JP2014189184A - Tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tractor which improves exhaust processing performance.SOLUTION: A tractor includes: an engine room (3) disposed at the front side of an operation seat and covered by an engine hood; an engine (7) disposed in the engine room; an exhaust pipe (8) which exhausts exhaust air of the engine (7); a selective catalyst reduction device (20) provided at the exhaust pipe (8) and disposed in an area of the engine room which is located above the engine (7); a first oxidation catalyst (21) provided at an area in the exhaust pipe (8) which is located between the engine (7) and the selective catalyst reduction device (20); and a second oxidation catalyst (22) which is provided at the downstream side in the exhaust pipe (8) relative to the selective catalyst reduction device (20) in an exhaust air flow direction. The exhaust pipe (8) includes an exterior first pipe part extending from the engine room (3) to the lateral side of the machine body; and an exterior second pipe part extending upward from a downstream side end part of the exterior first pipe part.

Description

  The present invention relates to a tractor.

  Conventionally, there is a work vehicle equipped with an exhaust treatment device. For example, Patent Document 1 discloses a technology of an exhaust pipe structure of a self-propelled working machine in which a vertical exhaust pipe is arranged on the front side of an operation unit arranged behind a bonnet.

JP 2010-216269 A

  It is desired that the exhaust treatment performance of the exhaust treatment device can be improved. For example, exhaust gas regulations are required to improve the exhaust treatment performance of work vehicles such as tractors.

  An object of the present invention is to provide a tractor capable of improving exhaust treatment performance.

  In order to solve the above-described problems and achieve the object, a tractor (1) according to the present invention is disposed in front of an operation seat (15) and covered with a hood (2), and the engine room (3), An engine (7) disposed in the engine room (3), an exhaust pipe (8) for exhausting the exhaust of the engine (7), the exhaust pipe (8), and the engine room (3) in the engine room A selective catalyst reduction device (20) disposed above the engine (7), and a first catalyst provided in the exhaust pipe (8) between the engine (7) and the selective catalyst reduction device (20). An oxidation catalyst (21); and a second oxidation catalyst (22) provided downstream of the selective catalyst reduction device (20) in the exhaust pipe (8) in the flow direction of the exhaust gas, the exhaust gas The pipe (8) is connected to the engine room ( ) From the downstream end of the first external pipe (8c) and the external second pipe (8c) extending from the downstream end of the external first pipe (8c). 8d).

  In the tractor, the first oxidation catalyst (21) is disposed on the left side of the engine (7) as viewed from the operation seat, and the second oxidation catalyst (22) is as viewed from the operation seat. It is preferably arranged on the right side of the engine (7).

  In the tractor, the second oxidation catalyst (22) is preferably provided in the external second pipe portion (8d).

  In the tractor, the downstream side of the selective catalyst reduction device (20) of the exhaust pipe (8) is below the side of the engine (7) in the engine room to the vicinity of the frame (9) of the fuselage. It is preferable that it extends toward.

  A tractor according to the present invention is a first selective catalyst reduction device provided in an exhaust pipe and disposed above the engine in an engine room, and a first catalyst provided between the engine and the selective catalyst reduction device in the exhaust pipe. An oxidation catalyst, and a second oxidation catalyst provided downstream of the selective catalyst reduction device in the exhaust pipe in the exhaust flow direction. According to the tractor according to the present invention, there is an effect that exhaust treatment performance can be improved.

