JP6200682B2 - Tractor - Google Patents

Description

The present invention relates to a work vehicle such as an agricultural machine (tractor, combine) or a construction machine (bulldozer, hydraulic excavator, loader) equipped with an engine, and more specifically, particulate matter (soot, contained in exhaust gas). The present invention relates to a tractor provided with an exhaust gas purification device for removing particulate oxide or nitrogen oxides (NOx) contained in the exhaust gas.

  In a work vehicle such as a tractor or wheel loader, an opening / closing fulcrum shaft is arranged at the rear of the bonnet for covering the engine in order to improve the efficiency of maintenance work of the engine arranged at the front of the traveling machine body. The bonnet was rotated. Conventionally, a filter case having a diesel particulate filter and a catalyst case having a urea selective reduction catalyst are provided as exhaust gas purifiers (exhaust gas aftertreatment devices) in the exhaust path of a diesel engine. There has been known a technique for purifying exhaust gas discharged from a diesel engine by providing exhaust gas into a filter case and a catalyst case (see, for example, Patent Document 1 or 2).

JP 2009-74420 A US Patent Application Publication No. 2011/283687

  When the catalyst case is assembled away from the engine as in Patent Document 2, an exhaust pipe for supplying exhaust gas from the engine to the catalyst case is formed by a support member that supports the catalyst case on the traveling machine body. Therefore, there is a problem that it is necessary to form the support member in a special structure, and the manufacturing cost cannot be easily reduced. Further, when the support member is assembled to the traveling machine body in a cantilevered manner, the catalyst case or the support member needs to be supported in an anti-vibration manner, and the mounting structure of the catalyst case or the support member cannot be easily simplified. is there.

Therefore, the present invention seeks to provide an improved tractor by examining these current conditions.

In order to achieve the above object, the present invention relates to a cabin on which an operator is boarded, a bonnet disposed in front of the cabin, a first case for removing particulate matter in the exhaust gas of the engine, and the exhaust gas of the engine. In a tractor including a second case for removing nitrogen oxides therein, a traveling machine body frame on which the cabin is mounted, a case support for supporting the second case, and a pair of left and right provided on the left and right outer portions of the cabin The case support body is arranged in front of the getting-on / off step disposed on one side of the pair of left-right getting-on steps and below the second case. wherein the second case is supported in a portrait orientation, the the one side end of the passenger steps and the second casing are connected through the casing supporting member, the case supporting portion A tail pipe that is attached to a front surface of the step and a lower end surface of the second case and connected to an upper end portion of the second case; and a pipe cover that covers the tail pipe, and the tail pipe includes the tail pipe The first case is connected to a mounting bracket attached to the front corner frame of the cabin via a pipe cover, and the first case is positioned above the engine so that the upper end of the first case is higher than the upper end of the second case. The exhaust gas inlet of the first case is positioned on the rear side of the engine, and the exhaust gas flows from the rear part to the front part of the first case .

In the tractor, the exhaust inlet of the second case is connected to the exhaust outlet of the first case via the urea mixing pipe, and the first case is supported on the upper part of the engine, and the first case parallel to the exhaust gas moving direction of the case, it may be those obtained by extending the urea mixing tube.

According to the present invention, the operation includes an operating unit on which the operator is boarded, a first case for removing particulate matter in the exhaust gas of the engine, and a second case for removing nitrogen oxides in the exhaust gas of the engine. The vehicle includes a traveling machine body frame for mounting the driving unit and a case support body for supporting the second case, wherein the case support body is disposed on the traveling machine body frame, and the traveling machine body frame is provided on the vehicle body frame. Since the second case is attached via the case support, the case support can be installed on the highly rigid traveling machine frame, and the manufacturing cost can be easily reduced by simplifying the case support. The support rigidity of the second case can be easily improved, and the assembly workability of the second case can be easily improved. Further, the second case support structure can be easily simplified as compared with a conventional structure that also supports the second case by using an exhaust pipe.

