaust gas outlet pipe162(exhaust gas discharge side) are distributed to the front and the rear of the diesel engine5on both ends (one end in the exhaust gas moving direction and the other end in the exhaust gas moving direction) of the DPF52.

The DPF52is configured to accommodate, for example, a diesel oxidation catalyst163and a soot filter164arranged in series. The diesel oxidation catalyst163is made of, for example, platinum. The soot filter164has a honeycomb structure. In the above-described configuration, nitrogen dioxide (NO2) generated by oxidation in the diesel oxidation catalyst163is taken into the soot filter164. The particulate matter contained in the exhaust gas of the diesel engine5is collected by the soot filter164and continuously oxidized and removed by the nitrogen dioxide (NO2). Thus, in addition to the removal of the particulate matter (PM) in the exhaust gas of the diesel engine5, the content of carbon monoxide (CO) and hydrocarbon (HC) in the exhaust gas of the engine1is reduced. The diesel oxidation catalyst39and the soot filter40correspond to a gas purification filter accommodated in a purification housing38.

The DPF52includes an upstream case (first case)165, an intermediate case (second case)166, and a downstream case (third case)167. The exhaust gas inlet pipe161is provided on the outer circumferential surface of the upstream case165. The intermediate case166is coupled to the upstream case165. The exhaust outlet pipe162is inserted in the downstream case167from the outer circumferential surface. The upstream case165and the intermediate case166are arranged in series and coupled to each other to form a gas purification housing168. The gas purification housing168is made of heat-resistant metal material. The gas purification housing168accommodates the diesel oxidation catalyst163and the soot filter164via a cylindrical inner case (not shown). The downstream case167includes an inner case (not shown) having multiple silencing holes. The space between the downstream case167and the inner case is filled with a silencing material made of ceramic fiber to form a silencer.

One end of the upstream case165that is an upstream end in the exhaust gas moving direction is covered with an upstream lid169. The other end of the upstream case165that is a downstream end in the exhaust gas moving direction is open. The upstream case165has a cylindrical shape with the downstream end in the exhaust gas moving direction open. The intermediate case166has a cylindrical shape with both ends open. One end of the downstream case167that is an upstream end in the exhaust gas moving direction is open. The other end of the downstream case167that is a downstream end in the exhaust gas moving direction is covered with a downstream lid174. The downstream case167has a cylindrical shape with the upstream end in the exhaust gas moving direction open. A tailpipe229(seeFIGS.22and32) is coupled to the exhaust gas outlet pipe162, which is located on the outer circumferential surface of the downstream case167, via an exhaust pipe227(seeFIGS.22and32). Exhaust gas is discharged to the outside from the exhaust gas outlet pipe162via the exhaust pipe227and the tailpipe229.

Coupling portions of the upstream case165and the intermediate case166are coupled by sandwiching the coupling portions from both sides in the exhaust gas moving direction with a pair of thick plate-like sandwich flanges170,171. That is, a joining flange located at a downstream open edge of the upstream case165and a joining flange located at an upstream open edge of the intermediate case166are sandwiched by the sandwich flanges170,171to couple the downstream end of the upstream case165to the upstream end of the intermediate case166. This configures the gas purification housing168. At this time, tightening the sandwich flanges170,171with bolts detachably couples the upstream case165to the intermediate case166. Coupling portions of the intermediate case166and the downstream case167are coupled by sandwiching the coupling portions from both sides in the exhaust gas moving direction with a pair of thick plate-like sandwich flanges172,173. Tightening the central sandwich flanges170,171with bolts detachably couples the upstream case165to the intermediate case166.

The exhaust gas inlet pipe161is provided on the outer circumferential portion at the exhaust introduction side (exhaust inlet side) of the upstream case165. The exhaust introduction side of the exhaust gas inlet pipe161communicates with the exhaust discharge side of the turbine case82via an exhaust relay passage, which is the exhaust connecting pipe84in this embodiment. The exhaust connecting pipe84is approximately L-shaped as viewed from the side. The exhaust connecting pipe84includes an exhaust introduction side at the front and is coupled to the exhaust discharge side of the turbine case82. The exhaust connecting pipe84also includes the exhaust discharge side at the upper section and is coupled to the exhaust gas inlet pipe161of the DPF52. The exhaust connecting pipe84includes a coupling support portion84a, which extends downward from the outer circumferential surface. The lower end of the coupling support portion84ais coupled to the left side surface of the exhaust manifold57. That is, the exhaust connecting pipe84is secured to the diesel engine5by fastening the exhaust connecting pipe84to the exhaust manifold57and the turbocharger81with bolts.

Sensor bosses175are located on the outer circumferential surface of the gas purification housing168. The sensor bosses175are coupled to temperature sensors186,187(seeFIGS.32and33) and sensor pipes188,189(seeFIG.27). In this embodiment, the upstream case165accommodates the oxidation catalyst163and the upstream section of the soot filter164. The intermediate case165accommodates the downstream section of the soot filter164. The sensor boss175that is coupled to an upstream temperature sensor186is provided on the outer circumferential surface of the upstream case165at a position upstream of the oxidation catalyst163in the exhaust gas moving direction. The sensor boss175that is coupled to a downstream temperature sensor187and an upstream sensor pipe188is provided at a position between the oxidation catalyst163and the soot filter164. The sensor boss175that is coupled to a downstream sensor pipe189is provided on the outer circumferential surface of the intermediate case166at a position downstream of the soot filter164in the exhaust gas moving direction.

Next, a configuration for mounting the exhaust gas purification device52to the diesel engine5will be described with reference toFIGS.9to18. The diesel engine5includes a housing support that supports and secures the exhaust gas purification device52(gas purification housing168). The housing support includes an inlet side bracket176and an outlet side bracket177. The inlet side bracket176and the outlet side bracket177have a great width in a direction that intersects the output shaft53of the diesel engine5. The inlet side bracket176and the outlet side bracket177are detachably coupled to the cylinder head55of the diesel engine5directly or via the intake manifold56or the exhaust manifold57. The inlet side bracket176and the outlet side bracket177are distributed and stand upright on the front and the rear of the cylinder head55and on both sides of the output shaft53. The inlet side bracket176is located at the rear of the cylinder head55and supports the exhaust introduction side of the gas purification housing168. The outlet side bracket177is located at the front of the cylinder head55and supports the exhaust discharge side of the gas purification housing168.

The inlet side bracket176is located at the rear of the cylinder head55(above the flywheel housing60). The inlet side bracket176includes a securing bracket (first bracket)178. The lower edge of the securing bracket178is bolted to the rear surface of the cylinder head55. A relay bracket179is bolted to the upper end of the securing bracket178. The proximal end of an extended bracket (third bracket)180is bolted to the middle of the relay bracket (second bracket)179. The distal end of the extended bracket180is fastened to the upstream lid169of the gas purification housing168with bolts and nuts.

The outlet side bracket177is located at the front of the cylinder head55(close to the cooling fan59). The outlet side bracket177of this embodiment is separated into an outlet side first bracket (fourth bracket)181and an outlet side second bracket (fifth bracket)182. The outlet side first bracket181is an approximately L-shaped member that extends upward from the right side of the cylinder head55and bends to the left side above the cylinder head55. The outlet side second bracket182is an approximately L-shaped member that extends upward from the left side of the cylinder head55and bends to the right side above the cylinder head55. Thus, the outlet side bracket177has an approximately inverted U shape in front of the cylinder head55and is secured to extend over the cylinder head55at a position rearward of the thermostat case70.