FIG. 1 is a left side view of the tractor according to the first embodiment. FIG. 2 is a front view of the tractor according to the first embodiment. FIG. 3 is a right side view of the tractor according to the first embodiment. FIG. 4 is a top view of the tractor according to the first embodiment. FIG. 5 is a front view in the engine room of the tractor according to the first embodiment. FIG. 6 is a left side view in the engine room of the tractor according to the first embodiment. FIG. 7 is a top view in the engine room of the tractor according to the first embodiment. FIG. 8 is a cross-sectional view showing the arrangement of the urea water tank according to the first embodiment. FIG. 9 is a front view of the exhaust pipe according to the second embodiment. FIG. 10 is a top view in the engine room of the tractor according to the second embodiment. FIG. 11 is a front view inside an engine room according to a reference example of the second embodiment. FIG. 12 is a front view of the exhaust pipe according to the third embodiment. FIG. 13 is a right side view of the tractor 1 according to the fourth embodiment. FIG. 14 is a right side view in the engine room according to the fourth embodiment. FIG. 15 is a perspective view inside the engine room according to the fourth embodiment. FIG. 16 is a flowchart according to the control of the fifth embodiment. FIG. 17 is a schematic configuration diagram of a tractor according to the sixth embodiment. FIG. 18 is a perspective view showing a main part of the tractor according to the sixth embodiment. FIG. 19 is a view showing a storage part of the urea water tank. FIG. 20 is a diagram illustrating a fixed portion of the urea water tank. FIG. 21 is a diagram illustrating an example of a combine that can be equipped with a urea water tank.

  Hereinafter, a tractor according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[First Embodiment]
The first embodiment will be described with reference to FIGS. 1 to 8. The present embodiment relates to a tractor. 1 is a left side view of a tractor according to the first embodiment of the present invention, FIG. 2 is a front view of the tractor according to the first embodiment, and FIG. 3 is a right side view of the tractor according to the first embodiment. 4 is a top view of the tractor according to the first embodiment, FIG. 5 is a front view inside the engine room of the tractor according to the first embodiment, and FIG. 6 is an inside view of the engine room of the tractor according to the first embodiment. A left side view and FIG. 7 are top views in the engine compartment of the tractor according to the first embodiment.

  The tractor 1 is a work vehicle that performs work on a farm field or the like. As shown in FIGS. 1 to 4, the tractor 1 according to the first embodiment includes an engine room 3 disposed in front of an operation seat 15 and covered with a bonnet 2, and an exhaust pipe 8. Yes. Further, as shown in FIG. 5, the tractor 1 includes an engine 7 disposed in the engine room 3, and a selective catalyst reduction device disposed in the exhaust pipe 8 and disposed above the engine 7 in the engine room 3. 20, a first oxidation catalyst 21, and a second oxidation catalyst 22. The exhaust pipe 8 discharges exhaust from the engine 7. The first oxidation catalyst 21 is provided between the engine 7 and the selective catalyst reduction device 20 in the exhaust pipe 8. The second oxidation catalyst 22 is provided downstream of the selective catalyst reduction device 20 in the exhaust pipe 8 in the exhaust flow direction.

  According to the tractor 1 according to the present embodiment, the selective catalyst reduction device 20, the first oxidation catalyst 21 provided on the upstream side of the selective catalyst reduction device 20, and the downstream side of the selective catalyst reduction device 20 are provided. By having the second oxidation catalyst 22, it is possible to improve the exhaust treatment performance and appropriately purify and discharge the exhaust of the engine 7. In the present specification, unless otherwise specified, “upstream side” indicates the upstream side in the exhaust flow direction, and “downstream side” indicates the downstream side in the exhaust flow direction.

  As shown in FIG. 1, the bonnet 2 is disposed on the front side of the body of the tractor 1. The tractor 1 has a cabin 10, front wheels 4, rear wheels 5, a transmission 6, and a urea water tank 25. The cabin 10 is arranged on the rear side of the machine body with respect to the bonnet 2. The cabin 10 includes a roof 11, a front pillar 12, a center pillar 13, and a rear pillar 14. Each pillar 12, 13, 14 is a vertical support extending in the vertical direction, and one pillar is arranged on each of the left side and the right side of the body. In this specification, “the left side of the fuselage” indicates the left side when looking forward from the operation seat 15, and “the right side of the fuselage” indicates the right side when looking forward from the operation seat 15.