According to the present invention, the operating unit on which the operator is boarded is configured by a cabin, and the cabin is mounted on the traveling machine body frame, and the vehicle body frame has a vertically long posture via the case support. Since the lower part of the second case is attached and the upper part of the second case in a vertically long posture is connected to the front corner frame of the cabin, the lower part of the second case is fixed on the case support. And can improve the assembly workability of the relatively heavy second case, and can easily prevent the lateral shake of the second case by connecting the front corner frame of the cabin and the upper part of the second case, The outer shape of the second case can be compactly formed in a vertically long cylindrical shape that is easy to fit along the front corner frame of the cabin.

According to the present invention, the exhaust inlet of the second case is connected to the exhaust outlet of the first case via the urea mixing pipe, and the first case is supported on the upper part of the engine, Since the urea mixing pipe is extended in parallel with the exhaust gas movement direction of the first case, the urea mixing pipe is heated by the heat generated on the engine or the first case side, and the urea mixing is performed. The urea mixing tube heating that can reduce the crystallization of urea water in the pipe and is heated by the heat generated by the engine to a length necessary for mixing the urea water with the exhaust gas as ammonia or longer. The length of the part can be increased, and the exhaust gas hatching function for removing nitrogen oxides in the exhaust gas in the second case can be improved.

It is a perspective view of the tractor which shows 1st Embodiment. It is the same top view. It is a top view of an engine part. It is a right view of the same part. It is a left view of the same part. It is a right view of an exhaust gas purification apparatus. It is a top view of the engine part which shows 2nd Embodiment.

  Below, 1st Embodiment which actualized this invention is described based on drawing (FIGS. 1-6). First, a farm tractor 1 equipped with a diesel engine will be described with reference to FIGS. A farm tractor 1 as a work vehicle shown in FIGS. 1 and 2 is configured to perform a plowing work and the like for plowing a farm field by mounting a plow working machine (not shown). FIG. 1 is a perspective view of the tractor 1, and FIG. 2 is a plan view thereof. In the following description, the left side in the forward direction of the tractor 1 is simply referred to as the left side, and the right side in the forward direction is also simply referred to as the right side.

  As shown in FIGS. 1 and 2, a farm tractor 1 as a work vehicle supports a traveling machine body 2 with a pair of left and right front wheels 3 and a pair of left and right rear wheels 4, and a diesel engine at the front of the traveling machine body 2. 5 and driving the rear wheel 4 and the front wheel 3 with the diesel engine 5, the vehicle is configured to travel forward and backward. The upper surface side and the left and right side surfaces of the diesel engine 5 are covered with an openable / closable bonnet 6.

  In addition, on the upper surface of the traveling machine body 2, behind the hood 6, a driving cabin 7 is installed as a driving unit on which an operator gets on. Inside the cabin 7 is provided a front column 10 including a control seat 8 on which an operator sits, a control handle 9 as steering means, and the like. A fuel tank 12 that supplies fuel to the diesel engine 5 is provided below the boarding step 11 at the bottom of the cabin 7. In the front column 10, left and right brake pedals 13, a clutch pedal 14, a transmission pedal 15, a forward / reverse switching lever 16 and the like are disposed as steering devices.

  The traveling machine body 2 also includes a mission case 17 for shifting the output from the diesel engine 5 and transmitting it to the rear wheels 4 (front wheels 3). The rear of the mission case 17 is connected to a tiller mechanism (not shown) and the like via a traction mechanism 21 such as a left and right lower link 18, a top link 19, and a left and right lift arm 20, and the like. The plowing machine and the like are driven by a PTO shaft (not shown) provided on the rear side surface of 17. Furthermore, the traveling machine body 2 of the tractor 1 includes a diesel engine 5, a transmission case 17, a clutch case 22 that connects them, a front chassis 23 that extends forward from the diesel engine 5, and the like. In addition, a pair of left and right boarding steps 24 for the operator to get on and off are arranged on the left and right outer portions of the cabin 7.

  Next, the diesel engine 5 will be described with reference to FIGS. As shown in FIGS. 3 to 5, an intake manifold 33 is disposed on one side surface of the cylinder head 32 of the diesel engine 1. The cylinder head 32 is mounted on a cylinder block 35 in which an engine output shaft (crank shaft) and a piston (not shown) are incorporated. An exhaust manifold 36 is disposed on the other side of the cylinder head 32, and the front end and the rear end of the engine output shaft are projected from the front and rear surfaces of the cylinder block 35.

