JP2007239503A - Exhaust emission control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contribute to improvement in exhaust emission control efficiency by allowing an increase in the effective passage length of a catalytic converter without an increase in the whole length of the catalytic converter. <P>SOLUTION: In an exhaust emission control device for an engine, the catalytic converter 10 is disposed to exhaust passages 5, 6 of the engine E. An exhaust inlet chamber 21 is formed to connect upstream parts of the exhaust passages to one end of the catalytic converter 10, and an exhaust outlet chamber 22 is formed to connect downstream parts of the exhaust passages 5, 6 thereto, so that the chambers communicate with catalyst chambers 25, 26 of the catalytic converter 10 in parallel to each other. The other end of the catalytic converter 10 is provided with an exhaust inverting chamber 23 guiding exhaust gas which flows from the exhaust inlet chamber 21 and passes through the catalyst chambers 25, 26 into the exhaust outlet chamber 22 through the catalyst chambers 25, 26 again. When the total volume of the catalyst chambers 25, 26 is A, and the volume of the exhaust inverting chamber 23 is B, A/B is set to be 0.1 to 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement in an exhaust emission control device for an engine in which a catalytic converter is interposed in an exhaust passage of the engine.

Such an exhaust emission control device for an engine is already known as disclosed in Patent Documents 1 and 2.
Japanese Utility Model Publication No. 60-29625 JP-A-8-68316

  In conventional exhaust purification systems for such engines, the exhaust to be purified is allowed to flow in one direction through the catalytic converter. Therefore, if an attempt is made to increase the exhaust gas purification efficiency by increasing the flow length of the catalytic converter, the catalyst The overall length of the converter becomes longer, leading to an increase in the length of the engine exhaust system.

  The present invention has been made in view of such circumstances, and can increase the effective flow path length in the catalytic converter without increasing the total length of the catalytic converter, and can contribute to the improvement of exhaust purification efficiency. An object of the present invention is to provide an exhaust purification device.

In order to achieve the above object, the present invention provides an exhaust purification apparatus for an engine, wherein a catalytic converter is interposed in an exhaust passage of the engine, and an exhaust introduction chamber for connecting an upstream portion of the exhaust passage to one end of the catalytic converter. And an exhaust lead-out chamber connecting the downstream part of the exhaust passage so that they communicate in parallel with the catalyst chamber of the catalytic converter, while the other end of the catalytic converter is connected to the exhaust introduction chamber When an exhaust gas reversing chamber for guiding the exhaust gas that has passed through the catalyst chamber to the exhaust gas exhausting chamber again through the catalyst chamber is formed, and the total volume A of the catalyst chamber and the volume of the exhaust gas reversing chamber are B, the following ( 1) Formula
0.1 <A / B <4 (1)
The first feature is to establish the above.

  The exhaust path corresponds to the exhaust pipe 5 and the exhaust muffler 6 of the embodiment of the present invention described later.

  According to the present invention, in addition to the first feature, the catalyst chamber is divided into a first catalyst chamber connected to the exhaust introduction chamber and a second catalyst chamber connected to the exhaust lead-out chamber. A second feature is that the two catalyst chambers communicate with each other through the exhaust gas reversal chamber.

  Furthermore, in addition to the second feature, the present invention has a third feature that the first catalyst chamber and the second catalyst chamber are formed so that one of them surrounds the other.

  Furthermore, the present invention is characterized in that, in addition to the second or third feature, a partition member for partitioning both chambers is disposed between the first catalyst chamber and the second catalyst chamber.

  The partition member corresponds to a partition tube 28 in an embodiment of the present invention described later.

  Furthermore, in addition to any of the first to fourth features, the present invention has a fifth feature that the catalytic converter is disposed directly under the engine.

  Furthermore, the present invention is characterized in that, in addition to any of the first to fourth features, the catalytic converter is disposed in an exhaust muffler in the exhaust passage.