The lower end surface (proximal end) of the outlet side first bracket181is bolted to the upper surface of the intake manifold56. The upper left end (distal end) of the outlet side first bracket181is bolted to the upper right end (distal end) of the outlet side second bracket182. The lower right end (proximal end) of the outlet side second bracket182is bolted to the left side front portion of the cylinder head55. The outlet side second bracket182includes an upper end curved surface (U-shaped pressure-receiving surface)182aat the upper end (distal end) of the outlet side second bracket182. The upper end curved surface182areceives the outer circumferential surface of the gas purification housing168and is bolted to a bracket fastening portion172a. The bracket fastening portion172ais formed at the lower section of the sandwich flange (outlet sandwich flange)172of the gas purification housing168.

As is clear from the above description, the exhaust gas purification device52of this embodiment is detachably coupled to the cylinder head55, the intake manifold56, and the exhaust manifold57of the engine5via the housing support above the diesel engine5. The housing support includes the exhaust connecting pipe84, the inlet side bracket176, and the outlet side bracket177. The inlet side bracket176and the exhaust connecting pipe84, which are located upstream in the exhaust gas moving direction (exhaust introduction side), are distributed to the cylinder head55and the exhaust manifold57. The outlet side bracket177(the outlet side first bracket181and the outlet side second bracket182), which is located downstream in the exhaust gas moving direction (exhaust discharge side), is distributed to the cylinder head55and the intake manifold56. Thus, the exhaust gas purification device52is supported at four points.

This configuration supports the exhaust gas purification device52, which is one of the components of the engine5, with high rigidity and prevents damage on the exhaust gas purification device52that is caused by, for example, vibration. In particular, in this embodiment, since the lower end of the inlet side bracket176and the outlet side second bracket182are fastened to the cylinder head55, a mounting reference position of the exhaust gas purification device52with respect to the engine5is set with high accuracy. Thus, even the exhaust gas purification device52, which is heavier than an after-treatment device such as a muffler, is appropriately mounted on a predetermined position.

As illustrated inFIGS.11,13, and15, the securing bracket178is a plate-like member that has a great width in a direction intersecting the exhaust gas moving direction of the DPF52(the output shaft53of the diesel engine5). The section of the securing bracket178lower than the recirculation exhaust gas pipe78is bolted to the cylinder head55. That is, the recirculation exhaust gas pipe78, which is coupled to the EGR cooler80, detours behind the securing bracket178and is coupled to the intake throttle member77. The securing bracket178includes a front component coupling portion (first component coupling portion)178a, which includes bolt holes at a section above the recirculation exhaust gas pipe78. A hanging fixture86is detachably bolted to the front component coupling portion178a.

The securing bracket178further includes a bracket coupling portion178b. The bracket coupling portion178bis located on the upper surface of the upper end portion and includes bolt holes. The relay bracket179is detachably bolted to the bracket coupling portion178b. The securing bracket178also includes a side component coupling portion (second component coupling portion)178c. The side component coupling portion178cis located on the right side of the upper end portion and includes bolt holes. A component securing bracket (exhaust pipe securing bracket)210(seeFIGS.31and32) for securing an external component such as the exhaust pipe227(seeFIGS.31and32) is bolted to the side component coupling portion178c.

As illustrated inFIGS.11,13, and15, the bottom surface at the lower end portion of the relay bracket179is abut against the upper surface at the upper end portion of the securing bracket178. In this state, the relay bracket179is bolted to the securing bracket178. The relay bracket179includes a base plate179aand a coupling plate179b. The base plate179aextends upward from the lower end portion secured to the bracket coupling portion178bof the securing bracket178. The coupling plate179bstands upright at the rear of the plate179a. The coupling plate179bis welded to the base plate179a. The coupling plate179bof the relay bracket179includes fore-and-aft position adjusting bolt holes elongated in the fore-and-aft direction. Mounting bolts that are loosely inserted through the position adjusting bolt holes from the right are screwed to the right side surface of the extended bracket180so that the relay bracket179is securely coupled to the extended bracket180. The extended bracket180is configured such that the coupling portion that is coupled to the relay bracket179stands upright at the rear of the fixed portion that is fixed to the upstream lid169of the gas purification housing168.

The mounting position of the extended bracket180, which is secured to the gas purification housing168, in the fore-and-aft direction is adjustable with respect to the relay bracket179, which is secured to the securing bracket178, in a range corresponding to the dimension in which the mounting bolts move forward and rearward in the fore-and-aft position adjusting bolt holes of the relay bracket179. Thus, the mounting position of the DPF52in the fore-and-aft direction (exhaust gas moving direction) is adjustable with respect to the securing bracket178, which is secured to the cylinder head55, by adjusting the position of the mounting bolts in the fore-and-aft position adjusting bolt holes of the relay bracket179.

At the inlet side of the gas purification housing168, as described above, the lower end of the coupling support portion84aof the exhaust connecting pipe84, which communicates with the exhaust gas inlet pipe161, is bolted to the exhaust manifold57. That is, the exhaust connecting pipe84is configured to be the housing support that supports the inlet side of the gas purification housing168together with the inlet side bracket176. Thus, the exhaust gas inlet side of the DPF52is supported with a high rigidity by the inlet side bracket176, which is coupled to each of the rear surface o/f the cylinder head55and the upstream lid169, and the exhaust connecting pipe84coupled to each of the left side of the exhaust manifold57and the exhaust gas inlet pipe161.

Furthermore, as illustrated inFIGS.9,11,13, and15, embedded bolts85are provided on an upward-facing mounting surface84bof the exhaust connecting pipe84. Fore-and-aft position adjusting bolt holes that are elongated in the fore-and-aft direction are formed in an inlet flange161aof the exhaust gas inlet pipe161. The embedded bolts85are loosely inserted through the inlet flange161aof the exhaust gas inlet pipe161from below, and nuts85aare screwed to the upper ends of the embedded bolts85so that the exhaust gas inlet pipe161is detachably fastened to the housing support85. The mounting position of the DPF52with respect to the exhaust connecting pipe84in the fore-and-aft direction is adjustable in a range corresponding to the dimension in which the embedded bolts85move forward and rearward in the bolt holes elongated in the fore-and-aft direction in the inlet flange161a.

That is, the mounting position of the rear section of the gas purification housing168in the fore-and-aft direction is adjustable with respect to the exhaust connecting pipe84and the inlet side bracket176by moving the embedded bolts85and the mounting bolts forward and rearward with respect to the fore-and-aft position adjusting bolt holes of each of the relay bracket179and the inlet flange161a. Thus, the mounting position of the DPF52with respect to the diesel engine5is easily determined, and the mounting accuracy of the DPF52, which is secured to the diesel engine5, is improved. Also, deformation force is prevented from being applied to the gas purification housing168due to, for example, an error in the coupling position of the exhaust connecting pipe84, the inlet side bracket176, and the outlet side bracket177. That is, even with the configuration in which the DPF52is located at a position above the diesel engine5where the DPF52is likely to be shaken, for example, the machine vibration of the DPF52is easily reduced.

