Exhaust gas purification device for internal combustion engines

Abstract

In an exhaust gas purification device having a cone section on the upstream side, the pressure pulsation of the incoming exhaust gas is reliably attenuated, improving the purification efficiency of the catalyst carrier. [Solution] A tapered cone section is provided upstream of the outer cylinder housing the catalyst carrier, a small diameter section is provided upstream of the cone section that communicates with the exhaust gas flow path, a pre-chamber is provided between the cone section and the catalyst carrier inside the outer cylinder, a resonance chamber is provided at least on the outer surface of the outer cylinder of the pre-chamber, and the resonance chamber and the pre-chamber are connected by a resonance neck pipe.

Description

Technical Field

[0001] The present invention relates to an exhaust gas purification device for an internal combustion engine.

Background Art

[0002] An exhaust gas purification device that is installed in the exhaust pipe of an internal combustion engine and purifies the exhaust gas discharged from the internal combustion engine is also called a catalytic converter, and a catalyst carrier is housed inside it. Although the exhaust gas discharged from the internal combustion engine has exhaust pulsation, it is known that the exhaust pulsation affects the purification efficiency of the catalyst carrier, and it is required to weaken the exhaust pulsation before the exhaust gas flows into the catalyst carrier. For this purpose, it is known that it is effective to provide a large-volume space upstream of the catalyst carrier in the catalytic purification device, but it has been difficult to achieve due to reasons such as inability to secure mounting space for vehicles, etc., and causing a decrease in the temperature of the exhaust gas.

[0003] Therefore, as an alternative means, for example, as disclosed in Patent Document 1, it has been proposed to provide protrusions on the inner surface of the exhaust pipe upstream of the catalytic purification device and merge the generated Karman vortices into the exhaust gas to reduce the exhaust pulsation (pulsation amplitude). Further, in Patent Document 2 and Patent Document 3, it has been proposed to form a resonance chamber outside the upstream cone portion of the exhaust gas purification device and connect a neck pipe to the cone portion, thereby reducing the exhaust pulsation by the resonance effect of the Helmholtz resonator and achieving silencing of a specific frequency.

[0004]

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0006] However, in the method of providing a protrusion on the inner surface of the exhaust pipe upstream of the catalyst support, there is a concern that the resulting turbulence may actually hinder the uniform inflow of exhaust gas to the front of the catalyst support, resulting in uneven inflow and failure to obtain the desired purification efficiency. Furthermore, in the method of providing a resonator in the tapered section of the exhaust gas purification device and connecting it to a resonant neck pipe, the resonant neck pipe opens in the tapered section where the exhaust gas expands and its flow velocity decreases, making it difficult for pressure fluctuations to enter the resonator, resulting in a problem of weak exhaust pulsation damping effect due to resonance.

[0007] In view of the above-mentioned problems, the present invention aims to provide an exhaust gas purification device for an internal combustion engine that has a tapered cone portion on the upstream side, which can reliably attenuate the pressure pulsation of the incoming exhaust gas and improve the purification efficiency of the catalyst carrier. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides an exhaust gas purification device interposed in the exhaust passage of an internal combustion engine, having a catalyst carrier for purifying exhaust gas, comprising: a tapered cone portion provided upstream of an outer cylinder housing the catalyst carrier; a small-diameter portion provided upstream of the cone portion and connected to the exhaust gas passage; a pre-chamber provided between the cone portion and the catalyst carrier inside the outer cylinder; and a resonance chamber provided at least on the outer surface of the outer cylinder of the pre-chamber, with the resonance chamber and the pre-chamber connected by a resonance neck pipe. [Effects of the Invention]