  As shown in FIGS. 3 to 5, a flywheel housing 38 is fixed to the rear surface of the cylinder block 35. A flywheel (not shown) is provided in the flywheel housing 38. The front side of the clutch case 22 is connected to the rear side of the flywheel housing 38. The power of the diesel engine 5 is extracted from the rear end side of the engine output shaft on which the flywheel is pivoted toward the transmission case 17. Further, an oil pan 39 is disposed on the lower surface of the cylinder block 35, a cooling fan 40 is disposed on the front surface side of the cylinder block 35, and a radiator 41 is installed facing the cooling fan 40. An oil cooler 42, an air cleaner 43, a battery 44, and the like are disposed on the front chassis 23 in front of the radiator 41.

  As shown in FIGS. 3 to 5, an exhaust gas recirculation device (EGR) 45 that takes in exhaust gas for recirculation is disposed in the intake manifold 3. An air cleaner 43 shown in FIG. 4 is connected to the intake manifold 33. The external air that has been dedusted and purified by the air cleaner 43 is sent to the intake manifold 33 and supplied to each cylinder of the diesel engine 5.

  With the above configuration, a part of the exhaust gas discharged from the diesel engine 5 to the exhaust manifold 36 is recirculated from the intake manifold 33 to each cylinder of the diesel engine 5 via the exhaust gas recirculation device 45. The combustion temperature of the diesel engine 5 is lowered, the amount of nitrogen oxide (NOx) discharged from the diesel engine 5 is reduced, and the fuel efficiency of the diesel engine 5 is improved.

  A cooling water pump 46 that circulates cooling water in the cylinder block 35 and the radiator 41 is provided. A cooling water pump 46 is arranged on the cooling fan 40 installation side on the front side of the diesel engine 5. The cooling water pump 46 and the cooling fan 40 are connected to the engine output shaft of the diesel engine 5 via a V belt or the like, and the cooling water pump 46 and the cooling fan 40 are driven. While the cooling water is fed from the cooling water pump 46 into the cylinder block 35 via the EGR cooler 47 of the exhaust gas recirculation device 45, the diesel engine 5 is cooled by the cooling fan 40 wind. .

  As shown in FIG. 4, each of the injectors 51 for four cylinders of the diesel engine 5 is provided with a fuel pump 52 and a common rail 53 that connect the fuel tank 12 shown in FIG. A common rail 53 and a fuel filter 54 are arranged on the intake manifold 33 installation side of the cylinder head 32, and a fuel pump 52 is arranged in the cylinder block 35 below the intake manifold 33. Each injector 51 has an electromagnetic switching control type fuel injection valve (not shown).

  While the fuel in the fuel tank 12 is sucked into the fuel pump 52 via the fuel filter 54, the common rail 53 is connected to the discharge side of the fuel pump 52, and the cylindrical common rail 53 is connected to each injector 51 of the diesel engine 5. It is connected. The surplus of the fuel pumped from the fuel pump 52 to the common rail 53 is returned to the fuel tank 12, high-pressure fuel is temporarily stored in the common rail 53, and the high-pressure fuel in the common rail 53 is used for each diesel engine 5. Supplied inside the cylinder.

  With the above configuration, the fuel in the fuel tank 12 is pumped to the common rail 53 by the fuel pump 52, the high-pressure fuel is stored in the common rail 53, and the fuel injection valves of the injectors 51 are controlled to open and close. High-pressure fuel in the common rail 53 is injected into each cylinder of the diesel engine 5. That is, by electronically controlling the fuel injection valve of each injector 51, the fuel injection pressure, injection timing, and injection period (injection amount) can be controlled with high accuracy. Therefore, nitrogen oxides (NOx) discharged from the diesel engine 5 can be reduced.

