JP2004301019A - Catalytic converter system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalytic converter system for a two-wheeler capable of improving purification performance of exhaust gas without degrading appearance of the two-wheeler. <P>SOLUTION: This catalytic converter system 1 is a system disposed at an exhaust system of an internal combustion engine 2 for the two-wheeler. The catalytic converter system 1 includes a first catalyst 31 disposed at a disposal position on an exhaust port 202 side and a second catalyst 32 disposed at the disposal position on an outer portion side among two disposal positions in an exhaust passage 10 from the exhaust port 202 of a cylinder 20 of the internal combustion engine 2 to the air. An intermediate pipe between the first catalyst 31 and the second catalyst 32 has a double pipe structure. The pipe at the inside of the intermediate pipe acts as the exhaust passage 10, and insulation material is disposed at a gap on the outer periphery. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
【Technical field】
The present invention relates to a catalytic converter system for purifying exhaust gas of an internal combustion engine for a motorcycle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an exhaust gas purifying apparatus for purifying exhaust gas of an internal combustion engine for a motorcycle, secondary air introduced into an exhaust passage promotes combustion of unburned components such as CO in the exhaust gas, thereby reducing exhaust gas. There is a device for purifying (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-B-63-2005 (pages 1-3, Fig. 2)
[0004]
[Problem to be solved]
However, the above-mentioned conventional exhaust gas purification apparatus has the following problems. That is, as described above, the exhaust gas purification device that only introduces the secondary air may not be able to sufficiently improve the exhaust gas purification performance.
On the other hand, the exhaust path of an internal combustion engine for a motorcycle is generally constituted by an exhaust pipe having a metallic glossy surface such as a stainless steel material in order to make the appearance of the motorcycle attractive. Is an important point.
Therefore, if a large-capacity catalyst body with improved exhaust gas purification performance is mounted on the exhaust path of the motorcycle, the exhaust pipe may be enlarged in diameter, and the appearance of the motorcycle may be impaired.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to provide a catalytic converter system for a motorcycle having high exhaust gas purification performance without fear of impairing the appearance of the motorcycle. is there.
[0006]
[Means for solving the problem]
The present invention relates to a catalytic converter system arranged in an exhaust system of an internal combustion engine for a motorcycle,
The catalytic converter system includes a first catalyst body disposed at a position on the exhaust port side among two positions in an exhaust path from an exhaust port of the cylinder of the internal combustion engine to the outside, (Claim 1). The catalytic converter system for a motorcycle according to claim 1, further comprising a second catalytic body disposed at the disposition position.
[0007]
The catalytic converter system of the present invention has a first catalytic body and a second catalytic body at two locations in the exhaust path.
By arranging the first catalyst body and the second catalyst body at two locations in the exhaust path, the burden on each catalyst can be relatively reduced. And, by making the size of each catalyst small, it is possible to avoid an increase in the diameter of the exhaust pipe constituting the exhaust path, and to shorten the length of each catalyst in the exhaust gas flow direction. Further, the second catalyst body is hardly affected by traveling wind or the like, and has high environmental resistance.
Therefore, according to the catalytic converter system configured as described above, the appearance of the motorcycle is less likely to be impaired, and the exhaust efficiency of the internal combustion engine is less likely to be impaired.
[0008]
In addition, the first catalyst on the exhaust port side reaches the activation temperature early by the supply of the high-temperature exhaust gas discharged from the internal combustion engine, and causes a reaction of CO, HC and the like in the exhaust gas. When a reaction such as CO or HC occurs, heat of the reaction is generated in the first catalyst body.
[0009]
The exhaust gas passing through the first catalyst body is heated by the reaction heat and rises in temperature.
Then, the second catalyst body supplied with the high-temperature exhaust gas can reach the activation temperature at an early stage, and can exhibit its exhaust gas purification performance stably.
[0010]
As described above, the catalytic converter system of the present invention, in which the first catalyst body and the second catalyst body are combined, is an excellent system having high exhaust gas purification performance with a low risk of damaging the appearance of the motorcycle. .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the exhaust path refers to a path constituting a shortest path from the exhaust port to the outside.
Here, in a two-wheeled vehicle having a plurality of the above-described exhaust paths, a bypass pipe for mutually communicating different exhaust paths is provided in order to improve exhaust efficiency, suppress exhaust pulsation, improve exhaust noise, and the like. There are cases.
On the other hand, as described above, the exhaust path is the shortest path from the exhaust port to the outside. Therefore, the exhaust path does not include the bypass pipe, and the connection point between the bypass pipe and the exhaust path does not form the collecting portion.
