KR101597181B1 - After-treatment apparatus of engine-exhaust gas used in CNG vehicle - Google Patents

Abstract

According to an embodiment of the present invention, an after-treatment apparatus for an exhaust gas for a compressed natural gas (CNG) vehicle comprises: an oxidation catalyst part; a selective reduction catalyst part; and a urea mixing pipe. The oxidation catalyst part is longitudinally installed to allow introduction of an exhaust gas discharged from an engine. The selective reduction catalyst part is formed in parallel with the oxidation catalyst part to allow introduction of the exhaust gas passing through the oxidation catalyst part. The urea mixing pipe is formed to connect the oxidation catalyst part with the selective reduction catalyst part. An exit of the oxidation catalyst part connected to the urea mixing pipe is formed with an internal diameter gradually becoming smaller. Accordingly, the back pressure of the exhaust gas discharged from the oxidation catalyst part can be reduced, and flowage uniformity within the oxidation catalyst part can be improved such that the amount of exhaust gas passing through a catalyst can be increased, thereby increasing efficiency in purifying the exhaust gas.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an exhaust gas post-

The present invention relates to an exhaust gas aftertreatment apparatus for a compressed natural gas vehicle, and more particularly, to an exhaust gas aftertreatment apparatus for a compressed natural gas vehicle capable of improving flow uniformity of exhaust gas and reducing back pressure by exhaust gas .

Compressed Natural Gas (CNG) is a natural gas that is widely produced in the earth, but usually refers to a combustible gas composed mainly of hydrocarbons. The types of CNG can be divided into oil gas from the oil field, coal gas from the coal field, and water-soluble gas dissolved in water regardless of the petroleum or coal adult.

The coal gas and the water soluble gas are mainly composed of methane and contain carbon dioxide, oxygen and nitrogen. However, they are called dry gas because they do not liquefy even when pressurized at normal temperature. The oil gas contains propane and butane in addition to methane. It is called wet gas.

When using CNG as a fuel, the cost is low and the economy is excellent. The mixture is mixed with the air in the gas state and enters the cylinder, so that the state is uniform and the combustion is completed at a value close to the theoretical air mixing ratio. Not only is it quiet, but it also has the advantage that there is no knocking phenomenon because the burning speed is slower than gasoline and the octane number is high.

And, CNG engine is excellent in economy, fuel cost, injection rate of engine oil, life of engine are excellent compared with gasoline, and since it has low boiling point, it is completely vaporized in cylinder and does not dilute oil, and carbon is not easily generated. In addition, since additives are not used, the oil is not contaminated by carbon or ash, and there is no sulfur component, so that metal corrosion due to exhaust gas does not occur. Therefore, there is little air pollution, the hygienic and toxic CO content is small, and there is almost no smell of exhaust gas and no smoke.

However, due to the growing interest in the environment, environmental regulations are becoming increasingly strict, and active research is underway on CNG vehicles. Particularly, in Europe and the like, the exhaust gas of a vehicle is more strictly regulated, and there is a growing demand for an exhaust gas aftertreatment apparatus for a compressed natural gas vehicle having a structure capable of enhancing the purification efficiency of the exhaust gas.

In addition, the exhaust gas purifying apparatus for a vehicle such as a conventional CNG (compressed natural gas) bus has a limitation in facilitating the contact between the catalyst and the exhaust gas or allowing the exhaust gas to flow over the entire area of the catalyst. Further, since only one kind of catalyst is used, there is a disadvantage in that the purification efficiency is not high.

 In addition, even when two or more kinds of catalysts are used, there is a problem in that the exhausting device is configured according to the size of the space without considering the flow efficiency of the exhaust gas due to the limitation of the space where the exhausting device is installed.

Korean Prior Art No. 230874 (catalyst for purification of compressed natural gas vehicle exhaust gas and purification method thereof) is known as a related art.

An object of the present invention is to provide an exhaust gas post-treatment apparatus for a compressed natural gas vehicle having a structure capable of reducing back pressure of exhaust gas and improving flow uniformity.

