JP6680621B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

  The exhaust gas purification device for an internal combustion engine described in Patent Document 1 has a catalyst provided in an exhaust passage. The catalyst is a NOx storage reduction catalyst, which stores NOx contained in the exhaust when the exhaust air-fuel ratio is lean, and releases and reduces the stored NOx when the exhaust air-fuel ratio is rich. This purifies the exhaust gas flowing through the exhaust passage. The exhaust gas purification device for an internal combustion engine also has an addition valve provided on the exhaust gas upstream side of the catalyst in the exhaust passage. The addition valve injects fuel that is a reducing agent toward the exhaust gas upstream side. When the fuel injection is directed to the upstream side of the exhaust gas, the atomization of the fuel is promoted by mixing with the exhaust gas. By injecting fuel from the addition valve and making the exhaust air-fuel ratio rich, the NOx stored in the NOx storage reduction catalyst is released and reduced.

Japanese Unexamined Patent Publication No. 2006-77691

  In the exhaust gas purification device for the internal combustion engine described in Patent Document 1, the reducing agent is injected from the addition valve toward the exhaust gas upstream side. Therefore, the reducing agent may unintentionally adhere to the functional component arranged on the exhaust passage upstream of the addition valve in the exhaust passage. The reducing agent adhering to the functional component contributes to the generation of deposits on the functional component. Further, the functional component is partially cooled by the attachment of the reducing agent. Therefore, if such cooling is repeated, the functional component may be distorted and durability may be reduced.

  In order to suppress such adhesion of the reducing agent, a plurality of shielding plate may be provided between the addition valve and the functional component in the exhaust passage. The shield plate protrudes from the inner circumferential surface of the exhaust passage toward the inside of the exhaust passage, and shields the reducing agent sprayed from the addition valve so as not to further reach the exhaust upstream side. With such a configuration, although the reducing agent can be prevented from adhering to the functional component, the flow passage area of the exhaust passage is also reduced by the shielding plate, so that the pressure loss of the exhaust passage may increase.

  In an exhaust gas purification device for an internal combustion engine, it is desirable to prevent the reducing agent from adhering to the functional component while suppressing an increase in pressure loss in the exhaust passage.

  An exhaust gas purification apparatus for an internal combustion engine for solving the above-mentioned problems is provided in an exhaust passage, a catalyst for purifying exhaust gas flowing through the exhaust passage, and an exhaust gas upstream side of the catalyst in the exhaust passage, the exhaust upstream side of the catalyst. And an addition valve for injecting a reducing agent toward the side and an exhaust gas upstream side of the addition valve in the exhaust passage, extending from the inner peripheral surface of the passage toward the inside of the exhaust passage, and injected from the addition valve. A plurality of shielding portions for shielding the spray of the reducing agent, and the plurality of shielding portions are arranged such that the positions of the tips extending toward the inside of the exhaust passage are different from each other in the exhaust flow direction. ing.

  When the positions of the respective tips of the plurality of shields are arranged at the same position in the flow direction of the exhaust gas, the respective tips of the shields are located in the same passage cross section. Therefore, when the cross section of the exhaust passage is viewed, the flow passage area of the portion where each tip of the shielding portion is located tends to be small. Therefore, by providing the shielding portion, the pressure loss in the exhaust passage is likely to increase.

  In the above configuration, the plurality of shields are arranged such that the positions of the respective tips are different from each other in the exhaust flow direction, and the tips of the shields are not located in the same passage cross section. Therefore, when looking at the passage cross section of the exhaust passage, the flow passage area of the portion where the tip of the shielding portion is located is when the position of each tip of the shielding portion is arranged at the same position in the exhaust flow direction. It becomes larger than the area of the channel. As a result, even if the shielding portion that blocks the spray of the reducing agent injected from the addition valve is provided, it is possible to prevent the pressure loss in the exhaust passage from greatly increasing. Therefore, according to the above configuration, it is possible to suppress the reducing agent from adhering to the functional component while suppressing an increase in pressure loss in the exhaust passage.