The exhaust gas discharge side (exhaust outlet side) of the exhaust connecting pipe84that extends upward from the coupling support portion84a, which is fastened to the exhaust manifold57, is tilted rightward (toward the cylinder head55) with respect to the vertical direction (up and down direction). That is, when the exhaust connecting pipe84is viewed from the rear, the upward-facing mounting surface84bof the exhaust connecting pipe84is located to the right of a position directly above the coupling portion between the coupling support portion84aand the exhaust manifold57. The upward-facing mounting surface84bof the exhaust connecting pipe84is tilted with respect to a horizontal surface such that the right edge is lowered. The exhaust connecting pipe84is located such that the upper ends of the embedded bolts85are tilted to the right side. Thus, when the inlet flange161aof the exhaust gas inlet pipe161is secured to the upward-facing mounting surface84bof the exhaust connecting pipe84, the DPF52is lowered from above right to below left with respect to the exhaust connecting pipe84.

At this time, since the mounting bolts that are screwed to the securing bracket178are loosely fitted in the relay bracket179, the bolt holes of the inlet flange of the exhaust gas inlet pipe161are fitted to the embedded bolts85of the tilted exhaust connecting pipe84. As illustrated inFIG.15, the width Dx of the bracket coupling portion178bon the upper surface of the securing bracket178is greater than the width Dy of the lower end of the relay bracket179. That is, when the DPF52is lowered diagonally downward to couple the exhaust gas inlet pipe161to the exhaust connecting pipe84so that the DPF52is mounted onto the diesel engine5, the entire surface of the lower end of the relay bracket179is reliably received by the bracket coupling portion178bon the upper surface of the securing bracket178.

As illustrated inFIGS.12,14, and16, the outlet side first bracket181includes a proximal end181a. The proximal end181aincludes a plurality of vertical through holes. The mounting bolts that are to be screwed to bolt holes provided in the upper surface of the intake manifold56are inserted in the through holes. The proximal end181aof the outlet side first bracket181includes, for example, a proximal end component coupling portion (third component coupling portion)181b. The proximal end component coupling portion181bsecures a component securing bracket (compressor securing bracket)212(seeFIGS.28and33) for securing an external component such as an air conditioner compressor211(seeFIGS.28and33). The proximal end component coupling portion181bincludes some of the through holes for receiving the mounting bolts and bolt holes for threadedly receiving mounting bolts to fasten the component securing bracket212. That is, the component securing bracket212is fastened to the outlet side first bracket181with the mounting bolts and simultaneously fastened to the intake manifold56together with the outlet side first bracket181by the mounting bolts screwed to the through holes of the proximal end component coupling portion181b.

The outlet side first bracket181includes a bent portion (middle portion)181c. The upper surface of the bent portion181cincludes, for example, a middle component coupling portion (fourth component coupling portion)181d. The middle component coupling portion181dsecures a component securing bracket (warm water pipe securing bracket)208(seeFIGS.30,32, and33) for securing external components such as air conditioner warm water pipes203,204(seeFIGS.30,32, and33). In this embodiment, the bent portion181cof the outlet side first bracket181includes a flat step. The middle component coupling portion181dis provided on the upper surface of the step. The middle component coupling portion181dincludes bolt holes for threadedly receiving mounting bolts for fastening the component securing bracket208.

As illustrated inFIGS.12,14, and16, the outlet side second bracket182includes a proximal end182b. The proximal end182bincludes a plurality of through holes extending in the left and right direction for receiving mounting bolts that are to be screwed to the bolt holes provided on the left side of the intake manifold56. The outlet side second bracket182includes a bent portion (middle portion)182c. The bent portion182cincludes a rear component coupling portion (fifth component coupling portion)182d. The rear component coupling portion182dincludes bolt holes on the rear surface. A hanging fixture87is detachably bolted to the rear component coupling portion182d. After the diesel engine5is mounted on the work vehicle, the hanging fixture87is removed. In this case, for example, a component fixture (shield securing bracket)207(seeFIGS.26and33) for supporting an upstream relay pipe223and a shield206(seeFIGS.22and26), which will be described later, is bolted to the rear component coupling portion182d. The outlet side second bracket182includes the upper end curved surface (U-shaped pressure-receiving surface)182aat the upper end portion extending from the bent portion182ctoward the right side distal end. The upper end curved surface182acorresponds to the outline of the gas purification housing168.

As illustrated inFIGS.16to18, an engagement shaft (projection), which is an embedded bolt183in this embodiment, is provided at the upper end central portion of the outlet side second bracket182. The embedded bolt183projects forward from the front surface of the upper end central portion of the outlet side second bracket182. The bracket fastening portion172aof the outlet sandwich flange172of the gas purification housing168includes an engagement shaft (recess), which is a downward-opening bolt insertion notch184in this embodiment. That is, a bolt hole for receiving the embedded bolt183is notched in the bracket fastening portion172aof the outlet sandwich flange172in such a manner as to open upward. This forms the bolt insertion notch184.

The embedded bolt183of the outlet side second bracket182is configured to be engageable with the bolt insertion notch184in the bracket fastening portion172aof the outlet sandwich flange172. The downstream side of the gas purification housing168in the exhaust gas moving direction (exhaust discharge side) is placed on the upper end of the outlet side second bracket182, and the bolt insertion notch184is engaged with the embedded bolt183so that the downstream side of the gas purification housing168in the exhaust gas moving direction (exhaust discharge side) is supported by the outlet side second bracket182.

The engagement of the embedded bolt183with the bolt insertion notch184holds the exhaust discharge side of the gas purification housing168at a predetermined position. That is, in addition to placing the relay bracket179, which is secured to the gas purification housing168via the extended bracket180, on the upper end of the securing bracket178and placing the exhaust introduction end of the exhaust gas inlet pipe161on the upper end (exhaust discharge end) of the exhaust connecting pipe84, the bolt insertion notch184of the gas purification housing168is engaged with the embedded bolt183of the outlet side second bracket182so that the gas purification housing168is temporarily fixed on the inlet side bracket176and the outlet side bracket177.

Thus, the mounting position of the exhaust gas purification device52with respect to the diesel engine5is easily determined, and an operator who performs a mounting operation can take hands off the exhaust gas purification device52in the temporarily fixed state. It is therefore unnecessary to perform the mounting operation such as fastening bolts and a removing operation while supporting the entire weight of the exhaust gas purification device52. This significantly reduces trouble in mounting and removing the exhaust gas purification device52and in assembly and disassembly of the exhaust gas purification device52.

Subsequently, with the bolt insertion notch184engaged with the embedded bolt183, an engagement nut185is screwed to the embedded bolt183(perform additional tightening) so that the bracket fastening portion172aof the outlet sandwich flange172of the gas purification housing168is coupled to the upper end central portion of the outlet side second bracket182. Unlike this embodiment, the embedded bolt183may be provided on the gas purification housing168, and the bolt insertion notch184may be provided on the outlet side second bracket182.

Since one of the outlet side bracket177and the gas purification housing168includes a projection (embedded bolt183) or a recess (bolt insertion notch184), and the other one of the outlet side bracket177and the gas purification housing168includes the recess (bolt insertion notch184) or the projection (embedded bolt183), the mounting position of the gas purification housing168is easily determined by the engagement of the embedded bolt183(projection) and the bolt insertion notch184(recess). The projection and the recess are engagement bodies. It is therefore unnecessary to perform the mounting operation such as fastening bolts while supporting the entire weight of the DPF52, and the operator can take hands off the DPF52while performing the mounting operation. This improves workability in assembly and disassembly of the DPF52.