According to an aspect of the present invention, there is provided an exhaust gas post-treatment apparatus for a compressed natural gas vehicle, comprising: an oxidation catalytic unit extended to flow exhaust gas discharged from an engine; A selective reduction catalyst part formed parallel to the oxidation catalyst part and through which the exhaust gas passed through the oxidation catalyst part flows; And a urea mixing pipe formed to connect the oxidation catalyst part and the selective reduction catalyst part. The outlet of the oxidation catalyst part connected to the urea mixing pipe may be formed such that the inner diameter gradually decreases.

The oxidation catalytic unit may include a catalytic case formed in a cylindrical shape; An exhaust gas inflow pipe formed to penetrate through one side of the catalyst case along the diameter direction of the catalyst case; An oxidation catalyst provided inside the catalyst case to be spaced apart from the inflow pipe; And an outlet cone formed adjacent to one end of the catalyst to face the inlet pipe.

A plurality of gas discharge holes may be formed in the inflow pipe located inside the catalyst case.

The exhaust gas flow path of the inflow pipe and the exhaust gas flow path of the outlet cone may be formed to be orthogonal.

A catalyst supporting member for supporting the catalyst is provided in the case. The outer diameter of the catalyst supporting member is the same as the inner diameter of the case, and may be larger than the outer diameter of the catalyst.

Wherein one end of the catalyst adjacent to the inlet pipe is supported by the catalyst supporting member while passing through the catalyst supporting member and the other end of the catalyst adjacent to the outlet cone is supported in contact with one end face of the outlet cone have.

The distance between one end of the catalyst and the center of the inflow pipe may be smaller than the height of the outlet cone.

The outlet cone includes a catalyst supporting part for contacting and supporting one end face of the catalyst; A case supporting portion formed at one end of the catalyst supporting portion and supported by the inner surface of the case; A joint portion bent at the other end of the catalyst supporting portion; A cone portion extending from the joint portion toward the center of the case; And an outlet formed at one end of the cone portion.

The cone portion may be formed so that the diameter gradually decreases from the joint portion to the outlet portion, and the cross section of the cone portion may be formed to have a curved line.

The cross section of the cone portion may be formed as a curve having a curvature radius of 70 mm to 140 mm.

The joint portion may be formed to have a gentle slope than the cone portion.

INDUSTRIAL APPLICABILITY The exhaust gas post-treatment apparatus for a compressed natural gas vehicle of the present invention can reduce the back pressure of the exhaust gas flowing out from the oxidation catalyst section and improve the flow uniformity in the oxidation catalyst section, And as a result, it is possible to increase the purification efficiency of the exhaust gas.

Further, the exhaust gas aftertreatment apparatus for a compressed natural gas vehicle of the present invention is advantageous in downsizing the post-treatment apparatus because the purification efficiency is not lowered even if the size of the oxidation catalyst unit is reduced.

Further, the exhaust gas post-treatment apparatus for a compressed natural gas vehicle of the present invention can cope with strict exhaust gas regulations such as Tier 4 Final or Euro 6 or Stage IV by having an oxidation catalyst part, a selective reduction catalyst part and a urea mixing pipe together .

The exhaust gas aftertreatment apparatus for a compressed natural gas vehicle according to the present invention is formed into a curved surface so that the stress or back pressure applied to the outlet cone provided at the outlet end of the oxidation catalyst unit can be minimized, So that it is not necessary to weld the outlet cone to the catalyst case, and it is also possible to prevent the catalyst from being damaged by the welding heat.

1 and 2 are perspective views of an exhaust gas post-treatment apparatus for a compressed natural gas vehicle according to an embodiment of the present invention.
3 is a cross-sectional view of the oxidation catalyst portion in the post-treatment apparatus according to FIG.
FIG. 4 is a view showing the internal components of the oxidation catalyst part in the post-treatment apparatus according to FIG. 1. FIG.
5 is a perspective view showing the catalyst and the outlet cone of the oxidation catalyst part in the post-treatment apparatus according to FIG.
6 is a perspective view illustrating the catalyst and outlet cone according to FIG.
7 is a perspective view and a sectional view showing an outlet cone according to FIG.
8 and 9 are tables showing experimental data of a post-processing apparatus according to an embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are omitted for clarity of explanation.

