JPS6113690Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an exhaust gas purification device for purifying exhaust gas from an internal combustion engine.

BACKGROUND ART Various types of exhaust gas purification devices have already been proposed. For example, in the case of Utility Model Publication No. 52-19069, the shape of the outer case is cylindrical. Although such a cylindrical outer case has the advantage of being less likely to cause membrane vibration due to exhaust pulsation, When installed, it has the disadvantage that the diameter must be reduced.

Therefore, as an exhaust purification device installed under the floor of an automobile, one in which the outer case has a flat rectangular shape is known.

Problems to be Solved by the Invention The exhaust gas purification device in which the outer case has a flat rectangular shape has the following new problems.

That is, since the exhaust gas purification device having the above shape has many flat parts, the membrane vibrates violently due to exhaust pulsation, which causes noise.

Means for Solving the Problems In this invention, a throttle is provided at the end of the inlet pipe that has a highly rigid part such as a flange on the exhaust gas inlet side of the exhaust purification device having the above-mentioned shape.

Effect With the above configuration, the pulsating pressure of the exhaust gas flowing into the exhaust gas purification device is absorbed and relaxed by the throttle at the end of the inlet pipe, and the membrane vibration of the flat rectangular case is suppressed. . Since the above-mentioned throttle is formed at the end of the inlet pipe that has a highly rigid part such as a flange, this end of the inlet pipe does not become a new noise source that causes membrane vibration.

Embodiment FIG. 1 shows an exhaust purification device of the type installed under the floor of an automobile, and shows an outer case 3 in the shape of a flat rectangular parallelepiped, which has an exhaust gas inlet 1 at one end and an exhaust gas outlet 2 at the other end. A heat insulating material 5 is interposed between the inner case 4 and the inner case 4, and a catalyst bed 6 is installed in the inner case 4 so as to divide the upper and lower parts into two, and the center part is supported by a stay 7. . As shown in FIG. 2, these inner cases 4 have a shape with ribs 13, 14 that are convex on the inside and an embossment 15 in the center, and the inner case 4 immediately after the exhaust gas inlet 1 and the catalyst bed. An upper chamber 8 is formed between the exhaust gas and the upper surface of the catalyst bed 6, and the exhaust gas is uniformly distributed and distributed from the upper surface to the lower surface of the catalyst bed 6 through this upper chamber 8, and is purified by contact reaction with the catalyst. Ru.

As shown in FIG. 3, an inlet pipe 10 having a throttle 9 on the inner end side is attached to the exhaust gas inlet 1 portion.

When the throttle 9 is provided at the exhaust gas inlet 1 in this way, the pulsating pressure of the exhaust gas is alleviated by the throttle effect and enters the upper chamber 8, where it rapidly expands and is diffused. Noise caused by vibration etc. is significantly reduced.

By installing the above-mentioned throttle 9, the noise level outside the vehicle was reduced by 1.0 dB (A characteristic) at a position of 10 m from the start of full throttle acceleration from 4500 rpm in 2nd gear, 7.5 m on the left side and 1.5 m in height in an actual vehicle test. .

In addition, the relationship between the noise level (A characteristic) and engine speed during full acceleration in second gear at a position 10 cm to the side of case 3 is compared to that without throttle 9 (solid line) as shown in Figure 5. It was confirmed that the noise prevention effect of the one with diaphragm 9 (dotted line) was significantly lowered by about 10 dB in some areas.

The one shown in Fig. 4 is a dual-internal and external exhaust pipe 1 with a heat-insulating structure connected to the inlet side of the purifier.
The ends of the inner tubes 11 of Nos. 1 and 12 are extended and inserted into the upper chamber 8 of the purifier, and a throttle 16 is formed in this portion.

In this case as well, the same effect as in the case of FIG. 3 is obtained.

The aperture diameters of the apertures 9 and 16 described above are determined from the aspects of sound, engine output, and exhaust gas (AS system, EGR system).

Note that the present invention is not limited to the exhaust purification device of the embodiment shown in the drawings, but can also be applied to a catalyst bed having a cylindrical shape, a catalyst bed disposed orthogonally to the flow direction of exhaust gas, and a catalyst bed using a granular catalyst. , it is fully applicable to those employing a honeycomb structure.

Effects of the invention This invention is based on an exhaust gas purification system in which the outer case has a flat rectangular shape, and a restriction is provided at the end of the inlet pipe that has a highly rigid part such as a flange on the exhaust gas inlet side. It absorbs and alleviates the pulsating pressure of the exhaust gas, suppresses membrane vibration of the case, and reduces noise. Moreover, since the member provided with the restriction is the inlet pipe end having a highly rigid part such as a flange, this does not cause membrane vibration and does not become a new source of noise. Since the exhaust pulsation is absorbed and relaxed on the inlet side of the exhaust purification device, it is possible to suppress wear and tear on the catalyst due to the exhaust pulsation. Furthermore, since the above-mentioned aperture is simply formed at the end of the existing inlet pipe, there is no need to use a separate member, and the present invention can be implemented easily and inexpensively.

[Brief explanation of the drawing]

Fig. 1 is a schematic cutaway side view showing an example of an exhaust gas purification device to which the present invention is applied, Fig. 2 is a plan view thereof, and Figs. 3 and 4 are parts to which the present invention is applied to the exhaust gas inlet. Two examples are shown in enlarged sectional views, and FIG. 5 is a comparison diagram of noise characteristics between an exhaust gas purification device to which the present invention is applied and a conventional device. 1...Exhaust gas inlet, 2...Exhaust gas outlet, 3
...Outer case, 4...Inner case, 6...Catalyst bed, 8...Upper chamber, 9, 16...Aperture.

Claims (1)

[Scope of utility model registration request] An exhaust gas purification device having a flat rectangular outer case, characterized in that a throttle is provided at the end of an inlet pipe that has a highly rigid part such as a flange on the exhaust gas inlet side.