  According to the first feature of the present invention, in the catalytic converter, the exhaust gas that has passed from the exhaust introduction chamber to the catalyst chamber is reversed in the exhaust reversal chamber, passed again to the catalyst chamber, and then guided to the exhaust lead-out chamber. The exhaust gas reciprocates in the catalyst chamber, and therefore the total flow path length of the catalyst chamber is substantially twice the total length of the catalytic converter, so the catalytic converter is effective without increasing the total length of the catalytic converter. The flow path length can be greatly increased, and the exhaust purification system can be made compact.

  In addition, the forward and backward flow of exhaust gas in the catalyst chamber mutually heats up, so that the first and second catalyst chambers can be activated early after the engine is started, and exhaust purification efficiency is effectively improved. It can contribute to the improvement.

  Furthermore, by setting the ratio of the volume A of the catalyst chamber to the volume B of the exhaust gas reversing chamber, that is, A / B, is set to 0.1 to 4.0, at least a decrease in engine output performance can be avoided.

  According to the second feature of the present invention, in the catalytic converter, interference between the forward flow of the exhaust gas passing through the first catalyst chamber and the return flow passing through the second catalyst chamber is avoided, and the back pressure of the engine is reduced. The increase can be suppressed and the output performance of the engine can be improved.

  According to the third feature of the present invention, the contact area between the first and second catalyst chambers can be obtained easily and activation of the first and second catalyst chambers can be further promoted.

  According to the fourth aspect of the present invention, in the catalytic converter, interference between the forward flow of the exhaust gas passing through the first catalyst chamber and the return flow passing through the second catalyst chamber is reliably avoided, and the back of the engine. This can suppress the increase in pressure and contribute to the improvement of engine output performance.

  According to the fifth feature of the present invention, it is possible to install a compact catalytic converter using a dead space directly under the engine.

  According to the sixth aspect of the present invention, a compact catalytic converter can be installed by using the dead space in the exhaust muffler, and the catalytic converter can be kept warm by the exhaust muffler, so that its early activation is effective. The noise reduction effect can be enhanced by the catalytic converter.

  Hereinafter, embodiments of the present invention will be described based on preferred examples shown in the accompanying drawings.

  FIG. 1 is a side view of a motorcycle equipped with an exhaust emission control device for an engine according to a first embodiment of the present invention, FIG. 2 is an enlarged side view around the engine in FIG. 1, and FIG. 4 is an enlarged longitudinal sectional view of the exhaust purification device taken along line 4-4 in FIG. 3, FIG. 5 is a sectional view taken along line 5-5 in FIG. 4, and FIG. 6 shows a second embodiment of the present invention. FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 6, FIG. 8 is a diagram corresponding to FIG. 6 showing a third embodiment of the present invention, and FIG. 9 is a diagram showing a fourth embodiment of the present invention. FIG. 10 is a sectional view taken along line 10-10 of FIG. 9, FIG. 11 is a longitudinal sectional view of an exhaust muffler showing a fifth embodiment of the present invention, and FIG. It is a performance comparison diagram.

  First, the description starts with the description of the first embodiment of the present invention shown in FIGS.

  In FIG. 1, a motorcycle M is configured by mounting an engine E that drives a rear wheel 2r at the center of a vehicle body 1 that supports a front wheel 2f and a rear wheel 2r. The engine E is a four-cycle type in which the cylinder portion 4 protrudes slightly upward from the front surface of the crankcase 3, and an exhaust pipe 5 communicating with an exhaust port inside the cylinder portion 4 is attached to the lower surface of the cylinder portion 4. The exhaust muffler 6 disposed on one side of the rear wheel 2r is connected to the rear end of the exhaust pipe 5.

  As shown in FIGS. 2 and 3, an exhaust purification device D having a cylindrical catalytic converter 10 is provided in the middle of the exhaust pipe 5. This exhaust purification device D has its both ends in the long hole direction facing the left and right direction of the motorcycle M, directly below the crankcase 3 and within its lateral width, and in front of the step bar 11 that is bolted to the bottom surface of the crankcase 3. Be placed. Thus, the dead space directly under the engine E is used for the arrangement of the exhaust purification device D, and the influence of heat from the exhaust purification device D on the left and right steps 12, 12 attached to both ends of the step bar 11 is avoided. Can do.

