JPH07158431A - Exhaust emission control device - Google Patents

Abstract

PURPOSE:To install a carrier in the state of being positioned into an outer pipe while allowing its free thermal expansion to the outer pipe of an exhaust pipe in an exhaust emission control device formed by holding a catalyst by the cylindrical carrier having numerous holes in the peripheral wall and inserting the carrier fittingly and coaxially into the exhaust pipe. CONSTITUTION:One end 54a of a carrier 54 is made collide with a contact part 57 protrusively provided on the inner peripheral surface of an outer pipe 55. A heat resisting elastic member 59 is interposed in the radially compressed state between the outer peripheral surface part of the other end of the carrier 54 and a recessed place 58 formed at the inner peripheral surface part of the outer pipe 55 facing the outer peripheral surface part, and the elastic member 59 is axially compressed between a pressing piece so and the end part 58b or the recessed place 58 by this pressing piece 60 protrusively provided at the outer peripheral surface of the carrier 54 so as to be engaged with the axial inner end face 59b of the elastic member 59.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an engine, and more particularly to an exhaust gas formed by supporting a catalyst on a cylindrical carrier having a large number of holes in its peripheral wall and coaxially inserting the catalyst into an exhaust pipe. Purification device

[0002]

2. Description of the Related Art Conventionally, in such an exhaust gas purifying apparatus, the carrier is fixed to the outer pipe by fixing the carrier to the outer pipe, as disclosed in, for example, Japanese Patent Laid-Open No. 3-85316. It is fixed by welding, or as disclosed in JP-A-3-229913, a bridge made of a thin plate is provided on the outer peripheral surface of the carrier, and the carrier is fitted into the outer tube through the bridge. Etc. were taken.

[0003]

[Problems to be Solved] However, since the carrier rises in temperature and thermally expands due to the catalytic action of the catalyst to be supported, in the case of fixing the carrier by welding, a large thermal stress is generated in the weld fixing portion with the outer pipe. Therefore, the carrier and the outer tube are likely to be deformed or damaged. Further, if the catalyst adheres to the welded part, the welding is hindered, so that the welded part must be masked when the catalyst is applied to the carrier.

In the type in which the carrier is fitted into the outer tube via the bridge, it is difficult to obtain sufficient accuracy because the bridge is made of a thin plate, and the carrier is allowed to undergo its thermal expansion and positioned at a fixed position. It is difficult to give a necessary and sufficient tightening margin. Further, the tightening margin may become loose due to repeated heating. Further, the catalyst is also carried on the bridge portion, which is uneconomical.

[0005]

The present invention has been made in view of such circumstances, and in the present invention, a catalyst is supported on a cylindrical carrier having a large number of holes in its peripheral wall, In an exhaust gas purification device in which this is coaxially inserted into an exhaust pipe, an outer peripheral surface portion of at least one end of the carrier and a recess formed in an inner peripheral surface portion of the exhaust pipe outer pipe facing the outer peripheral surface portion. A heat-resistant elastic member is interposed between the elastic member and the outer peripheral surface of the elastic member in a state of being compressed in the radial direction. The mating pressing piece compresses axially between the pressing piece and the end of the recess.

According to the present invention, since the carrier is slidably held by the outer tube via the elastic member, the carrier can freely thermally expand with respect to the outer tube, and thermal stress is generated between the two. It never happens. Further, the vibration due to the exhaust flow is effectively absorbed by the elastic member.

Moreover, the carrier is positively positioned and held at a predetermined position in the outer tube in both the radial direction and the axial direction by the reaction force of the elastic member compressed in the radial direction and the axial direction, and is undesirably left in the outer tube. There is no upset.

Further, since the carrier is not welded to the outer pipe,
There is no need to bother the masking of the weld when supporting the catalyst, and there is no risk of the catalyst being affected by welding heat.

[0009]

EXAMPLES FIG. 1 is an overall side view of a motorcycle 1 equipped with an exhaust emission control device according to the present invention. Reference numeral 2 denotes a vehicle body frame, which includes a main frame 4 extending obliquely downward and rearward from a head pipe 3 above the front portion, a rear frame 5 extending obliquely upward and rearward from a lower rear portion of the main frame 4, and a rear portion from an intermediate portion of the main frame 4. The rear end of the seat frame 6 is connected to the rear portion of the rear frame 5 and extends to the rear.