  The roof 11 is supported by a pair of front pillars 12, a pair of center pillars 13, and a pair of rear pillars 14. The cabin 10 has a space closed inside by a transparent glass or the like attached between the pillars 12, 13, and 14. Moreover, the cabin 10 can visually recognize the outside from the inside through glass or the like. As shown in FIGS. 1 and 3, an operation seat 15 is arranged in the cabin 10. The driver sits on the operation seat 15 and operates each operation device in the cabin 10.

  As shown in FIG. 2, a windshield 16 is attached between the pair of front pillars 12. The driver in the cabin 10 can visually recognize the front of the aircraft through the windshield 16 from the inside of the cabin 10.

  The transmission 6 appropriately changes the rotational power generated by the engine 7 and transmits it to the rear wheels 5. Further, the transmission 6 can transmit the rotational power of the engine 7 to the front wheels 4 as necessary. That is, the tractor 1 according to the present embodiment can switch between two-wheel drive and four-wheel drive. The urea water tank 25 is a tank that stores urea water. The urea water tank 25 is provided with a fuel gauge for detecting the remaining amount of urea water in the tank. The urea water tank 25 is disposed in the front part of the bonnet 2. In the tractor 1 of the present embodiment, the urea water tank 25 is mounted in the front grill of the bonnet 2. Thereby, the urea water tank 25 can be mounted without significantly changing the configuration and layout of other components. Further, since the urea water tank 25 is mounted on the front portion of the vehicle, that is, the urea water tank 25 is disposed at the passage of the cooling air by the cooling fan that blows the cooling air to the radiator, the engine 7 or the like. It is possible to suppress deterioration of urea water due to exposure to water.

As shown in FIGS. 6 and 7, the rotation axis X of the engine 7 extends in the front-rear direction of the airframe. The exhaust pipe 8 is directly connected to the exhaust side outlet of the turbocharger 7 a of the engine 7. As shown in FIGS. 5 to 7, a first oxidation catalyst 21 is provided at a connection portion of the exhaust pipe 8 with the turbocharger 7 a. The first oxidation catalyst 21 oxidizes nitrogen monoxide NO in the exhaust discharged from the engine 7 to form nitrogen dioxide NO ₂ . The first oxidation catalyst 21 is disposed inside the cylindrical first housing portion 21a. The first accommodating portion 21a is connected to an end portion on the front side of the aircraft body of the turbocharger 7a, and extends toward the front side of the aircraft body. The exhaust discharged from the engine 7 flows from the rear side of the aircraft toward the front side of the aircraft through the first storage portion 21a.

  The selective catalyst reduction device 20 and the second oxidation catalyst 22 are arranged inside a cylindrical second housing part 23. The second housing portion 23 is disposed above the engine 7 in the engine room 3. The axial direction of the second housing portion 23 is the width direction of the airframe, and is the direction orthogonal to the rotational axis X of the engine 7. The first oxidation catalyst 21 and the selective catalyst reduction device 20 are communicated with each other through the internal first pipe portion 8 a of the exhaust pipe 8. The internal first pipe portion 8a is disposed in the engine room 3, and connects the end portion on the front side of the machine body on the outer peripheral surface of the first storage section 21a and the end surface 23a on the left side of the machine body of the second storage section 23. Yes. The internal first pipe portion 8a extends upward from the first housing portion 21a, then bends toward the rear of the body, and then bends toward the right side of the body and is connected to the second housing portion 23.

  The selective catalyst reduction device 20 is disposed on the left side of the machine body with respect to the second oxidation catalyst 22 in the second housing portion 23. That is, the second oxidation catalyst 22 is arranged downstream of the selective catalyst reduction device 20 in the exhaust flow direction. The internal second pipe portion 8 b is connected to the end surface 23 b on the right side of the machine body of the second housing portion 23. The internal second pipe portion 8 b is disposed in the engine room 3 and guides the exhaust gas that has passed through the second oxidation catalyst 22 to the outside of the engine room 3. The internal second pipe portion 8 b is a portion on the downstream side of the selective catalyst reduction device 20 of the exhaust pipe 8. The internal second pipe portion 8b extends from the second housing portion 23 toward the right side of the machine body, then bends downward, and extends in the engine room 3 with the side of the engine 7 facing downward. The internal second pipe portion 8b extends downward to the vicinity of the frame 9 shown in FIG. The frame 9 forms a skeleton of the airframe in the tractor 1 and supports the engine 7.