[0012]
In the present invention, each of the exhaust paths extending from the internal combustion engine has a converging portion that merges with another exhaust path at at least one position in the exhaust path.
The first catalyzer is disposed on the exhaust port side with respect to all the converging portions, and the second catalyzer is disposed on the outer side with respect to all the converging portions. (Claim 2).
In this case, the first catalyst body disposed close to the internal combustion engine receives the supply of the high-temperature exhaust gas discharged from the internal combustion engine, and is activated very early, and has excellent exhaust gas immediately after starting. It can exhibit purification performance.
[0013]
Further, each of the exhaust paths extending from the internal combustion engine has a converging portion that merges with another exhaust path at one location in the exhaust path.
It is preferable that the first catalyst body and the second catalyst body are disposed on the outer side with respect to the collecting portion.
In this case, if the first catalyst body is arranged downstream of the collecting portion, the number of the first catalyst bodies to be mounted is reduced with respect to the number of cylinders, which is the number of cylinders constituting the internal combustion engine. can do.
For this reason, the catalytic converter system can be advantageously configured in terms of cost.
[0014]
Further, each of the exhaust paths extending from the internal combustion engine has a junction at two locations in the exhaust path that merges with another exhaust path.
The first catalyst body is disposed between a first collecting part disposed on the exhaust port side of the collecting part and the other second collecting part,
Further, it is preferable that the second catalyst body is disposed on the outer side with respect to the second collecting part (claim 4).
In this case, if the first catalyst is disposed between the first collecting portion and the second collecting portion, the number of cylinders, which is the number of cylinders constituting the internal combustion engine, is reduced. Thus, the number of the first catalyst bodies to be mounted can be suppressed, and the catalytic converter system can be configured efficiently.
The first catalyst, which is disposed in the middle of the two gatherings, is activated early by the supply of the high-temperature exhaust gas discharged from the internal combustion engine, and can exhibit excellent exhaust gas purification performance.
[0015]
A muffler for silencing exhaust noise is provided at the outlet on the outside of the exhaust path.
It is preferable that at least a part of the second catalyst body is housed inside the muffler (claim 5).
In this case, if the second catalyst body is mounted inside the muffler, the appearance of the motorcycle is less likely to be affected.
[0016]
Further, the catalytic converter system has at least one first catalytic body and at least one second catalytic body, and is a sum total of exhaust gas purifying capabilities of all the first catalytic bodies. Is preferably set to be larger than the total purification capacity, which is the sum of the exhaust gas purification capacities of all the second catalyst bodies.
[0017]
In this case, most of the harmful components in the exhaust gas are removed by the first catalyst having a large total purification capacity, and the harmful components remaining after passing through the first catalyst are removed by the second catalyst. It can be effectively removed from the medium.
According to such a combination of the first catalyzer and the second catalyzer, the first catalyzer is reduced in size as compared with a catalytic converter system in which the second catalyzer is not disposed, and the catalyst is mounted. The effect on the appearance of the motorcycle can be suppressed.
[0018]
Here, the exhaust gas purification capacity is a value expressed using an index such as a purification rate indicating the ratio of the amount of the removed harmful component to the amount of the harmful component in the inflowing exhaust gas. . Generally, the purifying ability of the catalyst depends on the surface area of the wall surface of the flow path through which the exhaust gas flows and the amount of the noble metal catalyst such as platinum, rhodium, and palladium carried.
[0019]
Further, S1 / S2, which is a ratio of the number of cells S1 per unit area of the first catalyst body to the number S2 of cells per unit area of the second catalyst body, is preferably 1.3 to 10. (Claim 7).
In this case, by increasing the number S1 of cells per unit area of the first catalyst body relatively, a large surface area of the first catalyst body is ensured, and exhaust gas purification in the first catalyst body is performed. Performance can be improved.
On the other hand, if the value of S1 / S2 exceeds 10, the exhaust gas purifying ability of the second catalyst is relatively suppressed, so that harmful components remaining after passing through the first catalyst are removed from the second catalyst. There is a possibility that the catalyst cannot be efficiently removed.
[0020]
Further, the catalytic converter system has at least one first catalytic body and at least one second catalytic body, and is a sum total of exhaust gas purifying capabilities of all the first catalytic bodies. Is preferably set to be smaller than the total purification capacity, which is the sum of the exhaust gas purification capacities of all the second catalyst bodies (claim 8).
[0021]
In this case, the first catalyst body disposed on the exhaust port side can be activated at an early stage to generate heat of reaction such as CO and HC in the first catalyst body.