Furthermore, as illustrated inFIGS.17and18, the opening direction of the bolt insertion notch184matches with a direction in which the inlet flange161aof the exhaust gas inlet pipe161of the DPF52is mounted onto the upward-facing mounting surface84bof the exhaust connecting pipe84. That is, the bolt insertion notch184is open in a direction parallel to the inclination direction of the embedded bolts85, which are provided on the upward-facing mounting surface84bof the exhaust connecting pipe84. Thus, when the DPF52is secured to the exhaust connecting pipe84, the inlet side bracket176, and the outlet side bracket177to be supported by the exhaust connecting pipe84, the inlet side bracket176, and the outlet side bracket177, the bolt insertion notch184is easily engaged with the embedded bolt183while fitting the position adjusting bolt holes of the inlet flange161aof the exhaust gas inlet pipe161to the embedded bolts85. This further improves workability in assembly and disassembly of the DPF52.

When the DPF52is temporarily supported with the bolt insertion notch184being engaged with the embedded bolt183, the upward-facing mounting surface84bof the exhaust connecting pipe84receives the exhaust gas inlet pipe61, the bracket coupling portion178bof the securing bracket178receives the relay bracket179, and the upper end curved surface182aof the outlet side second bracket182receives the outer circumferential surface of the gas purification housing168. Since the temporarily fixed DPF52is temporarily supported by the exhaust connecting pipe84, the securing bracket178, and the outlet side second bracket182in a stable manner, the operator can take hands off the DPF52in this state.

On the exhaust gas inlet side of the DPF52, the upward-facing mounting surface84bof the exhaust connecting pipe84and the coupling plate179bof the relay bracket179further form a V-shaped pressure-receiving surface. The exhaust gas outlet side of the DPF52is placed on the upper end curved surface182aof the outlet side second bracket182. Thus, when the DPF52is temporarily supported on the exhaust connecting pipe84, the inlet side bracket176, and the outlet side bracket177, the exhaust gas inlet side and the exhaust gas outlet side of the DPF52are restricted from moving in a direction intersecting the output shaft53of the engine5by the V-shaped pressure-receiving surface and the U-shaped pressure surface. This configuration prevents the DPF52from falling off.

As illustrated inFIGS.7to11, hanging fixtures86,87are coupled to the inlet side bracket176and the outlet side bracket177. The hanging fixtures86,87are used for attaching, for example, hanging wires. Thus, when the diesel engine5is unloaded to the work vehicle, hanging wires respectively inserted in hanging through holes of the hanging fixtures86,87are engaged with, for example, a hook of a chain block to lift the diesel engine5so that mounting and removing operation of the diesel engine5can be performed.

The hanging fixture86is coupled to the securing bracket178of the inlet side bracket176, which is located on the rear right of the diesel engine5, and the hanging fixture87is coupled to the outlet side second bracket182of the outlet side bracket177, which is located on the front left of the diesel engine5. That is, since the hanging fixtures86,87are arranged diagonally opposite to each other with respect to the diesel engine5, the diesel engine5is hung by, for example, the chain block in a stable position. Furthermore, since the hanging fixtures86,87are attachable and detachable, the hanging fixtures86,87can be removed when the diesel engine5is mounted on the work vehicle. This configuration reduces the space occupied by the diesel engine5in the engine compartment of the work vehicle.

Next, a configuration in which the diesel engine5is mounted on the work vehicle, which is a tractor1in this embodiment, will be described with reference toFIGS.19to33. A traveling body2of the tractor1according to this embodiment is supported by traveling sections, which are a pair of left and right front wheels3and a pair of left and right rear wheels4in this embodiment. The rear wheels4and the front wheels3are driven by a power source mounted on the front section of the traveling body2. The power source is the common rail diesel engine5(hereinafter, simply referred to as the engine) in this embodiment. The tractor1travels forward and backward by driving the rear wheels4and the front wheels3. The engine5is covered with a hood6. A cabin7is provided on the upper surface of the traveling body2. An operator's seat8and a steering wheel (round steering wheel)9are located inside the cabin7. The steering wheel9is steered to move the steering direction of the front wheels3to left and right. A step10is provided on the lower section outside the cabin7. The step10is used by an operator to get on and off. The fuel tank11, which supplies fuel to the engine5, is provided below the bottom portion of the cabin7.

The traveling body2includes the engine frames (front frames)14, which include a front bumper (frame coupling member)12and front axle cases13, and left and right body frames (rear frames)15. The left and right body frames15are detachably secured to the rear portions of the engine frames14. A front axle16rotationally projects outward from the left side of the left front axle case13and from the right side of the right front axle case13. The front wheels3are secured to the left side of the left front axle case13and the right side of the right front axle case13via the front axle16. A transmission case17is coupled to the rear portion of the body frame15. The transmission case17changes speed of rotational power from the engine5as required and transmits the rotational power to the four front and rear wheels3,3,4,4. A tank frame18is bolted to the left and right body frames15and the bottom surface of the transmission case17. The tank frame18is a rectangular frame plate as viewed from the bottom and bulges outward in the left and right direction. The fuel tank11of this embodiment is separated into two left and right parts. The left and right parts of the fuel tank11are distributed on the upper surface of the left and right bulging sections of the tank frame18. Left and right rear axle cases19are mounted on the left and right external side surfaces of the transmission case17to project outward. Left and right rear axles20are rotationally inserted in the left and right rear axle cases19. The rear wheels4are secured to the transmission case17via the rear axles20. The upper sections of the left and right rear wheels4are covered with left and right rear fenders21.

A hydraulic lifting and lowering mechanism22is detachably secured to, for example, the rear upper surface of the transmission case17. The hydraulic lifting and lowering mechanism22lifts and lowers a farm implement such as a rotary tiller. The farm implement, such as a rotary tiller, is coupled to the rear portion of the transmission case17via a three point link mechanism including a pair of left and right lower links23and a top link24. A power take-off (PTO) shaft25projects rearward from the rear side of the transmission case17. The PTO shaft25transmits PTO drive power to the farm implement, such as a rotary tiller.

The flywheel61is directly coupled to the engine output shaft53, which projects rearward from the rear side of the engine5. A main drive axle27and a main transmission input shaft28are coupled with each other via a power transmission shaft29. The main drive axle27projects rearward from the flywheel61. The main transmission input shaft28projects forward from the front side of the transmission case17. The power transmission shaft29includes universal couplings on both ends. A hydraulic continuously variable transmission, a steering reverser, a traveling sub-transmission gear mechanism, and a rear wheel differential gear mechanism are located in the transmission case17. Rotational power of the engine5is transmitted through the main drive axle27and the power transmission shaft29to the main transmission input shaft28in the transmission case17. The rotational speed of the rotational power is changed by the hydraulic continuously variable transmission and the traveling sub-transmission gear mechanism. The speed-changed power is transmitted to the left and right rear wheels4via the rear wheel differential gear mechanism.

Front wheel output shafts30project forward from the lower part of the front surface of the transmission case17. A front wheel transmission shaft (not shown) projects rearward from each front axle case13, which embeds a front wheel differential gear mechanism (not shown). The front wheel transmission shafts are coupled to the front wheel output shafts30via front wheel drive shafts31. The speed-changed power changed by the hydraulic continuously variable transmission and the traveling sub-transmission gear mechanism in the transmission case17is transmitted from the front wheel output shafts30, the front wheel drive shafts31, and the front wheel transmission shafts via the front wheel differential gear mechanisms in the front axle cases13to the left and right front wheels3.

