JP4974548B2 - Engine exhaust purification system - Google Patents

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 a conventional engine exhaust gas purification device, the exhaust gas to be purified flows through the catalytic converter in one direction. Therefore, if the flow path length of the catalytic converter is increased to increase the exhaust gas purification efficiency, 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 engine exhaust purification device in which a cylindrical catalytic converter is interposed in an exhaust path of an engine, wherein the catalytic converter includes a cylindrical shell having both ends opened, A honeycomb-shaped catalyst carrier having a large number of flow paths extending in the axial direction of the shell and fitted and fixed to the inner peripheral surface of the shell, on the outer peripheral surface of one end of the shell Is fitted and joined to the first cap so that the opening end of the first cap covering the one end surface of the catalyst carrier across the first space is overlapped with the one end so as to overlap in the radial direction. The first space having a circular cross section perpendicular to the axis of the catalytic converter is connected to an exhaust introduction chamber having a semicircular cross section that connects the upstream portion of the exhaust passage and the downstream portion of the exhaust passage. Divided into an exhaust outlet chamber with a semicircular cross section A flat partition wall is provided for partitioning, and the partition wall is arranged close to and perpendicular to the one end face so as to bisect the one end face of the catalyst support body. The plurality of flow paths are divided into a first catalyst chamber that is continuous with the exhaust introduction chamber and a second catalyst chamber that is continuous with the exhaust lead-out chamber. the open end of the second cap having a hemispherical dome portion covering the other end face of the body across the second space, to be fitted with and connected so as to overlap the other end and the radial direction of the shell Thus, the first feature is that the second space is an exhaust gas reversing chamber that reversely guides the exhaust gas that has passed through the first catalyst chamber toward the second catalyst chamber.

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

In addition to the first feature of the present invention, when the total volume of the catalyst chamber is A and the volume of the exhaust gas reversing chamber is B, the following equation (1)
0.1 <A / B <4 (1)
It shall be the second, characterized in that to establish.

Furthermore, the present invention is an engine exhaust purification device having the first or second feature, wherein the catalytic converter is mounted on a motorcycle so that the catalytic converter has its axis directed in the vehicle width direction of the motorcycle. Te is disposed within the transverse width just below the engine, and that the motorcycle steps are arranged on the outer side of the engine at the rear than the catalytic converter third feature.

Furthermore, in addition to the first or second feature , the present invention has a fourth feature that the catalytic converter is disposed directly under the engine.

Furthermore, the present invention is, in addition to any of the first to fourth features, the catalytic converter, a fifth characteristic in that disposed in the exhaust muffler of the exhaust path.

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 first catalyst chamber is reversed in the exhaust reversal chamber, passed again to the second catalyst chamber, and then to the exhaust lead-out chamber. Therefore, the exhaust gas reciprocates in the catalyst chamber composed of a large number of axial flow paths of the honeycomb-shaped catalyst support , and thus the total flow path length of the catalyst chamber is substantially the total length of the catalytic converter. Therefore, the effective flow path length of the catalytic converter can be significantly increased without increasing the total length of the catalytic converter, and the exhaust emission control device can be made compact. In addition, the forward and backward flow of the exhaust gas in the catalyst chamber mutually heat each other, so that the first and second catalyst chambers can be activated early after the engine is started, and the exhaust purification efficiency is effectively improved. It can contribute to the improvement. Further, 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 an increase in engine back pressure is suppressed, and engine output performance is reduced. Can contribute to improvement.

  According to the second feature of the present invention, 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, so that at least the engine output performance is achieved. A decrease can be avoided.

According to the third aspect of the present invention, the dead space directly under the engine is used for the arrangement of the exhaust purification device mounted on the motorcycle, and the influence of the exhaust purification device on the left and right steps is avoided. Can do.

According to the fourth aspect of the present invention, a compact catalytic converter can be installed using a dead space directly under the engine.

According to the fifth feature of the present invention, it is possible to install a compact catalytic converter by utilizing the dead space in the exhaust muffler, and to keep the catalytic converter warm by the exhaust muffler, thereby effecting early activation. The noise reduction effect can be enhanced by the catalytic converter.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on preferred examples shown in the accompanying drawings.

  FIG. 1 is a side view of a motorcycle equipped with an engine exhaust gas purification apparatus according to an 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 gas purification device taken along line 4-4 in FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 in FIG. 6 shows the first reference example, the corresponding diagram of FIG. 4, FIG. 7 is a sectional view taken along line 7-7 of FIG. 6, FIG. 8 is the corresponding diagram of FIG. 6 showing the second reference example, and FIG. 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 fourth reference example, and FIG. It is a performance comparison diagram with the conventional apparatus.