FIG. 3 is a cross-sectional view of an oxidation catalyst portion of the post-treatment apparatus according to FIG. 1. FIG. 4 is a cross-sectional view of the exhaust gas purifying apparatus for a compressed natural gas vehicle according to an embodiment of the present invention. Fig. 5 is a perspective view showing the catalyst and the outlet cone of the oxidation catalyst part in the post-treatment apparatus according to Fig. 1, Fig. 6 is a perspective view showing the catalyst and outlet cone according to Fig. 7 is a perspective view and a cross-sectional view showing an outlet cone according to FIG. 6, and FIGS. 8 and 9 are tables showing experimental data of a post-processing apparatus according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, an exhaust gas post-treatment apparatus 100 for a compressed natural gas vehicle according to an embodiment of the present invention includes an oxidation catalyst unit 100, A selective catalytic reduction unit 160 which is formed in parallel with the oxidation catalyst unit 110 and into which exhaust gas having passed through the oxidation catalyst unit 110 flows and an oxidation catalyst unit 110, And may include a urea mixing pipe 120 formed to connect the part 160.

Here, the outlet of the oxidation catalyst unit 110 connected to the urea mixing pipe 120 may be formed such that the inner diameter gradually decreases. Since the outlet end of the oxidation catalyst unit 110 has an inner diameter gradually reduced, the exhaust gas purified and discharged from the oxidation catalyst unit 110 can be collected and sent to the mixing pipe 120.

The oxidation catalyst unit 110 and the selective reduction catalyst unit 160 may have a cylindrical shape and may be disposed adjacent to each other in parallel. The overall size of the post-processing apparatus 100 can be reduced by disposing the oxidation catalyst unit 110 and the selective reduction catalyst unit 160 side by side without being arranged in a line.

The oxidation catalyst unit 110 and the selective reduction catalyst unit 160 are connected by a urea mixing pipe 120. The urea mixing pipe 120 is connected to the outlet end of the oxidation catalyst unit 110 and the selective reduction catalyst unit 160 Connect the inlet end. Since the outlet end of the oxidation catalyst unit 110 and the inlet end of the selective reduction catalyst unit 160 are opposite to each other, it is necessary for the urea mixing pipe 120 to have a bent shape changing at least twice.

The oxidation catalyst unit 110 is a device for removing pollutants by primarily post-treating the exhaust gas of a CNG vehicle such as a bus, and a catalyst (carrier) is provided therein. The exhaust gas inlet pipe 113 is formed across the catalytic casing 101 of the oxidation catalytic unit 110 in the radial direction of the casing 101. This allows the exhaust gas to flow evenly over the entire area of the catalyst. The exhaust gas passing through the catalyst flows into the selective reduction catalyst unit 160 through the outlet cone 140.

1 to 4, the oxidation catalyst unit 110 includes a catalyst case 101 formed in a cylindrical shape, an exhaust gas passage 101 formed to penetrate one side of the catalyst case 101 along the diameter direction of the catalyst case 101, An oxidation catalyst 130 provided inside the catalyst case 101 so as to be spaced apart from the gas inlet pipe 113 and the inlet pipe 113 and an outlet cone 130 formed adjacent to one end of the catalyst 130 to face the inlet pipe 113. [ (140).

The catalyst case 101 is a cylindrical member, and an empty space in which the catalyst 130 can be accommodated is formed therein. After the catalyst 130 and the outlet cone 140 are installed in the catalyst case 101, the end caps 111 and 112 are installed at both ends in the longitudinal direction of the catalyst case 101 to block both ends. Elastic supporting members 133 and 134 may be installed on one side of the end caps 111 and 112. [ It is preferable that the end caps 111 and 112 are formed in a flat surface while the elastic supporting members 133 and 134 have a somewhat curved shape.

