JPH0437224Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a catalytic converter installed in the exhaust system of an internal combustion engine to purify exhaust gas, and in particular, the structure of the catalytic converter is designed to reduce pressure loss. Regarding.

[Prior Art] Conventionally, in order to reduce pressure loss in a catalytic converter, a step has been formed between an exhaust gas inlet and an outlet, and a catalyst carrier is disposed at an angle in this step. A catalytic converter has been proposed (Utility Model Application Publication No. 188812/1983).

Figures 5 and 6 show the above-mentioned U.K. 60-
The catalytic converter disclosed in Japanese Patent No. 188812 is shown. In FIG. 5, a catalytic converter 1 has an inlet portion 2 connected to the engine side via a front pipe, and an outlet portion 3 connected to the muffler via a center pipe. The inlet section 2 and the outlet section 3 extend substantially horizontally and are vertically offset from each other in height. That is, there is a step between the inlet section 2 and the outlet section 3, and the catalyst carrier 4 is held at this step at an angle θ ₁ from the horizontal direction. The angle θ ₁ in this case is set to an angle of 45 degrees or less, and the cell 5 of the catalyst carrier 4
The flow path is parallel to the catalyst carrier axis B. That is, the angle between the catalyst carrier axis B and the flow path of the cell 5 is ψ ₁ =0°.

By tilting the catalyst carrier 4 in this way, pressure loss due to turbulent flow is suppressed to a small level, and the cross-sectional area of the catalyst carrier is expanded, thereby reducing pressure loss within the catalyst carrier due to a decrease in flow resistance. There is.

The catalyst carrier shown in FIG. 5 is manufactured by the method shown in FIG. 7. In Figure 7,
10 indicates an extrusion molding machine, and extrusion molding machine 1
The catalyst carrier 4 extruded from 0 to a width L is cut to have a catalyst length l at right angles to the direction of extrusion. That is, in this method, the catalyst carrier axis B and the flow path of the cell 5 are parallel, and the angle of the flow path of the cell 5 with respect to the catalyst carrier axis B is ψ ₁ = 0°
Become.

In addition, in the above-mentioned Japanese Utility Model Application No. 60-188812, in order to further reduce the pressure loss, the flow passages of the cells 5 in the catalyst carrier are aligned with the catalyst carrier axis B as shown in FIG.
It is disclosed that the flow resistance is made to be inclined in the direction where the flow resistance becomes smaller.

In this case, the flow path of the cell 5 is set at an angle ψ ₁ (0° or more and 90°−θ or less) with respect to the catalyst carrier axis B. This catalyst carrier 4 is manufactured by the method shown in FIG. That is, the catalyst carrier 4 extruded from the extrusion molding machine 10 is cut so that the catalyst carrier axis B makes an angle ψ ₁ (0° or more and 90° − θ or less) with respect to the flow path direction of the cell 5. Ru.
In this case, the catalyst length l is cut so that it becomes the catalyst wall l'(l'>l), and furthermore, in order to install it in the same converter, it is cut to length L in the major axis direction.

Therefore, the catalyst carrier 4 cut in this way
If this is used, the flow path of the cell 5 is formed along the flow direction of the exhaust gas, so that it is possible to reduce the pressure loss.

[Problems to be solved by the invention] However, it has become clear that in a catalytic converter using a cut catalyst carrier as described above, the pressure loss actually increases as shown in Figure 3 C. Ta. This is the outer circumference 4 of the catalyst carrier 4.
Since a is the holding part, the opening of the flow path of the cell 5 is blocked by the holding part, creating an unused part 4b in the catalyst carrier 4, and the reason why the effective passage cross-sectional area of the catalyst carrier 4 is reduced. This is due to

Focusing on the above points, the present invention aims to expand the effective passage area of the catalyst carrier, minimize the flow resistance when exhaust gas flows into the cells of the catalyst carrier, and further reduce pressure loss in the catalytic converter. The purpose is to

[Means for Solving the Problems] A catalytic converter of the present invention that meets this purpose is a catalytic converter in which a catalyst carrier is held at an angle between an inlet and an outlet of exhaust gas, and the catalyst The flow passages of the cells within the carrier are inclined in a direction that reduces flow resistance with respect to the axis of the catalyst carrier, and the outer peripheral portion of the catalyst carrier is formed and held approximately parallel to the flow passages of the cells. .

[Function] In the catalytic converter configured as described above, the flow paths of the cells in the catalyst carrier are inclined in a direction that reduces the flow resistance of exhaust gas, so that the exhaust gas flows easily and the flow rate increases to the square of the flow velocity. The flow resistance, which increases proportionally to , decreases and the pressure loss within the catalyst carrier is reduced. Furthermore, since the outer periphery where the catalyst carrier is held is formed almost parallel to the cell flow path, all exhaust gas that flows into the cell flow path from the upstream end passes through the cell flow path and flows downstream. be discharged. That is, unlike the conventional structure, the flow path of the cell is no longer blocked by the holding portion, the effective passage cross-sectional area of the catalyst carrier is expanded, and the pressure loss is reduced accordingly.

[Embodiments] Hereinafter, preferred embodiments of the catalytic converter of the present invention will be described with reference to the drawings.

