JP3275711B2 - Exhaust gas purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an exhaust gas purifying apparatus.

[0002]

2. Description of the Related Art Exhaust gas emitted from an internal combustion engine such as a gasoline engine includes carbon monoxide (CO) and hydrocarbons (H).
C) and harmful components such as nitrogen oxides (NOx). Exhaust gas exhaust purifying devices for detoxifying these harmful components are roughly classified into two types according to the concept.

One is to achieve complete combustion of fuel in a combustion chamber of an engine to prevent generation of harmful components. The other is to make the exhaust gas discharged from the combustion chamber of the engine harmless before it is released to the atmosphere, even if it contains harmful components.

As a means for purifying the latter exhaust gas, that is, as a purifying device, a catalyst made of platinum, rhodium and palladium is provided in the exhaust device, and the exhaust gas discharged from the combustion chamber of the engine is brought into contact with the catalyst. In some cases, the harmful substances are converted into carbon dioxide (CO ₂ ), water (H ₂ O), nitrogen (N ₂ ), etc. to make them harmless by promoting oxidation of exhaust gas by a chemical reaction.

As an exhaust gas purifying apparatus used for a motorcycle, for example, Japanese Patent Application Laid-Open Nos. Hei 2-61312 and Hei 5-33635,
Japanese Patent Application Laid-Open No. 7-269331 discloses an example.

[0006]

However, as shown in JP-A-5-33635 and JP-A-7-269331, when the catalyst plate is fixed to the outer wall of the exhaust device along the flow of the exhaust gas, the catalyst length is reduced. As the catalyst becomes longer, it takes time to raise the temperature of the catalyst, and the purification performance of the exhaust gas decreases. In order to accelerate the temperature rise of the catalyst, the catalyst plate may be installed on the upstream side of the exhaust device, but there is a possibility that the engine output is reduced.

Further, if the area of the catalyst plate is increased in order to improve the exhaust gas purifying performance, the size of the exhaust device is increased, which causes an increase in weight and cost.

[0008] Further, if the exhaust device is bent into a complicated shape, the catalyst plate must be processed in the same manner, which increases the cost.

Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 2-61312, when a monolith type catalyst is used, a large amount of heat is generated per space volume in the exhaust device. Needed and costly.

The present invention has been made in consideration of the above circumstances, and has as its object to provide an exhaust gas purifying apparatus which improves the exhaust gas purifying performance without increasing the size of the exhaust apparatus.

[0011]

In order to solve the above-mentioned problems, an exhaust gas purifying apparatus according to the present invention has an exhaust pipe connected to an engine, and an exhaust pipe connected to the exhaust pipe. A muffler to be connected, a plurality of expansion chambers formed in the muffler, a diffuser pipe disposed in the muffler and having one end connected to the exhaust pipe, and a catalyst supported in the muffler. In the exhaust gas purification device provided, the muffler has a first expansion chamber formed on the side opposite to the exhaust pipe connection side, while the diffuser pipe has a downstream opening opened from the exhaust pipe into the first expansion chamber. The catalyst is formed in a pipe shape and installed in the diffuser pipe, and an exhaust gas outflow end of the pipe-shaped catalyst is provided. But also the exhaust outlet side end portion of the diffuser pipe is obtained by projecting the direction of flow of the exhaust gas.

According to another aspect of the present invention, there is provided an exhaust gas purifying apparatus for supporting the pipe-shaped catalyst inside a diffuser pipe by a mounting stay, and A flow passage for exhaust gas is formed between the catalyst and the diffuser pipe.