[0009] According to the present invention, in an exhaust gas purification device having a cone portion on the upstream side, the pressure pulsation of the incoming exhaust gas can be reliably attenuated, thereby improving the purification efficiency of the catalyst carrier. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of an exhaust gas purification device according to the first embodiment of the present invention. [Figure 2] Cross-sectional view of an exhaust gas purification device according to a second embodiment of the present invention. [Figure 3] Cross-sectional view of an exhaust gas purification device according to a third embodiment of the present invention. [Figure 4] Cross-sectional view of an exhaust gas purification device according to a fourth embodiment of the present invention. [Figure 5] Cross-sectional view of an exhaust gas purification device according to a fifth embodiment of the present invention. [Figure 6] Cross-sectional view of an exhaust gas purification device according to a sixth embodiment of the present invention. [Figure 7] Cross-sectional view of an exhaust gas purification device according to a seventh embodiment of the present invention. [Figure 8] Cross-sectional view of an exhaust gas purification device according to an eighth embodiment of the present invention. [Figure 9] Cross-sectional view of an exhaust gas purification device according to a ninth embodiment of the present invention. [Figure 10] Cross-sectional view of an exhaust gas purification device according to a tenth embodiment of the present invention. [Figure 11] Cross-sectional view of an exhaust gas purification device according to an eleventh embodiment of the present invention. [Figure 12] Vertical / cross-sectional view of an exhaust gas purification device according to a twelfth embodiment of the present invention. [Figure 13] Cross-sectional view of an exhaust gas purification device according to a thirteenth embodiment of the present invention. [Figure 14] Cross-sectional view of an exhaust gas purification device according to a fourteenth embodiment of the present invention. [Figure 15] Cross-sectional view of an exhaust gas purification device according to a fifteenth embodiment of the present invention. [Figure 16] Cross-sectional view of an exhaust gas purification device according to a sixteenth embodiment of the present invention. [Figure 17] Cross-sectional view of an exhaust gas purification device according to a seventeenth embodiment of the present invention. [Figure 18] Cross-sectional view of an exhaust gas purification device according to an eighteenth embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, desirable embodiments of the present invention will be described with reference to FIGS. 1 to 18. In this embodiment, the internal combustion engine and the exhaust gas purification device are shown in a state of being mounted on a vehicle or the like and operating, and the left side of the figure is taken as the exhaust upstream direction where an internal combustion engine not shown is present, and will be described below.

[0012] (First Embodiment) FIG. 1 shows a cross-sectional view of an exhaust gas purification device 1 according to the first embodiment of the present invention. The exhaust gas purification device 1 includes an outer cylinder 2, an upstream cone portion 3, an upstream small-diameter portion 4, a downstream cone portion 5, and a downstream small-diameter portion 6. The housing of the exhaust gas purification device 1 is the outer cylinder 2 and is cylindrical, but the cross-section may be rectangular or polygonal. The upstream cone portion 3 is provided on the upstream side of the outer cylinder 2 and has a tapered shape that tapers toward the upstream. The upstream small-diameter portion 4 is formed at the upstream end of the upstream cone portion 3. Further, on the downstream side of the outer cylinder 2, a downstream cone portion 5 that tapers toward the downstream is provided, and a downstream small-diameter portion 6 is formed at the downstream end of the downstream cone portion 5.

[0013] And, inside the outer cylinder 2 near the downstream, a catalyst carrier 8 is firmly held via a buffer material (ceramic mat) 7. In this embodiment, the catalyst carrier 8 assumes a three-way catalyst, but is not limited thereto, and may be a catalyst carrier such as an oxidation catalyst (DOC), a NOx selective reduction catalyst (SCR), a NOx storage reduction catalyst (LNT), or a catalyst carrier with a heater. And, a pre-chamber 9 which is a space is formed on the upstream side of the catalyst carrier 8 in the outer cylinder 2, and a post-chamber 10 is formed on the downstream side, and the pre-chamber 9 is set to have a larger space capacity than the post-chamber 10.

[0014] A covering case 11 is provided on the outer surface of the front chamber 9 in the outer cylinder 2, and the annular gap between the outer surface of the outer cylinder 2 and the inner surface of the covering case 11 is formed as a resonance chamber 15, which will be described later. The covering case 11 is positioned outside the outer cylinder 2 with a gap, and the resonance chamber 15 is formed by the outer cylinder 2 and the covering case 11. More specifically, the covering case 11 has a central large-diameter section 12, and a variable-speed section 14 and a connecting section 13 are integrally formed on the upstream and downstream sides thereof, and the inner surface of the connecting section 13 is in close contact with the outer surface of the outer cylinder 2 and is airtightly fixed by welding or the like.