  The exhaust pipe 5 is divided into an exhaust upstream pipe 5a connected to the engine E and an exhaust downstream pipe 5b connected to the exhaust muffler 6 with the exhaust purification device D as a boundary, and the exhaust upstream and downstream pipes 5a and 5b are separated from each other. Both are connected to one end in the longitudinal direction of the exhaust purification device D.

  From the downstream part of the exhaust upstream pipe 5a to the exhaust downstream pipes 5a and 5b, a protector plate 13 that covers the outer surfaces thereof is attached, and an under guard plate 14 that covers the lower surface of the exhaust purification device D is attached.

  4 and 5, the exhaust purification device D includes a cylindrical three-way catalytic converter 10 and dome-shaped first cap 18 and second cap coupled to both ends of the catalytic converter 10 in the long hole direction. 19.

  The catalytic converter 10 is fitted and fixed to the inner peripheral surface of a cylindrical shell 16 whose both ends are open, and has a honeycomb-shaped catalyst carrier 17 having a large number of flow paths 24, 24. The catalyst carrier 17 carries a catalyst such as platinum, rhodium, palladium, etc. facing a large number of flow paths 24, 24. As shown in FIG. 5, for example, the honeycomb-shaped catalyst carrier 17 is made of a stainless steel plate and is formed by closely winding a flat plate 17a and a corrugated plate 17b which are superposed on each other.

  The first and second caps 18 and 19 are fitted and coupled to both ends of the shell 16. The first cap 18 is provided with a partition wall 20 that divides the inside into an exhaust introduction chamber 21 and an exhaust lead-out chamber 22, and an exhaust upstream pipe 5 a and an exhaust downstream pipe 5 b coupled to the first cap 18 are provided in the exhaust introduction chamber. 21 and the exhaust outlet chamber 22 communicate with each other.

  The partition wall 20 is arranged vertically in close proximity to the one end surface so as to bisect the one end surface of the catalyst carrier 17, whereby the plurality of channels 24, 24. The first catalyst chamber 25 communicating with the exhaust introduction chamber 21 and the second catalyst chamber 26 communicating with the exhaust outlet chamber 22 are divided.

  The inside of the second cap 19 is an exhaust reversing chamber 23 that communicates between the first and second catalyst chambers 25 and 26.

  In the above, the total volume A of the first and second catalyst chambers 25 and 26 and the volume B of the exhaust gas reversing chamber 23 are set so that the following equation (1) is established.

0.1 <A / B <4 (1)
Preferably, A / B is set to approximately 1.5.

  Next, the operation of the first embodiment will be described.

  During the operation of the engine E, the exhaust gas exiting from the exhaust port first flows into the exhaust introduction chamber 21 from the exhaust upstream pipe 5a, passes through a number of flow paths 24, 24. It moves to the reversal chamber 23, reverses to the second catalyst chamber 26 side, passes through the multiple flow paths 24, 24... Of the second catalyst chamber 26, moves to the exhaust outlet chamber 22, and flows out to the exhaust downstream pipe 5b.

  By the way, when the catalytic converter 10 having the first and second catalyst chambers 25 and 26 is activated by the heat of the exhaust gas passing through the catalyst converter 10 and the radiant heat from the engine E, the first and second catalyst chambers 25, In NO. 26, NOx in the exhaust gas is reduced to nitrogen gas and CO and HC are oxidized to detoxify these three harmful components. In the catalytic converter 10 of the present invention, the first and second catalyst chambers 25 are provided. , 26 are adjacent to each other in parallel, and the exhaust gas that has passed through the first catalyst chamber 25 is inverted in the exhaust gas reversing chamber 23 so as to pass through the second catalyst chamber 26. Therefore, the first and second catalyst chambers 25, 26 The total flow path length is twice the total length of the catalyst carrier 17. Therefore, the effective flow path length of the catalyst carrier 17 can be significantly increased without increasing the total length of the catalyst carrier 17, and the exhaust purification device can be made compact. As a result, the narrow area directly under the engine E can be achieved. Installation in a dead space is also possible.