The turbocharger81of the engine5includes the compressor case83, which embeds the blower wheel. The intake-air introduction side of the compressor case83is coupled to the intake-air discharge side of the air cleaner221via the supply pipe222, and the intake-air discharge side of the compressor case83is coupled to the upstream relay pipe223. The turbocharger81includes the turbine case82, which embeds the turbine wheel. The exhaust introduction side of the turbine case82is coupled to the exhaust gas outlet of the exhaust manifold57, and the intake-air discharge side of the turbine case82is coupled to the exhaust gas inlet of the after-treatment device, which is the exhaust gas purification device52in this embodiment.

The EGR cooler80and the EGR apparatus75, which are distributed on both sides of the engine5, are coupled to each other by the recirculation exhaust gas pipe78. The recirculation exhaust gas pipe78is a circulation passage that detours around the rear surface of the engine5(close to the flywheel61). The EGR apparatus75is coupled to the downstream relay pipe225, which extends forward (toward the cooling fan59) on the right side of the engine5. The upstream relay pipe223and the downstream relay pipe225are distributed on both sides of the engine5and extend toward the front upper section of the engine5to be coupled to the intercooler224, which is located on a frame226at the front of the engine5. The air cleaner221is located on the upper section of the front surface of the frame226. The supply pipe222, which is coupled to the air cleaner221, extends over the frame226toward the rear section on the left side of the engine5.

With the above-described configuration, dust is removed from the fresh air (external air) taken into the air cleaner221to purify the fresh air, and the fresh air is then drawn into the compressor case83of the turbocharger81via the supply pipe222. The pressurized fresh air that has been compressed in the compressor case83of the turbocharger81is supplied to the EGR body case of the EGR apparatus75via the relay pipes223,225and the intercooler224. Some of the exhaust gas (EGR gas) from the exhaust manifold57is cooled by the EGR cooler80, and the cooled EGR gas is then supplied to the EGR body case of the EGR apparatus85via the recirculation exhaust gas pipe78.

The exhaust gas purification device52includes the exhaust gas inlet pipe161on the case outer circumferential surface at one end (rear end) of the exhaust gas purification device52in the longitudinal direction. The exhaust gas inlet pipe161communicates with the exhaust gas discharge side of the turbine case82in the turbocharger81via the exhaust connecting pipe84. The exhaust gas purification device52includes the exhaust gas outlet pipe162on the case outer circumferential surface at the other end (front end) of the exhaust gas purification device52in the longitudinal direction. The exhaust gas outlet pipe162is coupled to the exhaust pipe227. In the exhaust gas purification device52, the exhaust gas inlet pipe161is open downward to the left, and the exhaust gas outlet pipe162is open upward to the right. The exhaust pipe227is located to extend over the engine5from the front left side toward the rear right side of the diesel engine5. The exhaust pipe227is located between the exhaust gas purification device52and the downstream relay pipe225to be approximately parallel to the exhaust gas purification device52and the downstream relay pipe225.

The exhaust gas purification device52and the exhaust pipe227are arranged above the engine5next to each other in the left and right direction to be parallel to the output shaft of the engine5. That is, the exhaust gas purification device52and the exhaust pipe227are arranged next to each other such that the exhaust gas purification device52covers the left section of the upper surface of the engine5, and the exhaust pipe227covers the right section of the upper surface of the diesel engine5. The downstream relay pipe225, which connects the intercooler224and the intake connecting pipe84, is located further rightward of the exhaust pipe227. This configuration prevents the exhaust gas purification device52that is heated to a high temperature from thermally affecting the downstream relay pipe225.

The exhaust pipe227, which is coupled to the exhaust side of the exhaust gas purification device52, is inserted in the exhaust gas inlet port of the tailpipe229on the rear right side of the diesel engine5. The tailpipe229is located on the front right side of the cabin7and extends toward the exhaust gas discharge side from below upward. The tail pipe229is bent toward the diesel engine5below the cabin7so that the tail pipe229has a J-shape. The exhaust pipe227also includes an umbrella-like upper surface cover228on the outer circumferential surface above the section at which the exhaust pipe227is inserted in the tailpipe229. The upper surface cover228is secured to the outer circumferential surface of the exhaust pipe227to extend in a radial pattern. The upper surface cover228covers the exhaust gas inlet port of the tailpipe229and prevents dust and rain water from entering the tailpipe229.

The tailpipe229is formed such that the lower bent portion extends over the body frame15from the inner side to the outer side. The tailpipe229includes an exhaust gas inlet port provided on the inner side of the body frame15at an upper section, and the exhaust gas discharge port of the exhaust pipe227is inserted in the exhaust gas inlet port. That is, the coupling portion between the tailpipe229and the exhaust pipe227has a two-layer pipe structure. When exhaust gas flows from the exhaust pipe227to the tailpipe229, outside air is simultaneously allowed to flow into the tailpipe229through the space between the exhaust pipe227and the tailpipe229. This configuration cools the exhaust gas that flows in the tailpipe229. Furthermore, the tailpipe229is configured to be covered with a heat insulator230. Engine covers232are located below the hood6on the left and right sides to cover the left and right sides of the engine compartment. The engine covers232are made of perforated plates.

Next, a configuration of the engine compartment frame below the hood6will be described with reference toFIGS.20to24. The hood6includes a front grille231at the front lower section to cover the front of the engine compartment. The engine covers232are formed of perforated plates and are located below the hood6on the left and right side to cover the left and right side of the engine compartment. That is, the hood6and the engine covers232cover the front, the upper section, and the left and right sides of the diesel engine5.

The front end inner surfaces of the pair of left and right engine frames (front frames)14are coupled to the left and right outer surfaces of the frame coupling member12. The frame coupling member12is formed of a rectangular metal casting. The diesel engine5is supported on the engine frames14, which are held by the frame coupling member12. A frame bottom plate233is held by the upper edges of the left and right engine frames14and the upper surface of the front bumper12to cover the front end upper sections of the engine frames14. The radiator235stands upright on the frame bottom plate233to be located in front of the engine5. A fan shroud234is secured to the rear surface of the radiator235. The fan shroud234surrounds the outer circumference of the cooling fan59and connects the radiator235to the cooling fan59.

The radiator235includes a coolant discharge port at the upper section and a coolant introduction port at the lower section. The coolant discharge port of the radiator235communicates with the coolant introduction port of the thermostat case70via a coolant supply pipe201. The coolant introduction port of the radiator235communicates with a coolant discharge port of the coolant pump71via a coolant return pipe202. The coolant in the radiator235is supplied to the coolant pump71via the coolant supply pipe201and the thermostat case70. When the coolant pump71is driven, the coolant is supplied to the water-cooling jacket (not shown), which is formed in the cylinder block54and the cylinder head55, to cool the engine5. The coolant that has contributed to cooling the engine5is returned to the radiator235via the coolant return pipe202.

The thermostat case70is also coupled to the warm water pipe203, and the coolant pump71is also coupled to the warm water pipe204. The coolant (warm water) that has contributed to cooling the engine5is circulated to an air conditioner (not shown) of the cabin7. Thus, warm water circulates in the air conditioner (not shown) of the cabin7, and the air conditioner (not shown) supplies warm air into the cabin7. This configuration allows an operator to adjust the temperature in the cabin7to a desired temperature.