[0015] In the front chamber 9 of the outer cylinder 2, a tubular resonant neck pipe 16, which constitutes a Helmholtz resonator, is airtightly fixed by welding or the like, passing through the opening 17. The Helmholtz resonator is formed by the aforementioned resonant chamber 15 and the resonant neck pipe 16. Furthermore, an upstream exhaust passage (not shown), which is connected to an upstream internal combustion engine (not shown), is airtightly connected to the upstream small-diameter section 4 of the exhaust purification device 1 by welding or the like. The resonant neck pipe 16 is an example in which a tubular body is provided that passes through the outer cylinder as the resonant neck pipe of a Helmholtz resonator.

[0016] The attenuation of exhaust pulsation in the exhaust purification device 1 with this configuration will now be explained. Exhaust gas with significant exhaust pulsation discharged from the internal combustion engine flows down the upstream exhaust passage and enters the exhaust purification device 1 from the upstream small-diameter section 4. As the exhaust gas passes through the upstream cone section 3, which gradually expands in diameter toward the downstream, its pressure and velocity decrease due to expansion, but it enters the pre-chamber 9 while maintaining significant exhaust pulsation.

[0017] The pre-chamber 9 is connected to a Helmholtz resonator consisting of a resonant neck pipe 16 and a resonant chamber 15. As is well known, the resonant frequency (natural frequency) of a Helmholtz resonator is determined by the speed of sound of the incoming gas, the volume of the resonant chamber, and the length and inner diameter of the resonant neck pipe, and exhaust gas pulsations are attenuated over a wide frequency range centered on the resonant frequency. Therefore, when exhaust gas flows from the pre-chamber 9 to the front of the catalyst carrier 8, the exhaust gas pulsations are significantly attenuated, allowing it to flow uniformly across the front of the catalyst carrier 8. This enables it to react completely with the catalyst supported in each cell (flow channel) of the catalyst carrier 8, thereby improving exhaust gas purification efficiency.

[0018] Furthermore, since the resonance chamber 15 is an annular space located outside the outer cylinder 2 and shares its outer surface with the outer cylinder 2, it is easy to secure volume while suppressing an increase in the outer diameter of the exhaust gas purification device, minimizing the deterioration of mountability in vehicles and the like. In addition, the annular space of the resonance chamber 15 creates a heat retention effect in the pre-chamber 9, suppressing the cooling of exhaust gas within the pre-chamber 9 and allowing it to flow into the catalyst carrier 8. Moreover, the annular space and the covering case 11 act as an insulating layer and insulating material, suppressing heat dissipation and thus also having the effect of suppressing heat damage to surrounding components.

[0019] Although the exhaust gas purification device 1 in this embodiment is a catalytic converter alone, integrating it with the exhaust manifold allows for attenuation of exhaust pulsations at locations where the exhaust gas temperature is high and exhaust pulsations are pronounced upstream, thereby more effectively improving the purification rate. Of course, it may also be installed as a standalone unit at an intermediate or downstream position in the vehicle's exhaust system, as in conventional designs, or it may be incorporated into the muffler.

[0020] (Second Embodiment) Figure 2 shows a cross-sectional view of an exhaust gas purification device 20 according to a second embodiment of the present invention. Note that the same numbering is omitted for components identical to those in the first embodiment, and the same applies to the following embodiments. The exhaust gas purification device 20 differs from the exhaust gas purification device 1 in its resonant neck pipe 216 and opening 217. The resonant neck pipe 216 is canopy-shaped or trough-shaped and is positioned within the resonant chamber 15. It is airtightly fixed with its side wall end in contact with the outer cylinder 2, forming a tunnel-shaped flow path inside, and functioning as a substitute for the annular resonant neck pipe 16. It is important to note that the cross-sectional area of ​​the tunnel-shaped flow path of the resonant neck pipe 216 and the cross-sectional area of ​​the opening 217 should be equal.

