JP6391405B2 - Exhaust gas purification device - Google Patents

Description

  The present invention relates to an exhaust gas purifying apparatus such as a diesel engine mounted on an agricultural machine (tractor, combine) or construction machine (bulldozer, hydraulic excavator, loader), and more specifically, particulates contained in the exhaust gas. The present invention relates to an exhaust gas purification device that removes substances (soot, particulates), nitrogen oxides (NOx) contained in exhaust gas, and the like.

  Conventionally, in the exhaust path of a diesel engine, as an exhaust gas aftertreatment device, a DPF case in which a diesel particulate filter for removing particulate matter in the exhaust gas of the diesel engine is installed, and in the exhaust gas of the diesel engine A technology for purifying exhaust gas discharged from a diesel engine by providing an SCR case with a urea selective reduction catalyst for removing nitrogen oxides and introducing exhaust gas into the DPF case and the SCR case. It is known (see, for example, Patent Documents 1 to 3).

Japanese Patent No. 4703260 Japanese Patent No. 4605205 Japanese Patent No. 5020185

  As in Patent Document 1 or 2, an SCR case can be easily assembled in a structure in which an exhaust connecting pipe for mixing urea water into exhaust gas is provided and the exhaust inlet of the SCR case is connected to the exhaust connecting pipe via a flange. In addition, a structure in which an exhaust connecting pipe is formed by an outer pipe and an inner pipe having a double pipe structure as in Patent Document 3 can prevent a temperature drop of exhaust gas supplied from the engine to the SCR case.

  However, when the exhaust inlet of the SCR case is connected to the exhaust pipe of the double pipe structure via the flange, the flange joint of the exhaust pipe is locally cooled, and the temperature of the inner pipe joint decreases, so There is a problem that a lump is easily generated and causes an increase in exhaust resistance.

  Accordingly, the present invention seeks to provide an exhaust gas purifying device that has been improved by examining these current conditions.

The present invention includes a urea mixing tube for injecting urea water into exhaust gas of the engine, the exhaust gas purifying apparatus Ru comprising a SCR casing for removing nitrogen oxide materials in the exhaust gas of the engine, outside the double pipe structure forming the urea mixing tube at the tube and the inner tube, wherein a structure that form a SCR case than said inlet opening of the inner case at the inner casing and the outer casing of the double case structure An inner pipe is formed to have a small diameter, and an exhaust gas outlet side end portion of the inner pipe is inserted into the SCR case inlet, and the exhaust gas is more than the inlet opening of the exhaust gas inlet pipe. An outlet opening of the inlet pipe is formed to have a large diameter, the exhaust gas inlet pipe is fixed to the inner case body, and the exhaust gas inlet side of the outer pipe is connected to the exhaust gas inlet pipe of the SCR case via a flange body. one obtained by connecting the ends That.

According to the present invention, the urea mixing pipe for injecting urea water into the exhaust gas of the engine and the SCR case for removing the nitrogen oxides in the exhaust gas of the engine are provided, and the exhaust of the urea mixing pipe through the flange body In the exhaust gas purifying apparatus in which the exhaust gas inlet side of the SCR case is connected to the gas outlet side, the urea mixing tube is formed by an outer tube and an inner tube of a double tube structure, and the exhaust gas from the SCR case The exhaust pipe outlet side end of the outer pipe is connected to the gas inlet pipe via a flange body, and the exhaust pipe outlet side end of the inner pipe is inserted inside the SCR case inlet. Therefore, it is possible to prevent the exhaust gas of the inner pipe from contacting the flange body connecting portion of the outer pipe and the exhaust gas inlet pipe, and to reduce crystallization of urea water mixed with the exhaust gas, Previous Urea crystalline mass produced in the flange body connecting portion of the outer tube exhaust gas inlet pipe can be reduced, that the exhaust resistance of the inner tube the urea crystalline mass grows increases easily prevented.

According to the present invention, the SCR case is formed by an inner case body and an outer case body having a double case structure, and the exhaust gas inlet pipe is fixed to the inner case body. The urea mixing tube can be connected to the SCR case without bringing the inner tube into contact with the case, and the formation of urea crystal lumps near the SCR case inlet can be prevented.

According to the present invention, the inner pipe is formed with a smaller diameter than the inlet opening of the inner case body, while the outlet opening of the exhaust gas inlet pipe is formed with a larger diameter than the inlet opening of the exhaust gas inlet pipe. Therefore, the inner pipe can be easily prevented from coming into contact with the inlet opening edge of the inner case body, and the exhaust gas inlet pipe can be welded and fixed with high rigidity by being separated from the inlet opening edge of the inner case body. .