FIG. 1 shows a catalytic converter according to an embodiment of the present invention. In the figure, 20 indicates a catalytic converter, and the housing 21 of the catalytic converter 20 has an inlet part 23 connected to a front pipe 22 as an exhaust pipe on the upstream side and an outlet part connected to a center pipe 24 on the downstream side. 25 is formed. A connecting flange 2 is provided at the end of the inlet portion 23.
6 is provided, and a connecting flange 27 is also provided at the end of the outlet portion 25. Entrance section 23
The outlet portion 25 and the outlet portion 25 are formed to extend substantially horizontally, and are shifted in height from each other in the vertical direction. In other words, there is a step between the inlet portion 23 and the outlet portion 25, and this step portion forms the slope portion 2 having an inclined surface.
1a.

A monolithic catalyst carrier 26 having a honeycomb-shaped cross section is disposed between the inlet portion 23 and the outlet portion 25 to purify exhaust gas. The catalyst carrier 26 is manufactured through a manufacturing process as shown in FIG. First, when the material is extruded from the extrusion molding machine 33, a catalyst carrier 26 having a width L and having a large number of channels 28 along the direction of extrusion is formed.
is formed. In the extruded catalyst carrier 26, the catalyst carrier axis A is set at an angle ψ (ψ=0° or more and 90°−θ or less) with respect to the flow path direction of the cell 28, and the catalyst length is l. It is cut along the cutting line 29 as shown in FIG. That is, the side surface of the extruded material becomes the outer peripheral part 30 of the catalyst carrier 26, and the outer peripheral part 30
is parallel to the flow path of the cell 28.

Catalyst carrier 26 thus cut and formed
In this case, the outer peripheral portion 30 is the inclined portion 21a of the housing 21.
is placed so as to face the Catalyst carrier 26
The wire net 3 is interposed between the outer peripheral part 30 of the catalyst carrier 26 and the inclined part 21a of the housing 21.
1 and a sealing material 32 for sealing against leakage of exhaust gas. The catalyst carrier 26 is inclined to become higher toward the downstream side, and the angle between the upstream end face of the catalyst carrier 26 and the flow of exhaust gas is set to θ. In this case, the angle between the catalyst carrier axis A and the flow path of the cell 28 is ψ = 90°
-θ is set.

Next, the operation of the above catalytic converter will be explained.

Exhaust gas led to the inlet 23 of the catalytic converter 20 flows into the channel of the cell 28 from the upstream end of the catalyst carrier 26, passes through this channel, and is discharged from the downstream end to the outlet 25. be done. in this case,
The flow paths of the cells 28 of the catalyst carrier 26 are set at an angle ψ with respect to the catalyst carrier axis A, as shown in FIG. Therefore, the flow resistance of exhaust gas is improved and the pressure loss within the catalytic converter 26 is reduced. The catalyst carrier 26 is held in the housing 21 via a wire net 31, and since the outer periphery 30 of the catalyst carrier 26 is formed approximately parallel to the flow path of the cell 28, the cell as shown in FIG. The unused portion 4b is eliminated, and the effective passage area of the catalyst carrier 26 is expanded. Therefore, catalyst carrier 2
The flow rate of the exhaust gas flowing through the exhaust gas 6 is reduced, flow resistance proportional to the square of the flow rate is reduced, and pressure loss is reduced. Therefore, the pressure loss caused by the catalytic converter 20, as shown in FIG. 3A, is significantly reduced compared to the pressure losses B and C of the conventional catalytic converter. In addition, the flow velocity distribution of exhaust gas is
It is kept uniform as in the catalytic converter shown in the figure.

[Effects of the invention] As explained above, when using the catalytic converter of the invention, the flow paths of the cells in the catalyst carrier are inclined in the direction where the flow resistance is small with respect to the axis of the catalyst carrier, and the catalyst carrier is retained. Since the outer periphery of the catalyst carrier is formed and held so as to be substantially parallel to the flow path of the cell, the effective passage area of the catalyst carrier can be expanded.
The effect is that pressure loss in the catalytic converter can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a catalytic converter according to an embodiment of the present invention, FIG. 2 is a plan view showing a part of the manufacturing process of the catalyst carrier in FIG. 1, and FIG. A relationship diagram showing the relationship between exhaust gas flow rate and pressure loss in a conventional catalytic converter. Figure 4 shows the inclination of the catalyst carrier with respect to the flow direction of exhaust gas in the device of Figure 1 and the flow path of the cell with respect to the axis of the catalyst carrier. Explanatory diagram showing the inclination, fifth
The figure is a sectional view showing an example of a conventional catalytic converter, FIG. 6 is a sectional view showing another example of a conventional catalytic converter, and FIG. 7 shows a part of the manufacturing process of the catalyst carrier in FIG. FIG. 8 is a plan view showing a part of the manufacturing process of the catalyst carrier in FIG. 6. 20...Catalytic converter, 23...Inlet section, 2
5... Outlet part, 26... Catalyst carrier, 28... Cell,
30...Outer circumference of the catalyst carrier, A...Catalyst carrier axis, θ...Inclination of the catalyst carrier, ψ...Inclination of the flow path of the cell with respect to the catalyst carrier axis.

Claims (1)

[Scope of utility model registration request] In a catalytic converter in which a catalyst carrier is tilted and held between an exhaust gas inlet and an outlet,
The flow passages of the cells in the catalyst carrier are inclined in a direction that reduces flow resistance with respect to the axis of the catalyst carrier, and the outer peripheral portion of the catalyst carrier is formed and held substantially parallel to the flow passages of the cells. Features a catalytic converter.