JP6506958B2 - Exhaust purification system - Google Patents

Description

  The present invention relates to an exhaust gas purification apparatus for purifying an exhaust gas discharged from an internal combustion engine.

  As a device for purifying exhaust gas discharged from an internal combustion engine, an exhaust gas purification device in which a catalyst is disposed in an exhaust flow path is known. In this type of exhaust gas purification apparatus, a catalyst having a large cross-sectional area is used to improve the purification effect of the exhaust gas by the catalyst. Therefore, an enlarged diameter flow passage for expanding the diameter of the exhaust flow passage is formed on the upstream side of the catalyst, and a diameter reduced flow passage for reducing the diameter of the exhaust flow passage is formed on the downstream side of the catalyst. Further, in the exhaust flow path after the diameter reduction on the downstream side of the catalyst, an exhaust sensor for determining the purification effect of the exhaust gas by the catalyst is provided.

  By the way, the distribution of the component of the exhaust gas discharged from the internal combustion engine is not uniform in the exhaust flow path due to, for example, the dispersion of the combustion state between cylinders in the internal combustion engine. If such variations are not sufficiently improved even at the stage of outflow from the catalyst, the components of the exhaust gas that strikes the exhaust sensor will also vary. As a result, there is a problem that the determination of the purification effect of the catalyst based on the exhaust sensor can not be accurately performed.

  In order to solve such problems, a technology has been proposed in which a dispersion plate for dispersing the exhaust gas is provided on the upstream side of the exhaust sensor in the exhaust flow path after diameter reduction to make the components of the exhaust gas hitting the exhaust sensor uniform. (See Patent Document 1).

Japanese Utility Model Application Publication No. 5-1105

  However, in the configuration described in Patent Document 1 described above, there is a problem that the pressure loss of the exhaust flow path is greatly increased if the effect of making the components of the exhaust gas uniform is enhanced by the dispersion plate.

  An object of the present invention is to provide an exhaust purification system capable of improving the effect of making the components of the exhaust gas that strikes the exhaust sensor uniform while suppressing the increase in pressure loss in the exhaust flow path.

  One aspect of the present invention is an exhaust gas purification device, which includes a first cylindrical portion, a catalyst, a second cylindrical portion, an exhaust sensor, and a deflection portion. The first tubular portion forms an exhaust flow path. The catalyst is contained in the first cylindrical portion and purifies the exhaust gas flowing through the first cylindrical portion. The second tubular portion forms an exhaust flow passage on the downstream side of the first tubular portion and having a diameter smaller than that of the first tubular portion. The exhaust sensor is disposed in the second cylindrical portion. The deflection unit changes the flow direction of the exhaust gas upstream of the exhaust sensor. Specifically, the deflection unit is disposed in the first cylindrical portion.

  According to such a configuration, the deflection unit is provided in the first cylindrical portion that forms the exhaust flow passage having a diameter larger than that of the second cylindrical portion in which the exhaust sensor is disposed. As compared with the configuration in which the deflection portion is provided in the portion, it is possible to suppress an increase in pressure loss in the exhaust flow path. Therefore, it is possible to improve the effect of equalizing the components of the exhaust gas that hits the exhaust sensor while suppressing the increase in pressure loss in the exhaust flow path.

  In the above configuration, the deflection unit may be disposed downstream of the catalyst in the first cylindrical portion. According to such a configuration, by changing the flow direction of the exhaust gas flowing out of the catalyst in the deflection part, it is possible to efficiently make the components of the exhaust gas hitting the exhaust sensor uniform.

  In the above-described configuration, the opening area of the deflecting unit as viewed from the direction along the central axis of the first cylindrical portion may be equal to or larger than the cross-sectional area of the exhaust passage formed by the second cylindrical portion. According to such a configuration, an increase in pressure loss due to the deflection unit can be suppressed.

  In the above configuration, the deflection unit may include a plurality of blades. According to such a configuration, by changing the flow direction of the exhaust gas with a plurality of blades, the components of the exhaust gas can be efficiently made uniform.