  As shown in FIG. 2, the exhaust pipe 8 includes an external first pipe portion 8c and an external second pipe portion 8d. The lower end of the internal second pipe portion 8b is connected to the external first pipe portion 8c shown in FIG. The external first pipe portion 8c is disposed outside the engine room 3 and extends from the engine room 3 toward the side of the machine body. The external first pipe portion 8c extends from the engine room 3 toward the right side of the machine body and is connected to the external second pipe portion 8d. The external second pipe portion 8d is disposed outside the engine room 3, and extends upward from the downstream end of the external first pipe portion 8c.

  The external second pipe portion 8d extends in the vertical direction, as shown in FIGS. The external second pipe portion 8d is disposed along the front pillar 12 in the vicinity of the front pillar 12 on the right side of the machine body. In the present embodiment, the external second pipe portion 8d is disposed on a line connecting the operation seat 15 and the right front pillar 12, and the external second pipe portion 8d is suppressed from blocking the driver's view. Yes. The opening 8 e at the upper end of the external second pipe portion 8 d is provided at the same height position as the roof 11.

The selective catalyst reduction device 20 constitutes an SCR (Selective Catalytic Reduction) system together with the urea water injection nozzle 24 and the urea water tank 25. The selective catalyst reduction device 20 selectively purifies nitrogen oxides NOx in the exhaust by a reduction reaction with ammonia. As shown in FIG. 5, a urea water injection nozzle 24 is provided in the internal first pipe portion 8a. The urea water injection nozzle 24 injects urea water supplied from the urea water tank 25 into the internal first pipe portion 8a. That is, the urea water injection nozzle 24 injects urea water into the exhaust gas that has passed through the first oxidation catalyst 21. Ammonia is produced from urea in the urea water injected into the exhaust gas. The selective catalyst reduction device 20 reduces the nitrogen oxide NOx in the exhaust gas to nitrogen N ₂ by the generated ammonia.

  The second oxidation catalyst 22 oxidizes the exhaust gas that has passed through the selective catalyst reduction device 20. The second oxidation catalyst 22 oxidizes and purifies the ammonia remaining in the exhaust. Thereby, what is called ammonia slip in which a part of ammonia is discharged as it is is suppressed. A NOx sensor 26 is disposed between the selective catalyst reduction device 20 and the second oxidation catalyst 22. The NOx sensor 26 detects the concentration of nitrogen oxides in the exhaust gas that has passed through the selective catalyst reduction device 20.

  The control device 30 has a function of controlling the tractor 1. The control device 30 is an electronic control unit having a computer and has a function of controlling the urea water injection amount by the engine 7 and the urea water injection nozzle 24. The control device 30 is connected to the NOx sensor 26 and acquires a signal indicating the concentration of nitrogen oxides detected by the NOx sensor 26.

  The control device 30 controls the urea water injection amount by the urea water injection nozzle 24 based on the acquired concentration of nitrogen oxides. For example, the control device 30 stores in advance a table indicating a correspondence relationship between the concentration of nitrogen oxides in the exhaust gas and the injection amount of urea water, and referring to this table, the urea water by the urea water injection nozzle 24 is stored. Determine the injection amount. The control device 30 outputs the determined urea water injection amount as a command value for the urea water injection nozzle 24. The urea water injection nozzle 24 adjusts the injection amount of urea water so as to realize the command value output from the control device 30.

