JPH09256842A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a heat transmission quantity from a catalyst to a muffler and to shorten a time required for starting a catalyst action so as to improve exhaust gas purifying performance by arranging the catalyst inside the muffler connected to an exhaust pipe, supporting the catalyst in two point or more, and floatably supporting one of the two points or more via a heat insulator. SOLUTION: A first muffler 2 and a second muffler are connected to an exhaust pipe of an engine in a motorcycle in this order, and a pipe type catalyst 5 is arranged inside the first muffler 23. The catalyst 5 arranged at a predetermined interval from the inside wall of the first muffler 2 is supported in two points by means of two stays 7, 8. That is, the catalyst 5 is held via a reinforcing plate 10 by means of a bent part, in the center of the stay 7 after the catalyst 5 is fastened by means of a clamp in the reinforcing plate 10 via a heat insulator 9 arranged on the outer circumferential face of the catalyst 5, while both end parts of the stay 7 are fixed on the inside wall of the first muffler 2. In this way, a heat transmission quantity from the catalyst 5 to the first muffler 2 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device for purifying exhaust gas exhausted from an engine such as a motorcycle.

[0002]

2. Description of the Related Art There are plate type, pipe type and other types of catalysts for purifying engine exhaust gas.
Both of them are provided inside the muffler connected to the exhaust pipe extending from the engine exhaust port, and are attached to the muffler as follows.

The first is disclosed in Japanese Patent Laid-Open No. 4-109022. As shown in FIGS. 8 and 9, both end portions of a plate-shaped catalyst a are bent and the bent portions b are muffler. It is fixed to the inner wall of c. The second is FIG.
Also, as shown in FIG. 11, flange portions e are formed at both ends of the pipe-shaped catalyst d, and the flange portions e are fixed to the inner wall of the muffler f. As shown in FIGS. 12 and 13, No. 3 is for staying a pipe-shaped catalyst i via a ring-shaped wire mesh g formed by meshing a large number of wires and a reinforcing plate h provided on the outer periphery thereof. Hold by and
Both ends of the stay j are fixed to the inner wall of the muffler k. No. 4 is disclosed in JP-A-49-109718, and as shown in FIG. 14, elasticity is provided in the gap between the outer peripheral surface of the integrated catalyst 1 having a circular cross section and the inner peripheral surface of the muffler m. The ceramic fiber n and the foamed ceramic o having a heat insulating property are filled.

[0004]

In the first and second examples of the above-mentioned conventional example, the catalysts a and d are fixed to the mufflers c and f by welding, or are held by the metal. Since the amount of heat transfer to c and f is large, it takes time for the temperature of the catalysts a and d to rise at the beginning of operation in the cold state, and it takes time for the catalytic reaction to occur.
There has been an inconvenience that the exhaust gas is not purified for a relatively long time. Also, the catalysts a and d reach a certain temperature,
Since the heat of the catalyst is easily transferred to the muffler after the catalytic reaction is started and the muffler becomes high in temperature, measures against heat damage such as cowling are required, resulting in an increase in cost. Further, since vibrations of the vehicle and the engine are easily transmitted to the catalysts a and d, the catalyst may peel off, and it is necessary to increase the thickness of the catalyst in order to improve the strength. And increased costs.

In No. 3 of the above-mentioned conventional example, since the catalyst i is fixed to the muffler k through the wire mesh g, the problem as described above is relatively unlikely to occur, but there is only one supporting point. Moreover, since it is only supported by floating through the wire mesh g, it is not sufficient to fix the catalyst i. In No. 4 of the above-mentioned conventional example, heat insulation between the catalyst 1 and the muffler m is performed by the foamed ceramic o, but since almost the entire outer peripheral surface of the catalyst l is fixed to the muffler m via the foamed ceramic o, 2 at both ends of ceramic foam 0
Only the ceramic fibers n provided at one place or in addition to these, and three places provided at both ends are not sufficient to absorb vibrations from a vehicle or the like. The present invention has been made in view of the above problems, and an object of the present invention is to provide an exhaust gas purification device that can improve the purification performance and the durability of the catalyst and can reduce the cost.