  In addition, the first and second catalyst chambers 25 and 26 are mutually heated via their adjacent portions, and the area of the outer peripheral surface of the catalyst carrier 17 is reduced to suppress heat dissipation as much as possible. After the engine E is started, the first and second catalyst chambers 25 and 26 can be activated early, and the exhaust purification efficiency can be effectively improved.

  FIG. 12 shows the relationship between the ratio of the total volume A of the first and second catalyst chambers 25 and 26 to the volume B of the exhaust gas reversing chamber 23, that is, A / B, and the output improvement rate α of the engine E. It is shown based on. Here, the output improvement rate α is the maximum output of the engine E using the device of the present invention P, and the maximum output of the engine E having the conventional device in which the first and second catalyst chambers 25 and 26 are connected in a straight line. When Q is obtained, the following formula is obtained.

α (%) = (P−Q) × 100 / P
The test was carried out by changing the A / B values for three types of engines with displacements of 50 cc, 150 cc and 200 cc.

  As a result, when A / B is set to 0.1 to 4.0, it is confirmed that the engine output improvement rate is set to 0% or more, that is, at least the engine output performance is not deteriorated. When A / B was set to about 1.5, it was confirmed that the output improvement rate could be substantially maximized.

  Next, a second embodiment of the present invention shown in FIG. 6 will be described.

  In the second embodiment, a cylindrical partition wall 20 having a funnel-shaped opening end facing the one end surface of the catalyst carrier 17 is disposed concentrically with the catalyst carrier 17 in the first cap 18. The partition wall 20 is fixed to the first cap 18, and a cylindrical exhaust introduction chamber 21 is defined by the inner peripheral surface of the partition wall 20, and is defined by the outer peripheral surface of the partition wall 20 and the inner peripheral surface of the first cap 18. , An annular exhaust lead-out chamber 22 surrounding the exhaust introduction chamber 21 is defined. Of course, the exhaust upstream pipe 5 a is connected to the exhaust introduction chamber 21, and the exhaust downstream pipe 5 b is connected to the exhaust outlet chamber 22. Since the other configuration is the same as that of the previous embodiment, the same reference numerals are given to the portions corresponding to those of the previous embodiment in FIG. Therefore, also in the second embodiment, the ratio between the total volume A of the first and second catalyst chambers 25 and 26 and the volume B of the exhaust reversing chamber 23, A / B, is set in the same manner as in the first embodiment. Is done.

  According to the second embodiment, the catalyst carrier 17 is provided with a cylindrical partition wall 20 that partitions the inside of the first cap 18 into a columnar exhaust introduction chamber 21 and a cylindrical exhaust lead-out chamber 22 surrounding it. The plurality of flow paths 24, 24... Of the catalyst carrier 17 communicate with the columnar first catalyst chamber 25 communicating with the exhaust introduction chamber 21 and the exhaust lead-out chamber 22. It is divided into a cylindrical second catalyst chamber 26 surrounding the first catalyst chamber 25.

  Therefore, the exhaust gas that has passed through the multiple flow paths 24, 24... Of the first catalyst chamber 25 from the exhaust introduction chamber 21 and has moved to the exhaust gas reversing chamber 23 is reversed while spreading radially, and the second catalyst chamber 26 is exhausted. Since the process proceeds toward the lead-out chamber 22, the first catalyst chamber 25 can be effectively warmed and heated by the second catalyst chamber 26, and the activation of the catalyst carrier 17 can be accelerated. it can.

  Next, a third embodiment of the present invention shown in FIGS. 7 and 8 will be described.

  In the third embodiment, a cylindrical partition tube 28 for partitioning the first catalyst chamber 25 and the second catalyst chamber 26 is disposed on the catalyst carrier 17, and the first cap 18 is provided at one end of the partition tube 28. 7 are connected to each other, and other configurations are the same as those of the second embodiment. Therefore, in FIGS. 7 and 8, the same reference numerals are used for the portions corresponding to the second embodiment. A duplicate description is omitted. Of course, the ratio A / B between the total volume A of the first and second catalyst chambers 25 and 26 and the volume B of the exhaust reversing chamber 23 is set in the same manner as in the first embodiment.

