JP2001073751A - Catalytic exhaust gas purifier of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an uniform deterioration and prolonged term of replacement of monolith catalyst, by constructing exhaust gas discharge pipe which is connected to the outlet head room of catalyst case, in such a location, viewing from the direction of axial line of monolith catalyst, that shifted to the side that exhaust pipes exist, from the axial line of monolith catalyst. SOLUTION: Among four cylinders of four cylindered engine, exhaust pipe 4 from first cylinder is connected to the exhaust pipe from fourth cylinder, and exhaust pipe 5 from cylinder 2 is connected to the exhaust pipe from third cylinder respectively. Each exhaust pipe 4, 5 are connected into one and connected to inlet head room 9 of catalyst case 8 in such a manner that the axis line of both exhaust pipe 4, 5 may tilt diagonally to the entrance surface 11b of monolith catalyst 11 which is installed in catalyst case 8. The exhaust gas discharge pipe 13 which is connected to the outlet head room 10 located below the catalyst case 8, parallel with the axis line of monolith catalyst 14, here, the location of this discharge pipe 13 is shifted to the side that exhaust pipes 4, 5 exist, from the axial line of monolith catalyst with the distance of e.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for purifying exhaust gas from each cylinder in an internal combustion engine by introducing the exhaust gas into a catalyst case containing a monolithic catalyst.

[0002]

2. Description of the Related Art Conventionally, this type of catalytic exhaust gas purifying apparatus has, for example, an exhaust pipe from each cylinder and an axis line of the monolith catalyst in an inlet head chamber at one end of a catalyst case containing a monolith catalyst. An exhaust gas outlet pipe is connected to the outlet head chamber at the other end of the catalyst case so as to extend in the direction of the axis of the monolith catalyst, while being connected to the inlet face at one end at an angle. After purifying the introduced exhaust gas by contact with the monolith catalyst,
The exhaust gas is discharged from the exhaust gas outlet pipe.

[0003]

As described above, the exhaust pipe from each cylinder is provided in the head chamber at one end of the catalyst case.
In the case where the axis is inclined and connected to the inlet surface of the monolith catalyst, the catalyst case can be brought close to each cylinder, so that there is an advantage that the inside of the catalyst case can be maintained at a high temperature.

On the other hand, in the conventional purifying apparatus, the exhaust pipe from each cylinder is connected to the head chamber with its axis inclined to the inlet face of the monolith catalyst, while the exhaust pipe at the other end of the catalyst case is connected. The exhaust gas outlet pipe connected so as to extend in the direction of the axis of the monolith catalyst is configured so as to be located at a substantially central portion of the monolith catalyst when viewed from the axial direction of the monolith catalyst. There was a problem.

[0005] That is, the exhaust gas flowing obliquely from the exhaust pipe into the inlet head chamber is mainly directed toward a substantially central portion of the inlet surface of the monolith catalyst when viewed from the axial direction of the monolith catalyst. The flow of the gas passing through the through holes in the monolith catalyst toward the outlet side is substantially equal to the flow in the substantially central portion of the through holes in the monolith catalyst, which is in a straight line with the exhaust gas outlet pipe at the outlet side. In the hole, the flow becomes larger than the flow passing through each through hole of the other portion, in other words, the substantially center of the through hole in the monolith catalyst, which communicates in a straight line with the exhaust gas outlet pipe on the outlet side on the outlet side. In this part, the exhaust gas passing through each through hole in the part tends to be larger than the exhaust gas passing through the through hole in the other part. Since the deterioration of the definitive catalyst to proceed to earlier, is the must quickly the time to replace the monolithic catalyst.

Exhaust gas flowing obliquely from the exhaust pipe into the inlet head chamber may also be present in a portion of the inlet surface of the monolith catalyst opposite to the exhaust pipe when viewed from the axial direction of the monolith catalyst. The problem described above also occurs when the exhaust gas outlet pipe is disposed at a position displaced on the side opposite to the exhaust pipe with respect to the axis of the monolith catalyst when viewed from the axial direction of the monolith catalyst. Was to do.