[0006]

In order to achieve the above-mentioned object, the present invention provides a catalyst inside a muffler connected to an exhaust pipe extending from an engine exhaust port. It is characterized in that it is supported at at least two points, and at least one point is floatingly supported via a heat insulating material. The invention according to claim 2 is characterized in that, in the invention according to claim 1, the floating support position is located on the engine exhaust port side of the muffler.

In the invention described in claim 1, since at least one point of the catalyst is supported through the heat insulating material, the amount of heat transfer from the catalyst to the muffler is small, and therefore the temperature of the catalyst rises quickly and The reaction time is relatively short. Further, the reaction heat of the catalyst is difficult to be transferred to the muffler, and therefore, it is not necessary to take measures against heat damage such as cowling.

According to the second aspect of the present invention, the exhaust gas at the engine exhaust side has a high temperature and the reaction with the catalyst is more vigorous, so that the reaction heat of the catalyst becomes higher. Since the supporting position is provided, it is difficult for the high temperature catalytic reaction heat to be transmitted to the muffler.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an exhaust gas purifying apparatus according to the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is an overall side view of a motorcycle in which an exhaust gas purifying apparatus according to the present invention is incorporated. An exhaust pipe (not shown) of an engine 1 is connected with a first muffler 2 and a first muffler 2 The second muffler 3 is connected to. An under cowl 4 is provided on the side of the engine 1.

Inside the first muffler 2, as shown in FIG. 2, a pipe-shaped catalyst 5 is provided. Pipe type catalyst 5
Is a stainless steel porous plate formed in a cylindrical shape, and as shown in FIG. 3, the inner and outer peripheral surfaces thereof and the periphery of each hole are coated with a noble metal catalyst 6. Returning to FIG. 2, the catalyst 5 is arranged such that its longitudinal direction is substantially along the axial direction of the first muffler 2 and at a predetermined distance from the inner wall of the first muffler 2, and the two stays 7, It is supported by 8 points at 2 points.

FIGS. 4 and 5 show the structure for supporting the catalyst 5 by the stay 7 shown in the portion A of FIG. 2. To support the catalyst 5 by the stay 7, it is arranged on the outer peripheral surface of the catalyst 5. After the catalyst 5 is clamped by the clamp of the reinforcing plate 10 via the heat insulating material 9, the catalyst 5 is held via the reinforcing plate 10 by the bent portion 11 at the center of the stay 7, and the both ends of the stay 7 are Fix to the inner wall of muffler 2. As the heat insulating material 9, a ceramic fiber having a heat insulating property and a cushioning property, a stainless mesh in which a material made of stainless steel is arranged in a mesh shape, or the like is used. 6 and 7 show the support structure of the catalyst 5 by the stay 8 shown in the portion B of FIG. 7. After the reinforcing plate 12 is fixed to the peripheral surface of the catalyst 5, the reinforcing plate 12 is welded to the stay. 8 is fixed to the bent portion 13, and further, both ends of the stay 8 are fixed to the inner wall of the first muffler 2.

The support of the catalyst 5 by the stay 7 is, so to speak, floating support via the heat insulating material 9, while the support of the catalyst 5 by the stay 8 is fixed support by welding, but the positional relationship between them is supported by the stay 7. The location is set so as to be located on the engine exhaust port side 14 of the first muffler 2. This is because, on the engine exhaust side, the exhaust gas has a high temperature and the reaction with the catalyst is more vigorous, so that it is necessary to make it difficult for the reaction heat to be transferred to the first muffler 2. By doing so, the strength deterioration of the welded portion of the first muffler 2 due to the high temperature can be prevented more effectively. In addition, in the above, the number of supporting points for the catalyst 5 is two
Although the example of the case of the place is described, the present invention is not limited to this, and the number of supporting places can be appropriately increased. Further, the number of floating supporting points is not limited to one, but can be increased appropriately. However, even in this case, the floating portion is located on the engine exhaust port side for the above reason.