  According to the third embodiment, in the catalyst carrier 17, the first catalyst chamber 25 and the second catalyst chamber 26 are reliably partitioned by the partition cylinder 28, so that the first catalyst chamber 25 faces the exhaust reversal chamber 23. Interference between the forward flow of the exhaust gas and the return flow of the exhaust gas flowing from the second catalyst chamber 26 toward the exhaust lead-out chamber 22 can be reliably avoided, thereby contributing to an improvement in engine output.

  Next, a fourth embodiment of the present invention shown in FIGS. 9 and 10 will be described.

  In the fourth embodiment, the catalytic converter 10 includes a cylindrical shell 16, a partition tube 28 that is integrally connected to the cylindrical partition wall 20 and arranged concentrically in the shell 16, and an inner peripheral surface of the shell 16. The catalyst carrier 17A, 17B, 17C made of a punching plate joined to the outer peripheral surface of the partition tube 28 and the inner peripheral surface of the partition tube 28, and supported on the surfaces of the catalyst support members 17A, 17B, 17C. The partition tube 28 defines a first catalyst chamber 25 on the inside thereof, and the shell 16 and the partition tube 28 surround the first catalyst chamber 25 for fitting. A cylindrical second catalyst chamber 26 is defined.

  Since the other configuration is the same as that of the second embodiment, the same reference numerals are assigned to the portions corresponding to the second embodiment in FIGS. 9 and 10, and the duplicated description is omitted. Of course, also in the fourth embodiment, the ratio of the total volume A of the first and second catalyst chambers 25 and 26 to the volume B of the exhaust reversing chamber 23, A / B, is the same as in the first embodiment. Is set.

  According to the fourth embodiment, the catalyst carrier 17A, 17B, 17C is configured by the punching plate, whereby the configuration of the catalytic converter 10 can be simplified and the cost can be reduced.

  Finally, a fifth embodiment of the present invention shown in FIG. 11 will be described.

  The fifth embodiment corresponds to the exhaust purification device according to the second embodiment provided in the exhaust muffler 6. That is, the downstream end of the exhaust pipe 5 extending from the engine E (see FIG. 1) is connected to the front end of the cylindrical muffler body 30 of the exhaust muffler 6, and the tail pipe 31 that is open to the atmosphere is attached to the rear end. The inside of the muffler body 30 is partitioned into three chambers, a first silencing chamber 34 at the middle, a second silencing chamber 35 at the front side, and a third silencing chamber 36 at the rear side by a pair of front and rear partition plates 32, 34. The catalytic converter 10 that faces both ends from the chamber 34 to the second silencing chamber 35 is attached to the front partition 20.

  The structure of the catalytic converter 10 may be the same as that of the catalytic converter 10 of the first to fourth embodiments, but the catalytic converter 10 of the second embodiment is used in the illustrated example. Therefore, in FIG. 11, the same reference numerals are assigned to the portions corresponding to the second embodiment of the catalytic converter 10, and the duplicate description is omitted.

  The second silencing chamber 35 is provided with a cylindrical partition wall 20 integrally connected to the downstream end of the exhaust pipe 5 and facing the front end surface of the catalyst carrier 17 of the catalytic converter 10, thereby the second silencing chamber. 35 is partitioned into an exhaust introduction chamber 21 inside the partition wall 20 and an exhaust lead-out chamber 22 outside the partition wall 20. Accordingly, the first catalyst chamber 25 is constituted by a large number of flow paths communicating with the exhaust introduction chamber 21 of the catalyst carrier 17, and the first flow paths 24, 24. A second catalyst chamber 26 surrounding the catalyst chamber 25 is configured.

  The exhaust gas that has passed through the first catalyst chamber 25 from the exhaust introduction chamber 21 is reversed in the first silencing chamber 34 and moves to the second catalyst chamber 26, so that the first silencing chamber 34 functions as an exhaust reversing chamber.

  A communication pipe 37 that communicates between the second silencing chamber 35 and the third silencing chamber 36 is attached to the two partition plates 32 and 33.