At the front of the vehicle body, a front fork 8 pivotally supported by the head pipe 3 and rotated by a handle 7 extends vertically, and a front wheel 9 is pivotally supported at the lower end thereof.
A rear fork 11 is pivotally supported at a lower rear end of the main frame 4 via a pivot shaft 10 so as to be vertically swingable, and a rear wheel 12 is pivotally supported at a rear end thereof via a rear axle 13. A rear cushion 14 is provided between the rear fork 11 and the seat rail 6. An engine 15 is suspended and mounted on the main frame 4 between the front wheels 9 and the rear wheels 12. Then, a drive chain 19 is stretched between a drive sprocket 17 provided on the output shaft 16 of the engine 15 and a driven sprocket rocket 18 provided on the rear axle 13, and the rear wheels 12 drive the engine 15 via the drive chain 19. Driven by.

The outside of the vehicle body is covered with cowlings 20 from the front surface to both side surfaces, and the rear portion is a rear vehicle body cover 21.
Are covered by. 22 is a fuel tank, 23 is a seat, 24
Is a radiator disposed on the front surface of the engine 15.

The engine 15 is a two-cycle engine, and an intake system 26 having a carburetor 25 communicates with a crank chamber in a crankcase 27. The exhaust system 29 connected to the exhaust port of the cylinder 28 descends in front of the engine 15, bends and extends rearward below the engine 15, and then extends diagonally upward to the side of the rear wheel 12, It opens to the rear. The exhaust system 29 is formed by sequentially connecting an expansion pipe 31, a connecting pipe 32, a silencer 33, and a discharge pipe 34 to an exhaust pipe 30 extending from a cylinder 28.

FIG. 2 is an enlarged view of only the exhaust system 29 of FIG. As shown in FIG. 2, a catalytic converter 35 for purifying exhaust gas is provided in the expansion pipe 31, and secondary air for assisting the catalytic reaction of the catalytic converter 35 is further provided in the exhaust pipe 30. On the upstream side, in the vicinity of the cylinder exhaust port, the exhaust gas is added from the secondary air supply pipe 36. Secondary air supply pipe 36 is flange 37
Attached to the exhaust pipe 30 (see Fig. 3),
A reed valve 38 is provided at the upstream air intake, and when the inside of the exhaust pipe 30 becomes a negative pressure, the reed valve 38 opens, and the outside air becomes 2
The secondary air is introduced into the exhaust pipe 30 via the secondary air supply pipe 36.

The exhaust pipe 30 is divided into an upstream side portion 30a and a downstream side portion 30b. Both of these portions 30a, 30b.
A valve chamber 42 is formed at the connection portion of the. The valve chamber 42 is fixed to the end portion of the exhaust pipe portion 30a on the upstream side, and the flange 43 is formed on the end surface opposite to the portion 30a. The flange 43 is fixed to the downstream exhaust pipe portion 30b.
The exhaust pipe portions 30a and 30b are connected by abutting 44 and fastening them with bolts 45.

An opening / closing valve 46 is provided in the valve chamber 42.
The opening / closing valve 46 is a butterfly valve including a rotatable valve shaft 47 penetrating the valve chamber 42 in the diametrical direction and a disc-shaped valve body 48 fixed to the valve shaft 47. The exhaust passage is biased in the direction to close it completely.

A pulley 49 is fixed to one end of the valve shaft 47 protruding outward from the valve chamber 42, and a wire 50 is attached to the pulley 49.
Is wound and the end portion is fixed to the pulley 49. Wire 50
Is passed through a sleeve 52 whose one end is fixed to a bracket 51 fastened to the flange 43 by the bolt 45. As shown in FIG. 1, the sleeve 52 extends to the vaporizer 25, and the other end is fixed in the vicinity thereof. The other end of the wire 50 is connected to a throttle valve (not shown) provided on the carburetor 25. Therefore, the opening / closing valve 46 changes the exhaust passage area in conjunction with the throttle valve, and changes the output endurance and exhaust endurance of the engine according to the throttle valve opening.

By the way, the exhaust pipe portion 30b on the downstream side constitutes an exhaust gas purification device 53 according to the present invention. The exhaust gas purification device 53 has a relatively simple structure for supplementing the exhaust gas purification action of the catalytic converter 35. Exhaust gas is sufficiently purified by the exhaust gas purification device 53 and the catalytic converter 35, and by providing the exhaust gas purification device 53, the catalytic converter 35
Durability increases.

FIG. 3 is a sectional view showing the exhaust pipe portion 30b, that is, the exhaust purification device 53 in a further enlarged manner. The exhaust gas purification device 53 includes a cylindrical catalyst carrier 54 carrying a catalyst and an outer pipe of the exhaust pipe.
It is configured by being inserted coaxially with this in 55.