According to the reaction heat, the second catalyst having a large total purification ability can quickly reach the activation temperature via the exhaust gas from the first catalyst to the second catalyst. , It is possible to stably maintain its active state.
Therefore, in the catalytic converter system, the second catalytic body having the large total purifying ability can function stably to efficiently purify the exhaust gas.
[0022]
Further, S2 / S1, which is a ratio of the number of cells S1 per unit area of the first catalyst body to the number S2 of cells per unit area of the second catalyst body, is preferably 1.3 to 10. (Claim 9).
In this case, by reducing the number S1 of cells per unit area of the first catalyst body relatively, the number of cell partitions separating each cell can be reduced, and the flow of exhaust gas per unit area can be reduced. It is possible to increase the area to be used.
The entire first catalyst body having an enlarged area through which the exhaust gas flows can be configured to have a small diameter. Therefore, it is possible to suppress the influence on the appearance of the motorcycle caused by the provision of the first catalyst body.
On the other hand, when the value of S2 / S1 exceeds 10, the capacity of the first catalyst body becomes relatively small, and the second catalyst body is efficiently heated by the heat generated in the first catalyst body. It may not be possible.
[0023]
Further, it is preferable that the intermediate pipe constituting the exhaust path between the first catalyst body and the second catalyst body has a heat insulating portion exhibiting a heat insulating structure at least in a part of the axial direction ( Claim 10).
In this case, the temperature of the exhaust gas supplied to the second catalyst body is kept high, and the active state of the second catalyst body can be stably maintained.
In the case of a motorcycle, since the intermediate pipe is often exposed to the outside, it is particularly effective to form the heat insulating portion in the intermediate pipe.
[0024]
The heat insulating portion of the intermediate pipe is formed in a radial direction between an inner pipe constituting a part of the exhaust path and an outer pipe having a double pipe structure. Preferably, it is formed in the gap layer (claim 11).
In this case, the heat insulating portion can be formed on the intermediate pipe with little risk of affecting the appearance of the intermediate pipe.
[0025]
Further, it is preferable that a material having heat insulating properties is arranged in the heat insulating portion of the intermediate pipe.
In this case, by arranging a heat insulating material (a material having heat insulating properties) in the heat insulating portion, it is possible to further suppress a decrease in the temperature of the exhaust gas in the intermediate pipe.
If the temperature of the exhaust gas supplied to the second catalyst body can be kept high, the active state of the second catalyst body can be stably maintained, and the exhaust gas purification performance can be further improved.
[0026]
Further, the section of the exhaust pipe constituting the exhaust path, which is perpendicular to the axial direction at the portion accommodating the first catalyst body, has a height which is vertically set when the exhaust pipe is mounted on a motorcycle. H1 is
The cross section of the exhaust pipe at a portion closer to the exhaust port and at a portion closer to the outside than the disposition position of the first catalyst body is perpendicular to the axial direction with respect to the height H2 located in the vertical direction. , H1 ≦ 2 × H2 (claim 13).
[0027]
In this case, the first catalyst body can be mounted while suppressing the influence on the beauty of the motorcycle.
The cross-sectional shape orthogonal to the axial direction of the exhaust pipe is not limited to a circular shape, but may be an elliptical shape that is wide in the horizontal direction of the motorcycle as long as the relationship of H1 ≦ 2 × H2 is satisfied. And so on.
On the other hand, when the height H1 exceeds twice the height H2, a viewer who looks at the motorcycle equipped with the exhaust pipe from the side view can see a part of the exhaust pipe containing the first catalyst body. There is a risk that the shape may feel uncomfortable.
[0028]
Preferably, the heat capacity of the first catalyst body is larger than the heat capacity of the second catalyst body.
In this case, the second catalyst can be efficiently heated by utilizing the heat generated by the first catalyst and the second catalyst can be quickly shifted to the active state.
[0029]
【Example】
(Example 1)
The catalytic converter system 1 for a motorcycle according to the present embodiment will be described with reference to FIGS.
The catalytic converter system 1 of this example is a system arranged in an exhaust system of an internal combustion engine 2 for a motorcycle.
The catalytic converter system 1 is disposed at a position on the exhaust port 202 side among two positions in the exhaust path 10 extending from the exhaust port 202 of each cylinder 20 of the internal combustion engine 2 to the outside. It has a catalyst body 31 and a second catalyst body 32 arranged at a position on the outside.
The details will be described below.
[0030]
As shown in FIG. 1, the internal combustion engine 2 of this embodiment is configured as a spark ignition type having four cylinders and four cycles.
