JPH10299468A - Exhaust manifold catalytic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve initial purifying performance during starting of an engine, reduce drift of exhaust gas flow, and reduce pressure loss, by providing a structure in which plural catalytic converters and thermal resistant alloy made pipes as main structure members are constituted so as to collect an exhaust gas after purifying of the exhaust gas. SOLUTION: When the converters are applied to four air cylinder engine, a flange 7 which has four holes corresponding to four exhaust gas outlets #1-#4 from an engine block is provided, and metal catalytic converters 1-4 are connected so that they are corresponding to each hole of the flange 7. The converters are connected to backward exhaust gas system through a collecting tube 5 and a flange 6. Because the catalytic converter with this structure collects exhaust gas exhausted from each cylinder after purifying the exhaust gas with metal catalytic converters 1-4, the metal catalytic converters 1-4 can be miniaturized and are mounted near the engine block, and therefore, a temperature rising characteristic during starting of an engine is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold catalytic converter which is installed in an exhaust gas system of an automobile engine and integrates an exhaust manifold for collecting exhaust gas and a catalytic converter.

[0002]

2. Description of the Related Art An exhaust gas system of an automobile engine includes an exhaust manifold for collecting exhaust gas discharged from each cylinder of the engine, a catalytic converter for purifying exhaust gas, a heat-resistant pipe, a silencer, and the like. Exhaust manifolds include those made of inexpensive cast iron and those assembled by welding heat-resistant alloy pipes. At present, the former is changing from the former to the latter from the viewpoint of weight reduction and lower heat capacity.

A carrier in a catalytic converter for purifying exhaust gas is a metal carrier in which a honeycomb body formed of a heat-resistant stainless steel foil is loaded in a metal case made of a heat-resistant stainless steel, or a ceramic honeycomb. A body-loaded ceramic carrier is used. The metal carrier has a feature that it has excellent initial purification ability at the time of engine start and a small pressure loss as compared with the ceramic carrier.

In a conventional metal carrier, a honeycomb body is manufactured by laminating a flat foil having a thickness of about 50 μm and a corrugated corrugated foil on the flat foil, and winding the flat foil. Then, the honeycomb body is inserted into a metal case, and a contact portion between the flat foil and the corrugated foil is joined, and the honeycomb body and the metal case are joined to form a metal carrier.

[0005] A wash coat is applied to such a metal carrier or a ceramic carrier to carry a catalytic metal to form a catalytic converter. On the other hand, in some cases, a wash coat is applied to a metal honeycomb body or a ceramic honeycomb body to support a catalyst metal, and then loaded and fixed in a metal case to form a catalytic converter.

[0006] The exhaust manifold collects exhaust gas discharged from a plurality of cylinders, how to quickly discharge exhaust gas from an automobile engine, and how to control the gas flow at the downstream side of the catalytic converter. Designed with emphasis on both. This is because the former affects the engine output, and the latter affects the catalyst purification performance and pressure loss.

[0007] The exhaust manifold is also required to be compact from the viewpoint of mountability in an engine room with limited space. However, when collecting the exhaust gas from a plurality of cylinders, a buffer member such as a straight pipe is required to make the flow of the exhaust gas uniform. Reducing the size of the exhaust manifold leads to the elimination of shock absorbers, that is, the delivery of exhaust gas to downstream catalytic converters without adequately correcting exhaust gas flow deviations.

As a countermeasure against this problem, Japanese Patent Application Laid-Open No. 8-212
Japanese Patent Publication No. 31 proposes an exhaust manifold having a special shape. This is achieved by providing a weir with a structure in which the inner wall is partially protruded at the inlet side of the exhaust outlet end, which expands in the throat shape of the exhaust manifold collecting part, and deflects the exhaust gas flow, thereby reducing the size. And to achieve both exhaust gas flow homogenization.

On the other hand, an exhaust manifold and a catalytic converter are integrated to form an exhaust manifold catalytic converter, so that an attempt has been made to eliminate a connecting member and reduce the size of the exhaust manifold. For example, Japanese Patent Application No. Hei 7-27
No. 8101 proposes that a metal honeycomb is inserted in a compressed state from an outlet side of a collecting pipe in which branch pipes of an exhaust manifold are gathered at one place. Also, Japanese Utility Model Laid-Open No. 6-30425, Japanese Utility Model Laid-open No. 6-30
No. 418 and Japanese Utility Model Laid-Open No. 6-30417,
An exhaust manifold having the above-mentioned integrated special shape has been proposed.