  In the above-described configuration, the component that constitutes at least a part of the first cylinder and the deflection unit may be formed of a single component. According to such a configuration, it is not necessary to separately provide a component for forming the deflection portion, and further, since a process for joining the first cylindrical portion is not necessary, productivity can be improved. . In addition, it is possible to prevent the dropout of the deflection part.

  On the other hand, in the above configuration, the deflection unit may be disposed as a separate component from the first cylindrical unit. According to such a configuration, a material having a property different from that of the first tubular portion can be used. Therefore, heat resistance, strength and the like suitable for the respective functions can be given to the first cylindrical portion and the deflection portion.

BRIEF DESCRIPTION OF THE DRAWINGS It is an external view of the exhaust system containing the exhaust gas purification device of 1st Embodiment. It is a sectional view of an exhaust gas purification device of a 1st embodiment. Fig. 3 (A) is a side view of the catalyst case of the first embodiment as viewed from the direction orthogonal to the central axis thereof, Fig. 3 (B) is a perspective view of the catalyst case of the first embodiment, and Fig. 3 (C) is It is the rear view which looked at the catalyst case of 1st Embodiment from the direction which becomes the downstream of an exhaust flow path along the central axis. FIG. 4 is a development view of the catalyst case of the first embodiment. FIG. 5A is a view showing a simulation result of pressure distribution in the exhaust purification system of the comparative example, and FIG. 5B is a view showing a simulation result of the flow of exhaust gas in the exhaust purification system of the comparative example. FIG. 6A shows a simulation result of pressure distribution in the exhaust gas purification apparatus of the first embodiment, and FIG. 6B shows a simulation result of the flow of exhaust gas in the exhaust gas purification apparatus of the first embodiment is there. It is sectional drawing of the exhaust gas purification device of 2nd Embodiment. FIG. 8A is a side view of the deflecting unit of the second embodiment as viewed from the direction orthogonal to the central axis thereof, and FIG. 8B is a perspective view of the deflecting unit of the second embodiment. It is sectional drawing of the exhaust gas purification device of a 1st modification. FIG. 10A is a front view of the deflecting portion of the first modification as viewed from the upstream side of the exhaust channel along the central axis of the catalyst case, and FIG. 10B is the deflecting portion of the first modification 10 (C) is a side view of the catalyst case as seen from the direction orthogonal to the central axis of the catalyst case, and FIG. It is a sectional view of an exhaust gas purification device of the 2nd modification. FIG. 12A is a front view of the deflecting portion of the second modification as viewed from the upstream side along the central axis of the exhaust flow channel, and FIG. 12B is a side view of the deflecting portion of the second modification The side view seen from the direction orthogonal to the central axis, and Drawing 12 (C) are perspective views of the deflection part of the 2nd modification.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.
[1. First embodiment]
[1-1. Constitution]
The exhaust gas purification apparatus 1 shown in FIGS. 1 and 2 is an apparatus for purifying exhaust gas discharged from an internal combustion engine of a vehicle, and is disposed downstream of an exhaust manifold 5 which combines exhaust gases discharged from cylinders of the internal combustion engine. Provided in

  The exhaust purification device 1 includes an upstream cone 11, a catalyst case 12, a downstream cone 13, a catalyst 14, and an exhaust sensor 15. The upstream side cone 11, the catalyst case 12 and the downstream side cone 13 form a part of an exhaust passage for guiding the exhaust gas discharged from the internal combustion engine to the outside of the vehicle.

  The upstream side cone 11 is provided on the downstream side of the exhaust manifold 5 and forms an exhaust flow path that leads the exhaust gas flowing in via the exhaust manifold 5 to the catalyst 14. The exhaust flow passage formed by the upstream side cone 11 is a truncated cone-like enlarged diameter flow passage whose inner diameter is gradually expanded to the downstream side.