The internal combustion engine 2 mixes the intake air introduced from the air cleaner 23 and passed through the throttle valve 25 with the fuel injected from the injector 28 in the intake passage 22 to form an air-fuel mixture having a predetermined air-fuel ratio. It is configured to distribute and supply from 201 to each cylinder 20.
[0031]
As shown in FIG. 1, a spark plug 27 is provided for each cylinder 20 in the cylinder head 21 of the internal combustion engine 2. A high voltage generated by the ignition coil / igniter 270 is applied to each ignition plug 27 at each ignition timing, and the mixture in each cylinder 20 is ignited.
On the other hand, the exhaust gas burned in each cylinder 20 of the internal combustion engine 2 is exhausted from an exhaust port 202 and externally passed through a first catalyst body 31 and a second catalyst body 32 disposed at two places in the exhaust path 10. (In the atmosphere).
[0032]
As shown in FIG. 2, the exhaust path 10 includes an exhaust pipe 11, a first housing pipe 310 in which the first catalyst body 31 is arranged, a muffler unit 390, and a space between the muffler unit 390 and the first housing pipe 310. And an intermediate pipe 12 disposed therein.
[0033]
In the present embodiment, the exhaust path 10 is configured as a three-part structure including the exhaust pipe 11, the first storage pipe 310, and the intermediate pipe 12, but is configured as a two-part structure in which the first storage pipe 310 is omitted. It can also be configured.
In this case, the first catalyst body 31 can be disposed by inserting the first catalyst body 31 from either end of the intermediate pipe 12 or the exhaust pipe 11.
[0034]
As shown in FIG. 2, the exhaust pipe 11 has two first pipes (not shown) communicating with the respective exhaust ports 202 (FIG. 1) of the two-cylinder cylinder 20, and the first pipes form the collecting part 14. And a second pipe section 112 that is assembled through the second pipe section 112.
That is, the exhaust pipe 11 is a pipe having two inlets on the first pipe part side and one outlet on the second pipe part 112 side.
[0035]
The first housing pipe 310, the intermediate pipe 12, and the muffler 19 are configured to extend from the outlet side of the exhaust pipe 11 on the second pipe portion 112 side.
That is, in the four-cylinder internal combustion engine 2 of the present embodiment, the four exhaust paths 10 corresponding to the respective cylinders 20 extend from the exhaust port 202 to the muffler 19 (external side) in a four-input, two-output exhaust system. Has formed.
[0036]
As shown in FIG. 2, the exhaust pipe 11 has a flange portion (not shown) for connecting to the internal combustion engine 2 at an end on the first pipe portion side and a first housing pipe on an end portion on the second pipe portion 112 side. An exhaust pipe having an end for connecting to 310.
In this example, an oxygen sensor (O2 sensor) 330 is provided in the second pipe portion 112 of the exhaust pipe 11.
[0037]
The internal combustion engine 2 of this embodiment is configured to detect the air-fuel ratio λ by measuring the residual oxygen concentration in the exhaust gas using the oxygen sensor 33.
Note that an air-fuel ratio (A / F) sensor may be provided instead of the oxygen sensor 27. In this case, the air-fuel ratio λ is directly detected based on the exhaust gas discharged from the internal combustion engine 2. be able to.
[0038]
As shown in FIG. 2, the first housing pipe 310 is a unit in which the first catalyst body 31 is disposed. The outer diameter D1 of the first housing pipe 310 of this example is set to 90 mm, which is approximately 1.1 times the outer diameter D2 of the second pipe portion 112 of the exhaust pipe 10 which is 80 mm.
Both ends of the first housing pipe 310 are connected to the second pipe portion 112 of the exhaust pipe 11 and an intermediate pipe 12 described later by butt welding.
[0039]
As shown in FIG. 4, the first catalyst body 31 is made of a thin plate-like metal (such as stainless steel), and is provided on a catalyst carrier having 200 cells 311 per square inch (cell number S1 = 200) as a catalyst. It is a three-way catalyst supporting platinum, rhodium and the like.
In this example, the activation temperature of the first catalyst body 31 is set to 300 degrees, and is configured to promote the reaction of CO, HC, NOx, etc. in the exhaust gas in a temperature range exceeding the activation temperature. It is.
The first catalyst body 31 of the present example has a length of 50 mm in the communication direction of the cell 311 and has a substantially cylindrical shape with a diameter of 70 mm.
[0040]
The intermediate pipe 12 is provided with a heat insulating portion 125 having a double pipe structure over the entire area in the axial direction, and is configured to allow exhaust gas to flow through the inner pipe.
