JP2588996Y2 - Exhaust gas purification device - Google Patents

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 purifying exhaust gas of an engine by a catalyst.

[0002]

2. Description of the Related Art As such an exhaust gas purifying device, a device in which a catalyst is carried on a cylindrical carrier having a large number of holes in a peripheral wall and the catalyst is inserted into an exhaust pipe is conventionally known. -85316 and JP-A-3-229913.

In the exhaust gas purifying apparatus, the exhaust gas flows along the inner and outer surfaces of the carrier while entering and exiting the large number of holes, so that the exhaust gas comes into contact with the catalyst carried on the both surfaces and is purified by the catalyst. You.

[0004]

However, such a catalyst purifying action is mainly limited to the exhaust gas portion flowing along the peripheral wall of the carrier, and the catalytic action is applied to the exhaust gas portion flowing through the exhaust pipe and the central portion of the carrier. The exhaust gas portion passes through the carrier as it is, and the purification efficiency is reduced.

Accordingly, the present invention is intended to improve the exhaust gas purifying apparatus as described above, to further improve the contact between the exhaust gas and the catalyst, and to improve the purification efficiency.

[0006]

Therefore, according to the present invention, in the exhaust gas purifying apparatus in which a cylindrical catalyst carrier is fitted coaxially in an exhaust pipe, the carrier has a front end.
A relatively large diameter end portion supported on the inner wall of the exhaust pipe,
The diameter is gradually reduced from both ends toward the center in the axial direction.
And each cone has a drum shape.
Ru catalyst by supporting provided with a number of through-holes.

According to the present invention, at the conical portion of the carrier,
The peripheral wall is inclined with respect to the flow direction of the exhaust gas, extends across the flow to near the center thereof , and furthermore, at the upstream end.
After reducing the diameter to the central small diameter part, then the downstream end
Diameter to Runode towards parts, with spans catalysis even near the center of the exhaust gas, the exhaust gas flows along well the inner and outer surfaces of the carrier into and out of the hole in the wall, thus improving purification efficiency I do.

[0008]

FIG. 1 is an overall side view of a motorcycle 1 provided with an exhaust emission control device according to the present invention. Reference numeral 2 denotes a body frame, which is a main frame 4 extending obliquely downward and rearward from a head pipe 3 above a 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 rear frame 5 includes a seat rail 6 and the like connected to the rear portion of the rear frame 5.

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

The outside of the vehicle body is covered by a cowling 20 from the front to both sides, and the rear is a rear vehicle body cover 21.
Covered by 22 is the fuel tank, 23 is the seat, 24
Is a radiator arranged on the front of the engine 15.

The engine 15 is a two-cycle engine, and an intake system 26 having a carburetor 25 communicates with a crankcase in a crankcase 27. The exhaust system 29 connected to the exhaust port of the cylinder 28, after descending in front of the engine 15, bends and extends rearward below the engine 15, and then extends diagonally upward on the side of the rear wheel 12, thereby extending the vehicle body. It opens to the back. The exhaust system 29 is formed by sequentially connecting an expansion pipe 31, a connection 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 a catalytic reaction of the catalytic converter 35 is supplied to the exhaust pipe 30. The exhaust gas is added to the exhaust gas from the secondary air supply pipe 36 on the upstream side and near the cylinder exhaust port. Secondary air supply pipe 36 has flange 37
The exhaust pipe 30 has a reed valve 38 at the air inlet on the upstream side. When the inside of the exhaust pipe 30 has a negative pressure, the reed valve 38 is opened, and external air is used as secondary air. The air is introduced into the exhaust pipe 30 via the next air supply pipe 36.

A valve chamber 39 is formed at an intermediate portion of the exhaust pipe 30, and an on-off valve 40 is provided in the valve chamber 39. This on-off valve 40
Is a rotatable valve shaft 41 that penetrates the valve chamber 39 in the diameter direction,
A butterfly valve comprising a disc-shaped valve element 42 fixed to the valve shaft 41, and is urged in a direction to completely close the exhaust passage as shown in the figure.

A pulley 43 is fixed to one end of the valve shaft 41 protruding outward from the valve chamber 39, and a wire 44 is attached to the pulley 43.
Is wound and the end is fixed to the pulley 43. Wire 44
Is passed through a sleeve 47 having one end fixed to a bracket 46 connected to the valve chamber 39 by bolts 45. As shown in FIG. 1, the sleeve 47 extends to the vaporizer 25, and the other end is fixed in the vicinity thereof. The other end of the wire 44 is connected to a throttle valve (not shown) provided in the carburetor 25.
Therefore, the on-off valve 40 changes the exhaust passage area in conjunction with the throttle valve, and changes the output characteristics and exhaust characteristics of the engine according to the throttle valve opening.

On the upstream side of the on-off valve 40, the exhaust pipe 30
The exhaust gas purifying device 48 according to the present invention is provided. This exhaust gas purifying device 48 has a relatively simple structure for supplementing the exhaust gas purifying action of the catalytic converter 35. The exhaust gas is sufficiently purified by the exhaust gas purification device 48 and the catalytic converter 35, and the durability of the catalytic converter 35 is increased by providing the exhaust gas purification device 48.