An object of the present invention is to provide a catalytic purifying apparatus which solves this problem.

[0008]

In order to achieve the above technical object, the present invention provides an exhaust pipe from each cylinder in an inlet head chamber at one end of a catalyst case containing a monolith catalyst. An exhaust gas outlet pipe is connected to the outlet head chamber at the other end of the catalyst case while being connected to the inlet face of one end of the catalyst at an angle, such that the exhaust gas outlet pipe extends in the axial direction of the monolith catalyst. In the exhaust gas purifying apparatus, the exhaust gas outlet pipe is disposed at a position shifted from the axis of the monolith catalyst toward the side where the exhaust pipe exists, as viewed from the axial direction of the monolith catalyst. " I made it.

[0009]

The exhaust gas flowing obliquely from the exhaust pipe into the inlet head chamber is substantially at the center of the inlet surface of the monolith catalyst when viewed from the axial direction of the monolith catalyst, and the exhaust pipe is connected to the exhaust pipe. Since it tends to flow more toward the opposite side, the exhaust gas outlet pipe on the outlet side of the monolith catalyst is viewed from the axial direction of the monolith catalyst,
If it is located at the approximate center of the monolithic catalyst or at a position shifted to the side opposite to the exhaust pipe, a portion of the through hole in the monolithic catalyst at the approximate center and the side opposite to the exhaust pipe The exhaust gas passing through each through hole in the above becomes larger than the exhaust gas passing through each through hole in the other portion, and the catalyst deterioration in this portion proceeds first.

On the other hand, as described above, the exhaust gas outlet pipe on the outlet side of the monolith catalyst is shifted from the axis of the monolith catalyst to the side where the exhaust pipe exists, as viewed from the axial direction of the monolith catalyst. In the case where the monolithic catalyst is disposed, each of the through-holes of the monolithic catalyst that communicates in a straight line with the exhaust gas outlet pipe on the outlet side thereof is substantially at the center of the inlet surface of the monolithic catalyst. And, it is possible to increase the flow of the exhaust gas passing through each through hole in this part from the part opposite to the exhaust pipe to the exhaust pipe side, and to the extent that this amount can be increased, the substantial center Exhaust gas passing through each through hole in the portion and the portion opposite to the exhaust pipe is reduced.

Therefore, according to the present invention, the deterioration of the monolith catalyst can be equalized in various places, so that the time for replacing the monolith catalyst can be extended.

In particular, by forming the inner peripheral edge of the opening of the exhaust pipe to the inlet head chamber into a curved surface, the exhaust gas flowing from the exhaust pipe is supplied to the inlet of the monolith catalyst. The above effects can be further promoted because the particles can be dispersed over a wide area on the surface.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 indicates that the ignition order is the first cylinder A1-third cylinder A3-fourth cylinder A4-second cylinder A
Reference numeral 2 denotes a four-cylinder internal combustion engine,
1 shows a catalytic type exhaust gas purifying device for the present invention.

The exhaust gas purifying apparatus 2 is connected to the internal combustion engine 1 by an exhaust pipe connected to a flange 3 so as to communicate with each of exhaust ports from the cylinders A1, A2, A3, and A4. 4, 5, 6, 7, and a catalyst case 8 having a built-in monolithic catalyst 11 having an inlet head chamber 9 at an upper part and an outlet head chamber 10 at a lower part and having a large number of through holes 11a. .

Each of the cylinders A1, A2, A3, A4
Among them, the exhaust pipe 4 from the first cylinder A1 has the exhaust pipe 7 from the fourth cylinder A4, and the exhaust pipe 5 from the second cylinder A2 has the third
The exhaust pipes 6 from the cylinder A3 are respectively joined, and the exhaust pipes 4 from the first cylinder A1 and the exhaust pipes 5 from the second cylinder A2 are joined.
The axis 12 of these exhaust pipes 4 and 5 is inclined obliquely downward with respect to the inlet face 11 b at one end of the monolithic catalyst 11 in the inlet head chamber 9 of the catalyst case 8. It is connected.