  As shown in FIG. 3 to FIG. 6, as an exhaust gas purification device 61 for purifying exhaust gas discharged from each cylinder of the diesel engine 5, a diesel party that removes particulate matter in the exhaust gas of the diesel engine 5 is used. A first case 62 as a curate filter (DPF) and a second case 63 as a urea selective catalytic reduction (SCR) system for removing nitrogen oxides in exhaust gas of the diesel engine 1 are provided. As shown in FIG. 4, an oxidation catalyst 64 and a soot filter 65 are provided in the first case 62. The second case 63 includes an SCR catalyst 66 and an oxidation catalyst 67 for reducing urea selective catalyst.

  Exhaust gas discharged from each cylinder of the diesel engine 5 to the exhaust manifold 36 is discharged to the outside via the exhaust gas purification device 61 and the like. The exhaust gas purification device 61 is configured to reduce carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM), and nitrogen oxides (NOx) in the exhaust gas of the diesel engine 5. doing.

  The first case 62 is configured in a horizontally long long cylindrical shape extending long in a direction parallel to the output shaft (crankshaft) of the diesel engine 5 in plan view. A DPF inlet pipe 68 for taking in exhaust gas is provided on one end of the first case 62 in the cylindrical shape. Of the front and rear surfaces of the diesel engine 5, the one end side and the other end side of the first case 62 in the exhaust gas movement direction can be attached to and detached from the front and rear surfaces of the cylinder head 32 via the front support leg body 69 and the rear support leg body 70. I support it. That is, the first case 62 is attached to the upper surface side of the diesel engine 5 through the front support leg 69 and the rear support leg 70. The first case 62 is supported in parallel with the exhaust manifold 36 with the longitudinal direction of the cylindrical first case 62 facing the longitudinal direction of the diesel engine 5.

  A supercharger 71 for forcibly sending air to the diesel engine 5 is disposed at the exhaust gas outlet of the exhaust manifold 36. The DPF inlet pipe 68 is communicated with the exhaust manifold 36 via the supercharger 71, and the exhaust gas of the diesel engine 5 is introduced into the first case 62 from the DPF inlet pipe 68. On the other hand, a DPF outlet pipe 72 for discharging exhaust gas is provided on the other end of the first case 62 in the cylindrical shape. The DPF outlet pipe 72 of the first case 62 is connected to the inlet side of the urea mixing pipe 73, and the exhaust gas of the first case 28 is introduced into the urea mixing pipe 73.

  On the other hand, the 2nd case 63 is comprised in the vertically long elongate cylindrical shape extended long in the up-down direction. An SCR inlet pipe 74 for taking in exhaust gas is provided on the lower end side of the cylindrical shape of the second case 63. An SCR inlet pipe 74 is connected to the outlet side of the urea mixing pipe 73 through a bellows-like connecting pipe 75 that can be bent and stretched. Furthermore, the end of the urea mixing pipe 73 to which the bellows-like connecting pipe 75 is connected is detachably fixed to the side surface of the cylinder block 35 with a pipe bracket 76. That is, the urea mixing pipe 73 is fixed to the diesel engine 5 through the first case 62 and the pipe bracket 76. The first case 62 and the urea mixing pipe 73 are attached to the diesel engine 5 supported by vibration isolation. Can be fixed together. The mechanical vibration on the urea mixing pipe 73 side is blocked by the bellows-like connecting pipe 75 and is not transmitted to the SCR inlet pipe 74 side.

  In addition, as shown in FIG. 6, the lower end side of the tail pipe 81 is connected to the cylindrical upper end side of the second case 63. The tail pipe 81 is erected substantially vertically along the cabin frame 82 at the right corner of the operation cabin 7. The tail pipe 81 and the pipe cover 84 are fixed to the cabin frame 82 via the pipe mounting bracket 83, and the cylindrical upper end side of the second case 63 is detachably fixed to the cabin frame 82 via the case mounting bracket 85. doing.