  The catalyst case 12 includes a cylindrical portion 121 and a deflection portion 30, as also shown in FIGS. 3 (A) and 3 (B). The cylindrical portion 121 forms an exhaust passage downstream of the upstream cone 11. The deflection unit 30 projects into the exhaust flow channel at the downstream side of the cylindrical portion 121. The specific shape of the deflection unit 30 will be described later.

  The downstream side cone 13 has a central axis 122 common to the catalyst case 12 and forms an exhaust flow path on the downstream side of the catalyst case 12. Specifically, the downstream cone 13 includes a large diameter cylindrical portion 131, a reduced diameter portion 132, and a small diameter cylindrical portion 133.

  The large diameter cylindrical portion 131 extends the exhaust flow path formed by the catalyst case 12 to the downstream side, and has substantially the same inner diameter as the catalyst case 12 (specifically, slightly larger than the outer diameter of the catalyst case 12 The exhaust flow path is formed, and the deflection unit 30 is accommodated. The reduced diameter portion 132 forms a truncated cone-shaped reduced flow path whose inner diameter is gradually reduced to the downstream side. The small diameter cylindrical portion 133 forms an exhaust flow passage which maintains a constant inner diameter reduced by the reduced diameter portion 132. Therefore, the diameter of the exhaust flow path formed by the small diameter cylindrical portion 133 (the inner diameter of the small diameter cylindrical portion 133) is larger than the diameter of the exhaust flow path formed by the large diameter cylindrical portion 131 (the inner diameter of the large diameter cylindrical portion 131) small.

The catalyst 14 is accommodated in the catalyst case 12 (specifically, the cylindrical portion 121), and purifies the exhaust gas flowing through the catalyst case 12.
The exhaust sensor 15 is a sensor for determining the exhaust gas purification effect of the catalyst 14, and is provided downstream of the catalyst 14. Specifically, the exhaust sensor 15 is disposed in the small diameter cylindrical portion 133 so that the sensor portion protrudes in the exhaust flow passage formed by the small diameter cylindrical portion 133, and the exhaust flow passage formed by the small diameter cylindrical portion 133 is The component (oxygen concentration in the present embodiment) of the flowing exhaust gas is detected.

Next, the specific shape of the deflection unit 30 will be described.
The deflection unit 30 is provided on the downstream side of the catalyst 14 as a part of the catalyst case 12 and has a function of deflecting and dispersing the exhaust gas on the upstream side of the exhaust sensor 15. The deflection unit 30 includes a plurality of (eight in the present embodiment) blades 31 (see FIG. 3C), and guides the exhaust gas to swirl. In addition, the shape of each blade | wing 31 is not specifically limited.

  The vanes 31 are arranged at equal intervals along the circumferential direction of the cylindrical portion 121 when viewed from the direction along the central axis 122 of the catalyst case 12 (specifically, the cylindrical portion 121). Further, in the deflecting portion 30, a portion (opening) in which the blade 31 does not exist is formed as viewed from the direction along the central axis 122. Specifically, in the deflection unit 30, the total area of the opening of the deflection unit 30 (the area obtained by subtracting the projected area of the blades 31 from the cross-sectional area of the exhaust flow passage formed by the cylindrical portion 121) It is designed to be equal to or larger than the cross-sectional area of the exhaust flow path formed by 133.

  The catalyst case 12 is formed of a developed metal plate 12a (for example, a stainless steel plate) as shown in FIG. The developed metal plate 12 a includes a band portion 121 a for forming the cylindrical portion 121 and a plurality of protruding pieces 31 a for forming the plurality of blades 31. The processing (tube forming processing) which rounds this band part 121a in a cylindrical shape, and forms cylinder part 121, and the processing (bending processing) which bends projecting piece 31a, and forms blade 31 with respect to unfolded metal plate 12a As a result, the catalyst case 12 is formed. The order of the tube forming process and the bending process may be earlier.