Further, in order to solve the above-mentioned problems, the exhaust gas purifying apparatus according to the present invention has an exhaust pipe connected to the engine and a muffler connected to the exhaust pipe. A plurality of expansion chambers formed in the muffler, a diffuser pipe disposed in the muffler and having one end communicated with the exhaust pipe, and an exhaust gas flowing out of the diffuser pipe is supplied to each expansion chamber inside the muffler. In the exhaust gas purifying apparatus, which is expanded in the chamber and then discharged to the outside of the muffler, and the exhaust gas is purified by a catalyst carried in the muffler, the muffler has a first expansion chamber on a side opposite to an exhaust pipe connection end. On the other hand, the diffuser pipe has a downstream opening opened from the exhaust pipe into the first expansion chamber. The catalyst is configured in a pipe shape, and the pipe-shaped catalyst is installed in the diffuser pipe, and a monolithic catalyst is attached to a downstream opening of the diffuser pipe, and the expansion chamber of the muffler is expanded. A tail pipe for discharging exhaust gas to the outside of the muffler is provided in parallel with the pipe-shaped catalyst.

Further, in order to solve the above-mentioned problem, the exhaust gas purifying apparatus according to the present invention is configured such that the exhaust pipe is connected to the engine and the exhaust pipe is connected to the exhaust pipe. A muffler, a plurality of expansion chambers formed in the muffler, a diffuser pipe disposed in the muffler and having one end connected to the exhaust pipe, and an exhaust gas flowing out of the diffuser pipe is provided in the muffler. In the exhaust gas purifying device, the exhaust gas is discharged to the outside of the muffler after being expanded around the diffuser pipe in the expansion chamber, and the exhaust gas is purified by a pipe-shaped catalyst carried in the muffler. While the first expansion chamber is formed on the side opposite to the pipe connection side, the diffuser pipe is A downstream opening is opened from the exhaust pipe into the first expansion chamber, and a plurality of pipe-shaped catalysts having different diameters are prepared, and at least a part of the plurality of pipe-shaped catalysts having different diameters is axially provided. It is arranged concentrically inside the diffuser pipe in an overlapping state.

Further, the exhaust gas purifying apparatus according to the present invention comprises:
In order to solve the above-described problem, as described in claim 5, an exhaust pipe connected to the engine, a muffler connected to the exhaust pipe, a plurality of expansion chambers formed in the muffler, In an exhaust gas purifying apparatus provided with a diffuser pipe disposed in the muffler and having one end communicated with the exhaust pipe, and a catalyst supported in the muffler, the muffler is disposed on a side opposite to an exhaust pipe connection end. While one expansion chamber is formed, the diffuser pipe has a downstream opening opening from the exhaust pipe into the first expansion chamber, and the catalyst is formed in a pipe shape and installed in the diffuser pipe. The pipe-shaped catalyst is supported inside the diffuser pipe by a mounting stay at one location substantially at the center, and the pipe In which flow path of the exhaust gas between the catalyst and the diffuser pipe is formed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a right side view of a scooter type vehicle 1 showing a first embodiment of the present invention. As shown in FIG. 1, the scooter type vehicle 1 has a front wheel 3 which is steered left and right by a handlebar 2 disposed at an upper front portion thereof, and a rear wheel driven by an engine 4 disposed at a lower rear portion of the vehicle. 5 is provided. In addition, the space between the operation seat 6 disposed above the engine 4 and the handlebar 2 is lowered so that a step board 7 is formed. Driving seat 6
Is arranged on a rear body cover 8 in which an article storage room (not shown) is installed, and the engine 4 is arranged below the rear body cover 8.

The engine 4 constitutes a power unit 10 together with a transmission case 9 provided with a V-belt type transmission, an automatic centrifugal clutch and a transmission mechanism (not shown), and a front end of the power unit 10 is pivotally pivoted to a body frame (not shown). Be worn.

An exhaust system 11 extends from the lower part of the engine 4 of the power unit 10 toward the upper rear of the vehicle.
The exhaust device 11 includes an exhaust pipe 12 connected to the engine 4 and a muffler 13 connected downstream of the exhaust pipe 12, and is disposed, for example, on the right side of the vehicle.

FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG.
2 shows cross-sectional views along the line IV-IV in FIG.

The muffler 13 of the exhaust system 11 reduces exhaust noise from the engine 4. As shown in FIGS. 2 to 4, the muffler 13 has a plurality of partitions 14, 15, for example, three expansion chambers. Is divided into Specifically, a first expansion chamber 16, a second expansion chamber 17, and a third expansion chamber 18 are formed from the downstream side (left side in FIG. 2) of the muffler 13.