That is, a heat insulating portion 125 made of an air layer is formed in a gap on the outer peripheral side of the pipe inside the intermediate pipe 12 having the double pipe structure, and the heat radiation of the exhaust gas is suppressed by the heat insulation of the air. It is.
Also, one end of the intermediate pipe 12 has an end 121 for abutting and welding with the end of the first housing pipe 310, and the other end has a flange 129 for connecting to the muffler 19. And
[0041]
In addition, the heat insulating part 125 can also contain a heat insulating material made of glass wool, Kevlar, or the like. In this case, the heat radiation amount of the exhaust gas can be further suppressed.
Furthermore, in the present example, the heat insulating portion 125 is formed over the entire area of the intermediate pipe 12 in the axial direction. Instead, the heat insulating portion 125 is formed on a part of the intermediate pipe 12 in the axial direction. You can also. In particular, if the heat insulating portion is formed on the side of the large-diameter muffler 19, it is possible to further suppress the sense of incongruity that may be caused by the increase in the diameter due to the double pipe structure.
[0042]
The muffler 19 is a unit having an exhaust port 199 (see FIG. 1) opened at the end on the outside (atmosphere side) and a connection pipe 195 opened at the other end. In addition, the end face where the connection pipe 195 is opened is configured to connect the flange portion 129.
The second catalyst body 32 is housed in the connection pipe 195 housed inside the muffler main body 191. In the present embodiment, the entirety of the second catalyst body 32 is accommodated inside the muffler main body 191.
Alternatively, as shown in FIG. 3, the second catalyst body 32 can be provided so that a part of the second catalyst body 32 is housed inside the muffler main body 191.
[0043]
As shown in FIG. 5, the second catalyst body 32 is made of a thin plate-like metal (such as stainless steel), and is provided on a catalyst carrier having 100 cells 321 per square inch (the number of cells S2 = 100) as a catalyst. It is a three-way catalyst supporting platinum, rhodium and the like. The activation temperature of the second catalyst body 32 is set at 300 ° C., and is configured to promote the reaction of harmful components such as CO, HC and NOx in the exhaust gas in a temperature range exceeding the activation temperature. I have.
The second catalyst body 32 of the present example has a length of 50 mm in the communication direction of the cell 321 and has a substantially cylindrical shape with a diameter of 70 mm.
[0044]
Further, in the internal combustion engine 2 of the present embodiment, as shown in FIG. 1, the air introduction path on the air cleaner 23 side and the exhaust pipe 11 are communicated by the secondary air passage 40. A secondary air control valve 41 for appropriately introducing secondary air from the air cleaner 2 toward the exhaust pipe 11 is provided in the middle of the secondary air passage 40.
[0045]
The internal combustion engine 2 is configured to be controlled by an ECU (Electronic Control Unit) not shown. The ECU is a unit including a CPU for executing various arithmetic processes, a ROM for storing a control program, a RAM for storing various data, and the like.
The ECU of this embodiment is configured to input detection signals from various sensors and output control signals to the injector 28, the secondary air control valve 41, the ignition coil / igniter 270, and the like.
[0046]
When the internal combustion engine 2 is in a light load range, the ECU opens the secondary air control valve 41 and operates the internal combustion engine 2 by open control not based on the output of the oxygen sensor 33. is there.
On the other hand, when the internal combustion engine 2 is in the middle to high load range, the secondary air control valve 41 is closed, and the internal combustion engine 2 is feedback-controlled based on the output of the oxygen sensor 33 so that the air-fuel ratio λ becomes appropriate. I have.
[0047]
Next, the operation and effect of the catalytic converter system 1 for a motorcycle according to the present embodiment will be described.
The catalytic converter system 1 according to the present embodiment has the following effects: (1) the effect of rapidly rising the exhaust gas purification performance at the start of the internal combustion engine 2; and (2) the activation of the second catalyst body 32 at an early stage. This system has the function and effect of being able to stably maintain, and (3) the combination of the first catalyst body 31 and the second catalyst body 32 to achieve excellent exhaust gas purification performance.
The contents of each operation and effect will be described below.
[0048]
First, the effect of the above item (1) that the exhaust gas purification performance rises quickly when the internal combustion engine 2 is started will be described.
In the exhaust system of the internal combustion engine 2 of a motorcycle, the above-described exhaust path 10 is generally provided by an exhaust pipe or the like which is provided so as to be exposed outside the vehicle body. Therefore, as shown by the broken line in FIG. 6, the temperature of the exhaust gas of the internal combustion engine 2 decreases as the distance from the exhaust port 202 (FIG. 1) increases, and the degree of the decrease is sharp.