[1-2. Action]
Next, the operation of the exhaust purification system 1 of the present embodiment will be described.
As shown in FIGS. 1 and 2, the exhaust gas discharged from each cylinder of the internal combustion engine is led to the catalyst 14 through the exhaust manifold 5 and the upstream cone 11 and purified by the catalyst 14. The purified exhaust gas flows out from the catalyst 14 to the large-diameter cylindrical portion 131 of the downstream cone 13 and is guided and dispersed by the deflection unit 30 so as to be swirled. As a result, it flows into the small diameter cylindrical portion 133 in a state where the deviation of the component is suppressed, and is detected by the exhaust sensor 15.

[1-3. effect]
According to the embodiment described above, the following effects can be obtained.
(1a) In the exhaust gas purification device 1, the deflection portion 30 is provided in the large diameter cylindrical portion 131 forming an exhaust flow passage having a larger diameter than the small diameter cylindrical portion 133 in which the exhaust sensor 15 is disposed. For this reason, as compared with the configuration in which the deflection portion 30 is provided in the small diameter cylindrical portion 133, the increase in pressure loss in the exhaust flow path can be suppressed. Therefore, according to the present embodiment, it is possible to improve the effect of making the components of the exhaust gas that strikes the exhaust sensor 15 uniform while suppressing the increase in pressure loss in the exhaust flow path.

  (1b) In the exhaust gas purification device 1, the opening area of the deflection unit 30 viewed from the direction along the central axis 122 of the large diameter cylindrical portion 131 is equal to or larger than the cross sectional area of the exhaust flow passage formed by the small diameter cylindrical portion 133 . Therefore, according to the present embodiment, an increase in pressure loss by the deflection unit 30 can be suppressed.

  (1c) The deflection unit 30 includes the plurality of blades 31. Therefore, by changing the flow direction of the exhaust gas flowing out of the catalyst 14 with the plurality of blades 31, the components of the exhaust gas can be efficiently made uniform.

  (1d) Since the cylindrical portion 121 and the deflection portion 30 are formed by the catalyst case 12 which is a single component, it is not necessary to separately provide a component for forming the deflection portion 30. Moreover, since the process for joining (for example, welding or brazing) with the cylindrical portion 121 or the large-diameter cylindrical portion 131 is unnecessary, productivity can be improved. In addition, detachment of the deflection unit 30 can be prevented.

[1-4. simulation result]
Next, simulation results will be described. FIGS. 5A and 5B show simulation results of the exhaust gas purification apparatus of the comparative example not provided with the deflection unit 30. FIG. 6A and 6B show simulation results of the exhaust purification system 1 of the first embodiment. 5 (A) and 6 (A), the pressure distribution of the exhaust flow path is expressed by concentration, and the light-colored portion shows that the pressure is low.

  The exhaust gas control apparatus 1 according to the first embodiment shown in FIG. 6A does not have a large change in pressure distribution, and the pressure loss is slight compared with the exhaust gas control apparatus according to the comparative example shown in FIG. It stayed up.

  Further, as shown in FIG. 5 (B), in the exhaust gas control apparatus of the comparative example, the exhaust gas flows with little dispersion. On the other hand, as shown in FIG. 6 (B), in the exhaust gas control system 1 of the first embodiment, the exhaust gas is guided by the deflection unit 30 so as to be swirled and dispersed.

As described above, according to the exhaust gas purification device 1 of the first embodiment, it is possible to make the components of the exhaust gas uniform while suppressing the increase in the pressure loss of the exhaust flow passage by the deflection unit 30.
[2. Second embodiment]
The exhaust gas control apparatus 2 of the second embodiment shown in FIG. 7 is different from the exhaust gas control apparatus 1 of the first embodiment in that a catalyst case 22 and a deflection unit 40 are used instead of the catalyst case 12. . That is, in the second embodiment, the catalyst case 22 and the deflection unit 40 are configured as separate parts. The other basic configuration is the same as that of the first embodiment, and the same reference numerals are used for the configuration common to the first embodiment, and the description is omitted.