Further, an exhaust gas outlet pipe 13 is connected to an outlet head chamber 10 at a lower portion of the catalyst case 8 so as to extend in a direction of an axis 14 of the monolith catalyst 11.

When the exhaust gas outlet pipe 13 is viewed from the direction of the axis 14 of the monolith catalyst 11, the dimension e is appropriately set on the side of the monolith catalyst 11 where the two exhaust pipes 4 and 5 are present. It is provided only at the shifted position.

The inner peripheral edge of the opening of each of the exhaust pipes 4 and 5 into the inlet head chamber 9 is formed on a curved surface 15.

In this configuration, the exhaust gas flowing obliquely from the exhaust pipes 4 and 5 into the inlet head chamber 9 is formed on the inlet face 11 b of the monolith catalyst 11 when viewed from the direction of the axis 14 of the monolith catalyst 11. Near the center, and
There is a tendency that a large amount of exhaust gas flows toward a portion opposite to the exhaust pipes 4 and 5 and a flow of exhaust gas toward a portion of the inlet surface 11b near the exhaust pipes 4 and 5 is smaller than the above.

In this case, the monolith catalyst 11
When viewed from the direction of the axis 14 of the monolith catalyst 11, the exhaust gas outlet pipe 13 on the outlet side of the
Is provided at a position which is appropriately shifted by the dimension e from the side where the gas exists, so that each of the through holes 11a in the monolith catalyst 11 is closer to the exhaust pipes 4 and 5 when viewed from the direction of the axis 14 of the monolith catalyst 11. A plurality of each through holes 11a
Is connected to the exhaust gas outlet pipe 13 on the outlet side in a straight line, so that the plurality of through holes 11
a, it is possible to increase the amount of exhaust gas that passes through the inside of the exhaust pipe 4. The exhaust gas passing through the through holes 11a on the side opposite to the exhaust pipes 4 and 5 is increased by the amount of exhaust gas passing through the plurality of through holes 11a on the side of the exhaust pipes 4 and 5 as described above. Only
The deterioration of the catalyst can be equalized in various places.

Further, since the inner peripheral edges of the openings of the exhaust pipes 4 and 5 with respect to the inlet head chamber 9 are formed on the curved surface 15, the exhaust gas flowing from the exhaust pipes 4 and 5 can be monolithically catalyzed. 11 can be distributed over a wide area on the entrance surface 11b.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine A1, A2, A3, A4 Cylinder 2 Exhaust gas purifier 4, 5, 6, 7 Exhaust pipe 8 Catalyst case 9 Inlet head chamber 10 Outlet head chamber 11 Monolithic catalyst 11a Through hole 11b Inlet surface 12 Exhaust pipe axis 13 Exhaust gas outlet pipe 14 Axis of monolith catalyst 15 Curved surface

Claims (2)

[Claims] An exhaust pipe from each cylinder is connected to an inlet head chamber at one end of a catalyst case containing a monolith catalyst, with its axis inclined to the inlet face of one end of the monolith catalyst. An exhaust gas outlet pipe connected to an outlet head chamber at the other end of the monolith catalyst so that the exhaust gas outlet pipe extends in the axial direction of the monolith catalyst. A catalytic exhaust gas purifying device for an internal combustion engine, wherein the catalytic exhaust gas purifying device is disposed at a position shifted from the axis of the monolithic catalyst toward the side where the exhaust pipe exists, as viewed from the axial direction of the catalyst. 2. A catalytic exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein an inner peripheral edge of an opening of said exhaust pipe with respect to an inlet head chamber is formed in a curved surface.