6, the horizontal axis indicates the position in the direction of exhaust gas flow from the internal combustion engine 2, the left end indicates the exhaust port 202, and the right end indicates the inlet of the muffler 19 (FIG. 1). The vertical axis indicates the temperature of the exhaust gas.
[0049]
Therefore, as in the catalytic converter system 1 of the present embodiment, if the first catalytic body 31 is disposed on the upstream side of the exhaust passage 10, that is, close to the exhaust port 202, the high-temperature exhaust gas is supplied to the first catalytic body 31. The activation temperature can be reached early by supplying gas.
In particular, according to the catalytic converter system 1 of the present example, the first catalytic body 31 can be configured to be small and the heat capacity thereof can be suppressed, as compared with the case where the system is configured by a single catalytic body.
Therefore, when the internal combustion engine 2 is started, as shown in FIG. 7, the first catalyst body 31 is quickly heated to the activation temperature (the temperature indicated by the dotted line in the figure), and quickly transitions to the activation state ( In the figure, it is indicated by a solid line.) Note that, in the same figure, the broken line shows, for reference, the rising characteristics of the catalyst in a system in which a single catalyst having a larger capacity than the first catalyst 31 is arranged at the same position. .
[0050]
Next, a description will be given of the operation and effect (2) described above, in which the second catalyst body 32 can be activated at an early stage and its activated state can be stably maintained.
When the first catalyst body 31 is activated, an oxidation reaction of CO, HC, or the like occurs in the first catalyst body 31, and the reaction heat can be generated. Since the exhaust gas can be heated by the reaction heat, the temperature of the exhaust gas can be increased at a position corresponding to the first catalyst body 31 as shown by a solid line in FIG.
[0051]
Therefore, according to the catalytic converter system 1 of the present embodiment, it is possible to supply high-temperature exhaust gas and quickly raise the temperature of the second catalyst body 32 to transition to the active state.
Further, even when the internal combustion engine 2 is in a low-load operation state and the temperature of the exhaust gas is lowered, the exhaust gas heated by the first catalyst body 31 is supplied so that the second catalyst body 32 is supplied. Can be stably maintained.
[0052]
That is, as shown in FIG. 8, the catalytic converter system 1 of the present embodiment has a configuration in which the second catalyst body 32 rises to the active state, as compared with a system including only the second catalyst body 32 (temperature change indicated by a broken line). Is fast, and the temperature after the start-up is kept high.
Therefore, the effect of the external environment such as the load state of the internal combustion engine 2 and the outside air temperature can be suppressed, and the active state of the second catalyst body 32 can be stably maintained.
Therefore, according to the catalytic converter system 1 of the present embodiment, purification of the exhaust gas can be started early after the start of the internal combustion engine 2, and the purification performance can be stably maintained.
That is, according to the catalytic converter system 1, there is little possibility that harmful components in the exhaust gas are released into the atmosphere.
[0053]
Next, the effect of the above item (3) that excellent exhaust gas purification performance can be realized by the combination of the first catalyst body 31 and the second catalyst body 32 will be described.
In this example, the first catalyst body 31 is a catalyst body having a cell number S1 per square inch of 200, and the second catalyst body 32 is a catalyst body having a cell number S2 per square inch of 100. .
The catalytic converter system 1 is configured so that a sufficient exhaust gas purifying action performance can be obtained by the combination of the first catalyst body 31 and the second catalyst body 32.
[0054]
In other words, even if harmful components such as CO and HC remain in the exhaust gas after passing through the first catalyst body 31, the active state is maintained by the reaction heat of the first catalyst body 31. The two catalysts 32 can remove harmful components in the exhaust gas.
Therefore, in the catalytic converter system 1 of the present embodiment, the first catalyst body 31 can be downsized by supplementing the exhaust gas purification performance with the second catalyst body 32. In addition, according to the first catalyst body 31 that is reduced in size, there is little possibility that the aesthetic appearance of the two-wheeled vehicle is impaired regardless of the arrangement location.
[0055]
As described above, in the catalytic converter system 1 of the present embodiment having the above-mentioned effects (1) to (3), by configuring the system by combining the first catalyst body 31 and the second catalyst body 32, The size of the catalyst has been reduced. Therefore, the catalytic converter system 1 can be mounted with less risk of impairing the appearance of the motorcycle.