1 is a schematic diagram schematically showing the configuration of a first embodiment of an exhaust purification device for an internal combustion engine. The top view which shows typically the aspect of injection of the reducing agent from the addition valve in the same embodiment. Sectional drawing which followed the 3-3 line of FIG. The top view which shows the structure of the modification of 1st Embodiment. The top view which shows typically the structure of 2nd Embodiment of the exhaust gas purification apparatus of an internal combustion engine. The top view which shows the structure of the modification of 2nd Embodiment. The top view which shows the structure of the other modification of 2nd Embodiment.

(First embodiment)
A first embodiment of an exhaust emission control device for an internal combustion engine will be described with reference to FIGS. The present embodiment is an example in which the exhaust gas purification device for an internal combustion engine is applied to a diesel engine.

  As shown in FIG. 1, a cylinder 10A is formed in a cylinder block 10 of the internal combustion engine. A piston 11 is slidably accommodated in the cylinder 10A. A cylinder head 12 is fixed to the upper end of the cylinder block 10. A combustion chamber 13 is formed by the cylinder 10A, the piston 11, and the cylinder head 12.

  One end of an intake passage 14 is connected to the combustion chamber 13. The intake air supplied from the other end of the intake passage 14 flows through the intake passage 14 and is introduced into the combustion chamber 13. That is, in the intake passage 14, the one end side connected to the combustion chamber 13 is the intake downstream side, and the other end side is the intake upstream side. A compressor housing 21 of the supercharger 20 is provided in the intake passage 14. Further, the internal combustion engine is provided with an intake valve 15 which connects and disconnects the intake passage 14 and the combustion chamber 13. By opening the intake valve 15, intake air can be introduced from the intake passage 14 into the combustion chamber 13.

  A fuel injection valve 16 is provided in the combustion chamber 13. Fuel is supplied to the fuel injection valve 16 through a fuel supply system 30. The fuel supply system 30 has a fuel supply passage 31 whose one end is connected to the fuel injection valve 16. The other end of the fuel supply passage 31 is connected to a fuel tank 32 that stores fuel. A fuel pump 33 is provided on the path of the fuel supply passage 31. The fuel pump 33 is, for example, an electric pump, and pumps the fuel in the fuel tank 32 to the fuel supply passage 31 and supplies the fuel to the fuel injection valve 16. The fuel injection valve 16 injects fuel into the combustion chamber 13. The fuel injected into the combustion chamber 13 is mixed with the intake air introduced from the intake passage 14 to form an air-fuel mixture. The air-fuel mixture is pressurized by the rise of the piston 11 and combusts by self-ignition.

  An exhaust passage 17 is also connected to the combustion chamber 13. The exhaust gas generated by the combustion of the air-fuel mixture is discharged from the combustion chamber 13 to the exhaust passage 17. The exhaust passage 17 includes a first passage 17A having one end connected to the combustion chamber 13 and a second passage 17B connected to the other end of the first passage 17A. One end of the first passage 17A on the side of the combustion chamber 13 is curved in an arc shape, and the other end on the side opposite to the one end extends horizontally. The second passage 17B is bent from the other end of the first passage 17A and extends vertically downward. The exhaust gas discharged from the combustion chamber 13 flows into the second passage 17B through the first passage 17A. The exhaust gas that has flowed into the second passage 17B flows vertically downward along the bent bent portion 171B. That is, in the exhaust passage 17, one end side of the first passage 17A connected to the combustion chamber 13 is the exhaust upstream side, and the side separated from the one end side is the exhaust downstream side. On the central axis C of the exhaust passage 17 indicated by the one-dot chain line arrow in FIG. 1, the direction from the exhaust upstream side to the exhaust downstream side is called the exhaust flow direction. The internal combustion engine is provided with an exhaust valve 18 that connects and disconnects the exhaust passage 17 and the combustion chamber 13. Exhaust gas can be discharged from the combustion chamber 13 to the exhaust passage 17 by opening the exhaust valve 18.

  The exhaust purification device 40 of the internal combustion engine has a NOx storage reduction catalyst 41 provided in the second passage 17B of the exhaust passage 17. The NOx storage reduction catalyst 41 stores NOx contained in the exhaust when the exhaust air-fuel ratio is lean, and releases and reduces the stored NOx when the exhaust air-fuel ratio is rich. The NOx storage reduction catalyst 41 functions as a catalyst for purifying the exhaust gas flowing through the exhaust passage 17.