The carrier 54 is formed into a tubular shape by joining two halves formed by bending a plate material (punching plate) such as stainless steel having a large number of holes 56 and joining them by spot welding or the like. (See FIGS. 4 and 5). After the formation, the wall surface is coated with a catalyst made of a noble metal and carried. Similarly, the outer tube 55 is also formed by joining two halves. The shapes of the carrier 54 and the outer tube 55 are similar to each other, and when the carrier 54 is fitted into the outer tube 55, a uniform space is entirely provided between the outer peripheral surface of the carrier 54 and the inner peripheral surface of the outer tube 55. It can be formed.

The upstream end portion 55a of the outer tube 55 is reduced in diameter to extend along the outer peripheral surface of the carrier 54, and the flange 44 is welded to the end portion, but the inner peripheral portion of the flange 44 has an end portion. The contact portion 57 extends further inward than the inner circumference of the portion 55a.
The upstream end surface 54a of the carrier 54 is abutted against the contact portion 57. However, the end surface 54a is merely abutted against the abutting portion 57, and both are not fixed.

The outer pipe 55 is connected to the expansion pipe 31 on the downstream side, but the outer pipe 55 is formed with an enlarged diameter portion 55b at a position adjacent to the connection portion, and the enlarged diameter portion 55b forms an annular shape on the inner surface. The recess 58 is formed. An annular elastic member 59 is fitted in the recess 58. The elastic member 59 is formed by weaving a stainless steel wire having a diameter of about 0.2 mm into a net shape and forming the annular shape, and has heat resistance and elasticity. Elastic member 59
The outer peripheral surface of the downstream end of the carrier 54 is in contact with the inner peripheral surface of the elastic member 59, and the elastic member 59 is compressed between the inner peripheral surface of the recess 58 and the outer peripheral surface of the carrier 54 in the radial direction. It is sandwiched between.

A similar recess 58a is also provided in the middle portion of the outer tube 55, and in this part as well, the inner peripheral surface of the recess 58a and the carrier
A similar elastic member 59a is sandwiched between the outer peripheral surface of 54 and the outer peripheral surface in a state of being radially compressed. Thus the carrier 54
Is elastically supported by the outer tube 55 via elastic members 59 and 59a, and is positioned at concentric positions with the outer tube 55 at equal intervals.

A pressing piece 60 is projectingly provided on the outer peripheral surface of a portion of the carrier 54 which is in contact with the elastic member 59. This pressing piece 60
Is formed by bending outwardly the tongue pieces provided on both edges of the one half forming the carrier 54 (see FIG. 5).
Is engaged with the end surface 59b on the upstream side, that is, the axially inner side.
The pressing piece 60 is provided at a position where the elastic member 59 is compressed between the pressing piece 60 and the end wall portion 58b opposite to the recess 58 when engaged with the end surface 59b. Therefore, the carrier 54 is pushed in the axial direction by the reaction force of the elastic member 59, and the end face on the upstream side is
54a is always held in the engagement position with the contact portion 57, and thus the carrier 54 is axially positioned in the outer tube 55.

As described above, the carrier 54 has elastic members 59, 59b.
Of the elastic member 59 in the radial direction and in the axial direction of the elastic member 59 in the axial direction, and is not fixed to the outer tube 55. Therefore, a large thermal stress does not occur between the carrier 54 and the outer tube 55. Also, elastic members 59, 59a
Absorbs the vibration of the carrier 54 due to the exhaust flow, and this absorbs the outer tube 55.
To be transmitted to. Further, the carrier 54 is attached to the outer tube 55.
Since it is not welded to the carrier, there is no need to bother the masking of the weld when the catalyst is carried on the carrier 54, and there is no risk of the catalyst being affected by welding heat.

As described above, the downstream end of the carrier 54 is attached to the elastic member 59.
Although the embodiment has been described in which the upstream end is abutted against the contact portion 57, the downstream side may be held by the contact portion 57, and the upstream side may be held by the elastic member 59. Both ends may be held via the elastic member 59. In this case, the reaction forces in the axial direction due to the elastic members at both ends oppose each other to position the carrier 54 in the axial direction.

In the exhaust gas purifying apparatus in which the catalyst is carried on the tubular carrier as described above, it is difficult for the catalyst to act on the exhaust flow portion flowing through the center of the carrier, and the purifying efficiency is reduced accordingly. Tend to do. However, in this embodiment,
Since the on-off valve 46 is provided immediately upstream of the exhaust gas purification device 53, this improves the purification efficiency. That is,
Since the exhaust flow passes through the opening / closing valve 46 through the outer peripheral portion of the valve body 48, after exiting the opening / closing valve 46, the flow becomes a biased flow toward the outer peripheral side along the peripheral wall of the carrier 54, thus increasing the action of the catalyst. You will receive it.