[0021] Since the resonant neck pipe 16 of the exhaust gas purification device 1 extends radially (radially) in the outer cylinder 2, the diameter of the covering case 11 would increase if it were necessary to secure the length by setting the resonance frequency. However, in this embodiment, the resonant neck pipe 216 can be extended in the axial direction, making it easier to extend the resonant neck pipe 216.

[0022] (Third embodiment) Figure 3 shows a cross-sectional view of an exhaust gas purification device 30 according to a third embodiment of the present invention. In the exhaust gas purification device 30, a resonant neck pipe 316 having the same shape as the canopy-shaped or trough-shaped resonant neck pipe 216 in the exhaust gas purification device 20 is airtightly fixed to the inner surface of the outer cylinder 2. The resonant neck pipe 316 is provided on the inner surface side of the outer cylinder 2 with respect to the opening 317. In this embodiment as well, it is easy to extend the resonant neck pipe 316 in the axial direction, and it is also easy to increase the inner diameter of the resonant neck pipe 316 by expanding it in the centripetal direction. However, since the resonant neck pipe 316 is exposed in the pre-chamber 9, which is the exhaust gas passage, attention must be paid to the conflicting factors such as increased back pressure.

[0023] (Fourth Embodiment) Figure 4 shows a cross-sectional view of an exhaust gas purification device 40 according to a fourth embodiment of the present invention. The exhaust gas purification device 40 is configured in which the opening direction of the canopy-shaped or trough-shaped resonant neck pipe 316 in the exhaust gas purification device 30 is changed from downstream-facing to upstream-facing. The choice between upstream-facing and downstream-facing should be determined by considering the effect on the exhaust gas flow and the position of the resonant neck pipe 416.

[0024] (Fifth embodiment) Figure 5 shows a cross-sectional view of an exhaust gas purification device 50 according to a fifth embodiment of the present invention. In the exhaust gas purification device 50, the resonant neck pipe 516 is not tubular but is the opening in the outer cylinder 2 itself, and the length of the resonant neck pipe 516 is the plate thickness of the outer cylinder 2. Such a setting is possible when the length of the resonant neck pipe is not required for tuning the resonant frequency. The resonant neck pipe 516 is an example in which an opening drilled in the outer cylinder 2 is provided as the resonant neck pipe.

[0025] (Sixth Embodiment) Figure 6 shows a cross-sectional view of an exhaust gas purification device 60 according to the sixth embodiment of the present invention. The exhaust gas purification device 60 has a configuration in which the single opening resonant neck pipe 516 in the exhaust gas purification device 50 is multiplied. Three openings, which are resonant neck pipes 616, are drilled above the outer cylinder 62 (upper part of the figure), and three openings, which are resonant neck pipes 617, are drilled below the outer cylinder 2 (lower part of the figure), providing a total of six resonant neck pipes. In this embodiment as well, it is possible to improve the degree of freedom in setting the neck pipes when tuning the resonance frequency. Note that more openings (resonant neck pipes) than those shown may be provided.

[0026] (Seventh Embodiment) Figure 7 shows a cross-sectional view of an exhaust gas purification device 70 according to the seventh embodiment of the present invention. The exhaust gas purification device 70 has a second covering case 711 inside the covering case 11 of the exhaust gas purification device 1. Therefore, a second resonance chamber 715 is formed inside the second covering case 711, and the second resonance chamber 715 is connected to the resonance chamber 15 by a second resonance neck tube 717, forming a so-called tandem type double cushion resonator.

[0027] The tandem resonator design allows for tuning to two specific resonant frequencies, contributing to pulsation attenuation across a wider frequency range. Furthermore, the presence of two resonant chambers and two resonant necks increases the flexibility of the layout configuration.

[0028] (Eighth embodiment) Figure 8 shows a cross-sectional view of an exhaust gas purification device 80 according to the eighth embodiment of the present invention. The exhaust gas purification device 80 has a covering case 811 which is an extension of the covering case 11 of the exhaust gas purification device 50 in the downstream direction. This significantly increases the volume of the resonance chamber 815, improving the degree of tuning freedom. In addition, since it covers almost the entire area of ​​the outer cylinder 2, the heat retention and insulation functions can also be expanded.