  In the exhaust passage 17, the addition valve 42 is provided at the bent portion 171B of the second passage 17B. The addition valve 42 is provided on the exhaust gas upstream side of the NOx storage reduction catalyst 41. One end of the branch passage 19 is connected to the addition valve 42. The other end of the branch passage 19 is connected to the fuel supply passage 31. As a result, the fuel that is the reducing agent is supplied from the fuel supply system 30 to the addition valve 42. The injection direction of the addition valve 42 is directed to the exhaust gas upstream side, and the fuel is injected toward the exhaust gas upstream side, as indicated by the dots in FIG. Since the fuel injection is directed to the upstream side of the exhaust gas, the atomization of the fuel is promoted by mixing with the exhaust gas. The amount of fuel injected from the addition valve 42 is set so that the exhaust air-fuel ratio can be made rich. Therefore, when the fuel is injected from the addition valve 42, the exhaust air-fuel ratio becomes rich, and the stored NOx is released and reduced in the NOx storage reduction catalyst 41.

  In the first passage 17A of the exhaust passage 17, a turbine housing 22 of the supercharger 20 is provided as a functional component. The supercharger 20 also has a bearing housing 23 that connects a compressor housing 21 provided in the intake passage 14 and a turbine housing 22 provided in the exhaust passage 17. A compressor wheel 24 is housed in the compressor housing 21, and a turbine wheel 25 is housed in the turbine housing 22. A rotating shaft 26 is rotatably accommodated in the bearing housing 23. The rotating shaft 26 penetrates the compressor housing 21 and the turbine housing 22 and extends to the inside thereof, and one end thereof is connected to the compressor wheel 24 and the other end thereof is connected to the turbine wheel 25. Therefore, when the exhaust gas rotates the turbine wheel 25, the compressor wheel 24 also integrally rotates around the rotation shaft 26. As a result, the intake air in the intake passage 14 is compressed, and the compressed intake air is introduced into the combustion chamber 13.

  The exhaust passage 17 is provided with two shields 43. Each shielding portion 43 is provided in the first passage 17A, and is provided in the exhaust passage 17 on the exhaust upstream side of the addition valve 42 and on the exhaust downstream side of the turbine housing 22.

  As shown in FIG. 2, each of the shielding portions 43 projects from the inner peripheral surface of the exhaust passage 17 in the radial direction orthogonal to the central axis C of the exhaust passage 17, and extends toward the inside of the exhaust passage 17, respectively. That is, as shown in FIG. 2, when viewed in a horizontal cross section including the central axis C, each shielding portion 43 is erected vertically from the passage inner peripheral surface of the exhaust passage 17. The respective shielding portions 43 are provided at different positions in the exhaust gas flow direction, and the positions of the tips extending toward the inside of the exhaust passage 17 are arranged at different positions in the exhaust gas flow direction. . Below, the shielding part 43 located on the exhaust downstream side (left side in FIG. 2) is referred to as a first shielding part 44, and the shielding part 43 located on the exhaust upstream side (right side in FIG. 2) with respect to the first shielding part is referred to as the second shielding part 43. The shielding portion 45 is used. The protrusion height h1 of the first shield portion 44 from the passage inner peripheral surface of the exhaust passage 17 is the same as the protrusion height h2 of the second shield portion 45 from the passage inner peripheral surface of the exhaust passage 17 (h1 = h2). ).