[0010]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 8-212 is disclosed.
In the exhaust manifold proposed in Japanese Patent Publication No. 31, it is necessary to provide a catalytic converter on the downstream side. Further, the exhaust manifold catalytic converter proposed in Japanese Patent Application No. 7-278101 and each of the above publications in which an exhaust manifold and a catalytic converter are integrated, after exhaust gas discharged from a plurality of cylinders is collected. , Leading to the catalytic converter, the uniformity of the exhaust gas flow on the catalytic converter entrance side,
Reduction of pressure loss and reduction of the total size of the exhaust manifold and catalytic converter were naturally limited.

FIG. 3 shows an example of a conventional exhaust manifold catalytic converter. This is applied to a four-cylinder engine. There is a flange 7 having four holes corresponding to the four exhaust gas exhaust holes # 1, # 2, # 3, and # 4 from the engine block. Each of the holes has a collecting pipe (made of a heat-resistant alloy pipe). The manifold 8) is connected. Exhaust gas collected by the manifold 8 flows into the catalytic converter 9 where it is purified.

In this structure, first, # 1 and # 2, # 3 and #
4 each merge, and the two merge further. There are also bends along the way. When the exhaust gas passes through these confluences and bends, the gas flow always becomes deviated. Therefore, it is necessary to equalize the deviated gas flow by using a buffer member of a required length, for example, a straight pipe. . This leads to an increase in the size of the exhaust manifold, which makes it difficult to accommodate the exhaust manifold in a limited space in the engine room.

To improve this, exhaust manifolds of various shapes have been proposed, all of which have a structure in which exhaust gas is collected and then flows into a catalytic converter. With such a structure, there is a limit in downsizing.

On the other hand, in order to enhance the initial purification ability at the time of starting the engine, it is desired that the catalytic converter be quickly heated to the activation temperature of the catalyst, and it is advantageous to mount the catalytic converter near the engine which is a heat source. However, in the above-described conventional structure, the catalytic converter is farther from the engine by the size of the exhaust manifold. Further, since all the gases of the four cylinders are passed through one catalytic converter, a large-capacity catalytic converter is required, which is an obstacle to shortening the time required to raise the temperature when starting the engine.

The present invention solves the above-mentioned problems, and has an extremely excellent initial purification performance at the time of engine start, and furthermore, has a small deviation in the exhaust gas flow in the catalytic converter and has an excellent purification performance. It is another object of the present invention to provide a compact exhaust manifold catalytic converter having a small pressure loss.

[0016]

According to the present invention, there is provided an exhaust manifold catalytic converter for collecting exhaust gas discharged from each cylinder of an automobile engine, comprising a plurality of catalytic converters and a heat-resistant alloy. An exhaust manifold catalytic converter characterized in that a pipe is used as a main constituent member, and the exhaust gas is purified and then assembled.

It is preferable that a catalytic converter is arranged at each cylinder outlet of the automobile engine to collect exhaust gas after purifying it. Preferably, a metal catalytic converter is used as the catalytic converter, and more preferably, a metal catalytic converter based on a diffusion-bonded metal carrier is used.

[0018] By employing a structure in which exhaust gas is purified and then assembled, the exhaust gas has an extremely excellent initial purification performance at the time of engine start-up. An exhaust manifold catalytic converter that is excellent, has low pressure loss, and is compact.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. FIG. 1 is a schematic diagram showing an example of the exhaust manifold catalytic converter of the present invention. This example is applied to a four-cylinder engine, and the four
There is a flange 7 having four holes corresponding to the two exhaust gas exhaust holes # 1, # 2, # 3, and # 4. Small-capacity metal catalytic converters 1, 2, 3, and 4 are connected to correspond to the respective holes of the flange 7. It is then connected via a collecting pipe 5 and a flange 6 to a rear exhaust system.