  In the tractor 1 according to this embodiment, the first oxidation catalyst 21 is disposed on the left side of the engine 7 when viewed from the operation seat 15, and the second oxidation catalyst 22 is disposed on the right side of the engine 7 when viewed from the operation seat 15. ing. In the present embodiment, the first oxidation catalyst 21 and the second oxidation catalyst 22 are arranged in the engine room 3. By arranging the first oxidation catalyst 21 on the left side of the fuselage with respect to the engine 7 and the second oxidation catalyst 22 on the right side of the fuselage with respect to the engine 7, the oxidation catalysts 21 and 22 are arranged compactly in the engine room 3. can do.

  In the tractor 1 according to this embodiment, the urea water tank 25 is disposed on the front surface of the bonnet 2. FIG. 8 is a cross-sectional view showing the arrangement of the urea water tank 25 of the first embodiment. The urea water tank 25 is supported by the frame 9 and is located on the front surface of the bonnet 2. Thereby, the weight of a front weight can be reduced. By arranging the urea water tank 25 in the front part of the airframe to function as a front weight, an increase in the total weight of the tractor 1 due to the urea water tank 25 being loaded can be suppressed. The urea water tank 25 is disposed on the rear side of the machine body with respect to the cooling fan 18 that blows cooling air to the radiator 7b, the engine 7, and the like, and is positioned at a cooling air passage portion by the cooling fan 18.

  In the present embodiment, the exhaust is discharged from the upper end of the external second pipe portion 8d, but the position of the discharge port of the exhaust pipe 8 is not limited to this. For example, the exhaust gas may be discharged from the lower end of the internal second pipe portion 8b toward the diagonally forward direction of the airframe.

[Second Embodiment]
The second embodiment will be described with reference to FIGS. 9 and 10. In the second embodiment, components having the same functions as those described in the first embodiment are given the same reference numerals, and duplicate descriptions are omitted. FIG. 9 is a front view of an exhaust pipe according to the second embodiment, and FIG. 10 is a top view inside the engine room of the tractor according to the second embodiment. The tractor 1 of the second embodiment is different from the tractor 1 of the first embodiment in that a second oxidation catalyst 22 is provided in the internal second pipe portion 8b.

  As shown in FIG. 9, the second oxidation catalyst 22 is disposed in a third accommodating portion 27 provided in the internal second pipe portion 8b. The 3rd accommodating part 27 is cylindrical shape, The axial direction is the up-down direction of the body. The NOx sensor 26 is disposed on the upstream side of the third accommodating portion 27 in the internal second pipe portion 8b. According to this embodiment, there exists an advantage that the freedom degree of arrangement | positioning increases because the selective catalyst reduction apparatus 20 and the 2nd oxidation catalyst 22 are arrange | positioned in the different accommodating parts 23 and 27. FIG.

  The lower end of the internal second pipe portion 8b is connected to the external first pipe portion 8c. The downstream end of the external first pipe 8c is connected to the external second pipe 8d. The configuration of the external first tube portion 8c and the external second tube portion 8d can be the same as that of the first embodiment.

  In addition, as shown in FIG. 11, you may make it exhaust from the lower end of the internal 2nd pipe part 8b. FIG. 11 is a front view inside an engine room according to a reference example of the second embodiment. The internal second pipe portion 8b extends downward from the third housing portion 27 to the height position of the rotation axis X of the engine 7, and an opening (not shown) is formed at the lower end. Exhaust gas that has passed through the second oxidation catalyst 22 is discharged from the opening toward the front side of the aircraft.

[Third Embodiment]
A third embodiment will be described with reference to FIG. About 3rd Embodiment, the description which attaches | subjects the same code | symbol to the component which has the function similar to what was demonstrated by each said embodiment, and abbreviate | omits the description. FIG. 12 is a front view of the exhaust pipe according to the third embodiment. The exhaust pipe of the third embodiment is different from the exhaust pipe of the second embodiment in that the second oxidation catalyst 22 is disposed in the external second pipe portion 8d.

