JPH1037745A - Secondary air supplying device for exhaust emission control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To much lead secondary air into an exhaust device with a simple structure by forming a defuser on the way of the exhaust device, and arranging a secondary air supplying means to the defuser, in an engine supplying secondary air into the exhaust device for exhaust emission control. SOLUTION: In the exhaust device 9A of a motorcycle, a defuser 14 is integratedly formed in the vicinity of the joining part of an exhaust pipe 10 and an expansion part 11. At this time, the cross sectional area is changed along the shape of the expansion part 11 in the downstream side of the defuser 14. An air pipe 15A as a secondary air supplying means is arranged on the defuser 14. One end of the air pipe 15A is arranged in the defuser 14, and also the other end of the air pipe 15A is opened to the atmosphere. When the defuser 14 is arranged on the way of the exhaust device 9A, negative pressure of exhaust pulsation in the vicinity of the defuser 14 is increased, and secondary air is much led into the exhaust device 9A through the air pipe 15A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a secondary air supply device for purifying exhaust gas.

[0002]

2. Description of the Related Art As means for purifying exhaust gas of an engine, secondary air is supplied to the exhaust gas and HC in the exhaust gas is supplied.
(Hydrocarbons), the CO (carbon monoxide) or the like is used to convert the _H 2 0 (water) and CO ₂ (carbon dioxide).

As means for supplying secondary air into exhaust gas, for example, there is a means in which a pipe communicating with the atmosphere is provided in the middle of an exhaust pipe, and secondary air is sucked by negative pressure in the exhaust pipe.

In order to take in more secondary air into the exhaust pipe, for example, as shown in Japanese Utility Model Laid-Open Publication No. 52-18315, a frusto-conical body directed to the exhaust flow is provided at the tip of a secondary air supply pipe in the exhaust system. A secondary air supply port is opened behind the frustum, or as shown in Japanese Utility Model Laid-Open Publication No. 49-50611, a throttle pipe is provided in the exhaust system to reduce the negative pressure in the exhaust system. Some are trying to raise it.

[0005]

However, providing a frustum at the tip of the secondary air supply pipe complicates the structure, and it is particularly difficult to make the frustum. In addition, when a throttle pipe is provided in the exhaust device, the throttle pipe serves as exhaust resistance, and the output of the engine is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a secondary air supply device for purifying exhaust gas which can introduce more secondary air into an exhaust device with a simple structure. And

[0007]

In order to solve the above-mentioned problems, a secondary air supply device for purifying exhaust gas according to the present invention, as described in claim 1, supplies secondary air into an exhaust device. In a secondary air supply device for supplying and purifying exhaust gas of an engine, a diffuser (expansion part) is formed in the exhaust device, and a secondary air supply for communicating the inside of the exhaust device and the atmosphere to the diffuser. Means are provided.

In order to solve the above-mentioned problem, the opening of the secondary air supply means disposed in the exhaust device is formed in a diffuser shape (flapper shape).
It is formed in.

[0009]

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

FIG. 1 is a right side view showing an embodiment of a motorcycle to which the present invention is applied. As shown in FIG.
The motorcycle 1 has a body frame 2, and a two-stroke engine 3 is mounted at a lower center portion of the body frame 2, for example.

A steering mechanism 4 is provided in front of the vehicle body frame 2, and a front wheel 6 is rotatably steered by a handle bar 5 to the left and right. On the other hand, a swing arm 7 is pivotally attached to a lower center portion of the body frame 2 so as to freely swing, and a rear wheel 8 is supported at a rear end of the swing arm 7.

An exhaust device 9 extends from the lower portion of the engine 3 toward the rear and upper part of the vehicle. The exhaust device 9 includes, for example, an exhaust pipe 10 connected to the engine 3, an expansion section 11 provided downstream of the exhaust pipe 10, and an expansion section 1.
1 and a silencer 12 connected to the downstream side of the vehicle 1 and arranged, for example, on the right side of the vehicle.

The exhaust device 9 has a secondary air supply device 13 as a means for purifying exhaust gas of the engine 3.
The secondary air supply device 13 supplies secondary air into the exhaust gas in the exhaust device 9 and converts HC (hydrocarbon), CO (carbon monoxide) and the like in the exhaust gas into H ₂ 0 (water) and the like. CO
₂ (carbon dioxide).

FIG. 2 is a side view of an exhaust device 9A showing a first embodiment of a secondary air supply device 13A to which the present invention is applied. The silencer 12 is omitted and a part of the exhaust device 9A is crushed. Shown.