[0029] (Ninth Embodiment) Figure 9 shows a cross-sectional view of an exhaust gas purification device 90 according to the ninth embodiment of the present invention. The exhaust gas purification device 90 has a configuration in which the covering case 811 of the exhaust gas purification device 80 is extended to the maximum extent in the downstream direction and fixed to the downstream small diameter section 6 by a wall section 917 and a connecting section 918. This makes it possible to further increase the volume of the resonance chamber 915.

[0030] (Tenth embodiment) Figure 10 shows a cross-sectional view of an exhaust gas purification device 100 according to the tenth embodiment of the present invention. The exhaust gas purification device 100 has a covering case 1011 that is extended to the maximum extent in the upstream direction and fixed to the upstream small diameter section 4 by a wall section 1017 and a connecting section 1018. This also allows the volume of the resonance chamber 1015 to be increased.

[0031] (11th embodiment) Figure 11 shows a cross-sectional view of an exhaust gas purification device 200 according to the 11th embodiment of the present invention. The exhaust gas purification device 200 is a combination of the covering case 911 of the exhaust gas purification device 90 and the covering case 1011 of the exhaust gas purification device 100, and the covering case 2011 is configured to ensure maximum capacity in both the upstream and downstream directions. The upstream part of the covering case 2011 is fixed to the upstream small diameter part 4 by a wall part 2018 and a connecting part 2019, and the downstream part is fixed to the downstream small diameter part 6 by a wall part 2020 and a connecting part 2021. This allows us to maximize the volume of the resonance chamber 2015.

[0032] (12th embodiment) Figure 12 shows a front view (a) and a cross-sectional view (b) of the exhaust gas purification device 300 according to the twelfth embodiment of the present invention. This configuration is the exhaust gas purification device 50 of the fifth embodiment with the covering case 11 replaced by the covering case 3011. The covering case 3011 does not have an annular space as in the other embodiments, but rather covers a part of the outer cylinder 2 in the axial and circumferential directions.

[0033] A wall portion 3017 and a connecting portion 3018 are formed around the periphery of the roughly hat-shaped covering case 3011, and the lower surface of the connecting portion 3018 is in contact with the outer surface of the outer cylinder 2, and is airtightly fixed by welding or the like. This embodiment is suitable when the resonance chamber does not require a volume up to the annular space as in other embodiments, and a small volume is sufficient.

[0034] (Implementations 13-18) The 13th to 18th embodiments of the present invention, shown in Figures 13 to 18, are embodiments in which a rear chamber is further provided in the outer cylinder downstream of the catalyst carrier, and a second resonance chamber is added to the outer surface of the outer cylinder extending at least to the rear chamber, and the rear chamber and the second resonance chamber are connected by a second resonance neck pipe. In addition to the attenuation of exhaust gas pulsation by the front chamber side resonance chamber in the 1st to 12th embodiments, exhaust gas pulsation is also attenuated by the second resonance chamber on the rear chamber side, so that exhaust gas can flow more uniformly across the front of the catalyst carrier, and the exhaust gas purification efficiency can be further improved.

[0035] Furthermore, the exhaust gas, which becomes hot during the catalytic reaction as it passes through the catalyst support, flows into the second resonance chamber, heating and maintaining the temperature of the catalyst support from the outside of the outer cylinder. This allows for early catalytic activation and easier maintenance of catalytic activity, further contributing to exhaust gas purification.

[0036] (13th Embodiment) Figure 13 shows a cross-sectional view of an exhaust gas purification device 400 according to the thirteenth embodiment of the present invention. The exhaust gas purification device 400 differs from the exhaust gas purification device 1 in that the outer cylinder is extended downstream to form an outer cylinder 1410, a rear chamber 1420 is provided downstream of the catalyst carrier 8, and a covering case 1430 is provided on the outer circumferential surface of the outer cylinder 1410 extending into the rear chamber 1420, thereby providing an annular second resonance chamber 1440. On the upstream side of the covering case 1430, a tapered wall portion 1432 and a connecting portion 1431 are provided at its tip, and on the downstream side, a tapered wall portion 1434 and a connecting portion 1433 are provided at its tip, and the connecting portions 1431 and 1433 are hermetically fixed to the outer surface of the outer cylinder 1410.