The exhaust gas flowing into the catalyst case 101 flows into the oxidation catalyst unit 110 through the inlet pipe 113. The inlet pipe 113 is inserted into the cylindrical portion of the catalyst case 101. On the other hand, the outlet pipe 114 may be formed in the middle portion of the end cap 112. A connecting flange 115 connected to the flange 121 of the urea mixing pipe 120 may be formed at one end of the outlet pipe 114.

The urea mixing pipe 120 has a bent shape and the urea UREA is mixed before the exhaust gas passed through the oxidation catalyst unit 110 enters the selective reduction catalyst unit 160. To this end, A urea pipe 122 may be connected. The other end 123 of the urea mixing pipe 120 may be formed with a flange 124 for connection with the selective reduction catalyst unit 160.

A sensor mounting portion 129 may be formed at the inlet end of the urea mixing pipe 120. The temperature of the exhaust gas flowing into the urea mixing pipe 120 and the like can be measured through the sensor formed on the sensor mounting portion 129.

The overall shape of the selective reduction catalyst section 160 is similar to that of the oxidation catalyst section 110. That is, it may include a cylindrical case 161 and at least one selective reduction catalyst (not shown) formed inside the case 161. The gas flowing into the reduction catalyst section 160 flows through the inlet pipe 163 formed in the cylindrical case 161 and the exhaust gas that has passed through the reduction catalyst section 160 closes one end in the longitudinal direction of the case 161 Can be introduced through an outlet pipe (165) formed in the end cap (162). The inlet pipe 163 may be formed with a flange 164 for connection with the urea mixing pipe 120. The sensor mounting portion 167 may also be formed in the outflow pipe 165 of the selective reduction catalyst portion 160.

The selective reduction catalyst unit 160 is disposed in parallel with the oxidation catalyst unit 110. The selective reduction catalyst unit 160 has a size larger than that of the oxidation catalyst unit 110 and the outlet pipe 114 of the oxidation catalyst unit 110 and the inlet pipe 163 of the selective reduction catalyst unit 160 The oxidizing catalyst part 110 and the oxidizing catalyst part 110 are disposed side by side.

Hereinafter, the internal structure of the oxidation catalyst unit 110 will be described in detail with reference to the drawings.

3 to 7, the inlet pipe 113 of the oxidation catalyst unit 110 is inserted into the catalyst case 101. That is, the inflow pipe 113 is installed in the case 101 in the form of being embedded along the diameter direction of the catalyst case 101.

A plurality of gas discharge holes 113a may be formed in the inlet pipe 113 located inside the catalyst case 101. [ It is preferable that the gas discharge hole 113a is formed uniformly along the circumferential direction of the inlet pipe 113. The portion where the gas discharge hole 113a is formed may be a portion corresponding to the diameter of the catalyst 130. As described above, since the exhaust gas inflow pipe 113 is sufficiently positioned inside the case 101 and a plurality of gas exhaust holes 113a are formed in a portion exposed to the inside of the case 101, The amount or area of contact of the exhaust gas with the catalyst 130 can be increased and the catalyst 130 can be used as a whole. That is, it is possible to prevent the exhaust gas from intensively flowing into only a specific portion of the catalyst 130.

Meanwhile, the exhaust gas passage of the inlet pipe 113 and the exhaust gas passage of the outlet cone 140 may be formed to be orthogonal. The exhaust gas flow path of the outlet cone 140 may be formed in the longitudinal direction of the case 101 while the exhaust gas flow path of the inlet pipe 113 is formed in the radial direction of the case 101. Thus, the entire size of the oxidation catalyst part 110 can be reduced and the catalyst 130 can be used as a whole by forming the flow path of the inlet exhaust gas and the flow path of the outlet exhaust gas at right angles.