[0056]
Further, in the first catalyst body 31 and the second catalyst body 32 that are reduced in size, the heat capacity of each catalyst body can be reduced. Therefore, the temperature of the first catalyst body 31 and the second catalyst body 332 can be quickly raised, and the exhaust gas purification performance of the entire system can be quickly started.
[0057]
Further, according to the configuration of the catalytic converter system 1 of the present example in which the reaction heat generated in the first catalyst body 31 can be supplied to the second catalyst body 32, the influence of the temperature change of the exhaust gas at the exhaust port 202 is suppressed. As a result, the active state of the second catalyst body 32 can be stably maintained.
Therefore, in the catalytic converter system 1 of the present embodiment, the purification performance of the exhaust gas can be stably maintained irrespective of a change in the operating state of the internal combustion engine 2 or a change in the external environment.
[0058]
The relationship between the number S1 of cells of the first catalyst body 31 and the number S2 of cells of the second catalyst body 32 is such that the number S1 of cells of the first catalyst body 31 is Instead of making the number larger than the cell number S2, the magnitude relation can be reversed.
That is, the catalytic converter system can be configured by a combination of the first catalyst body having the number of cells S1 per square inch of 100 and the second catalyst body having the number of cells S2 per square inch of 200. .
[0059]
In this case, by suppressing the purification ability of the first catalyst body with respect to the purification ability of the exhaust gas by the second catalyst body, harmful components in the exhaust gas passing through the first catalyst body increase.
In this case, harmful components in the exhaust gas are efficiently removed by the large-capacity second catalyst body that stably maintains the active state by the reaction heat generated in the first catalyst body, and the exhaust gas purification of the entire system is performed. Can meet performance.
[0060]
That is, the first catalytic body constituting the catalytic converter system supplies heat to the second catalytic body having a multi-cell structure in addition to the function of purifying the exhaust gas by the first catalytic body itself. By maintaining the state, the importance of the role as a heat source for stably exhibiting the purification performance of the second catalyst body has increased.
Further, instead of the in-line four-cylinder internal combustion engine of the present embodiment, as shown in FIG. 9, a V-type four-cylinder internal combustion engine can be changed. In addition, it is also possible to change to an in-line multi-cylinder such as an in-line two-cylinder, a V-type multi-cylinder including a V-type two-cylinder, and a single-cylinder internal combustion engine.
[0061]
(Example 2)
This embodiment is an example in which the arrangement of the first catalyst body is changed based on the catalytic converter system of the first embodiment.
In the catalytic converter system 1 of the present embodiment, as shown in FIG. 10, a first catalyst body 31 is disposed on the upstream side of the collecting section 14 constituting the exhaust path 10.
[0062]
According to the catalytic converter system 1 of the present embodiment, the first catalytic members 31 are provided corresponding to the respective cylinders. Therefore, each first catalyst body 31 can be further downsized.
Further, the first catalyst body 31 arranged close to the exhaust port reaches the activation temperature more quickly when the internal combustion engine 2 is started, so that the emission of harmful components immediately after the start can be effectively suppressed.
Further, in this example, the heat insulating portion 125 based on the double pipe structure is formed only on the muffler 19 side of the intermediate pipe 12.
The other configuration and operation and effect are the same as those of the first embodiment.
Further, instead of the in-line four-cylinder internal combustion engine of the present embodiment, as shown in FIG. 11, a V-type multi-cylinder internal combustion engine such as a V-type two-cylinder or a V-type four-cylinder can be used.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an intake and exhaust system of an internal combustion engine including a catalytic converter system according to a first embodiment.
FIG. 2 is an explanatory diagram illustrating a catalytic converter system according to the first embodiment.
FIG. 3 is a cross-sectional view showing an arrangement structure of another second catalyst body according to the first embodiment.
FIG. 4 is a cross-sectional view illustrating a structure of a first catalyst body according to the first embodiment.
FIG. 5 is a cross-sectional view illustrating a structure of a second catalyst body according to the first embodiment.
FIG. 6 is a graph showing a relationship between a position in an exhaust gas flow direction and an exhaust gas temperature in the first embodiment.
FIG. 7 is a graph showing a temperature rising characteristic of a first catalyst body in Example 1.
FIG. 8 is a graph showing a temperature change of a second catalyst body in Example 1.
FIG. 9 is an explanatory diagram illustrating another catalytic converter system according to the first embodiment.
FIG. 10 is an explanatory diagram illustrating a catalytic converter system according to a second embodiment.
FIG. 11 is an explanatory diagram illustrating another catalytic converter system according to the second embodiment.