  On the other hand, a step frame 86 is fixed to the side surface of the clutch case 22, and the operation cabin 7 and the entry / exit step 24 are attached to the step frame 86, and the second case 63 is attached to the step frame 86 via the case frame 87. The end face is bolted so as to be detachable. That is, the back side of the case base 87 is bolted to the front side of the step frame 86, the lower end surface of the cylindrical shape of the second case 63 is brought into contact with the upper side of the case base 87, and the second case 63 is attached to the case base 87. The second case 63 is supported on the step frame 86. Accordingly, the first case 62 is horizontally disposed in the front-rear direction on the upper surface side of the diesel engine 5 (horizontal posture), while the second case 63 is placed in the vertical posture on the right side of the rear portion of the diesel engine 5 via the step frame 86. The first case 62 and the second case 63 can be compactly arranged around the hood 6 and the operation cabin 7 while being supported and capable of functionally forming the exhaust gas movement path of the diesel engine 5.

  Furthermore, a urea water tank 91 is mounted on the traveling machine body 2 (clutch case 22) at the rear of the hood 6. An oil injection port 92 for the fuel tank 12 is provided in the lower front portion on the left side of the cabin 7, and a water injection port 93 for the urea water tank 91 is provided on the upper surface of the rear portion of the bonnet 6. An oil injection port 92 and a water injection port 93 are disposed on the front surface on the left side of the cabin 57 where the operator gets on and off frequently, and the rear part of the diesel engine 5 (diesel engine 5 and urea water tank 91 is formed in the engine room formed by the bonnet 6. The urea mixing tube 73 is extended and supported in the right and left direction. Further, since the urea water tank 91 is installed between the front part of the front column 10 and the rear part of the diesel engine 5, heat generation and vibration generated on the diesel engine 5 side are absorbed by the urea water tank 91 and transmitted to the front column 10 side. And the temperature of the urea aqueous solution in the urea water tank 91 can be easily maintained even when working in a cold region. Crystallization can be reduced. Moreover, since a space for installing a partition material (a space for heat insulation and a space for vibration and soundproofing) is formed between the front column 10 and the diesel engine 5, the dead space can be used effectively so that the interior of the fuselage (engine The urea water tank 91 can be arranged compactly in the room.

  Further, a urea water injection pump 94 that pumps the urea aqueous solution in the urea water tank 91, an electric motor 95 that drives the urea water injection pump 94, and urea that is connected to the urea water injection pump 94 via a urea water injection pipe 96. A water injection nozzle 97 is provided. A urea water injection nozzle 97 is attached to the urea mixing pipe 73 via an injection pedestal 98, and a urea aqueous solution is sprayed from the urea water injection nozzle 97 into the urea mixing pipe 73. The urea water supplied into the urea mixing pipe 73 is configured to be mixed as ammonia in the exhaust gas from the first case 62 to the second case 63.

  It should be noted that the bellows-like connecting pipe 75 is covered with a heat-resistant heat insulating material 99 such as glass fiber to prevent the exhaust gas temperature in the bellows-like connecting pipe 75 from being lowered, and urea in the exhaust gas is crystallized. Is suppressed. The urea mixing pipe 73 has an elbow pipe part that changes the movement direction of the exhaust gas by about 90 degrees and a long cylindrical straight pipe part that is connected to the SCR inlet pipe 74. An injection pedestal 98 is welded and fixed to an elbow pipe part where the elbow pipe part and the straight pipe part are joined, and an aqueous urea solution is sprayed from the urea water injection nozzle 97 toward the inner hole of the straight pipe part from the elbow pipe part side. To do. Since the urea mixing pipe 73 is installed in the space between the rear part of the diesel engine 5 and the front part of the urea water tank 91, the urea mixing pipe 73 is heated by the heat generated on the diesel engine 5 side, and the exhaust gas in the urea mixing pipe 73 is exhausted. It can suppress that the temperature of (urea aqueous solution) falls, and can reduce the crystallization of the urea water in the urea mixing pipe 73 inside.

  With the above configuration, the oxidation catalyst 64 and the soot filter 65 in the first case 62 reduce carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas of the diesel engine 5. Next, urea water from the urea water injection nozzle 97 is mixed into the exhaust gas from the diesel engine 5 inside the urea mixing pipe 73. The SCR catalyst 66 and the oxidation catalyst 67 in the second case 63 reduce nitrogen oxides (NOx) in the exhaust gas in which urea water is mixed as ammonia. That is, exhaust gas with reduced carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) is discharged from the tail pipe 81 to the outside of the machine.