  First, the description of the 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. An 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 including a cylindrical catalytic converter 10 is provided in the middle of the exhaust pipe 5. This exhaust purification device D is disposed in the lateral width directly below the crankcase 3 with its both longitudinal ends directed in the left-right direction of the motorcycle M, and in front of the step bar 11 that is bolted to the bottom surface of the crankcase 3. Is done. In this way, the dead space immediately below the engine E is used for the arrangement of the exhaust purification device D, and the thermal effect of the exhaust purification device D on the left and right steps 12 and 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 thereof is attached to the exhaust purification device D.

  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 19 that are coupled to both longitudinal ends of the catalytic converter 10. It consists of.

The catalytic converter 10 is a honeycomb-shaped catalyst having a cylindrical shell 16 open at both ends, and a large number of flow paths 24, 24... Fitted and fixed to the inner peripheral surface of the shell 16 and extending in the axial direction. The catalyst carrier 17 is loaded with a catalyst such as platinum, rhodium, palladium, etc. facing the many 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 that are superposed on each other.

The first and second caps 18, 19 are joined by fitting their open end portions to the outer peripheral surfaces of both end portions of the shell 16 so as to overlap in the radial direction, and the first cap 18 is connected to the catalytic converter 10. One end surface of the catalytic converter 10 is covered with the first space interposed therebetween, and the second cap 19 covers the other end surface of the catalytic converter 10 with the second space interposed therebetween. In the first cap 18, the first space having a circular cross section perpendicular to the axis of the catalytic converter 10 is divided into an exhaust introduction chamber 21 and an exhaust outlet chamber 22 each having a semicircular cross section. A partition wall 20 for partitioning is provided, and the exhaust upstream pipe 5 a and the exhaust downstream pipe 5 b coupled to the first cap 18 are communicated with the exhaust introduction chamber 21 and the exhaust outlet chamber 22, respectively.

  The partition wall 20 is arranged vertically in close proximity to the one end face so as to bisect the one end face of the catalyst carrier 17, so that the plurality of flow paths 24, 24. The first catalyst chamber 25 communicates with the exhaust introduction chamber 21 and the second catalyst chamber 26 communicates with the exhaust lead-out chamber 22.

  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)
Desirably, A / B is set to approximately 1.5.

  Next, the operation of this embodiment will be described.

  During the operation of the engine E, the exhaust gas that has exited the exhaust port first flows into the exhaust introduction chamber 21 from the exhaust upstream pipe 5a, passes through a large 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 exhaust gas passing through the catalyst converter 10 and the radiant heat from the engine E, the first and second catalyst chambers 25 and 26 are activated. In 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. Accordingly, 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.

  12 shows the relationship between the ratio between 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, 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, it is obtained by the following formula.

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

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

  Next, a first reference example shown in FIG. 6 will be described.

  In the first reference example, a cylindrical partition wall 20 having a funnel-shaped opening end opposed to 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 5a is connected to the exhaust introduction chamber 21, and the exhaust downstream pipe 5b is connected to the exhaust outlet chamber 22. Since other configurations are the same as those of the previous embodiment, portions corresponding to those of the previous embodiment in FIG. 6 are denoted by the same reference numerals, and redundant description is omitted. Therefore, also in the first reference example, 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 set in the same manner as in the previous embodiment. The

  According to the first reference example, the cylindrical partition 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 that surrounds the columnar exhaust introduction chamber 21 is provided with the catalyst carrier 17. The plurality of flow paths 24, 24... Of the catalyst carrier 17 communicate with the columnar first catalyst chamber 25 that communicates 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 reversal chamber 23 is reversed while spreading radially to exhaust the second catalyst chamber 26 from the exhaust. Since the process proceeds toward the lead-out chamber 22, the first catalyst chamber 25 can be effectively kept warm and heated by the second catalyst chamber 26, and the activation of the catalyst carrier 17 can be further accelerated. it can.

  Next, a second reference example shown in FIGS. 7 and 8 will be described.

  In the second reference example, a cylindrical partition tube 28 that partitions the first catalyst chamber 25 and the second catalyst chamber 26 is disposed on the catalyst carrier 17, and a first cap 18 is provided at one end of the partition tube 28. 7 are connected to each other, and the other configuration is the same as that of the first reference example. Therefore, in FIG. 7 and FIG. And redundant description is omitted. Of course, the ratio, A / B, of 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 is set in the same manner as in the above embodiment.

  According to the second reference example, in the catalyst carrier 17, the first catalyst chamber 25 and the second catalyst chamber 26 are reliably partitioned by the partition tube 28, so that the first catalyst chamber 25 faces the exhaust gas reversal chamber 23. Interference between the forward flow of the exhaust gas and the return flow of the exhaust gas that moves 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 third reference example shown in FIGS. 9 and 10 will be described.

  In the third reference example, 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, which is joined to the outer peripheral surface of the partition tube 28 and the inner peripheral surface of the partition tube 28, is supported on the surfaces of the catalyst support members 17A, 17B, 17C. The partition cylinder 28 defines a first catalyst chamber 25 inside thereof, and the shell 16 and the partition cylinder 28 surround the first catalyst chamber 25 for fitting. A cylindrical second catalyst chamber 26 is defined.