Referring to FIG. 3, the oxidation catalyst 130 is located approximately at the center of the case 101, but the inner surface of the case 101 and the oxidation catalyst 130 are not in direct contact with each other. If the inner surface of the case 101 and the oxidation catalyst 130 are in direct contact with each other, the catalyst 130 may be damaged due to friction with the case 101 during insertion of the catalyst 130 into the case 101. In order to prevent such a problem, it is preferable to form the outer diameter of the catalyst 130 to be slightly smaller than the inner diameter of the case 101. [

A separate fixing member is required to fix the catalyst 130, which is smaller than the inner diameter of the case 101, to the inside of the case 101. [ In the present invention, a catalyst supporting member 131 for supporting the catalyst 130 is provided inside the case 101. The outer diameter of the catalyst supporting member 131 is the same as the inner diameter of the case 101, 130, respectively.

Referring to FIGS. 3 and 5, it can be seen that the catalyst supporting member 131 supports one end 130a of the catalyst 130 close to the inlet pipe 113. At this time, one end of the catalyst 130 may be provided so as to pass through the catalyst supporting member 131.

A catalyst passage hole (not shown) having the same size as the outer diameter of the catalyst 130 may be formed in the catalyst supporting member 131 so as to pass through the catalyst 130. The catalyst supporting member 131 can be held in contact with the inner surface of the case 101 in a state in which the catalyst 130 is placed on the catalyst passage hole. A uniform gap can be formed and maintained between the catalyst 130 and the inner surface of the case 101 by the catalyst supporting member 131. [

One end of the catalyst 130 adjacent to the inlet pipe 113 is supported by the catalyst supporting member 131 in a state of passing through the catalyst supporting member 131, And the other end can be held in contact with one end face of the outlet cone 140. [ That is, one end of the catalyst 130 may be supported by the catalyst supporting member 131 and the other end may be supported by the outlet cone 140. One end of the catalyst 130 is supported while being passed through the catalyst supporting member 131 while the other end of the catalyst 130 is supported in contact with the outlet cone 140.

The outer diameter of the catalyst supporting member 131 is equal to the maximum outer diameter of the outlet cone 140 and is preferably equal to the inner diameter of the case 101.

The distance L1 between the one end of the catalyst 130 and the center of the inlet pipe 113 may be smaller than the height L3 of the outlet cone 140 as shown in FIG. By making the distance L1 between the inlet pipe 113 and the catalyst 130 as close as possible, more exhaust gas can come into contact with the catalyst 130. [ The exhaust gas that has passed through the catalyst 130 is supplied to the catalyst 130 by making the height L3 of the outlet cone 140 larger than the distance L1 between the center of the inlet pipe 113 and one end of the catalyst 130. [ The back pressure generated in the process of passing through the outlet 141 smaller than the cross sectional area of the outlet cone 140 can be reduced and the flow uniformity of the exhaust gas passing through the outlet cone 140 can be improved. The length L2 of the catalyst 130 is longer than the height L3 of the outlet cone 140 so that the purification efficiency of the exhaust gas can be sufficiently secured.

5 to 7, the outlet cone 140 includes a catalyst supporting portion 135 for contacting and supporting one end face of the catalyst 130, an inner surface of the inner surface of the case 101, which is bent at one end of the catalyst supporting portion 135, A joint portion 137 formed by bending at the other end of the catalytic support portion 135, a cone portion 149 extending from the joint portion 137 toward the center of the case 101, (Not shown).

An outlet cone 140 may be provided at the outlet of the catalyst 130. That is, the outlet cone 140 is installed inside the case 101 of the oxidation catalyst unit 110, but may be positioned at the outlet end of the catalyst 130. The outlet cone 140 preferably has such a shape that the pressure due to collision with the exhaust gas or the stress due to such pressure is minimized. For this purpose, the outlet cone 140 has a funnel or tapered shape and preferably has a curved or straight cross-sectional shape.