FIG. 2 is a schematic diagram showing another example of the exhaust manifold catalytic converter of the present invention. This example is also applied to a four-cylinder engine, and has four exhaust gas exhaust holes # 1, # 2, # 3, and # from the engine block.
There is a flange 7 having four holes corresponding to four. A small-capacity metal catalytic converter 10 having an elliptical cross section is connected so as to correspond to the holes # 1 and # 2 of the flange 7, and has a small capacity so as to correspond to the holes # 3 and # 4 of the flange 7. Catalytic converter 1 with an oval cross section
1 is connected. It is then connected via a collecting pipe 5 and a flange 6 to a rear exhaust system.

In the exhaust manifold catalytic converter of the present invention, the exhaust gas discharged from each cylinder of the engine block is collected after being purified by the metal catalytic converter. In the example of FIG. 2, each of the metal catalyst converters 10 and 11 can be reduced in capacity.
And it can be mounted very close to the engine block.

Since the temperature of the catalytic converter rises passively by receiving the heat of the exhaust gas, the temperature rise characteristic at the time of starting the engine is improved as it is closer to the heat source, that is, the engine, and as the capacity is smaller. You. That is,
The catalyst activation temperature can be reached faster. This greatly improves purification performance.

Further, since the exhaust gas discharged from each cylinder flows into the metal catalytic converter without being collected, the deviation of the exhaust gas flow is slight, and the entire region of the metal catalytic converter can be effectively distributed without deviation. Since it can be used, the catalyst purification performance is also excellent. Further, the pressure loss is reduced because the bias of the exhaust gas flow is slight. And above all, in the present invention, the metal catalytic converter is one of the constituent members of the exhaust manifold,
An extremely compact configuration is possible. Therefore, it can be mounted in a narrow engine room.

In this embodiment, the exhaust manifold catalytic converter is constituted by using a metal catalytic converter, but a ceramic catalytic converter may of course be used. However, since the metal catalytic converter is more excellent in mountability, it is advantageous in manufacturing.

Even with the same metal catalytic converter, a metal catalytic converter using a diffusion-bonded metal carrier that does not use a brazing filler metal has a smaller heat capacity and a faster heating rate because no brazing filler metal is used. I do. In the example of the present invention in which a plurality of catalytic converters are used, a diffusion bonded metal carrier that does not use an expensive brazing material is advantageous. In addition, the diffusion-bonded metal carrier can be bonded with the same material without using a different bonding material such as a brazing material, so that it can be used even in a harsh environment at a higher temperature.

[0026]

【Example】

[Example of the present invention] An exhaust manifold catalytic converter of the present invention as shown in Fig. 1 was manufactured. For the catalytic converter, small capacity catalytic converters 1 to 4 having a capacity of 0.3 liter and having the following specifications are used.
A heat-resistant pipe having the following specifications was used. Honeycomb outer diameter 60mm Honeycomb length 110mm Honeycomb material Heat resistant oxidation resistant steel (20Cr-5Al) Outer cylinder outer diameter 63mm Outer cylinder length 113mm Outer cylinder wall thickness 1.5mm Outer cylinder material Heat resistant oxidation resistant steel (19Cr- 0.4Nb-0.4Cu) Heat-resistant pipe inner diameter 30mm Heat-resistant pipe wall thickness 2.0mm Heat-resistant pipe material Heat-resistant oxidation-resistant steel (19Cr-0.4Nb-0.4Cu) In this example, the exhaust manifold catalytic converter Has a total length L of about 400 mm.

[Conventional Example 1] A conventional exhaust manifold catalytic converter as shown in FIG. 3 was manufactured. The exhaust manifold 8 is made of heat-resistant and oxidation-resistant steel (19
Cr-0.4Nb-0.4Cu) pipe is welded and has a total length L of about 400 mm. As the catalytic converter, one large-capacity catalytic converter 9 having a capacity of 0.9 liter and having the following specifications was used. Honeycomb outer diameter 100mm Honeycomb length 120mm Honeycomb material Heat resistant oxidation resistant steel (20Cr-5Al) Outer cylinder outer diameter 103mm Outer cylinder length 123mm Outer cylinder wall thickness 1.5mm Outer cylinder material Heat resistant oxidation resistant steel (19Cr- (0.4Nb-0.4Cu) In this example, the total length L of the exhaust manifold catalytic converter was about 600 mm.