The front end of each of the left and right body frames15is coupled to the rear end of the corresponding one of the left and right engine frames14via a spacer297. The left and right body frames15are located to sandwich the left and right engine frames14. The sections of the pair of left and right body frames15located below the front section of the floor plate41are coupled to each other by a support beam frame236. The coupling surface (outer side) between each body frame15and the support beam frame236is flush with the coupling surface (outer side) between each spacer297and the associated body frame15. The support beam frame236is bolted to the left and right body frames15to hold the left and right body frames15. An engine support frame237is mounted on the upper surface of the support beam frame236. The lower end surface of the engine support frame237is bolted to the upper surface of the support beam frame236so that the engine support frame237surrounds the flywheel61of the diesel engine5together with the support beam frame236.

The engine mount fittings74, which are provided on left and right lower sides of the diesel engine5, are coupled to engine support brackets298via the engine mounts238. The engine support brackets298are located at the middle of the pair of left and right engine frames14. The engine mounts238each include an anti-vibration rubber239. Engine mount fittings60aare provided on the upper section of the flywheel housing60, which is located on the rear surface of the diesel engine5. The engine mount fittings60aare coupled to the upper surface of the engine support frame237via an engine mount240. The engine mount240includes anti-vibration rubbers241.

The engine mounts238are bolted to the upper sections of the engine support brackets298, which are coupled to the outer side at the middle of the pair of left and right engine frames14, with the anti-vibration rubbers239located on the lower side. The diesel engine5is sandwiched between the engine frames14with the pair of left and right engine mounts238so that the front section of the diesel engine5is supported. The rear surface of the diesel engine5is coupled to the front ends of the pair of left and right body frames15via the support beam frame236, the engine support frame237, and the engine mount240so that the rear section of the diesel engine5is supported by the front ends of the body frames15. The left and right front anti-vibration rubbers239and the left and right rear anti-vibration rubbers241support the diesel engine5on the traveling body2.

A pair of left and right support column frames242,243extend upright from the upper surface of the engine support frame237to sandwich the engine mount240from left and right sides. A hood shield244covers the rear of the hood6. The hood shield244is coupled to the pair of left and right support column frames242,243such that the lower edge of the hood shield244is separate from the upper surface of the engine mount240. Beam frames248are held between the upper sections of the fan shroud234and the hood shield244. Since the fan shroud234and the hood shield244, which are stably supported by the traveling body2, are coupled to each other by the pair of beam frames248, which are held between the fan shroud234and the hood shield244, these members integrally configure a sturdy engine compartment frame as a whole.

The exhaust gas purification device52, which is mounted on the upper section of the engine5, is located inside the rear section of the hood6. A heat insulator250is located between the hood6and the exhaust gas purification device52. Since the heat insulator250is located above the exhaust gas purification device52, the temperature of the hood6is prevented from being increased by exhaust heat generated by the exhaust gas purification device52and the diesel engine5. A space is formed between the hood6and the heat insulator250to insulate the inside of the engine compartment below the heat insulator250from the heat of the outside air. This configuration allows the exhaust gas purification device52to be operated under a high-temperature environment.

Furthermore, the hood shield244, which is located on the rear side of the hood6and covers at least the exhaust gas purification device52from the rear surface, is provided in addition to the above-described heat insulator250. Since heat in the engine compartment below the hood6is insulated by the hood shield244together with the heat insulator250, the temperature inside the cabin7is prevented from being increased by the exhaust heat from the engine compartment. Also, a gap between the hood shield244and the heat insulator250makes it unlikely that heat is kept in the engine compartment below the hood6. This inhibits heat damage on, for example, the exhaust gas purification device52itself and the hood6.

Extendable gas springs (hood dampers)256,256are located on the left and right sides of the heat insulator250below the hood6. One end (rear end) of each of the pair of left and right gas springs256,256is pivotally attached to the engine compartment frame, and the other end (front end) of each of the gas springs256,256is pivotally attached to the inner surface of the upper section of the hood6. The hood6is held in an open position by the tension of the gas springs256. Thus, when the front portion of the hood6is lifted to open the hood6with the upper end position of the hood shield244serving as a shaft fulcrum, the gas springs256keep the hood6in the open state. In this state, maintenance of the diesel engine5can be performed.

As illustrated inFIGS.23to25, the hood6of the tractor1has an inverted U-shaped cross-section. Since the left and right corners of the hood6are chamfered to incline diagonally and outwardly downward to the left and right as viewed from the front, the forward view of the operator seated in the operator's seat8, in particular, the view ahead of the left and right of the hood6is improved. While the exhaust gas purification device (DPF)52and the exhaust connecting pipe84oppose the left side inner wall of the hood6, the intake connecting pipe76opposes the right side inner wall of the hood6. While the exhaust connecting pipe84is located at a position facing the left side engine cover232, the exhaust connecting pipe84is located at a position facing the right side engine cover232.

As illustrated inFIGS.23and24, the intake connecting pipe76, which includes a hollow portion and supplies fresh air to the intake manifold56, is configured to be tilted toward the cylinder head55as the intake connecting pipe76extends upward. The intake connecting pipe76extends upward from the intake manifold56. That is, a fresh air introduction port located at the upper end of the intake connecting pipe76is offset with respect to a fresh air discharge port located at the lower end of the intake connecting pipe76toward the output shaft53of the engine5(center position of the engine5). The intake connecting pipe76is arranged to be in conformance with the shape of the hood6that narrows upward, and the intake throttle member77is located closer to the center position of the hood6than the intake connecting pipe76between the upper section of the engine5and the inner surface of the hood6. This configuration not only reduces the designed length of the downstream relay pipe225, which connects a fresh air discharge end of the intercooler224to the intake throttle member77, but also allows the downstream relay pipe225to be compactly accommodated in the hood6, which has an upwardly decreasing lateral width.

As illustrated inFIGS.23and24, the exhaust connecting pipe84, which includes a hollow portion that supplies exhaust gas from the exhaust manifold57to the exhaust gas purification device52, is configured to be tilted toward the cylinder head55as the exhaust connecting pipe84extends upward. The exhaust connecting pipe84is coupled to the exhaust gas inlet pipe161of the exhaust gas purification device52to support the exhaust gas purification device52. That is, the exhaust gas discharge port at the upper end of the exhaust connecting pipe84is offset toward the output shaft53of the engine5(center position of the engine5) with respect to the coupling support portion84aat the lower end of the exhaust connecting pipe84. The coupling support portion84ais coupled to the exhaust manifold57at the lower end. The exhaust gas inlet pipe161of the exhaust gas purification device52is tilted toward the outer side of the engine5(toward the inner wall of the hood6) as the exhaust gas inlet pipe161extends downward (toward the inlet flange161a).

The exhaust gas purification device52and the exhaust connecting pipe84are arranged to be in conformance with the shape of the hood6that narrows upward, and the exhaust gas purification device52is supported at a position closer to the center of the engine5between the upper section of the engine5and the inner surface of the hood6. Thus, the exhaust gas purification device52is compactly accommodated in the hood6, which has an upwardly decreasing lateral width. Supporting the exhaust gas purification device52, which is a heavy object, at a position closer to the center of gravity of the engine5inhibits increase in, for example, vibration and noise of the engine5caused by mounting the exhaust gas purification device52. This configuration also reduces influence on the shape of the hood6caused by mounting the exhaust gas purification device52on the engine5and prevents the shape of the hood6from becoming complicated.