[0037] The second resonance chamber 1440 and the rear chamber 1420, defined by the covering case 1430, are connected by a second resonance neck pipe 1450. The canopy-shaped or trough-shaped second resonance neck pipe 1450 is fixed to the inner surface of the outer cylinder 1410 inside the rear chamber 1420, and the tunnel-shaped flow path of the second resonance neck pipe 1450 is positioned to face upstream.

[0038] With this configuration, as described above, in addition to the attenuation of exhaust gas pulsation by the front-side resonance chamber in the first to twelfth embodiments, the exhaust gas pulsation is also attenuated by the second resonance chamber on the rear side, further improving exhaust gas purification efficiency. In particular, since the tunnel-shaped flow path of the second resonance neck pipe 1450 is positioned to protrude into the rear chamber 1420 and face upstream, the high-temperature exhaust gas discharged from the catalyst carrier 8 can be forcibly introduced into the second resonance neck pipe 1450 and the second resonance chamber 1440, thereby improving the heating and heat retention performance of the catalyst carrier.

[0039] (14th Embodiment) Figure 14 shows a cross-sectional view of an exhaust gas purification device 500 according to the 14th embodiment of the present invention. The exhaust gas purification device 500 has a configuration in which an upstream covering case 11 and a downstream covering case 1430 are integrated with the exhaust gas purification device 400. The covering case 1510 extends over the entire area of ​​the outer cylinder 1410, and a tapered wall portion 1512 and a connecting portion 1511 are provided on the upstream side of the covering case 1510, and a tapered wall portion 1514 and a connecting portion 1513 are provided on the downstream side, and the connecting portions 1511 and 1513 are airtightly fixed to the outer surface of the outer cylinder 1410. A donut-shaped partition plate 1520 is sandwiched between the covering case 1510 and the outer cylinder 1410, and the partition plate 1520 defines a resonance chamber 1516 and a second resonance chamber 1517.

[0040] According to this embodiment, the covering case can be used in common with the exhaust gas purification device 400 according to the 13th embodiment, which simplifies the component configuration and assembly work, and also allows for a larger volume of the resonance chamber.

[0041] (15th Embodiment) Figure 15 shows a cross-sectional view of an exhaust gas purification device 600 according to the 15th embodiment of the present invention. The exhaust gas purification device 600 is a combination of the exhaust gas purification device 400 of the 13th embodiment and the exhaust gas purification device 500 of the 14th embodiment, and is configured in which a covering case 11 is further provided inside a common covering case 1610. The covering case 1610 extends over the entire area of ​​the outer cylinder 1410, and a tapered wall portion 1612 and a connecting portion 1611 are provided on the upstream side of the covering case 1610, and a tapered wall portion 1614 and a connecting portion 1613 are provided on the downstream side, and the connecting portions 1611 and 1613 are airtightly fixed to the outer surface of the outer cylinder 1410. A resonance chamber 1615 defined by the covering case 11 can be placed inside a second resonance chamber 1616 defined by the covering case 1610.

[0042] According to this embodiment, compared to the exhaust gas purification device 500 according to the 14th embodiment, the resonance chamber 1615 can be placed inside the second resonance chamber 1616, so that the resonance chamber 1615 can be kept warm, which can contribute to accelerating the temperature rise of the catalyst, especially during warm-up.

[0043] (16th Embodiment) Figure 16 shows a cross-sectional view of an exhaust gas purification device 700 according to the 16th embodiment of the present invention. The exhaust gas purification device 700 is configured by adding a second resonant neck pipe 1710 to the exhaust gas purification device 500 according to the 14th embodiment. The second resonant neck pipe 1710 is airtightly fixed to the inner surface of the outer cylinder 1420, similar to the second resonant neck pipe 1450, and its opening faces downstream.

[0044] By connecting the two second resonance neck tubes 1450 and 1711 to the second resonance chamber 1711, the bandwidth of the resonance frequency can be set wider, and the exhaust attenuation effect and frequency range can be set wider.