The catalyst case 22 is a cylindrical member corresponding to the cylindrical portion 121 of the first embodiment, and forms an exhaust flow channel on the downstream side of the upstream cone 11.
The deflection unit 40 is joined (for example, welded or brazed) to the downstream end of the catalyst case 22 and protrudes to the exhaust flow path on the downstream side of the catalyst case 22. As shown in FIGS. 8A and 8B, the deflecting unit 40 has the same shape as the deflecting unit 30 of the first embodiment. Further, the deflecting unit 40 is formed of a material different from the catalyst case 22 (in the present embodiment, a material thicker than the catalyst case 22).

According to the second embodiment described above, the following effects can be obtained in addition to the effects of the first embodiment described above (but excluding the effects of (1d)).
(2a) Since the deflecting unit 40 is provided at a position where high temperature exhaust gas collides, higher heat resistance than the catalyst case 22 is required. In this respect, in the second embodiment, since the deflecting portion 40 is formed of a material having a thicker plate thickness than the catalyst case 22, the heat resistance of the deflecting portion 40 can be increased without excessively improving the heat resistance of the catalyst case 22. It can be improved. That is, since the deflection unit 40 is disposed as a separate component from the catalyst case 22, materials of different properties can be used, and heat resistance, strength, and the like suitable for each function can be provided. In the second embodiment, the configuration in which the deflecting unit 40 is formed of a material having a thicker plate thickness than the catalyst case 22 is exemplified. However, the present invention is not limited to this. You may form with the material of a highly heat-resistant material.

  In the first and second embodiments, the cylindrical portion 121 and the large diameter cylindrical portion 131 correspond to an example of a first cylindrical portion, and the small diameter cylindrical portion 133 corresponds to an example of a second cylindrical portion. The deflection unit 30 and the deflection unit 40 correspond to an example of the deflection unit. Further, the total area of the openings of the deflection unit 30 corresponds to an example of the opening area of the deflection unit.

[3. Other embodiments]
As mentioned above, although embodiment of this invention was described, it can not be overemphasized that this invention can take a various form, without being limited to the said embodiment.

(3a) In the above embodiment, the configuration in which the deflection unit including the plurality of blades disperses the exhaust gas has been illustrated, but the present invention is not limited to this.
For example, the exhaust purification system 3 of the first modification shown in FIG. 9 is different from the exhaust purification system 2 of the second embodiment in that a deflection unit 50 is used instead of the deflection unit 40. As shown in FIGS. 10A and 10B, the deflecting unit 50 is a part of the exhaust flow path with the flat projecting portion 51 (specifically, the exhaust is viewed from the direction along the central axis 122) It is comprised so that the part on the opposite side to the sensor 15 may be covered. According to such a configuration, the exhaust gas strikes the projecting portion 51, whereby the components of the exhaust gas are deflected in the direction of the exhaust sensor 15. As a result, since the component flows into the small diameter cylindrical portion 133 in a state in which the deviation of the component is suppressed, the same effect as the above embodiment can be obtained.

  Further, for example, the exhaust gas control system 4 of the second modification shown in FIG. 11 is different from the exhaust gas control system 2 of the second embodiment in that a deflecting unit 60 is used instead of the deflecting unit 40. As shown in FIGS. 12A and 12B, the deflection unit 60 is configured to cover the exhaust flow path with a circular flat plate portion in which the through hole 61 is formed. The through hole 61 is formed on the exhaust sensor 15 side as viewed from the direction along the central axis 122. With such a configuration, the same effect as that of the above embodiment can be obtained. In addition, although the deflection | deviation part 60 illustrated the shape of the flat plate in which the through-hole was formed in the 2nd modification, it is not limited to this. For example, the deflection unit 60 may be in the shape of a truncated cone having a through hole formed by spinning.

  The deflecting unit 50 and the deflecting unit 60 may be configured as part of the catalyst case, as in the first embodiment. In the first and second modifications, the deflection unit 50 and the deflection unit 60 correspond to an example of the deflection unit.