As illustrated inFIGS.24and25, the width W1of the flywheel housing60, which covers the flywheel61is narrower than the height H1. The flywheel61is located on the end surface that intersects the axis of the engine output shaft53. Since the width of the flywheel housing60is narrow, the engine5can be mounted on the traveling body2, which has a narrow lateral width, without interference by the flywheel housing60. In the traveling body2, each body frame15is provided on the outer side of the associated engine frame14via the associated spacer293. Thus, the width between the left and right body frames15is wider than the width between the left and right engine frames14. The flywheel housing60is located at the rear of the engine5. The main transmission input shaft28of the transmission case17, which is coupled to the body frames15, is coupled to the flywheel61. Thus, the flywheel housing60, which has the greatest lateral width in the engine5, is sufficiently located between the body frames15. This prevents the flywheel housing60from colliding with the traveling body2, which has a different vibration system and thus prevents failure or breakage of the engine5.

The flywheel housing60has an outline in which the left and right parts of a circle are cut off and in which the seat-like engine mount fittings60aproject from the upper section. The engine mount fittings60aat the upper section are coupled to the traveling body2via the engine mount240at the rear portion. The flywheel housing60is not only mountable on the traveling body2having a narrow width, but also includes the seat-like engine mount fittings60athat are capable of being coupled to the traveling body2. Thus, coupling the flywheel housing60having a high rigidity to the traveling body2reinforces for the rigidity achieved by the support structure of the engine5.

More particularly, the inverted U-shaped engine support frame237is provided above the support beam frame236, which is held between the pair of left and right body frames15. The flywheel housing60and the engine support beam frame237are arranged next to each other in the fore-and-aft direction. While the rear section of the engine mount240is coupled to the upper surface of the engine support frame237via the anti-vibration rubbers241, the front section of the engine mount240is coupled to the upper surface of the engine mount fittings60aon the flywheel housing60.

As illustrated inFIGS.24and26, a perforated heat insulator205is located below the exhaust gas purification device (DPF)52. The perforated heat insulator205covers the left side of the engine5. Since the heat insulator205is configured to cover the exhaust manifold57, the turbocharger81, and the exhaust connecting pipe84, high-heat sources in the engine5are covered with the heat insulator205. Thus, the temperature of the exhaust gas supplied to the DPF52is maintained high, and decrease in the regeneration ability of the DPF52is prevented. Since the heat insulator205is perforated and located to face the similarly perforated left side engine cover232, some of air heated by the engine5is discharged to the outside through the heat insulator205and the engine cover232. This configuration prevents heat retention on the left side of the engine5where the temperature is likely to become relatively high.

The heat insulator205is bolted to the exhaust gas introduction port side of the exhaust connecting pipe84(coupling portion coupled to the turbine case82of the turbocharger81) and coupled to the rear component coupling portion182dof the outlet side second bracket182via the shield securing bracket207to be supported by the engine5. The shield securing bracket207is also coupled to the upstream relay pipe223, which connects the fresh air introduction port of the intercooler224to the compressor case83of the turbocharger81, and the upstream relay pipe223is also supported by the outlet side second bracket182of the engine5.

As illustrated inFIGS.24and26, the heat insulating member206, which is coupled to one side of the engine5, is provided below the exhaust manifold57, and an engine starter69is located below the heat insulator206. The heat insulating member206, which is coupled to the left side of the cylinder block54, extends upright toward the engine cover232at a position between the engine starter69and the EGR cooler80. Thus, the heat insulating member206covers over the electric device, which is the starter69in this embodiment. This reduces thermal influence on the starter69caused by heat dissipation from the exhaust manifold57that is heated and prevents failure of the electric device, which is the starter69in this embodiment.

As illustrated inFIGS.27to29, the oil filter63, which filters lubricant from the oil pan62, is located on the lower right side of the cylinder block54via the oil filter support member (support bracket)88, which includes a hollow portion for allowing the lubricant to pass through the oil filter support member88. An oil pump (not shown) is located on the front side (close to the cooling fan59) at a section closer to the right side in the cylinder block54, and an oil passage (not shown) extends rearward from the oil pump (not shown). One side (left side) of the oil filter support member88is coupled to the coupling port (oil filter mounting position) that communicates with the above-described oil passage provided in the cylinder block54. The oil filter63is secured to the upper section of the other side (right side) of the oil filter support member88.

When the oil filter63is secured to the cylinder block54, the oil filter support member88is provided in between. Thus, the oil filter63is arranged at a position higher than the original mounting position in the cylinder block54. This prevents the oil filter63from interfering with the traveling body2even if the engine5is mounted on the traveling body2having a narrow lateral width. That is, as illustrated inFIGS.27and28, the oil filter63is located above the engine frame14due to the existence of the oil filter support member88. Thus, the oil filter63is accessible and can be replaced easily.

The engine side coupling portion is provided on one side (left side) of the oil filter support member88to be coupled to the coupling port (oil filter mounting position) provided in the cylinder block54. Also, a filter coupling portion88aand a lubricant outlet88bare vertically arranged on the other side (left side) of the oil filter support member88. The filter coupling portion88ais coupled to the oil filter63. The lubricant outlet88bdischarges lubricant to an external component.

The oil filter support member88includes an oil passage (not shown) formed in the oil filter support member88. Lubricant that is drawn in from the oil pan62by the oil pump (not shown) is received through the oil passage (not shown) in the cylinder block54and supplied to the oil filter63. The lubricant that has been filtered by the oil filter63is circulated to the cylinder block54and supplied to the lubrication parts of the engine5. At this time, some of the lubricant filtered by the oil filter63is supplied to the external component through the lubricant outlet88bvia a lubricant supply pipe89. Since part of a lubricant passage from the oil filter63to the external component is formed by the oil passage in the oil filter support member88, the oil filter support member88serves multiple functions. This configuration reduces the number of components of the engine apparatus.

In this embodiment, as illustrated inFIG.29, the lubricant introduction port of the turbocharger81is coupled to the lubricant outlet88bof the oil filter support member88via the lubricant supply pipe89. The turbocharger81includes an oil passage for supplying lubricant to a floating metal bearing. The lubricant supply pipe89, which communicates with the lubricant outlet88bof the oil filter support member88, is located along the right side of the cylinder block54and the rear and left surfaces of the cylinder head55and is coupled to the oil passage (oil passage for supplying lubricant to the floating metal bearing) provided in the turbocharger81.

As illustrated inFIG.30, the engine5includes the thermostat case70, which is located below the exhaust gas outlet side of the exhaust gas purification device52, and the coolant pump71, which is located below the thermostat case70and between the cooling fan59and the cylinder head55. The coolant inlet (coolant introduction port) of the thermostat case70, which is above the coolant pump71, is oriented rightward of the cylinder head55. The cooling fan59is located above the traveling body2, and the cooling fan59and the coolant pump71are arranged to be coaxial. Thus, the engine components are compactly arranged, and the size of the engine5is reduced. The engine5is thus capable of being mounted on a traveling vehicle that has a limited engine compartment shape like the tractor1of this embodiment.

The coolant inlet that is bent rightward above the thermostat case70communicates with the coolant outlet (coolant discharge port) at the upper section of the radiator235via the coolant supply pipe201. The radiator235is located forward of the engine5with the fan shroud234located in between. Also, the coolant discharge port of the coolant pump71projects rightward from the main body of the coolant pump71and communicates with the coolant introduction port at the lower section of the radiator235via the coolant return pipe202. The coolant supply pipe201and the coolant return pipe202, which are coupled to the radiator235, are both arranged on the right side of the engine5. This configuration not only reduces thermal influence on the coolant caused by exhaust heat from the engine5, but also improves workability in assembly and disassembly.