[Explanation of symbols]
1. . . Catalytic converter system,
10. . . Exhaust path,
11. . . Exhaust pipe,
12. . . Intermediate pipe,
19. . . Scarf,
2. . . Internal combustion engine,
20. . . Cylinder,
202. . . Exhaust port,
31. . . The first catalyst body,
32. . . The second catalyst body,
33. . . Oxygen sensor,
40. . . Secondary air passage,
41. . . Secondary air control,

Claims (14)

In a catalytic converter system arranged in the exhaust system of an internal combustion engine for motorcycles,
The catalytic converter system includes a first catalytic member disposed at an exhaust port side of two positions in an exhaust path extending from an exhaust port of the cylinder of the internal combustion engine to the outside; A catalytic converter system for motorcycles, comprising: a second catalytic body disposed at the disposition position of (1). 2. The exhaust path according to claim 1, wherein each of the exhaust paths extending from the internal combustion engine has a converging portion that merges with another exhaust path at at least one position in the exhaust path.
The first catalyzer is disposed on the exhaust port side with respect to all the converging portions, and the second catalyzer is disposed on the outer side with respect to all the converging portions. A catalytic converter system characterized by the above. 2. The exhaust path according to claim 1, wherein each of the exhaust paths extending from the internal combustion engine has a confluence with another exhaust path at one location in the exhaust path.
The catalytic converter system according to claim 1, wherein the first catalyst body and the second catalyst body are disposed on the outside of the assembly. 2. The exhaust path according to claim 1, wherein each of the exhaust paths extending from the internal combustion engine has a confluence with two other exhaust paths at two points in the exhaust path.
The first catalyst body is disposed between a first collecting part disposed on the exhaust port side of the collecting part and the other second collecting part,
The catalytic converter system is characterized in that the second catalytic body is disposed on the outside with respect to the second collecting part. 5. A muffler according to any one of claims 1 to 4, wherein a muffler for silencing exhaust noise is provided at an outlet on the outside of the exhaust path.
A catalytic converter system, wherein at least a part of the second catalyst body is housed inside the muffler. The catalyst converter system according to any one of claims 1 to 5, wherein the catalytic converter system has at least one first catalyst body and at least one second catalyst body, and all the first catalyst bodies. A catalyst characterized in that the total purifying capacity, which is the sum of the exhaust gas purifying capacities of the catalysts, is set larger than the total purifying capacity, which is the sum of the exhaust gas purifying capacities of all the second catalytic bodies. Converter system. In claim 6, S1 / S2, which is a ratio of the number of cells S1 per unit area of the first catalyst body to the number S2 of cells per unit area of the second catalyst body, is 1.3 to 10. A catalytic converter system characterized by the above. The catalyst converter system according to any one of claims 1 to 5, wherein the catalytic converter system has at least one first catalyst body and at least one second catalyst body, and all the first catalyst bodies. A catalyst characterized in that the total purifying capacity, which is the sum of the exhaust gas purifying capacities of the catalyst bodies, is set smaller than the total purifying capacity, which is the sum of the exhaust gas purifying capacities of all the second catalytic bodies. Converter system. In Claim 8, S2 / S1, which is the ratio of the number of cells S1 per unit area of the first catalyst body to the number of cells S2 per unit area of the second catalyst body, is 1.3 to 10. A catalytic converter system characterized by the above. 10. The heat insulating structure according to claim 1, wherein the intermediate pipe that constitutes the exhaust path between the first catalyst body and the second catalyst body has an adiabatic structure at least partially in an axial direction. 10. A catalytic converter system comprising a part. In Claim 10, the heat insulating portion of the intermediate pipe is provided in a radial direction between an inner pipe constituting a part of the exhaust path and an outer pipe having a double pipe structure. A catalytic converter system formed in a formed gap layer. 12. The catalytic converter system according to claim 11, wherein a heat insulating material is disposed in the heat insulating portion of the intermediate pipe. 13. The exhaust pipe constituting the exhaust path according to claim 1, wherein a cross-sectional shape of a portion of the exhaust pipe that accommodates the first catalyst body is perpendicular to an axial direction when the exhaust pipe is mounted on a motorcycle. The height H1 located in the direction is
Regarding the cross-sectional shape of the exhaust pipe at a portion on the exhaust port side and a portion on the external side with respect to the disposition position of the first catalyst body, which is orthogonal to the axial direction, with respect to the height H2 located in the vertical direction. , H1 ≦ 2 × H2. 14. The catalytic converter system according to claim 1, wherein the heat capacity of the first catalyst body is larger than the heat capacity of the second catalyst body.

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