  As shown in FIG. 3, the first shielding portion 44 and the second shielding portion 45 are provided at positions rotated by 180 ° in the circumferential direction of the exhaust passage 17, and are orthogonal to the vertical direction (vertical direction in FIG. 3). Are arranged in the orthogonal direction (left-right direction in FIG. 3). The first shielding portion 44 and the second shielding portion 45 are rectangular plate-shaped, and are arranged such that their longitudinal directions are oriented in the vertical direction. As shown in FIG. 2, fuel is injected from the addition valve 42 to the surfaces of the first shielding portion 44 and the second shielding portion 45 on the exhaust downstream side. As shown in FIG. 3, the size of the first shielding portion 44 is such that the area S1 of the surface of the first shielding portion 44 on the exhaust downstream side is injected from the addition valve 42 as indicated by the chain line in FIG. The spray is set to be larger than the cross-sectional area S2 of the spray when it reaches the first shielding portion 44 (S1> S2). Further, the size of the second shielding portion 45 is determined by the amount of the spray injected from the addition valve 42 such that the area S3 of the surface on the exhaust downstream side of the second shielding portion 45 is indicated by a chain double-dashed line in FIG. It is set to be larger than the cross-sectional area S4 of the spray when it reaches the second shielding portion 45 (S3> S4). As a result, the first shielding portion 44 and the second shielding portion 45 shield so that the spray of the fuel injected from the addition valve 42 does not reach the exhaust gas upstream side.

  As shown in FIG. 1, the control device 50 for an internal combustion engine receives signals output from an accelerator sensor 51 that detects an accelerator operation amount, a rotation speed sensor 52 that detects an engine rotation speed, and the like. The control device 50 of the internal combustion engine calculates the amount of fuel injected from the fuel injection valve 16 into the combustion chamber 13 based on the accelerator operation amount, the engine rotation speed, and the like. Then, the valve opening timing, the valve opening time, and the injection pressure of the fuel injection valve 16 are controlled so that the calculated amount of fuel is injected. The injection pressure is adjusted by controlling the driving amount of the fuel pump 33. Further, the control device 50 for the internal combustion engine calculates the NOx amount stored in the NOx storage reduction catalyst 41 from the fuel injection amount and the engine rotation speed. Then, before the calculated NOx storage amount becomes equal to or more than the allowable amount, the addition valve 42 is controlled to inject a predetermined amount of fuel into the exhaust passage 17, thereby making the exhaust air-fuel ratio rich and thereby reducing the NOx storage reduction. The NOx stored in the catalyst 41 is released and reduced.

The operation and effect of the exhaust gas purification device 40 for an internal combustion engine of this embodiment will be described.
(1) As shown in FIG. 2, the first shield portion 44 and the second shield portion 45 are arranged at positions where the tips of the first shield portion 44 and the second shield portion 45 extending toward the inside of the exhaust passage 17 are different from each other in the exhaust flow direction. Has been done. When the passage cross section that is a cross section orthogonal to the central axis C of the exhaust passage 17 is viewed, at the position where the tip of the first shielding portion 44 is provided, the passage inner circumference of the exhaust passage 17 from the tip of the first shielding portion 44 is provided. The length L1 to the surface is the diameter D of the exhaust passage 17 minus the protrusion height h1 of the first shielding portion 44 (L1 = D-h1). Then, in the passage cross section where the tip of the first shielding portion 44 is located, the flow passage area through which the exhaust can flow is the passage area of the exhaust passage 17 minus the area S1 of the first shielding portion 44.

  Further, when the passage cross section of the exhaust passage 17 is viewed, at the position where the tip of the second shielding portion 45 is provided, the length L2 from the tip of the second shielding portion 45 to the passage inner peripheral surface of the exhaust passage 17 is , The projection height h2 of the second shielding portion 45 is subtracted from the diameter D of the exhaust passage 17 (L2 = D−h2). In the passage cross section in which the tip of the second shielding portion 45 is located, the flow passage area through which the exhaust can flow is the passage area of the exhaust passage 17 minus the area S3 of the second shielding portion 45.

  On the other hand, if it is assumed that the positions of the tips of the first shielding portion 44 and the second shielding portion 45 are arranged at the same position in the exhaust flow direction, then the tips are located at the same passage cross section. To do. Therefore, when the passage cross section of the exhaust passage 17 is viewed, the distance between the tips of the first shield portion 44 and the second shield portion 45 at the position where these tips are provided is the same as the length L3 shown in FIG. become. The length L3 is obtained by subtracting the protrusion height h1 of the first shielding portion 44 and the protrusion height h2 of the second shielding portion 45 from the diameter D of the exhaust passage 17 (L3 = D-h1-h2). Then, in this case, in the passage cross section in which the respective tips of the first shielding portion 44 and the second shielding portion are located, the flow passage area through which the exhaust gas can flow varies from the passage area of the exhaust passage 17 to the first shielding portion 44. The area S1 and the area S3 of the second shield 45 are subtracted.