  Since other configurations are the same as those of the first reference example, portions corresponding to the first reference example are denoted by the same reference numerals in FIG. 9 and FIG. 10, and redundant description is omitted. Of course, also in the third reference example, 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 above embodiment. Is done.

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

  Finally, a fourth reference example shown in FIG. 11 will be described.

  The fourth reference example corresponds to the exhaust purification device of the first reference example 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 interior of the muffler body 30 is partitioned into a first chamber by a pair of front and rear partition plates 32, 34, which are a first silencing chamber 34 in the middle, a second silencing chamber 35 on the front side, and a third silencing chamber 36 on the rear side. 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 any of the catalytic converters 10 of the above-described embodiment and the first to third reference examples, but the catalytic converter 10 of the first reference example is used in the illustrated example. Therefore, in FIG. 11, the same reference numerals are assigned to the portions corresponding to the first reference example of the catalytic converter 10, and the overlapping 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 transferred 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 passes through the communication pipe 37, moves to the third silencing chamber 36, 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 embodiment and the reference example, and is silenced by repeating the expansion stepwise.

  According to the fourth reference example, the compact catalytic converter 10 can be installed by using the dead space in the exhaust muffler 6, and the catalytic converter 10 is kept warm by the exhaust muffler 6 so that it can be activated early. Can be effectively promoted, and the noise reduction effect can be enhanced by the catalytic converter 10.

  As mentioned above, although the Example and reference example of this invention were 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 an embodiment of the present invention. The enlarged side view around the engine in FIG. FIG. 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 first reference example. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. FIG. 7 is a diagram corresponding to FIG. 6 illustrating a second reference example. FIG. 7 is a diagram corresponding to FIG. 6 illustrating a third reference example. 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 the 4th reference example. The performance comparison diagram of this invention apparatus and a conventional apparatus.

D ... Exhaust gas purification device E ... Engine 5,6 ... Exhaust passage (exhaust pipe, exhaust muffler)
DESCRIPTION OF SYMBOLS 10 ... Catalytic converter 12 ... Step 16 ... Shell 17 ... Catalyst carrier 21 ... Exhaust introduction chamber 22 ... Exhaust outlet chamber 23 ... exhaust reversing chamber 24 ... flow path 25 ... first catalyst chamber 26 ... second catalyst chamber

Claims (5)

An engine exhaust gas purification apparatus having a cylindrical catalytic converter (10) interposed in an exhaust path (5, 6) of an engine (E),
The catalytic converter (10) has a cylindrical shell (16) whose both ends are open and a number of flow paths (24) extending in the axial direction of the shell (16), and an inner peripheral surface of the shell (16). A honeycomb-shaped catalyst carrier (17) fitted and fixed to
On the outer peripheral surface of the one end portion of the shell (16), an opening end portion of the first cap (18) that covers the one end surface of the catalyst carrier (17) with the first space interposed therebetween has a diameter different from that of the one end portion. Fitting and joining so as to overlap in the direction,
In the first cap (18), the first space having a circular shape in a cross section perpendicular to the axis of the catalytic converter (10) is connected to the upstream portion of the exhaust passage (5, 6). A flat partition wall that divides into a semicircular exhaust introduction chamber (21) and a semicircular exhaust exhaust chamber (22) that connects the downstream portion of the exhaust passage (5, 6). 20)
The partition wall (20) is arranged close to and perpendicular to the one end surface so as to bisect the one end surface of the catalyst carrier (17). The multiple flow paths (24) are 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 opening of the second cap (19) having a hemispherical dome portion covering the other end surface of the catalyst carrier (17) across the second space on the outer peripheral surface of the other end portion of the shell (16). the end, to combine fitted so as to overlap the other end and the radial direction of the shell (16), a second space, the exhaust having passed through the first catalyst chamber (25) An exhaust emission control device for an engine, characterized in that the exhaust gas reversal chamber (23) is configured to reversely guide the second catalyst chamber (26). The exhaust emission control device for an engine according to claim 1,
When the total volume of the first and second catalyst chambers (25, 26) is A and the volume of the exhaust gas reversing chamber (23) is B, the following equation (1)
0.1 <A / B <4 (1)
An exhaust purification device for an engine, characterized in that The exhaust emission control device for an engine according to claim 1 or 2, wherein the engine is mounted on a motorcycle .
The catalytic converter (10) is disposed in the lateral width directly below the engine (E) so that its axis is directed in the vehicle width direction of the motorcycle (M) , and the engine is located behind the catalytic converter (10). A step (12) of the motorcycle (M ) is arranged on the outer side of (E). The engine exhaust gas purification apparatus according to claim 1 or 2 ,
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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