As illustrated inFIGS.30to33, the warm water pipes203,204, which circulate warm water (coolant) to the air conditioner (not shown), are respectively coupled to the thermostat70and the coolant pump71. The warm water pipes203,204extend rearward on the right side position of the exhaust gas purification device52and are coupled to the air conditioner (not shown) in the cabin7. That is, the warm water pipes203,204, which are coupled to the thermostat70and the coolant pump71on the right side, extend rearward in a bundle located one above the other. The warm water pipes203,204are also arranged to pass above the bent portion (middle portion)181cof the outlet side first bracket181. The warm water pipes203,204are coupled to the middle component coupling portion181don the bent portion181cof the outlet side first bracket181via the warm water pipe securing bracket208to be supported by the engine5.

The DPF52includes the temperature sensors186,187, which detect exhaust gas temperature that flows through the gas purification housing168. The temperature sensors186,187are, for example, thermistor temperature sensors. The temperature sensors186,187are inserted in the gas purification housing168and include wiring connectors190,191for outputting measurement signals. The wiring connectors190,191of the temperature sensors186,187are secured to the warm water pipe securing bracket208. The warm water pipe securing bracket208is configured by a plate that is bent into an L-shape and extends upright from the bent portion181cof the outlet side first bracket181to be parallel to the DPF52.

While the warm water pipes203,204are secured to the left side (side facing the DPF52) of the warm water pipe securing bracket208, the wiring connectors190,191are secured to the right side (side further from the DPF52) of the warm water pipe securing bracket208. The warm water pipes203,204, which supply coolant (warm water) that has contributed to cooling the engine5to an external device such as the air conditioner, are provided close to the DPF52. This prevents decrease in the coolant temperature supplied to the external device. Providing a component to stand on the outer side of the warm water pipe securing bracket208insulates the heat of exhaust heat from the DPF52. The electric components, which are the wiring connectors190,191in this embodiment, are arranged on the further side of the warm water pipe securing bracket208from the DPF52. This reduces influence caused by the exhaust heat from the engine5and the DPF52, prevents failure caused by heat, and simultaneously inhibits noise from being superimposed on the output signal.

As illustrated inFIGS.27,32, and33, the DPF52includes the sensor pipes188,189, which are coupled to positions at the front and rear of the soot filter164in the gas purification housing168to detect the difference between the pressure of the exhaust gas in the section upstream of the soot filter164and the pressure of the exhaust gas in the section downstream of the soot filter164with a pressure difference sensor192. The deposition amount of the particulate matter in the soot filter164is converted based on the pressure difference detected by the pressure difference sensor192to grasp the state of clogging in the DPF. A sensor bracket209is located on the fan shroud234, which is located in front of the engine5and surrounds the cooling fan59. The pressure difference sensor192is secured to the sensor bracket209.

The sensor bracket209projects rearward from the rear surface of the fan shroud234and is located at a position higher than the sensor bosses175, which are coupled to the sensor pipes188,189, and rightward of the DPF52. The pressure difference sensor192is secured to the upper surface of the sensor bracket209, and the sensor pipes188,189are coupled to the sensor bracket209from the lower side. In this embodiment, the pressure difference sensor192, which is secured to the sensor bracket209, is located at a position higher than the DPF52.

Since the sensor192, which measures the internal environment of the DPF52, is secured to the upper section of the fan shroud234, the sensor192is located at an upstream section in the engine compartment along the flow direction of the cooling air. This configuration reduces influence of exhaust heat from the engine5and the DPF52and prevents failure of the sensor192that might otherwise be caused by the heat. Thus, the internal environment of the DPF52is properly grasped to optimally control the engine5.

The exhaust gas outlet pipe162of the DPF52is provided close to the cooling fan59. The pressure difference sensor192, which measures the pressure difference between the front and rear of the soot filter164in the DPF52, is secured to the upper section of the fan shroud234. The DPF52is located in a direction along the output shaft53of the engine5. The pressure difference sensor192, which measures the pressure at the front and rear of the soot filter164close to the exhaust outlet, is located at the upper section of the fan shroud234adjacent to the exhaust outlet. This configuration reduces the length of the sensor pipes188,189, which are located between the pressure difference sensor192and the DPF52, and reduces measurement errors caused by the pressure difference sensor192.

As illustrated inFIGS.31to33, the exhaust pipe227is coupled to the exhaust gas outlet pipe162, which is provided on the front right side of the outer circumferential surface of the DPF52facing upward. The exhaust pipe227is bent rearward along the exhaust gas flow direction and is arranged to be parallel to the DPF52. The exhaust pipe227is bent downward at the downstream section along the exhaust gas flow such that the exhaust gas discharge port faces downward. The exhaust gas discharge port of the exhaust pipe227is inserted in the exhaust gas introduction port of the tailpipe229, which is secured to the cabin7. A securing coupling member210ais provided at the middle of the outer circumference of the exhaust pipe227. The exhaust pipe227is supported by the engine5by coupling the securing coupling member210ato the bracket coupling portion178bof the securing bracket178via the exhaust pipe securing bracket210.

The tractor1includes the exhaust pipe (first exhaust pipe)227, which is coupled to the exhaust gas outlet pipe162of the DPF52and secured to the engine5, and the tailpipe (second exhaust pipe)229, which is provided downstream of the exhaust pipe227and secured to the traveling body2. The inner diameter of the tailpipe229is greater than the outer diameter of the exhaust pipe227, and the exhaust outlet end of the exhaust pipe227is inserted in and communicates with the exhaust inlet of the tailpipe229. The exhaust pipe227and the tailpipe229are securely coupled to the engine5, the traveling body2, and the cabin7, which have different vibration systems. This configuration prevents damage on the exhaust pipe227and the tailpipe229. Since the exhaust pipe227is configured to be inserted in the exhaust inlet of the tailpipe229, the outside air is introduced into the tailpipe229together with the exhaust gas from the exhaust pipe227. This cools the exhaust gas that is to be discharged outside.

As illustrated inFIG.33, the tractor1of this embodiment includes the air conditioner compressor211, which compresses refrigerant to be supplied to the air conditioner (not shown) of the cabin7. The air conditioner compressor211receives power transmitted from the front end of the output shaft53of the engine5via a compressor V-belt72cto be driven by the engine5. The air conditioner compressor211is located at a position higher than the coolant pump71on the front right side of the engine5. The air conditioner compressor211is mounted on the compressor securing bracket212. One end of the compressor securing bracket212is coupled to an extended bracket64a. The extended bracket64ais coupled to the front section of the fuel supply pump64.

The compressor securing bracket212is bent into an L-shape, and the air conditioner compressor211is secured to and located on the upper surface of the compressor securing bracket212. The compressor securing bracket212is supported by the engine5by coupling one end of the compressor securing bracket212at the lower end to the extended bracket64aand coupling the other end of the compressor securing bracket212at the upper end to the proximal end component coupling portion181bat the proximal end181aof the outlet side first bracket181. A pulley213is located on the front left side of the engine5. The pulley213keeps the compressor V-belt72cin tension. The pulley213, around which the compressor V-belt72cis wound, is secured to the front edge of a position adjustment bracket214to be able to adjust the position. The position adjustment bracket214is coupled to the thermostat case71and projects forward of the engine5.

The configurations of the components according to the invention of the present application are not limited to the illustrated embodiment, but may be modified in various forms without departing from the object of this invention.

The embodiments of the invention of the present application relates to an engine apparatus such as a diesel engine, and more specifically, to an engine apparatus that includes an exhaust gas purification device that removes particulate matter (soot, particulates) contained in exhaust gas.