[0045] (17th Embodiment) Figure 17 shows a cross-sectional view of an exhaust gas purification device 800 according to the 17th embodiment of the present invention. The exhaust gas purification device 800 is configured in a way that, compared to the exhaust gas purification device 700 according to the 16th embodiment, a donut-shaped slit second resonant neck pipe 1814 is provided instead of two second resonant neck pipes 1450 and 1711. To provide the second resonant neck pipe 1814, a separate second outer cylinder 1811 is provided downstream of the outer cylinder 1810. A tapered section 1812 and a straight section 1813 are formed upstream of the second outer cylinder 1811, and a donut-shaped slit second resonant neck pipe 1814 is formed between the tapered section 1812 and the straight section 1813 and the rear end edge of the outer cylinder 1810.

[0046] This configuration allows for greater flexibility in tuning, particularly when you want to set a larger cross-sectional area for the second resonance neck.

[0047] (18th embodiment) Figure 18 shows a cross-sectional view of an exhaust gas purification device 900 according to the 18th embodiment of the present invention. Compared to the exhaust gas purification device 700 according to the 16th embodiment, the exhaust gas purification device 900 is provided with a second resonant neck pipe 1913 which is an open hole instead of the two second resonant neck pipes 1450 and 1711, and the covering case 1920 is extended to the downstream end. The second resonant neck pipe 1913 is a plurality of holes drilled in the downstream cone portion 1911 at the rear end of the outer cylinder 1920. The covering case 1920 has a mounting portion 1922 externally fitted and fixed to the outside of the downstream small diameter portion 1912, which is the downstream end of the outer cylinder 1920.

[0048] This configuration allows for greater flexibility in tuning, particularly when it is desirable to reduce the cross-sectional area of ​​the second resonance neck and increase the volume of the second resonance chamber.

[0049] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and any changes in scope that deviate from the spirit of the present invention are still included within the scope of the present invention. [Explanation of Symbols]

[0050] 1, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 400, 500, 600, 700, 800, 900 Exhaust purifying device 2, 62, 1410, 1420, 1810, 1910 Outer cylinder 3. Upstream cone section 4. Upstream small diameter section 5. 1911 Downstream cone section 6, 1912 Downstream small diameter section 7. Cushioning material 8 Catalyst support 9. Vestibule 10, 1420 posterior chamber 11, 1011, 2011, 3011, 1430, 1510, 1610, 1920 Covered Case 15, 1015, 2015, 3015, 1516, 1615, 1816, 1924 Resonance chamber 1440, 1517, 1616, 1711, 1815, 1923 Second resonance chamber 16, 216, 316, 416, 516, 616, 716, 816, 916, 1016, 2016, 3016 Resonant neck tube 1450, 1710, 1814, 1913 2nd resonance neck

Claims

1. An exhaust gas purification device having a catalyst carrier for purifying exhaust gases and being installed in the exhaust passage of an internal combustion engine, A tapered cone portion is provided on the upstream side of the outer cylinder that houses the catalyst support, A small-diameter portion is provided on the upstream side of the cone portion and is connected to the exhaust gas passage, A pre-chamber provided between the cone portion and the catalyst carrier within the outer cylinder, It comprises at least a resonance chamber provided on the outer surface of the outer cylinder of the front chamber, An exhaust gas purification device for an internal combustion engine, wherein the resonance chamber and the pre-chamber are connected by a resonance neck pipe.

2. The exhaust gas purification device for an internal combustion engine according to claim 1, wherein the resonance chamber is formed by the outer cylinder and a covering case disposed outside the outer cylinder with a gap between them.

3. The exhaust gas purification device for an internal combustion engine according to claim 1 or 2, wherein the resonant neck pipe is an opening drilled in the outer cylinder or a pipe body that penetrates the outer cylinder.

4. A rear chamber is further provided on the downstream side of the catalyst carrier within the outer cylinder. At least the outer surface of the outer cylinder of the rear chamber is provided with a second resonance chamber, The exhaust gas purification device for an internal combustion engine according to claims 1 to 3, wherein the second resonance chamber and the rear chamber are connected by a second resonance neck pipe.

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