  As shown in FIG. 12, the third accommodating portion 27 is provided in the external second pipe portion 8d. The second oxidation catalyst 22 is provided inside the third housing portion 27. The outer diameter of the third accommodating portion 27 is smaller than the outer diameter of the cover 8f that covers the outer second pipe portion 8d. Therefore, according to the present embodiment, the second oxidation catalyst 22 can be disposed in the external second pipe portion 8d while preventing the driver's view from being obstructed.

[Fourth Embodiment]
The fourth embodiment will be described with reference to FIGS. 13 to 15. In the fourth embodiment, the same reference numerals are given to components having the same functions as those described in each of the above embodiments, and duplicate descriptions are omitted. 13 is a right side view of the tractor 1 according to the fourth embodiment, FIG. 14 is a right side view inside the engine room according to the fourth embodiment, and FIG. 15 is a perspective view inside the engine room according to the fourth embodiment. FIG. In the tractor 1 of the present embodiment, the cooling water bypass circuit (for internal circulation) of the engine 7 is introduced into the urea water tank, and the urea water is defrosted by the rise of the cooling water temperature in the warm-up process. As a result, the urea water can be quickly supplied into the exhaust pipe 8 even at a low temperature where the urea water is frozen, and the exhaust purification performance can be improved.

  As shown in FIG. 13, the urea water tank 28 is disposed at the front of the body of the tractor 1. As shown in FIG. 14, the urea water tank 28 of the present embodiment is disposed on the front side of the radiator 7 b in the engine room 3. The bypass pipe 29 is a bypass flow path for cooling water of the engine 7.

  As shown in FIG. 15, the bypass pipe 29 connects the thermostat housing 7c of the engine 7 and the water pump 7d. The radiator 7b is a heat exchanger and cools the cooling water of the engine 7. The thermostat is closed when the cooling water is at a low temperature lower than a predetermined temperature, bypasses the radiator 7b, and recirculates the cooling water from the thermostat housing 7c via the bypass pipe 29 to the water pump 7d. On the other hand, the thermostat opens when the cooling water is at a predetermined temperature or higher, and causes the cooling water to recirculate to the water pump 7d via the radiator 7b.

  As shown in FIG. 15, the bypass pipe 29 passes through the urea water tank 28. The bypass pipe 29 is disposed in the urea water tank 28 so as to come into contact with the urea water in the urea water tank 28. When the cooling water temperature is lower than the predetermined temperature and the thermostat is closed, the cooling water flows from the thermostat housing 7c through the bypass pipe 29 to the water pump 7d as shown in FIG. Thereby, the urea water in the urea water tank 28 can be heated using the water temperature for promoting warm-up by internal circulation. For example, the urea water can be quickly thawed when the urea water is frozen at an extremely low temperature (−10 ° C. or lower).

  Further, when the thermostat is opened when the cooling water temperature is equal to or higher than the predetermined temperature, the cooling water flows from the thermostat housing 7c to the water pump 7d via the radiator 7b. At this time, since the cooling water does not flow into the bypass pipe 29, the temperature of the urea water is suppressed from becoming high. According to this embodiment, the urea water in the urea water tank 28 can be thawed without significantly changing the component configuration.

[Fifth Embodiment]
The fifth embodiment will be described with reference to FIG. In the fifth embodiment, the same reference numerals are given to components having the same functions as those described in each of the above embodiments, and duplicate descriptions are omitted. FIG. 16 is a flowchart according to the control of the fifth embodiment. In this embodiment, when the urea water in the urea water tank decreases, the operation of the engine 7 is restricted and the function as the tractor 1 is restricted. By limiting the operation of the engine 7, an increase in pollutants in the exhaust is suppressed. The control flow in FIG. 16 is repeatedly executed at a predetermined interval when the engine 7 is operated, for example.