  Therefore, according to the present embodiment, the flow passage area of each of the portions where the tip of the first shielding portion 44 and the tip of the second shielding portion 45 are located is different from that of the first shielding portion 44 and the second shielding portion 45. The position of each tip is larger than the flow passage area when the positions are arranged at the same position in the exhaust flow direction. Accordingly, even if the first shielding portion 44 and the second shielding portion 45 that shield the spray of the fuel injected from the addition valve 42 are provided, it is possible to prevent the pressure loss in the exhaust passage 17 from greatly increasing. Therefore, according to the above configuration, it is possible to suppress the fuel from adhering to the functional component while suppressing an increase in the pressure loss of the exhaust passage 17.

The first embodiment can be modified and implemented as follows.
In the first embodiment, when viewed in a horizontal section including the central axis C of the exhaust passage 17, the first shielding portion 44 and the second shielding portion 45 are erected so as to extend vertically from the inner peripheral surface of the passage. However, the extending direction may be changed. For example, as shown in FIG. 4, the first shield portion 44 and the second shield portion 45 are inclined with respect to the radial direction orthogonal to the central axis C of the exhaust passage 17 so that they are located closer to the exhaust downstream side. The first shielding portion 44 and the second shielding portion 45 may be provided upright. The inclination angle θ1 of the first shield portion 44 with respect to the radial direction and the inclination angle θ2 of the second shield portion 45 with respect to the radial direction are the same. The first shielding portion 44 and the second shielding portion 45 are provided at different positions in the exhaust gas flow direction, and the positions of the tips in the exhaust gas flow direction are also different from each other. According to such a configuration, the exhaust gas is more likely to flow to the downstream side than when the first shielding part 44 and the second shielding part 45 are provided so as to extend vertically from the inner peripheral surface of the passage, so that the pressure loss of the exhaust gas is reduced. It is possible to enhance the effect of suppressing the increase of Further, since the first shielding portion 44 and the second shielding portion 45 are inclined toward the exhaust gas downstream side, the water droplets attached to the inner circumferential surface of the passage on the exhaust gas upstream side of the first shielding portion 44 and the second shielding portion 45. And the like easily move to the tip along the surface of the shielding portion 43 on the upstream side of the exhaust due to the flow of the exhaust. Therefore, it is possible to allow water droplets and the like attached to the inner peripheral surface of the passage to flow from the tip of the shielding portion 43 to the exhaust downstream side together with the exhaust, and to prevent such water droplets and the like from staying in the exhaust passage 17.

(Second embodiment)
A second embodiment of the exhaust emission control device for an internal combustion engine will be described with reference to FIG. In the present embodiment, the arrangement position of the addition valve 42 is different from that of the first embodiment. Hereinafter, a configuration different from that of the first embodiment will be described, and configurations similar to those of the first embodiment will be denoted by common reference numerals, and detailed description thereof will be omitted.

  As shown in FIG. 5, in the exhaust passage 17, the addition valve 42 is provided at the bent portion 171B in the second passage 17B. As shown in FIG. 5, the addition valve 42 is provided at a position eccentric to the first shielding portion 44 side with respect to the central axis C of the exhaust passage 17 when viewed in a horizontal section including the central axis C. That is, the addition valve 42 is arranged so as to be hidden behind the first shielding portion 44 located on the exhaust downstream side of the second shielding portion 45 when viewed from the exhaust upstream side.