A diffuser pipe 19 is connected to a downstream end of the exhaust pipe 12, and a downstream opening of the diffuser pipe 19 opens into the first expansion chamber 16.
In addition, the first communication pipe 20 includes the first expansion chamber 16 and the third expansion chamber 1.
8 and the second communication pipe 21 allows the third expansion chamber 18 and the second expansion chamber 17 to communicate with each other. And the second expansion chamber 17
From the tail pipe 22 extends toward the outside of the muffler 13.

Exhaust gas guided from the engine 4 to the muffler 13 via the exhaust pipe 12 and the diffuser pipe 19 is supplied from the first expansion chamber 16 to the third expansion chamber 18.
Then, while being guided from the third expansion chamber 18 to the second expansion chamber 17, the water expands sequentially to absorb sonic energy, and is discharged to the outside via the tail pipe 22.

A sound absorbing material 23 such as glass wool is disposed on the outer peripheral portion of the diffuser pipe 19 in the first expansion chamber 16 and on the inner wall surface of the muffler 13 to assist the noise reduction effect of the exhaust sound.

An exhaust gas purifying device 24 is provided in the exhaust device 11 provided in the scooter type vehicle 1. The purifying device 24 includes a pipe-shaped catalyst in which a catalyst material made of platinum, rhodium, palladium, or the like is coated on a surface of a pipe material such as stainless steel. The catalyst is composed of a plurality of pipe-shaped catalysts 25 and 26 having different diameters in this embodiment, and one of the pipe-shaped catalysts 26 and 26.
Is inserted into the other pipe-shaped catalyst 25 and installed concentrically in the diffuser pipe 19 in a state of being overlapped in the axial direction (in the present embodiment, partially overlapped). The pipe-shaped catalysts 25 and 26 are fixed concentrically to the inner wall of the diffuser pipe 19 by mounting stays 27 and 28.

Exhaust gas discharged from the engine 4 is passed through the diffuser pipe 19 to the pipe catalysts 25 and 2.
6, the oxidation of the exhaust gas is promoted by a chemical reaction, and harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) are removed from carbon dioxide (CO ₂ ) and water (H). ₂ O), nitrogen (N ₂ ), etc., and rendered harmless.

A state in which a plurality of pipe-shaped catalysts 25, 26 are concentrically stacked (a state in which the pipe-shaped catalysts 25, 26 are axially stacked and concentrically arranged as clearly shown in FIGS. 2 and 3). ), The catalyst length in the exhaust gas flow direction is shortened by the amount of overlap in the axial direction. Further, by fixing the pipe-shaped catalysts 25, 26 to the inner walls of the diffuser pipe 19 with the mounting stays 27, 28, the contact area between the catalyst substance and the muffler 13 member is reduced, and the heat transfer amount is small. As a result of these,
The temperature rise of the catalyst material is accelerated, and the chemical reaction of the catalyst material also starts early. Therefore, the exhaust gas purification performance immediately after the start of the engine 4 is improved.

Further, since the thermal stress due to the temperature difference between the catalyst material and the muffler 13 member can be small, no treatment for improving the heat resistance of the muffler 13 member is required, and the cost can be reduced.

Further, since the temperature rise of the catalyst material can be accelerated, there is no need to install the catalyst material on the upstream side of the exhaust device 11, and there is no possibility that the output of the engine 4 will be reduced.

Further, a plurality of pipe-shaped catalysts 25,
26 are concentrically stacked and the diffuser pipe 19 is
When the muffler 13 is small in size as in the scooter type vehicle 1, a sufficient catalyst surface area can be secured and exhaust gas can be efficiently purified.

FIG. 5 shows the monolithic catalyst 3 in the opening on the downstream side of the diffuser pipe 19 containing the pipe-shaped catalyst 29.
It is a figure showing the state where 0 was attached. Monolith type catalyst 3
By disposing the pipe-shaped catalyst 29 on the upstream side of the muffler 13, the heat of chemical reaction of the monolithic catalyst 30 can be reduced.
This eliminates the need for a treatment for improving the heat resistance of the member, thereby reducing costs and improving the durability of the monolithic catalyst 30.