  In step S10, the control device 30 determines whether or not the urea water level in the urea water tank is lowered. The control device 30 performs the determination in step S10 based on the detection result of the fuel gauge provided in the urea water tank. As a result of the determination, if it is determined that the urea water level is decreasing (step S10-Y), the process proceeds to step S20, and if not (step S10-N), the process proceeds to step S40.

  In step S <b> 20, the operation of the engine 7 is restricted by the control device 30. The control device 30 limits the rotation speed and the injection amount of the engine 7. In this embodiment, the rotational speed of the engine 7 is limited to 1,200 rpm or less, and the fuel injection amount is limited to an injection amount of 25% or less of the load factor. The upper limits of the engine speed and the fuel injection amount are determined so that, for example, the output is insufficient for working in a field or the like, and the output is sufficient for traveling for normal movement. In step S20, it may be determined that work is impossible. When the work cannot be performed, the control device 30 preferably notifies the driver that the work cannot be performed due to a shortage of urea water using a transmission device such as a lamp or a buzzer. When step S20 is executed, the process proceeds to step S30.

  In step S30, the control device 30 determines whether or not the urea water has been replenished. The control device 30 can make the determination in step S30 based on the detection result of the fuel gauge. As a result of the determination in step S30, if it is determined that the urea water has been replenished (step S30-Y), the process proceeds to step S40. If not (step S30-N), the process proceeds to step S10.

  In step S40, the control device 30 releases the restriction. The control device 30 releases the operation restriction of the engine 7 determined in step S20. When step S40 is executed, the process proceeds to step S50.

  In step S50, the control device 30 determines that work is possible. When the driver is notified that the work is impossible in step S20, it is desirable to cancel the notification in step S50. When step S50 is executed, the control flow ends.

  According to the control of the present embodiment, the operation of the engine 7 is limited when urea water is insufficient and it becomes difficult to purify nitrogen oxides in the exhaust gas. Thereby, the fall of exhaust process performance can be suppressed beforehand.

[Sixth Embodiment]
The sixth embodiment will be described with reference to FIGS. 17 to 21. In the sixth embodiment, components having the same functions as those described in the above embodiments are given the same reference numerals, and redundant descriptions are omitted. FIG. 17 is a schematic configuration diagram of the tractor 1 according to the sixth embodiment, FIG. 18 is a perspective view showing a main part of the tractor 1 according to the sixth embodiment, and FIG. 19 is a diagram showing a storage part of the urea water tank. FIG. 20 is a view showing a fixing portion of the urea water tank.

  The urea water tank 31 according to the present embodiment is configured to be detachable from the tractor 1. During periods when the tractor 1 is not used, the urea water tank 31 can be removed and stored indoors. Thereby, it becomes possible to suppress degradation of urea water. Further, as will be described later, it is preferable that the urea water tank 31 can be attached to and detached from a work vehicle such as a combine other than the tractor 1. Thereby, the urea water tank 31 can be shared by a plurality of types of work vehicles. If the urea water tank 31 is shared between work vehicles that use different times, it is possible to suppress deterioration due to long-term storage of urea water.

  As shown in FIG. 17, the urea water tank 31 is disposed in the cabin 10. In the present embodiment, the floor panel 17 shown in FIG. 18 constitutes the floor surface of the cabin 10. The urea water tank 31 is stored under the floor of the cabin 10. As shown in FIG. 19, the floor panel 17 includes an opening 17a and a lid 17b that closes the opening 17a. The opening 17a allows the urea water tank 31 to pass through.

  A fixed portion 32 shown in FIG. 20 is disposed below the opening 17a. The fixing part 32 holds the urea water tank 31, and has a holding surface 32a, a pair of side walls 32b and 32b, and an engaging part 32c. The holding surface 32 a is a surface facing upward, and supports the lower surface of the urea water tank 31. The pair of side walls 32b, 32b are wall portions protruding upward from the holding surface 32a, and face each other with the urea water tank 31 interposed therebetween. The engaging portion 32 c has a cylindrical shape and engages with the engaging portion 31 a of the urea water tank 31. The engaging portion 32 c of the holding portion 32 communicates with the urea water injection nozzle 24. The engaging portion 31 a of the urea water tank 31 has a cylindrical shape protruding from the lower surface of the urea water tank 31.