  As shown in FIGS. 1 to 6, an operation cabin 7 serving as an operation unit on which an operator is boarded, a first case 62 for removing particulate matter in the exhaust gas of the diesel engine 5, and the exhaust gas of the diesel engine 5 in the exhaust gas A work vehicle including a second case 63 for removing nitrogen oxides includes a step frame 86 as a traveling machine frame for mounting the driving unit 7 and a case base 87 as a case support for supporting the second case 63. The case frame 87 is arranged on the step frame 86, and the second case 63 is attached to the step frame 86 via the case frame 87. Therefore, the case base 87 can be installed on the highly rigid step frame 86, the manufacturing cost can be easily reduced by simplifying the size of the case base 87, and the support rigidity of the second case 63 can be easily improved. The assembly workability of the two cases 63 can be easily improved. Further, the second case 63 support structure can be easily simplified as compared with a conventional structure that also supports the second case 63 using the exhaust pipe.

  As shown in FIGS. 1 to 6, a driving unit on which an operator is boarded is configured by a driving cabin 7, and the driving cabin 7 is mounted on a step frame 86. A lower portion of the vertically long second case 63 is attached, and an upper portion of the vertically long second case is connected to a cabin frame 82 as a front corner frame of the operation cabin 7. Therefore, the lower part of the second case 63 can be fixed on the case base 87, the workability of assembling the relatively heavy second case 63 can be improved, and the cabin frame 82 of the operation cabin 7 can be connected to the upper part of the second case 63. Thus, the lateral swing of the second case 63 can be easily prevented, and the outer shape of the second case 63 can be compactly formed in a vertically long cylindrical shape that is easy to fit along the cabin frame 82 of the operation cabin 7.

  As shown in FIGS. 1 to 6, an operation cabin 7 is arranged behind a hood 6 in which a diesel engine 5 is installed, and urea water tank 91 for purifying exhaust gas and urea water is supplied from the urea water tank 91. A urea mixing pipe 73 is provided, and the exhaust inlet of the second case 63 is connected to the exhaust outlet of the first case 62 via the urea mixing pipe 73, and the steering handle 9 part of the driving cabin 7 and the diesel engine 5 are connected to each other. A urea water tank 91 is installed between them. Therefore, heat generation and vibration generated on the diesel engine 5 side can be suppressed from being transmitted to the operation cabin 7 side, and the urea water tank 91 is heated by the heat generation on the diesel engine 5 side. However, the temperature of the urea aqueous solution in the urea water tank 91 can be easily maintained, and the crystallization of the urea water can be reduced. Moreover, since it is necessary to partition between the driving cabin 7 and the diesel engine 5, the urea water tank 91 can be effectively used as the partition member, and the partition structure between the driving cabin 7 and the diesel engine 5 can be simplified, The urea water tank 91 can be compactly arranged inside the bonnet 6 (engine room).

  As shown in FIGS. 1 to 6, a urea mixing pipe 73 is extended between the rear part of the diesel engine 5 and the front part of the urea water tank 91 in a direction crossing the exhaust gas movement direction of the first case 62. I am letting. Therefore, the urea mixing pipe 73 can be arranged compactly between the rear part of the diesel engine 5 and the front part of the urea water tank 91, and the urea mixing pipe 73 is heated by the heat generated on the diesel engine 5 side. Even in the operation, the temperature of the urea aqueous solution in the urea mixing tube 73 can be easily maintained, and the crystallization of the urea water in the urea mixing tube 73 can be reduced.

  Next, the structure of the exhaust gas purifying device 61 of the second embodiment will be described with reference to FIG. In the exhaust gas purification device 61 of the first embodiment shown in FIG. 3, the DPF inlet pipe 68 is located on the front side of the diesel engine 5, the exhaust gas flows from the front part to the rear part of the first case 62, and the diesel engine 5 rear part. The exhaust gas moves to the urea mixing tube 73. On the other hand, in the exhaust gas purification device 61 of the second embodiment shown in FIG. 7, the DPF inlet pipe 68 is located on the rear side of the diesel engine 5, and the exhaust gas flows from the rear part to the front part of the first case 62. The exhaust gas is configured to move to a urea mixing pipe 73 provided in the upper part of the diesel engine 5 in parallel with the first case 62. That is, the urea mixing pipe 73 is extended and supported on the upper surface side of the diesel engine 5 in parallel with the first case 62 via the pipe bracket 76.