FIG. 6 is a right side view of a sports motorcycle showing a second embodiment to which the present invention is applied. FIG.
As shown in FIG.
A two-stroke engine 53 is mounted at the lower center of the body frame 52.

A steering mechanism 54 is provided in front of the body frame 52, and a front wheel 56 is
Is steerably pivotable left and right. On the other hand, the body frame 5
A swing arm 57 is pivotally attached to the center lower part of the swing arm 2 so as to freely swing, and a rear wheel 58 is rotatably supported at the rear end of the swing arm 57.

An exhaust device 59 extends from the lower part of the engine 53 toward the rear and upper part of the vehicle. This exhaust device 59
Is composed of an expansion chamber 60 connected to the engine 53 and a muffler 61 connected downstream of the expansion chamber 60, and is arranged, for example, on the right side of the vehicle.

FIG. 7 is a side view of the expansion chamber 60, which is partially broken. FIG. 8 is a view taken along the arrow VIII in FIG. 7, and FIG. 9 is a view taken along the line IX-IX in FIG.
It is sectional drawing which follows a line.

The expansion chamber 60 of the exhaust device 59 uses the pulsation of the exhaust gas to improve the output of the engine 53. The expansion chamber 60 has an expansion portion 62 at an intermediate portion thereof, as shown in FIGS. 7 and 8. It is bent into a complicated shape that follows the shape of the vehicle body.

An exhaust gas purifier 63 is provided in an exhaust device 59 provided in the motorcycle 51. The purification device 63 is a pipe-shaped catalyst in which a surface of a pipe material such as stainless steel or the like is coated with a catalytic substance made of platinum, rhodium, palladium, or the like, and has a plurality of different diameters, two in the present embodiment. Pipe-shaped catalyst 6
4 and 65 are installed in the expansion part 62 of the expansion chamber 60 in a state of being concentrically stacked (partially in the present embodiment). In addition, each pipe-shaped catalyst 64,
Reference numeral 65 is fixed to the inner wall of the expansion chamber 60 by mounting stays 66 and 67.

The length of the catalyst material can be shortened by concentrically stacking a plurality of pipe-shaped catalysts 64 and 65, so that even the expansion chamber 60 bent into a complicated shape with a short straight line portion is sufficient. A catalyst surface area can be secured, and exhaust gas can be efficiently purified.

[0039]

As described above, according to the exhaust gas purifying apparatus of the present invention, a sufficient catalytic surface area of the pipe-shaped catalyst can be secured, and the exhaust gas purifying performance is improved.
There is no reduction in engine output.

In a purifying apparatus for purifying exhaust gas by disposing a catalyst in a muffler constituting an exhaust device, a diffuser pipe is disposed in the muffler, and a catalyst material is coated on a surface of the pipe material. And, as a pipe-shaped catalyst, a plurality of the pipe-shaped catalysts having different diameters are installed concentrically in the diffuser pipe in a state where at least a part thereof is stacked in the axial direction, so that it is easy to stack the pipe-shaped catalysts, A sufficient catalyst surface area can be secured, the exhaust gas purification performance is improved, and the engine output is not reduced.

[Brief description of the drawings]

FIG. 1 is a right side view of a scooter type vehicle showing an embodiment of an exhaust gas purification device according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a longitudinal sectional view showing a state in which a monolithic catalyst is attached to a diffuser pipe.

FIG. 6 is a right side view of a sports motorcycle showing another embodiment of the exhaust gas purifying apparatus according to the present invention.

FIG. 7 is a side view of the expansion chamber.