In the above embodiment, the secondary air supply pipe 36
Is connected to the upstream side of the exhaust pipe 30 and in the vicinity of the cylinder exhaust port, but the secondary air supply pipe 36 may be connected to the valve chamber 42 as shown in FIG. By doing this, the valve chamber 42
The secondary air can be efficiently supplied by utilizing the low pressure generated around the valve element 48 inside, and the secondary air can be mixed well with the exhaust gas.

FIG. 7 shows an example in which an exhaust gas purification device 53 is provided in the exhaust pipe portion 30a on the upstream side. Since the structure of the exhaust emission control device 53 is exactly the same as that of the above-mentioned embodiment, the corresponding parts are designated by the same reference numerals and the detailed description thereof will be omitted. In the present embodiment, the on-off valve 46 is located on the downstream side of the exhaust purification device 53,
When the on-off valve 46 is appropriately controlled according to the operating conditions of the engine to control the flow of exhaust gas, the pressure in the exhaust pipe becomes almost positive and the pressure fluctuation also decreases. Purification efficiency is improved by increasing the residence time.

FIG. 8 shows an example in which the same exhaust gas purification device 53 is provided on both the exhaust pipe portions 30a and 30b.

[0030]

According to the present invention, a catalyst is supported on a tubular carrier having a large number of holes in its peripheral wall, and the catalyst is supported coaxially in an exhaust pipe. While permitting free thermal expansion of the outer tube, the outer tube can be reliably positioned and installed in the outer tube, and there is no trouble such as masking the welded portion when the catalyst is carried on the carrier.

[Brief description of drawings]

FIG. 1 is an overall side view of a motorcycle equipped with an exhaust emission control device according to the present invention.

FIG. 2 is an enlarged view showing only an exhaust system of the motorcycle.

FIG. 3 is an enlarged cross-sectional view of an exhaust emission control device portion of FIG.

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

5 is a cross-sectional view taken along the line VV of FIG.

FIG. 6 is a vertical sectional view of an exhaust pipe showing another embodiment.

FIG. 7 is a view similar to FIG. 6 showing still another embodiment.

FIG. 8 is a view similar to FIG. 6 showing another embodiment.

[Explanation of symbols]

1 ... Motorcycle, 2 ... Body frame, 3 ... Head pipe, 4 ... Main frame, 5 ... Rear frame, 6 ... Seat rail, 7 ... Handle, 8 ... Front fork, 9 ...
Front wheel, 10 ... pivot shaft, 11 ... rear fork, 12 ... rear wheel,
13 ... rear axle, 14 ... rear cushion, 15 ... engine, 16 ...
Output shaft, 17 ... Drive sprocket, 18 ... Driven sprocket, 19 ... Drive chain, 20 ... Cowling, 21 ... Rear body cover, 22 ... Fuel tank, 23 ... Seat, 24 ... Radiator,
25 ... Vaporizer, 26 ... Intake system, 27 ... Crankcase, 28 ... Cylinder, 29 ... Exhaust system, 30 ... Exhaust pipe, 31 ... Expansion pipe, 32 ... Connection pipe, 33 ... Silencer, 34 ... Exhaust pipe, 35 ... Catalytic converter, 36 ... Secondary air supply pipe, 37 ... Flange, 38 ... Reed valve, 42 ... Valve chamber, 43, 44 ... Flange, 45 ... Bolt, 46 ... Open / close valve, 47 ... Valve shaft, 48 ... Valve body, 49 ... pulley, 50 ... wire,
51 ... Bracket, 52 ... Trouser tube, 53 ... Exhaust gas purifying device, 54 ... Carrier, 55 ... Outer tube, 56 ... Hole, 57 ... Abutment part, 58 ... Recess, 59 ...
Elastic member, 60 ... Pressing piece.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takato Sekita 1-4-1 Chuo, Wako City, Saitama Stock Company Honda R & D Co., Ltd.

Claims (2)

[Claims] 1. An exhaust emission control device in which a catalyst is supported on a tubular carrier having a large number of holes on its peripheral wall, and the catalyst is coaxially inserted into an exhaust pipe, the outer periphery of at least one end of the carrier. A heat-resistant elastic member is interposed in a radially compressed state between the surface portion and the recess formed in the inner peripheral surface portion of the exhaust pipe outer pipe facing the outer peripheral surface portion, and the elastic member is provided. By a pressing piece that is provided so as to project on the outer peripheral surface of the carrier and engages with the end surface on the inner side in the axial direction of the elastic member,
An exhaust emission control device, characterized in that it is axially compressed between the pressing piece and the end of the recess. 2. The one end of the carrier is abutted against an abutting portion projecting on the inner peripheral surface of the outer tube.
Exhaust gas purification device described.