[Conventional Example 2] A conventional exhaust manifold catalytic converter as shown in FIG. 4 was manufactured. The exhaust manifold 8 is made of heat-resistant and oxidation-resistant steel (19
Cr-0.4Nb-0.4Cu) pipe is welded and has a total length L of about 200 mm. As the catalytic converter, one large-capacity catalytic converter 9 having a capacity of 0.9 liter and having the following specifications was used. Honeycomb outer diameter 100mm Honeycomb length 120mm Honeycomb material Heat resistant oxidation resistant steel (20Cr-5Al) Outer cylinder outer diameter 103mm Outer cylinder length 123mm Outer cylinder wall thickness 1.5mm Outer cylinder material Heat resistant oxidation resistant steel (19Cr- (0.4Nb-0.4Cu) In this example, the total length L of the exhaust manifold catalytic converter was about 500 mm.

FIG. 5 shows the results of comparison of the temperature rise characteristics of the central portion of the metal catalytic converter between the above-described example of the present invention and conventional example 1. FIG.
Shows temperature change up to second, engine speed is 2500 rp
Corresponds to changes up to m. The temperature rise rate of the small capacity metal catalytic converters 1 to 4 in the example of the present invention is much higher than that of the large capacity metal catalytic converter 9 in the conventional example. That is, at the time of engine start, the example of the present invention reaches the catalyst activation temperature in a shorter time than the conventional example, indicating that the initial purification performance of the exhaust gas is excellent.

In addition, the flow rate distribution of the gas flowing through the channel of the metal catalytic converter is measured and statistically processed for the above-mentioned examples of the present invention, Conventional Examples 1 and 2, and the uniformity index of the exhaust gas flow is obtained. (Uniformity Index:
γ) was calculated according to the procedure shown in Table 1. This γ is 1.00
In this case, the gas flow is completely uniform, and the smaller the gas flow, the more the exhaust gas flow is biased.

Table 2 shows a comparison of γ in each of the above examples with the setting such that the average gas flow velocity was 60 m / sec. In the example of the present invention, even though the overall length L of the exhaust manifold catalytic converter is reduced to about ／ of the conventional example 1, the same uniform exhaust gas flow can be obtained. It can be seen that both size and exhaust gas flow are excellent.

When γ = 0.85 and γ = 0.96, the former has a purification performance of about 20%, which is lower than the latter.

[0033]

[Table 1]

[0034]

[Table 2]

In the above, the effectiveness of the present invention has been described based on the case where the engine is a four-cylinder engine.

[0036]

As described above, the exhaust manifold according to the present invention has an extremely excellent initial purification performance at the time of engine start, and furthermore has a small exhaust gas flow bias in the metal catalytic converter and has excellent purification performance. , Low pressure loss, compact and excellent mountability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an exhaust manifold catalytic converter of the present invention.

FIG. 2 is a schematic sectional view showing another example of the exhaust manifold catalytic converter of the present invention.

FIG. 3 is a schematic sectional view showing an example of a conventional exhaust manifold catalytic converter.

FIG. 4 is a schematic cross-sectional view showing another example of a conventional exhaust manifold catalytic converter.

FIG. 5 is a graph showing a comparison between the temperature rise characteristics of the catalytic converter according to the present invention and the conventional example.

[Explanation of symbols]

 1, 2, 3, 4 ... small capacity metal catalytic converter 5 ... collecting pipe 6 ... outlet flange 7 ... inlet flange 8 ... manifold 9 ... large capacity metal catalytic converter 10, 11 ... elliptical small capacity metal catalytic converter

Claims (4)

[Claims] 1. An exhaust manifold catalytic converter for collecting exhaust gas discharged from each cylinder of an automobile engine, wherein a plurality of catalytic converters and a pipe made of a heat-resistant alloy are used as main constituent members, and the exhaust gas is collected after purifying the exhaust gas. An exhaust manifold catalytic converter characterized by having a structure that allows the exhaust manifold to be operated. 2. The exhaust manifold catalytic converter according to claim 1, wherein a catalytic converter is arranged at each of the cylinder outlets of the automobile engine, and the exhaust gas is purified and then assembled. 3. The exhaust manifold catalytic converter according to claim 1, wherein a metal catalytic converter is used as the catalytic converter. 4. The method according to claim 1, wherein a metal catalytic converter based on a diffusion bonded metal carrier is used.
4. The exhaust manifold catalytic converter according to 2 or 3.