The exhaust emission control device for an internal combustion engine of the present embodiment can obtain the following action and effect in addition to the action and effect of (1) described above.
(2) The exhaust gas flowing through the exhaust passage 17 is guided by the first shielding portion 44 and the second shielding portion 45, and flows while meandering as shown by the double-dashed line arrow in FIG. In the first embodiment shown in FIG. 2, the addition valve 42 is not hidden behind the first shielding portion 44 and the second shielding portion 45 when viewed from the exhaust upstream side, and is located at the flow center of the exhaust gas that meanders. It is located near. Therefore, the fuel injected from the addition valve 42 is efficiently mixed with the exhaust gas to promote atomization of the fuel. On the other hand, since the addition valve 42 is provided at a position close to the flow center of the exhaust gas, when the fuel injected from the addition valve 42 is blown back by the exhaust gas, the fuel tends to adhere to the addition valve 42. It is in. In the present embodiment, as shown in FIG. 5, the addition valve 42 is hidden behind the first shielding portion 44 and is arranged at a position apart from the flow center of the exhaust gas, so that the addition valve 42 is injected. The fuel blown back by the exhaust gas is unlikely to adhere to the addition valve 42. Therefore, according to this embodiment, it is possible to suppress the adhesion of the fuel to the addition valve 42.

The second embodiment may be modified and implemented as follows.
In the second embodiment, when viewed in a horizontal section including the central axis C of the exhaust passage 17, the first shielding portion 44 and the second shielding portion 45 are erected so as to extend vertically from the passage inner peripheral surface. However, the extending direction may be changed. For example, as shown in FIG. 6, the first shield portion 44 and the second shield portion 45 are inclined with respect to the radial direction orthogonal to the central axis C of the exhaust passage 17 so that they are located closer to the exhaust downstream side toward the tip end side. The first shielding portion 44 and the second shielding portion 45 may be provided upright. The inclination angle θ3 of the first shield portion 44 with respect to the radial direction and the inclination angle θ4 of the second shield portion 45 with respect to the radial direction are the same. The first shielding portion 44 and the second shielding portion 45 are provided at different positions in the exhaust gas flow direction, and the positions of the tips in the exhaust gas flow direction are also different from each other. According to such a configuration, the exhaust gas is more likely to flow to the downstream side than the case where the first shielding part 44 and the second shielding part 45 are provided so as to extend vertically from the inner peripheral surface of the passage. It is possible to enhance the effect of suppressing the increase of Further, since the first shielding portion 44 and the second shielding portion 45 are inclined toward the exhaust gas downstream side, water droplets attached to the inner circumferential surface of the passage on the exhaust gas upstream side of the first shielding portion 44 and the second shielding portion 45. And the like easily move to the tip along the surface of the shielding portion 43 on the upstream side of the exhaust due to the flow of the exhaust. Therefore, it is possible to allow water droplets and the like attached to the inner peripheral surface of the passage to flow from the tip of the shielding portion 43 to the exhaust downstream side together with the exhaust, and to prevent such water droplets and the like from staying in the exhaust passage 17.

  Further, as shown in FIG. 7, when viewed in a horizontal cross section including the central axis C of the exhaust passage 17, the tip end side of the first shielding portion 44 is positioned closer to the exhaust gas downstream side, and the second shielding portion 45 is disposed. The first shielding portion 44 and the second shielding portion 45 may be provided upright so as to be positioned closer to the tip end side on the exhaust upstream side with respect to the radial direction orthogonal to the central axis C of the exhaust passage 17. In the configuration shown in FIG. 7, the extending direction of the first shielding portion 44 and the extending direction of the second shielding portion 45 are parallel. The first shield portion 44 and the second shield portion 45 are located at the same position in the exhaust flow direction in the exhaust flow direction, but the tip of the first shield portion 44 is located downstream of the exhaust gas. Since the tip of the second shielding portion 45 extends toward the exhaust gas upstream side, the tip positions of the second shielding portion 45 are different from each other in the exhaust gas flow direction. In this configuration, since the exhaust passage is formed by the first shielding portion 44 and the second shielding portion 45, the exhaust is directed in the direction away from the addition valve 42 as shown by the double-dashed line arrow in FIG. Can be further away from the addition valve 42. Therefore, according to this structure, the effect of suppressing the fuel injected from the addition valve 42 and blown back by the exhaust gas from adhering to the addition valve 42 can be enhanced.