  The engaging portion 31a is provided with an open / close valve (not shown). When the engaging portion 31 a of the urea water tank 31 is engaged with the engaging portion 32 c of the fixing portion 32, the on-off valve is opened, and the urea water in the urea water tank 31 is supplied to the urea water injection nozzle 24. . Moreover, when the engaging part 31a of the urea water tank 31 is removed from the engaging part 32c of the fixed part 32, the on-off valve is closed and the outflow of urea water is restricted. A handle 31b is provided on the upper surface of the urea water tank 31 to facilitate attachment / detachment work and transport work.

  The urea water tank 31 can be mounted on other work vehicles. FIG. 21 is a diagram illustrating an example of a combiner on which the urea water tank 31 can be mounted. A combine 100 shown in FIG. 21 has a cabin 110. A cutting part is provided in front of the cabin 110 for cutting the planted cereal and transporting it toward the rear threshing apparatus. A grain tank for temporarily storing the grain after threshing is provided behind the cabin 110, and a threshing device is provided on the left side of the grain tank. The cabin 110 is provided with a floor panel and a fixing portion similar to the floor panel 17 and the fixing portion 32 shown in FIGS. 19 and 20. Therefore, the combine 100 can mount the urea water tank 31 common to the tractor 1. When the tractor 1 is used, the urea water tank 31 is mounted on the tractor 1 and used. When the combine 100 is used, the urea water tank 31 is detached from the tractor 1 and mounted on the combine 100 for use. If it does, degradation of urea water by long-term storage can be suppressed. In addition, the urea water tank 31 can be shared by different work vehicles, so that the cost can be reduced.

  The contents disclosed in the above embodiments can be executed in appropriate combination.

DESCRIPTION OF SYMBOLS 1 Tractor 2 Bonnet 3 Engine room 7 Engine 8 Exhaust pipe 8a Internal 1st pipe part 8b Internal 2nd pipe part 8c External 1st pipe part 8d External 2nd pipe part 9 Frame 10 Cabin 15 Operation seat 20 Selective catalyst reduction apparatus 21 1st One oxidation catalyst 22 Second oxidation catalyst 24 Urea water injection nozzle 25, 28, 31 Urea water tank 26 NOx sensor 30 Control device

Claims (4)

An engine room (3) disposed in front of the operator seat (15) and covered with a hood (2);
An engine (7) disposed in the engine room;
An exhaust pipe (8) for exhausting the exhaust of the engine (7);
A selective catalytic reduction device (20) provided in the exhaust pipe (8) and disposed above the engine (7) in the engine room;
A first oxidation catalyst (21) provided between the engine (7) and the selective catalyst reduction device (20) in the exhaust pipe (8);
A second oxidation catalyst (22) provided downstream of the selective catalyst reduction device (20) in the exhaust pipe (8) in the exhaust flow direction;
The exhaust pipe (8) includes an external first pipe part (8c) extending from the engine room (3) toward the side of the machine body, and the downstream side of the external first pipe part (8c). A tractor having an external second pipe portion (8d) extending upward from the end portion. The first oxidation catalyst (21) is disposed on the left side of the engine (7) when viewed from the operator seat (15),
The tractor according to claim 1, wherein the second oxidation catalyst (22) is disposed on the right side of the engine (7) when viewed from the operation seat (15). The tractor according to claim 1 or 2, wherein the second oxidation catalyst (22) is provided in the external second pipe portion (8d). The downstream side of the selective catalyst reduction device (20) of the exhaust pipe (8) extends downward from the side of the engine (7) to the vicinity of the frame (9) of the fuselage in the engine room. The tractor according to any one of claims 1 to 3.

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