  (3b) In the above embodiment, the exhaust purification devices 1 and 2 include the catalyst cases 12 and 22 and the downstream cone 13, that is, the catalyst cases 12 and 22 and the downstream cone 13 are separate components. Not limited to this. For example, the catalyst cases 12 and 22 and the downstream cone 13 may be configured as a single part. Further, for example, the catalyst cases 12 and 22 and the portions corresponding to the large diameter cylindrical portion 131 and the reduced diameter portion 132 of the downstream side cone 13 are a single component, and the portion corresponding to the small diameter cylindrical portion 133 is a separate component such as a pipe. It may be configured.

  (3c) In the above-mentioned embodiment, although the downstream cone 13 illustrated the composition which has central axis 122 common with catalyst cases 12 and 22, it is not limited to this. For example, the central axis of the downstream cone 13 may be offset from the central axis of the catalyst case 12 and may not be parallel.

(3d) In the said embodiment, although the oxygen sensor was illustrated as the exhaust gas sensor 15, it is not limited to this. For example, NOx sensor, but the present invention to an exhaust gas purification device air-fuel ratio sensor or the temperature sensor is used can be applied.

  (3e) In the above embodiment, the exhaust sensor 15 is illustrated as being disposed in the small diameter cylindrical portion 133. However, the present invention is not limited to this. For example, the reduced diameter portion 132 may be provided.

  (3f) In the above embodiment, the configuration in which the deflecting portions 30 and 40 are disposed downstream of the catalyst 14 in the first cylindrical portion (the cylindrical portion 121 and the large diameter cylindrical portion 131) has been illustrated. It is not limited. For example, it may be disposed upstream of the catalyst 14 in the first cylindrical portion, or may be disposed both upstream and downstream.

  (3g) The function possessed by one component in the above embodiment may be distributed as a plurality of components, or the function possessed by a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Further, part of the configuration of the above embodiment may be omitted as long as the problem can be solved. In addition, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of the other above-described embodiment. In addition, all the aspects contained in the technical thought specified from the wording as described in a claim are embodiment of this invention.

1, 2, 3, 4 ... exhaust purification device, 5 ... exhaust manifold, 11 ... upstream cone, 12, 22 ... catalyst case, 12a ... expanded metal plate, 13 ... downstream cone, 14 ... catalyst, 15 ... exhaust sensor 30, 40, 50, 60: deflection part, 31: blade, 31a: projecting piece, 51: projecting part, 61: through hole, 121: cylindrical part, 121a: band part, 122: central axis, 131: large diameter Cylindrical part, 132 ... reduced diameter part, 133 ... small diameter cylindrical part.

Claims (2)

A first tubular portion forming an exhaust flow path;
A catalyst which is contained in the first cylindrical portion and purifies exhaust gas flowing through the first cylindrical portion;
A second cylindrical portion that forms an exhaust flow passage smaller in diameter than the first cylindrical portion on the downstream side of the first cylindrical portion;
An exhaust sensor disposed in the second cylindrical portion;
A third cylindrical portion disposed between the first cylindrical portion and the second cylindrical portion and constituting a reduced flow path whose internal diameter is gradually reduced to the downstream side;
A deflection unit that changes the flow direction of the exhaust gas upstream of the exhaust sensor;
Equipped with
The deflection unit is disposed in the first cylindrical portion.
The deflection unit is disposed downstream of the catalyst,
The deflection unit includes a plurality of blades.
The parts constituting the first cylindrical part and the deflection part are formed as a single part, and the plurality of blades provided in the deflection part is a cylindrical part constituting the first cylindrical part Each of the divided parts obtained by dividing the downstream end into a plurality of parts is a bending line that intersects a line of intersection between a plane perpendicular to the central axis of the first cylindrical part and the cylindrical part, Bent towards the inside of the barrel of the
The deflection unit guides the exhaust gas to swirl;
The exhaust gas purification apparatus, wherein the exhaust gas sensor is an oxygen sensor, a NOx sensor, or an air-fuel ratio sensor. The exhaust gas purification apparatus according to claim 1 , wherein
The exhaust gas control apparatus according to claim 1, wherein an opening area of the deflection part viewed from a direction along a central axis of the first cylindrical part is equal to or larger than a cross-sectional area of an exhaust flow path formed by the second cylindrical part.