It is a front view of the exhaust-gas purification apparatus which shows 1st Embodiment. It is the same side view. It is the same perspective view. It is the same top view. FIG.

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. 1 is a front view of an exhaust gas purification device mounted on a diesel engine 1, FIG. 2 is a side view thereof, FIG. 3 is a perspective view thereof, FIG. 4 is a plan view thereof, and FIG.

  As shown in FIGS. 1 to 4, an exhaust manifold 6 is disposed on the side surface of the diesel engine 1. Further, as an exhaust gas purifying device 27 for purifying exhaust gas discharged from each cylinder of the diesel engine 1, as a diesel particulate filter (DPF case) for removing particulate matter in the exhaust gas of the diesel engine 1. And a second case 29 as a urea selective catalytic reduction system (SCR case) for removing nitrogen oxides in the exhaust gas of the diesel engine 1. As shown in FIG. 4, an oxidation catalyst 30 and a soot filter 31 are installed in the first case 28. The second case 29 includes an SCR catalyst 32 and an oxidation catalyst 33 for reducing urea selective catalyst.

  Exhaust gas discharged from each cylinder of the diesel engine 1 to the exhaust manifold 6 is discharged to the outside via the exhaust gas purification device 27 and the like. The exhaust gas purification device 27 is configured to reduce carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM), and nitrogen oxides (NOx) in the exhaust gas of the diesel engine 1. doing.

  The first case 28 and the second case 29 are configured in a substantially cylindrical shape extending long in the horizontal direction perpendicular to the output shaft (crankshaft) of the diesel engine 1 in plan view. On both sides of the first case 28 (one end side and the other end side in the exhaust gas movement direction), a DPF inlet pipe 34 for taking in exhaust gas and a DPF outlet pipe 35 for discharging exhaust gas are provided. Similarly, on both sides of the second case 29 (one end side and the other end side in the exhaust gas movement direction), an SCR inlet pipe 36 as an exhaust gas inlet pipe for taking in the exhaust gas, and exhaust gas toward the tail pipe An SCR outlet pipe 37 for discharging is provided.

  Further, the DPF inlet pipe 34 is connected to the exhaust gas outlet of the exhaust manifold 6 through a supercharger that forcibly sends air to the diesel engine 1, and the exhaust gas of the diesel engine 1 is introduced into the first case 28. On the other hand, the SCR inlet pipe 36 is connected to the DPF outlet pipe 35 via the urea mixing pipe 39 so that the exhaust gas of the first case 28 is introduced into the second case 29.

  Further, the urea mixing pipe 39 is formed by a straight tubular portion 45 that forms ammonia by hydrolysis of urea and a urea water injection portion 46 provided at an exhaust upstream side end portion of the straight tubular portion 45. The inlet flange body 46a of the urea water injection section 46 is fastened to the outlet flange body 35a of the DPF outlet pipe 35, and the exhaust gas inlet side of the straight tubular section 45 is welded and fixed to the exhaust gas outlet side of the urea water injection section 46. The exhaust gas is moved from the first case 28 to the urea mixing tube 39.

  As shown in FIG. 3, a urea water tank 75 for storing urea water, a urea water injection nozzle 76 for supplying urea, and a urea water injection pump 77 for pumping the urea water in the urea water tank 75 to the urea water injection nozzle 76 are provided. Prepare. The urea water tank 75 is installed in a device on which the diesel engine 1 is mounted. The urea water injection pump 77 is driven by the output of the diesel engine 1 or an electric motor. The urea water injection nozzle 76 is disposed in the urea water injection unit 46.

  With the above configuration, the urea water in the urea water tank 75 is pumped from the urea water injection pump 77 to the urea water injection nozzle 76, and the urea water is injected from the urea water injection nozzle 76 into the urea water injection unit 46 to mix urea. The urea water is mixed with the exhaust gas from the diesel engine 1 inside the pipe 39. The exhaust gas mixed with urea water passes through the second case 29 (SCR catalyst 32, oxidation catalyst 33), nitrogen oxides (NOx) in the exhaust gas are reduced, and discharged from the SCR outlet pipe 37 to the outside. The

  As shown in FIG. 1, a support frame body 81 is provided on the upper surface side of the diesel engine 1, and the first case 28 and the second case 29 are detachably fixed to the upper surface side of the support frame body 81. The exhaust gas movement direction of the cylindrical first case 28 and the second case 29 is directed in the horizontal lateral direction intersecting with the output shaft of the diesel engine 1.