The above-described embodiments can be modified and implemented as follows.
-The 1st shielding part 44 and the 2nd shielding part 45 do not need to be provided side by side in the said orthogonal direction. For example, the first shielding portion 44 may be provided vertically above and the second shielding portion 45 may be provided at a position rotated by 90 ° in the circumferential direction of the exhaust passage 17 with respect to the first shielding portion 44.

  The protrusion height h1 of the first shielding portion 44 may be lower than the protrusion height h2 of the second shielding portion 45 (h1 <h2), or higher than the protrusion height h2 of the second shielding portion 45. Good (h1> h2).

  When viewed in a horizontal cross section including the central axis C of the exhaust passage 17, the inclination angle of the first shielding portion 44 with respect to the radial direction may be different from the inclination angle of the second shielding portion 45 with respect to the radial direction. Further, one of the first shielding portion 44 and the second shielding portion 45 may be erected so as to extend vertically from the inner peripheral surface of the passage, and the other may be erected so as to be inclined with respect to the radial direction.

  The shape of the shielding portion 43 can be changed as appropriate. For example, it may be formed to have a semicircular shape or a polygonal shape in the cross section of the passage. In short, it is sufficient that the first shielding portion 44 and the second shielding portion 45 can shield the spray of the fuel injected from the addition valve 42 so as not to reach the exhaust gas upstream side.

  -The number of shields 43 is not limited to two, and may be three or more. Even with such a configuration, it suffices that the positions of the tips of the plurality of shields 43 be arranged at different positions in the exhaust flow direction.

  The reducing agent injected from the addition valve 42 is not limited to fuel. For example, when a urea SCR catalyst that reduces NOx using ammonia contained in exhaust gas is provided as a catalyst, the addition valve 42 can also inject urea water as a reducing agent.

  The catalyst for purifying the exhaust gas flowing through the exhaust passage 17 is not limited to the NOx storage reduction catalyst 41. For example, an oxidation catalyst that purifies the exhaust gas by oxidizing unburned fuel (HC) and carbon monoxide (CO) contained in the exhaust gas may be used.

  The passage shape of the exhaust passage 17 is not limited to the above. For example, the second passage 17B may be bent from the first passage 17A and extend vertically upward, or may be extended from the first passage 17A in the horizontal direction without being bent. Further, the first passage 17A may extend in a direction other than the horizontal direction.

  The example in which the exhaust gas purification device for an internal combustion engine is applied to a diesel engine has been described, but the same configuration as the above embodiment can be applied to a gasoline engine.

  10 ... Cylinder block, 10A ... Cylinder, 11 ... Piston, 12 ... Cylinder head, 13 ... Combustion chamber, 14 ... Intake passage, 15 ... Intake valve, 16 ... Fuel injection valve, 17 ... Exhaust passage, 17A ... First passage, 17B ... 2nd passage, 171B ... bent part, 18 ... exhaust valve, 19 ... branch passage, 20 ... supercharger, 21 ... compressor housing, 22 ... turbine housing, 23 ... bearing housing, 24 ... compressor wheel, 25 ... turbine Wheels, 26 ... Rotating shafts, 30 ... Fuel supply system, 31 ... Fuel supply passages, 32 ... Fuel tanks, 33 ... Fuel pumps, 40 ... Exhaust gas purification device of internal combustion engine, 41 ... NOx storage reduction catalyst, 42 ... Addition valve, 43 ... Shielding unit, 44 ... First shielding unit, 45 ... Second shielding unit, 50 ... Control device, 51 ... Accelerator sensor, 52 ... Rotation speed sensor Support.

Claims (1)

A catalyst provided in the exhaust passage for purifying the exhaust gas flowing through the exhaust passage,
An addition valve that is provided on the exhaust upstream side of the catalyst in the exhaust passage, and injects a reducing agent toward the exhaust upstream side;
A plurality of shielding portions that extend toward the inside of the exhaust passage from the passage inner peripheral surface on the exhaust upstream side of the addition valve in the exhaust passage, and that shield the spray of the reducing agent injected from the addition valve. Prepare,
The exhaust gas purifying apparatus for an internal combustion engine, wherein the plurality of shielding portions are arranged such that the positions of the tips extending toward the inside of the exhaust passage are different from each other in the exhaust flow direction.

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