FIG. 3 is a longitudinal sectional view showing the upstream portion of the exhaust pipe 30, that is, the portion where the exhaust gas purifying device 48 is installed, in a further enlarged manner. The exhaust gas purification device 48 is a cylindrical catalyst carrier that carries a catalyst.
49 is inserted into the exhaust pipe 30 coaxially with the exhaust pipe 30.

The carrier 49 is formed into a cylindrical shape by joining two halves formed by bending a plate material (punching plate) made of stainless steel or the like having a large number of holes 50 and joining them together by spot welding or the like. (See FIGS. 4 and 5).
After the formation, a catalyst made of a noble metal is coated and supported on the wall surface. Similarly, the exhaust pipe 30 is formed by joining the two halves. The carrier 49 has an upstream end along the inner peripheral surface of the exhaust pipe 30 and a downstream end with an elastic member 51.
And is elastically supported by the exhaust pipe 30 via the Elastic member
51 knits a stainless steel wire with a diameter of about 0.2 mm into a net,
This is formed into an annular shape and has heat resistance and elasticity.

The carrier 49, whose both ends are supported by the exhaust pipe 30 in this manner, is narrowed in the middle into a nozzle shape as shown in the figure. That is, the conical portions 49a and 49b whose diameters gradually decrease from both ends are joined together at the minimum diameter portion 49c,
A space 52 formed around the carrier 49 and the exhaust pipe 30
Gradually increases from both ends toward the minimum diameter portion 49c.

Since the carrier 49 has such a shape, the conical portions 49a and 49b intersect with the flow direction of the exhaust gas in the exhaust pipe 30, so that the carrier 49 has a simple cylindrical shape. A much larger amount of exhaust gas flows into the peripheral wall of the carrier 49 than in the case where it is provided. Figure 3 shows the carrier
The flow of the exhaust gas in the vicinity of 49 is schematically shown by a dashed line, and a portion a of the exhaust gas flowing into the conical portion 49a passes through a number of holes 50 provided in the portion, and the carrier
After exiting outside of the carrier 49, it flows along the outer surface of the carrier 49 and again in the conical portion 49b through the hole 50 in said portion.
The other part b flows into the inside of the carrier 49 along the peripheral wall of the carrier 49 as it is. During this time, both exhaust gas flows are in good contact with the catalyst carried on both the inner and outer surfaces of the carrier 49 and are efficiently purified.

A relatively small amount of the exhaust gas flow c flowing through the exhaust pipe 30 and the center of the carrier 49 passes without contacting the peripheral wall of the carrier 49, and the exhaust gas flow c also has a minimum diameter portion 49.
In the vicinity of c, since it is sufficiently close to the peripheral wall of the carrier 49,
The exhaust gas stream c also has a catalytic action, and eventually the exhaust gas purification device
The entire exhaust gas passing through 48 is efficiently purified.

[0021] In the above SL embodiment, are an exhaust gas purification device 48 provided in the straight pipe portion of the exhaust pipe 30, the present invention of the exhaust gas purifying a tapered tubular portion tube diameter of the exhaust pipe is gradually changed in the axial direction It is also possible to provide a device. In this case, the inclination angle of the conical portion of the carrier may be made larger than the taper angle of the exhaust pipe.

[0022]

According to the present invention, in an exhaust gas purifying apparatus in which a catalyst is carried on a cylindrical carrier having a large number of holes in a peripheral wall, and the catalyst is coaxially fitted in an exhaust pipe, the exhaust gas and the catalyst are combined. And the exhaust gas purification efficiency can be improved.

[Brief description of the drawings]

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

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

FIG. 3 is a longitudinal sectional view showing a further enlarged portion of the exhaust system where the exhaust gas purification device is installed.

FIG. 4 is a transverse sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a transverse sectional view taken along the line VV of FIG. 3;

[Explanation of symbols]

DESCRIPTION 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 ... carburetor, 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, 39 ... valve chamber, 40 ... open / close valve, 41 ... valve shaft, 42 ... valve body, 43 ...
Pulley, 44… Wire, 45… Bolt, 46… Bracket, 47
... sleeve, 48 ... exhaust purification device, 49 ... carrier, 50 ... hole, 51 ...
Elastic member, 52 ... space.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takato Sekida 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute Co., Ltd. (56) References JP-A-3-85316 (JP, A) JP-A Hei 3-294616 (JP, A) Japanese Utility Model 51-143011 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F01N 3/28 F01N 3/24

Claims (1)

(57) [Scope of request for utility model registration] 1. A tubular exhaust purification device being inserted into the coaxial exhaust pipe a catalyst carrier, the carrier is a
A relatively large diameter end portion supported on the inner wall of the exhaust pipe;
The diameter gradually decreases from both ends toward the center in the axial direction
It has a drum shape consisting of each conical portion, and a large number of
An exhaust gas purifying apparatus, wherein a through-hole is provided and a catalyst is supported .