  Next, the structure of the SCR inlet pipe 36 portion of the second case 29 will be described with reference to FIG. As shown in FIG. 5, an elbow tubular portion 85 is connected to the exhaust outlet side of the straight tubular portion 45 of the urea mixing tube 39. The elbow tubular portion 85 has an outer tube 86 formed by a pair of half-cracked cylinders obtained by dividing the cylinder into two in the longitudinal direction, and the longitudinal ends of the half-cracked cylinders of the outer tube 86 face outward. It is bent to form a joint flange portion 86a at the portion. Similarly, the elbow tubular part 85 has an inner tube 87 formed by a pair of half-cracked cylinders obtained by dividing the cylinder into two in the longitudinal direction, and the longitudinal ends of the half-cracked cylinders of the inner pipe 87 are outside. The joint flange portion 87a is formed in this portion. The joining flange portion 87a of the inner tube 87 is sandwiched and welded and fixed by the joining flange portion 86a of the outer tube 86, and the outer tube 86 and the inner tube 87 of the elbow tubular portion 85 are integrally formed.

  Further, the urea mixing tube 39 has an outer tube 88 and an inner tube 89 having a double tube structure. The exhaust inlet side of the inner pipe 87 protrudes from the cylindrical opening on the exhaust inlet side of the outer pipe 86 of the elbow tubular section 85, and the outer pipe 86 exhaust inlet side of the elbow tubular section 85 faces the outer pipe 88 exhaust outlet side of the urea mixing pipe 39. Are welded and fixed, and the inner pipe 87 exhaust inlet side of the elbow tubular portion 85 is welded and fixed to the inner pipe 89 exhaust outlet side of the urea mixing pipe 39. That is, the exhaust inlet side of the elbow tubular portion 85 is integrally connected to the exhaust outlet side of the urea mixing tube 39.

  In addition, the exhaust outlet side of the inner pipe 87 protrudes from the cylindrical opening on the exhaust outlet side of the outer pipe 86 of the elbow tubular section 85, and the outer pipe 86 of the elbow tubular section 85 extends to the outer pipe 88 exhaust outlet side of the urea mixing pipe 39. While fixing the exhaust inlet side by welding, an elbow side flange body 92 is fixed by welding to the outer pipe 88 exhaust outlet side. On the other hand, the inlet side flange body 93 is fixed by welding to the exhaust inlet side of the SCR inlet pipe 36, and the flange bodies 92, 93 are detachably fastened with bolts 91.

  The second case 29 is formed in a double cylinder structure by the inner case 146 and the outer case 147. In the inner case 146, the SCR catalyst 32 and the oxidation catalyst 33 for urea selective catalyst reduction are accommodated. The outer peripheral side of the inner case 146 and the inner peripheral side of the outer case 47 are connected via a thin plate support 148 and the like. A heat insulating case insulating material 149 is filled between the outer peripheral side of the inner case 146 and the inner peripheral side of the outer case 147.

  As shown in FIG. 5, the side lid 153 is fixed by welding to one end side (end portion on the exhaust upstream side) of the inner case 146 and the outer case 147. One end sides of the cylindrical openings of the inner case 146 and the outer case 147 are closed with a side lid 153. Further, exhaust gas inlets 154 and 155 are formed in the inner case 46 and the outer case 47 between the SCR catalyst 32 storage portion and the side lid 153. The exhaust gas inlet 155 of the outer case 47 is formed to have a larger diameter than the exhaust gas inlet 154 of the inner case 146, and the exhaust gas outlet side of the SCR inlet pipe 36 is welded and fixed to the outer peripheral side of the exhaust gas inlet 154 of the inner case 146. Yes.

  That is, the inner tube 87 of the elbow tubular portion 85 is formed with a smaller diameter than the inlet opening of the inner case 146, while the outlet opening of the SCR inlet tube 36 is formed with a larger diameter than the inlet opening of the SCR inlet tube 36. The SCR inlet pipe 36 is passed through the exhaust gas inlet 155 of the outer case 47, and the inside of the SCR inlet pipe 36 is communicated with the inner case 146. An exhaust gas supply chamber 99 of the second case 29 is formed inside the inner case 146 between the SCR catalyst 32 and the side lid 153, and from the exhaust gas outlet side of the SCR inlet pipe 36 toward the exhaust gas supply chamber 99, The exhaust gas outlet side of the inner pipe 87 of the elbow tubular portion 85 is projected.

  With the above configuration, the exhaust gas supply chamber 99 of the second case 29 is formed between the exhaust gas receiving end surface of the SCR catalyst 32 and the side lid 153 in which the surface facing the SCR catalyst 32 is recessed in a concave shape. The An exhaust gas in which urea water is mixed as ammonia is introduced from the inner pipe 87 of the elbow tubular portion 85 into the exhaust gas supply chamber 99, and the exhaust gas is allowed to pass through the SCR catalyst 32 and the oxidation catalyst 33, so that the second case 29 The nitrogen oxides (NOx) in the exhaust gas discharged from the SCR outlet pipe 37 are reduced.