  The exhaust gas that has passed through the second catalyst chamber 26 and has moved to the exhaust lead-out chamber 22 is transferred to the third silencing chamber 36 through the communication pipe 37 and is discharged from the tail pipe 31 to the atmosphere.

  Thus, by passing through the first and second catalyst chambers 25 and 26, it is purified by the same action as in the previous embodiments, and is silenced by repeating the expansion stepwise.

  According to the fifth embodiment, it is possible to install the compact catalytic converter 10 by using the dead space in the exhaust muffler 6 and to keep the catalytic converter 10 warm by the exhaust muffler 6 and to activate it early. Can be effectively promoted, and the noise reduction effect can be enhanced by the catalytic converter 10.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, A various design change can be performed in the range which does not deviate from the summary of this invention.

1 is a side view of a motorcycle provided with an engine exhaust gas purification apparatus according to a first embodiment of the present invention. The enlarged side view around the engine in FIG. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2. FIG. 4 is an enlarged longitudinal sectional view of the exhaust emission control device taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 5 is a correspondence diagram of FIG. 4 showing a second embodiment of the present invention. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. FIG. 7 is a view corresponding to FIG. 6 showing a third embodiment of the present invention. FIG. 7 is a view corresponding to FIG. 6 showing a fourth embodiment of the present invention. FIG. 10 is a sectional view taken along line 10-10 in FIG. 9; The longitudinal cross-sectional view of an exhaust muffler which shows 5th Example of this invention. The performance comparison diagram of this invention apparatus and a conventional apparatus.

Explanation of symbols

D ... Exhaust gas purification device E ... Engine 5,6 ... Exhaust passage (exhaust pipe, exhaust muffler)
DESCRIPTION OF SYMBOLS 10 ... Catalytic converter 21 ... Exhaust introduction chamber 22 ... Exhaust exhaust chamber 23, 34 ... Exhaust inversion chamber 25, 26 ... Catalyst chamber 25 ... ..First catalyst chamber 26 ... second catalyst chamber 28 ... partition member (partition tube)

Claims (6)

In an exhaust emission control device for an engine, in which an exhaust path (5, 6) of the engine (E) is provided with a catalytic converter (10),
An exhaust introduction chamber (21) for connecting the upstream portion of the exhaust passage (5, 6) and an exhaust outlet chamber (22) for connecting the downstream portion of the exhaust passage (5, 6) to one end of the catalytic converter (10). ) To communicate with the catalyst chambers (25, 26) of the catalytic converter (10) in parallel, while the exhaust introduction chamber (21) is formed at the other end of the catalytic converter (10). ) To form an exhaust reversing chamber (23, 34) for guiding the exhaust gas passing through the catalyst chamber (25, 26) through the catalyst chamber (25, 26) to the exhaust outlet chamber (22). When the total volume A of the chamber (25, 26) and the volume of the exhaust reversing chamber (23, 34) are B, the following equation (1)
0.1 <A / B <4 (1)
An exhaust emission control device for an engine, characterized in that The exhaust emission control device for an engine according to claim 1,
The catalyst chamber (25, 26) is divided into a first catalyst chamber (25) connected to the exhaust introduction chamber (21) and a second catalyst chamber (26) connected to the exhaust lead-out chamber (22). An exhaust emission control device for an engine, wherein the first and second catalyst chambers (25, 26) communicate with each other through the exhaust gas reversal chamber (23, 34). The engine exhaust gas purification apparatus according to claim 2,
An exhaust emission control device for an engine, wherein the first catalyst chamber (25) and the second catalyst chamber (26) are formed so that one of them surrounds the other. The engine exhaust gas purification apparatus according to claim 2 or 3,
An engine exhaust purification system comprising a partition member (28) for partitioning both chambers (25, 26) between the first catalyst chamber (25) and the second catalyst chamber (26). The engine exhaust gas purification apparatus according to any one of claims 1 to 4,
An exhaust emission control device for an engine, wherein the catalytic converter (10) is disposed directly under the engine (E). The engine exhaust gas purification apparatus according to any one of claims 1 to 4,
An exhaust emission control device for an engine, wherein the catalytic converter (10) is disposed in an exhaust muffler (6) in the exhaust passage (5, 6).

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