As shown in FIG. 2, a diffuser 14 (expansion portion) is integrally or integrally formed near a joint between the exhaust pipe 10 and the expansion portion 11 of the exhaust device 9A. Further, the cross-sectional area on the downstream side of the diffuser 14 is smoothly changed so as to follow the shape of the expansion portion 11. The diffuser 14 is provided with an air pipe 15A as secondary air supply means for communicating the inside of the exhaust device 9A with the atmosphere. One end of the air pipe 15A is disposed in the diffuser 14 so as to open toward the downstream side of the exhaust flow, and the other end of the air pipe 15A is open to the atmosphere. Reference numeral 16 denotes a hose for preventing the air pipe 15A from sucking in foreign matter, and the open end thereof is disposed at an appropriate position.

If the diffuser 14 is provided in the exhaust device 9A, the negative pressure of the exhaust pulsation near the diffuser 14 increases. If one end of the air pipe 15A is arranged in the diffuser 14, more secondary air can be introduced into the exhaust device 9A by the increased negative pressure.

Further, it is structurally relatively easy to provide the diffuser 14 in the exhaust device 9A, and it can be easily retrofitted to a conventional model. Of course, the air pipe 15
For A, a conventional model can be used as it is.

FIG. 3 is a side view of an exhaust device 9B showing a second embodiment of a secondary air supply device 13B to which the present invention is applied. The silencer 12 is omitted and a part of the exhaust device 9B is crushed. Shown. Further, the same components as those in the first embodiment are denoted by the same reference numerals.

As shown in FIG. 3, the exhaust device 9B is located near the joint between the exhaust pipe 10 and the expansion portion 11 of the exhaust device 9B.
An air pipe 15B is provided as secondary air supply means for communicating the inside of the device with the atmosphere. The exhaust device 9B has one end of the air pipe 15B opening toward the downstream side of the exhaust flow.
And the other end of the air pipe 15B is open to the atmosphere. Reference numeral 16 denotes a hose for preventing the air pipe 15 from sucking in foreign matter, and an open end thereof is disposed at an appropriate position.

An air pipe 15 arranged in the exhaust device 9
The opening 17 of B is formed in a diffuser shape (horn shape). The opening 17 of the diffuser is connected to the exhaust device 9.
Since the passage area of B may be reduced to cause exhaust resistance, the vicinity of the junction between the exhaust pipe 10 and the expansion portion 11 around the diffuser-shaped opening 17 is expanded in the radial direction.

Air pipe 1 arranged in exhaust device 9B
By forming the opening 17 of the 5B into a diffuser shape, a differential pressure (negative pressure) generated between the opening 17 and the exhaust gas flowing around the opening 17 becomes large. Of which can be introduced.

Further, forming the opening 17 of the air pipe 15B in a diffuser shape and providing the air pipe 15B in the exhaust device 9B are structurally relatively easy, and can be easily retrofitted to conventional models. is there.

Further, it is more effective to arrange the air pipe 15B having the diffuser-shaped opening 17 shown in the second embodiment on the diffuser 14 shown in the first embodiment.

[0024]

As described above, according to the secondary air supply device for purifying exhaust gas according to the present invention, the secondary air supply for purifying the exhaust gas of the engine by supplying the secondary air into the exhaust device. In the device, a diffuser (expansion portion) is formed in the exhaust device, and secondary air supply means for communicating the inside of the exhaust device with the atmosphere is provided in the diffuser, so that the exhaust pulsation that increases near the diffuser is reduced. Due to the negative pressure, more secondary air is introduced into the exhaust system.

Further, since the opening of the secondary air supply means disposed in the exhaust device is formed in a diffuser shape (a trumpet shape), more negative pressure due to the exhaust pulsation that increases around the opening causes more secondary air supply. The next air is introduced into the exhaust device.

[Brief description of the drawings]

FIG. 1 is a right side view showing an embodiment of a motorcycle to which the present invention is applied.

FIG. 2 is a side view of an exhaust device showing a first embodiment of a secondary air supply device to which the present invention is applied.

FIG. 3 is a side view of an exhaust device showing a second embodiment of a secondary air supply device to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motorcycle 3 Engine 9A, 9B Exhaust device 10 Exhaust pipe 11 Expansion part 12 Muffler 13A, 13B Secondary air supply device 14 Diffuser (expansion part) 15A, 15B Air pipe (secondary air supply means) 17 Diffuser shape opening of air pipe Department

Claims (2)

[Claims] In a secondary air supply device for supplying secondary air into an exhaust device to purify exhaust gas of an engine, a diffuser (expansion portion) is formed in the exhaust device 9A. A secondary air supply means for communicating the inside of the exhaust device 9A with the atmosphere, the secondary air supply device for purifying exhaust gas. 2. The exhaust gas purifying secondary air supply device according to claim 1, wherein the opening portion 17 of the secondary air supply means 15B disposed in the exhaust device 9B is formed in a diffuser shape (flapper shape).