8 is a view taken in the direction of the arrow VIII in FIG. 7;

FIG. 9 is a sectional view taken along the line IX-IX of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scooter type vehicle 4,53 Engine 11,59 Exhaust device 12 Exhaust pipe (Exhaust device) 13,61 Muffler (Exhaust device) 19 Diffuser pipe 24,63 Exhaust gas purification device 25,26,29,64,65 Pipe-shaped catalyst 27, 28, 66, 67 Mounting stay 51 Motorcycle 60 Expansion chamber (exhaust device) 62 Expansion section of expansion chamber

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01N 3/08-3/36

Claims (5)

(57) [Claims] 1. An exhaust pipe connected to an engine, a muffler connected to the exhaust pipe,
An exhaust gas purifying apparatus comprising: a plurality of expansion chambers formed in the muffler; a diffuser pipe disposed in the muffler and having one end connected to the exhaust pipe; and a catalyst supported in the muffler. In the muffler, a first expansion chamber is formed on the side opposite to the exhaust pipe connection side, while the diffuser pipe has a downstream opening opening from the exhaust pipe into the first expansion chamber, The pipe-shaped catalyst is installed in the diffuser pipe, and the exhaust gas outflow-side end of the pipe-shaped catalyst is made to protrude more in the exhaust gas outflow direction than the exhaust gas outflow-side end of the diffuser pipe. Exhaust gas purifier characterized. 2. The exhaust gas according to claim 1, wherein the pipe-shaped catalyst is supported inside the diffuser pipe by a mounting stay, and an exhaust gas passage is formed between the pipe-shaped catalyst and the diffuser pipe. Purification device. 3. An exhaust pipe connected to the engine, a muffler connected to the exhaust pipe,
A plurality of expansion chambers formed in the muffler, a diffuser pipe disposed in the muffler and having one end communicated with the exhaust pipe, and exhaust gas flowing out of the diffuser pipe is supplied to each expansion chamber inside the muffler. In the exhaust gas purifying device, which is expanded and then discharged to the outside of the muffler, and the exhaust gas is purified by a catalyst carried in the muffler, the muffler has a first expansion chamber formed on a side opposite to an exhaust pipe connection end. On the other hand, the diffuser pipe has a downstream opening opening from the exhaust pipe into the first expansion chamber, the catalyst is formed in a pipe shape, and the pipe-shaped catalyst is installed in the diffuser pipe. Attach a monolithic catalyst to the downstream opening of the diffuser pipe to expand the muffler expansion chamber. Exhaust gas purifying device in which a tail pipe for discharging to the outside of the muffler of the exhaust gas, characterized in that juxtaposed to said pipe-shaped catalyst. 4. An exhaust pipe connected to the engine, a muffler connected to the exhaust pipe,
A plurality of expansion chambers formed in the muffler, a diffuser pipe disposed in the muffler and having one end communicated with the exhaust pipe, and exhaust gas flowing out of the diffuser pipe are provided in the muffler. In the exhaust gas purifying apparatus, wherein the muffler is expanded around the diffuser pipe in the expansion chamber and then discharged to the outside of the muffler, and the exhaust gas is purified by a pipe-shaped catalyst carried in the muffler, the muffler is connected to an exhaust pipe. While the first expansion chamber is formed on the opposite side, the diffuser pipe has a downstream opening opening from the exhaust pipe into the first expansion chamber, and the catalyst includes a plurality of pipe-shaped catalysts having different diameters. Prepare,
An exhaust gas purifying apparatus, wherein the plurality of pipe-shaped catalysts having different diameters are arranged concentrically inside the diffuser pipe in a state where at least a part thereof is overlapped in the axial direction. 5. An exhaust pipe connected to an engine, a muffler connected to the exhaust pipe,
An exhaust gas purifying apparatus comprising: a plurality of expansion chambers formed in the muffler; a diffuser pipe disposed in the muffler and having one end connected to the exhaust pipe; and a catalyst supported in the muffler. The muffler has a first expansion chamber formed on the side opposite to the exhaust pipe connection end, while the diffuser pipe has a downstream opening opening from the exhaust pipe into the first expansion chamber, and the catalyst has a pipe shape. The pipe-shaped catalyst is supported inside the diffuser pipe by a mounting stay at a substantially central portion at one point, and the exhaust gas flows between the pipe-shaped catalyst and the diffuser pipe. An exhaust gas purification device, wherein a passage is formed.