  As shown in FIG. 7, the urea mixing pipe 73 is extended in parallel with the first case 28 extended in the front-rear direction on the upper surface side of the diesel engine 1, and urea disposed at a higher position than the cooling fan 24. A urea water injection nozzle 97 is attached to the front portion of the mixing pipe 73 via an injection pedestal 98, and a urea aqueous solution is sprayed from the urea water injection nozzle 97 into the urea mixing pipe 73. Compared to the length of the urea mixing pipe 73 arranged in the left-right direction of the diesel engine 1 as in the first embodiment shown in FIG. 3, in the embodiment shown in FIG. 7, the urea water supplied into the urea mixing pipe 73 is The distance mixed as ammonia in exhaust gas can be formed long. Therefore, in the embodiment shown in FIG. 7, the urea water in the urea mixing pipe 73 is appropriately mixed as ammonia in the exhaust gas from the first case 62 to the second case 63. Further, the urea mixing pipe 73 is heated by the heat generation on the diesel engine 5 side, and the temperature of the exhaust gas (urea aqueous solution) in the urea mixing pipe 73 can be suppressed from decreasing, and the urea water in the urea mixing pipe 73 can be suppressed. Crystallization can be reduced.

  As shown in FIG. 7, a urea water tank 91 for purifying exhaust gas and a urea mixing pipe 73 for supplying urea water from the urea water tank 91 are provided, and the first case 62 is connected to the exhaust outlet via the urea mixing pipe 73. The exhaust gas inlet of the two cases 63 is connected, and the first case 62 is supported on the upper part of the diesel engine 5, and the urea mixing pipe 73 is extended in parallel with the exhaust gas movement direction of the first case 62. Yes. Accordingly, the urea mixing pipe 73 is heated by the heat generated on the diesel engine 5 or the first case 62 side, and the crystallization of the urea water in the urea mixing pipe 73 can be reduced, and the urea water is mixed with the exhaust gas as ammonia. The length of the heating portion of the urea mixing pipe 73 that is heated by the heat generated by the diesel engine 5 can be made longer than the length necessary to do so, and the nitrogen oxides in the exhaust gas in the second case 63 It is possible to improve the exhaust gas hatching function for removing the gas.

5 Diesel engine 6 Bonnet 7 Driving cabin (driving part)
9 Steering handle 62 First case 63 Second case 73 Urea mixing tube 82 Cabin frame (front corner frame)
86 Step frame (running body frame)
87 Case base (case support)
91 Urea water tank

Claims (2)

A cabin on which an operator is boarded, a hood arranged in front of the cabin, a first case for removing particulate matter in engine exhaust gas, and a second case for removing nitrogen oxides in engine exhaust gas In a tractor comprising:
A structure comprising a traveling machine body frame for mounting the cabin, a case support for supporting the second case, and a pair of left and right boarding steps provided on left and right outer portions of the cabin, wherein the case support is Of the pair of left and right boarding steps, disposed in front of the boarding step disposed on one side and below the second case to support the second case in a vertically long posture ,
The one-side entry / exit step and the second case are connected via the case support, and the case support portion is attached to the front surface of the step and the lower end surface of the second case, A tail pipe coupled to the upper end of the two cases, and a pipe cover covering the tail pipe,
The tail pipe is connected to a mounting bracket attached to a front corner frame of the cabin via the pipe cover,
The first case is supported in a lateral posture on the upper part of the engine so that the upper end of the first case is higher than the upper end of the second case.
The exhaust gas inlet of the first case is located on the rear side of the engine, and the exhaust gas flows from the rear part to the front part of the first case .   In the bonnet, the first case is supported on the upper part of the engine, and a urea mixing pipe extends from the front to the rear in parallel with the exhaust gas movement direction of the first case. The tractor according to claim 1.

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