The connection between the cone 149 of the outlet cone 140 and the catalyst support 135 should have a structure that allows the cone 149 to be easily coupled to the catalyst support 135 while maintaining a perfect seal. To this end, the edges 135, 136 and 137 of the outlet cone 140 according to the present invention have a bent shape, and the bent portion has a substantially U-shaped cross-sectional shape. The U-shaped portion can be easily inserted into the case 101 due to the elastic restoring force of the edge of the outlet cone 140 and the contact state of the case 101 and the outlet cone 140 can be firmly maintained.

The case supporting portion 136 is a portion that is in surface contact with the inner surface of the case 101 and is bent in a direction parallel to the inner surface of the case 101 or is pressed against the inner surface of the case 101 in a state of being in contact with the case 101 It is preferably formed in such a shape as to have an elastic restoring force.

The catalyst supporting portion 135 is a portion for contacting and supporting one end face of the catalyst 130. [ That is, one end surface of the catalyst 130 facing the end cap 112 of the case 101 may be installed inside the case 101 in contact with the catalyst supporting portion 135. The catalyst support 135 should have a contact surface sufficient to support one end of the catalyst 130. However, the catalyst supporting portion 135 may be supported in a state where the catalyst 130 passes through the catalyst supporting member 131, as the case may be.

The joint portion 137 is a portion connecting the catalyst supporting portion 135 and the cone portion 149. 7, the joint portion 137 is formed at one end of the catalyst supporting portion 135. The case supporting portion 136, the catalyst supporting portion 135, and the joint portion 137 have a substantially U-shape. Since the edge of the outlet cone 140 that is in contact with the case 101 is bent in a U-like shape, a sufficient elastic restoring force is generated in a state where the outlet cone 140 is in contact with the case 101, The edge of the outlet cone 140 presses the inner surface of the case 101 to firmly hold the outlet cone 140 and the case 101 in a fixed state.

Referring to FIG. 7A, it is preferable that the joint portion 137 is formed so as to have a gentle inclination rather than a shape parallel to the inner surface of the case 101. That is, the joint portion 137 can be formed so as to have a gentle slope than the cone portion 149.

The cone 149 is extended from one end of the joint portion 137 so that the diameter of the cone portion 149 gradually decreases from the joint portion 137 to the outlet portion 141. The cone 149 is a portion for collecting and guiding the exhaust gas that has passed through the catalyst 130 toward the outlet portion 141.

The size of the outlet portion 141 is smaller than the sectional area of the catalyst 130 and the height of the outlet cone 140 is not sufficiently long so that the back pressure of the exhaust gas in the outlet cone 140 ) May become large or non-uniform flow may occur. In order to prevent such a problem, the cross section of the cone 149 may be formed to be a curved line in the present invention.

Referring to FIG. 7A, the cone 149 is formed such that its cross-sectional shape has a predetermined radius of curvature R. FIG. The cross section of the cone 149 may be formed as a curve having a curvature radius R of 70 mm to 140 mm.

8 and 9 show performance data according to the radius of curvature of the outlet cone 140 of the present invention. In FIGS. 8 and 9, the outline cone of the prior art has a straight line in cross section, and Comparative Examples 1 to 4 are embodiments of the present invention in which the radius of curvature R of the outlet cone is 140 mm, 110 mm, 90 mm and 70 mm, respectively .

8, the frequencies of three outlets according to the respective shapes of the outlets cones are determined from the first to sixth natural frequencies according to the shapes of the outlet cones, The maximum stress is the stress applied to the entire post-treatment apparatus including the outlet cone, and the stress of the outlet cone means the stress applied to the outlet cone. Referring to FIG. 8, it can be seen that, in the case of Comparative Examples 1 to 4, both the maximum stress and the outlet cone stress are smaller than those of the prior art. It can be confirmed that it is reduced by 10% or more from the conventional technology.