  As shown in FIGS. 1, 4, and 5, a urea mixing pipe 39 as an exhaust connecting pipe for injecting urea water into the exhaust gas of the diesel engine 1 and nitrogen oxides in the exhaust gas of the diesel engine 1 are removed. In an exhaust gas purification apparatus that includes a second case 29 as an SCR case and connects the exhaust gas inlet side of the second case 29 to the exhaust gas outlet side of the urea mixing pipe 39 via flange bodies 92 and 93, a double pipe A urea mixing tube 39 (elbow tubular portion 85) is formed by an outer tube 88 (outer tube 86) and an inner tube 89 (inner tube 87) having a structure, and serves as an exhaust gas inlet tube of the second case 29. The exhaust gas outlet side end portion of the outer tube 88 is connected to the SCR inlet tube 36 through the flange bodies 92 and 93, and the inner tube 89 (the inner tube 87 of the elbow tubular portion 85) is provided inside the second case 29 inlet. Exhaust gas outlet It is configured to inserted into the end. Therefore, it is possible to prevent the exhaust gas of the inner pipe 89 (the inner pipe 87 of the elbow tubular portion 85) from coming into contact with the flange bodies 92 and 93 connecting portions of the outer pipe 88 and the SCR inlet pipe 36, and urea mixed with the exhaust gas. Water crystallization can be reduced, and urea crystal lumps generated at the joints of the flanges 92 and 93 of the outer pipe 88 and the SCR inlet pipe 36 can be reduced, and the urea crystal lumps grow to form the inner pipe 89 ( It is possible to easily prevent the exhaust resistance of the inner pipe 87) of the elbow tubular portion 85 from increasing.

  As shown in FIG. 5, the second case 29 is formed by an inner case 146 body and an outer case 147 body having a double case structure, and the SCR inlet pipe 36 is fixed to the inner case 146 body. Therefore, the urea mixing tube 39 can be connected to the second case 29 without bringing the inner tube 89 (the inner tube 87 of the elbow tubular portion 85) into contact with the second case. Formation can be prevented.

  As shown in FIG. 5, the inner tube 87 of the elbow tubular portion 85 is formed to have a smaller diameter than the inlet opening of the inner case 146 body, while the outlet opening of the SCR inlet tube 36 has a larger diameter than the inlet opening of the SCR inlet tube 36. Forming. Therefore, the inner tube 87 of the elbow tubular portion 85 can be easily prevented from coming into contact with the inlet opening edge of the inner case 146 body, and the SCR inlet tube 36 can be separated from the inlet opening edge of the inner case 146 body. Can be fixed by welding to rigidity.

1 Diesel engine 29 2nd case (SCR case)
36 SCR inlet pipe (exhaust gas inlet pipe)
39 Urea mixing pipe 88 Urea mixing pipe outer pipe 89 Urea mixing pipe inner pipe 86 Elbow tubular outer pipe 87 Elbow tubular inner pipe 92 Elbow side flange body 93 Inlet side flange body 146 Inner case 147 Outer case

Claims (2)

Urea mixing tube for injecting urea water into exhaust gas of the engine, the exhaust gas purifying apparatus Ru comprising a SCR casing for removing nitrogen oxide materials in the exhaust gas of the engine,
The formed urea mixing tube at the outer tube and the inner tube of the double tube structure, a structure that to form the SCR case at inner case and the outer case of the double casing structure,
The inner pipe is formed to have a smaller diameter than the inlet opening of the inner case body, and the exhaust gas outlet side end of the inner pipe is inserted into the SCR case inlet.
Forming an outlet opening of the exhaust gas inlet pipe larger in diameter than an inlet opening of the exhaust gas inlet pipe, and fixing the exhaust gas inlet pipe to the inner case body;
An exhaust gas purification apparatus, wherein an exhaust gas outlet side end of the outer pipe is connected to an exhaust gas inlet pipe of the SCR case via a flange body . The exhaust gas inlet pipe penetrates the exhaust gas inlet of the outer case, and the inside of the exhaust gas inlet pipe communicates with the inner case, and between the SCR catalyst and the side lid in the inner case. The exhaust gas supply chamber is formed, and the exhaust gas outlet side of the inner tube of the urea mixing tube projects from the exhaust gas inlet tube toward the exhaust gas supply chamber. The exhaust gas purification apparatus as described.

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