Next, the operation will be described. Since the catalyst 5 is supported via the heat insulating material 9, the heat transfer amount from the catalyst 5 to the first muffler 2 is small. Therefore, the temperature of the catalyst 5 rises quickly, and the time until the catalytic reaction starts in the cold state is relatively short. Further, the reaction heat of the catalyst 5 is difficult to be transferred to the first muffler 2, and therefore it is not necessary to take measures against heat damage such as cowling. Furthermore, since a ceramic fiber having a cushioning property or a stainless mesh is used as the heat insulating material 9, vibration of the vehicle or the like is difficult to be transmitted to the catalyst 5, and
Since the catalyst is also held to be thermally deformable, the thermal stress is reduced and the durability of the catalyst 5 is improved. Therefore, the pipe-shaped catalyst 5 can be made thin, and the cost and the weight can be reduced.

Further, on the engine exhaust port side 14, the exhaust gas is at a high temperature and the reaction with the catalyst 5 is more vigorous.
The reaction heat of becomes higher, but this engine exhaust side 1
4 has a floating support position, so the first muffler 2
The heat of high-temperature catalytic reaction is difficult to transfer to.

[0015]

According to the invention described in claim 1, since the catalyst is supported through the heat insulating material, the heat transfer amount from the catalyst to the muffler is small, and the time until the catalytic reaction starts is relatively long. Since it is short, the purification performance of exhaust gas is improved. Further, the reaction heat of the catalyst is less likely to be transferred to the muffler, and therefore, it is not necessary to take measures against heat damage such as preventing the frame cover from melting and increasing the size of the muffler cover.

According to the second aspect of the present invention, the exhaust gas on the engine exhaust side has a high temperature and the reaction with the catalyst is more vigorous and the reaction heat of the catalyst becomes higher. However, the floating support position is on the engine exhaust side. Since it is provided, it is difficult for the high temperature catalytic reaction heat to be transmitted to the muffler.

[Brief description of drawings]

FIG. 1 is a side view showing an entire motorcycle incorporating an exhaust gas purifying apparatus according to the present invention.

FIG. 2 is likewise a partially cutaway sectional view showing an internal state of the first muffler.

FIG. 3 is likewise a sectional view showing a part of the catalyst.

FIG. 4 is also an enlarged view of a portion A of FIG. 1 and a cross-sectional view taken along line BB of FIG.

5 is a sectional view taken along line AA of FIG.

6 is an enlarged view of a portion B of FIG. 1 and a sectional view taken along the line D-D of FIG. 7.

FIG. 7 is likewise a sectional view taken along the line CC of FIG.

FIG. 8 is a cross-sectional view taken along the muffler axis of a conventional exhaust gas purification device.

9 is a sectional view taken along a plane orthogonal to the axis of FIG.

FIG. 10 is a sectional view of another exhaust gas purifying apparatus along the muffler axis.

11 is a sectional view taken along a plane orthogonal to the axis of FIG.

FIG. 12 is a sectional view of another exhaust gas purifying apparatus along the muffler axis.

FIG. 13 is likewise a sectional view taken along a plane orthogonal to the axis of FIG.

FIG. 14 is a sectional view of another exhaust gas purifying apparatus along the muffler axis.

[Explanation of symbols]

 1 engine 2 first muffler 5 catalyst 9 heat insulating material 14 engine exhaust port side

Claims (2)

[Claims] 1. A catalyst is provided inside a muffler connected to an exhaust pipe extending from an engine exhaust port, and the catalyst is at least two.
An exhaust gas purifying device characterized in that it is supported at more than one point, and at least one point is floatingly supported via a heat insulating material. 2. The exhaust gas purifying apparatus according to claim 1, wherein the floating support position is located on the engine exhaust port side of the muffler.