9, the back pressure according to the shape of the outlet cone, the flow uniformity (OC Uniformity) of the oxidation catalyst portion, and the flow uniformity (SCR Uniformity) of the selective reduction catalyst portion are compared. Referring to FIG. 9, it can be seen that Comparative Examples 1 to 4 of the present invention have lower back pressure and improved flow uniformity of the oxidation catalyst portion as compared with the prior art. It is confirmed that the back pressure in the vicinity of the inlet pipe 113 and the catalyst 130 is reduced and the flow uniformity in the oxidation catalyst section 110 and the selective reduction catalyst section 160 is improved when the outlet cone is formed into a curved surface have.

In this manner, the stress can be effectively dispersed by forming the cross section of the outlet cone so as to have a curved line, but when the radius of curvature is excessively large, the stress can be increased again. Accordingly, it is most preferable that the outlet cone 140 is formed such that the cross section of the cone 149 has a radius of curvature R of 70 mm to 140 mm.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It should also be understood that many modifications and variations are possible without departing from the scope of the invention, as would be understood by one of ordinary skill in the art.

100: exhaust gas aftertreatment device for compressed natural gas vehicle
101: catalyst case 110: oxidation catalyst part
113: inlet pipe 120: urea mixing pipe
130: oxidation catalyst 131: catalyst supporting member
135: catalyst supporting portion 136: case supporting portion
137: Joint 140: Outlet cone
149: Conv. 160: selective reduction catalyst part

Claims (11)

An oxidation catalytic part extending long enough to allow exhaust gas discharged from the engine to flow therein;
A selective reduction catalyst part formed parallel to the oxidation catalyst part and through which the exhaust gas passed through the oxidation catalyst part flows; And
And a urea mixing pipe configured to connect the oxidation catalyst part and the selective reduction catalyst part,
An outlet of the oxidation catalyst portion connected to the urea mixing pipe is formed so that the inner diameter gradually decreases,
Wherein the oxidation catalyst portion comprises:
A cylindrical catalyst case;
An exhaust gas inflow pipe formed to penetrate through one side of the catalyst case along the diameter direction of the catalyst case;
An oxidation catalyst provided in the catalyst case so as to be spaced apart from the exhaust gas inlet pipe; And
And an outlet cone facing the exhaust gas inflow pipe and contacting the other end of the oxidation catalyst,
The outlet cone
A catalyst supporting part for contacting and supporting one end face of the oxidation catalyst;
A case supporting portion formed at one end of the catalyst supporting portion and supported by the inner surface of the catalyst case;
A joint portion bent at the other end of the catalyst supporting portion;
A cone portion extending from the joint portion toward the center of the catalyst case; And
And an outlet formed at one end of the cone portion.
delete The method according to claim 1,
Wherein the exhaust gas inflow pipe located inside the catalyst case is formed with a plurality of gas exhaust holes.
The method according to claim 1,
Wherein the exhaust gas flow path of the exhaust gas inflow pipe and the exhaust gas flow path of the outlet cone are formed to be orthogonal to each other.
The method of claim 3,
Wherein a catalyst support member for supporting the oxidation catalyst is provided in the catalyst case and an outer diameter of the catalyst support member is equal to an inner diameter of the catalyst case and larger than an outer diameter of the oxidation catalyst, An exhaust gas aftertreatment device for a vehicle.
6. The method of claim 5,
Wherein one end of the oxidation catalyst spaced apart from the exhaust gas inflow pipe is supported by the catalyst supporting member in a state of passing through the catalyst supporting member and the other end of the oxidation catalyst contacting the outlet cone is connected to one end face And the exhaust gas after-treatment apparatus for a compressed natural gas vehicle.
6. The method of claim 5,
Wherein a distance between one end of the oxidation catalyst and the center of the exhaust gas inflow pipe is smaller than a height of the outlet cone.
delete The method according to claim 1,
Wherein the cone portion is formed so that the diameter gradually decreases from the joint portion to the outlet portion,
And the cross section of the cone portion is a curved line.
10. The method of claim 9,
Wherein the cross section of the cone portion is formed of a curved line having a curvature radius of 70 mm to 140 mm.
11. The method of claim 10,
Wherein the joint portion is formed so as to have a gentler inclination than that of the concave portion.

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