JPH0514085B2 - - Google Patents

Description

Detailed Description of the Invention A. Purpose of the Invention (1) Industrial Application Field The present invention supplies secondary air to the exhaust system of an engine in a motorcycle to oxidize unburned harmful components flowing through the exhaust system. The present invention relates to an exhaust gas purification device that removes exhaust gas.

(2) Prior art In a motorcycle equipped with a V-type engine in which the front and rear engine blocks are arranged in a V-shape in the longitudinal direction of the body frame, a front exhaust port that opens at the front of the front engine block is used. A front exhaust pipe connected to the engine block is extended rearward through the underside of the engine, and a rear exhaust pipe connected to a rear exhaust port opened at the rear surface of the rear engine block is formed shorter than the front exhaust pipe. At the same time, the layout of the exhaust system was designed to extend downward through the rear side of the engine, and connect the downstream open ends of the front and rear exhaust pipes to the exhaust muffler with a built-in catalytic converter via the exhaust collection chamber. The adopted method is conventionally known.

(3) Problems to be solved by the invention By the way, in a motorcycle equipped with the exhaust system layout as described above, the front exhaust pipe is relatively long.
Moreover, since the running wind hits this area well, it is easily cooled down, and therefore, the exhaust gas from the front engine block flowing through the front exhaust pipe has a slightly lower temperature before flowing into the exhaust collection chamber. If low-temperature exhaust gas is directly introduced into the catalytic converter built into the exhaust muffler, there is a risk that the efficiency of the catalyst's purification reaction of combustible harmful components will decrease.

In order to solve this problem, a known exhaust purification technology (2008) was developed in which a secondary air supply system for exhaust purification is connected to the front and rear exhaust ports provided in the front and rear engine blocks of the V-type engine, respectively. For example, it is conceivable to apply JP-A No. 55-46009 as is) to promote the oxidation reaction of combustible harmful components associated with the introduction of secondary air in the front exhaust pipe and suppress the drop in exhaust temperature. In that case, the secondary air supply system would also be communicated with the rear exhaust port.

However, in this type of motorcycle, the rear exhaust pipe is relatively short, and it is difficult for the running wind to directly hit it, so the exhaust from the rear engine block that flows through it flows into the exhaust collection chamber while being kept at a high temperature. . Therefore, there is no inherent need to introduce secondary air into the rear exhaust port to raise the exhaust temperature in the rear exhaust pipe.In fact, if the secondary air supply system is connected to the rear exhaust port,
The overall structure of the secondary air supply system becomes more complex, which increases the number of parts and the number of man-hours required for machining the rear engine block, leading to increased costs and troublesome maintenance.

The present invention has been proposed in view of the above, and an object of the present invention is to provide an engine exhaust purification device for a motorcycle in which the structure of a secondary air supply system can be simplified as much as possible without reducing the purification reaction efficiency of a catalytic converter. With the goal.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention includes a vehicle body frame equipped with a V-type engine in which front and rear engine blocks are arranged in a V-shape in the longitudinal direction. A front exhaust pipe connected to a front exhaust port opened at the front surface of the front engine block extends rearward through the lower side of the engine, and a rear exhaust pipe connected to the front exhaust port opened at the rear surface of the rear engine block. A rear exhaust pipe connected to the port is formed to be shorter than the front exhaust pipe and extends downward through the rear side of the engine, and the downstream open ends of the front and rear exhaust pipes are connected to each other through an exhaust collecting chamber. and a secondary air supply system for exhaust purification for supplying secondary air only to the front exhaust port of the front and rear exhaust ports in a motorcycle connected to an exhaust muffler having a built-in catalytic converter. It is characterized by communicating with each other.

(2) Effect Even though the front exhaust pipe is relatively long and is located so that it is easily cooled by the wind while driving, the exhaust gas flowing through it has the effect of accelerating the oxidation reaction due to the secondary air supply to the front exhaust port. Therefore, the temperature reaches the exhaust collection chamber while the temperature drop is suppressed as much as possible. On the other hand, since the rear exhaust pipe is relatively short and located behind the rear engine block, it is difficult to be cooled by the running wind, so the exhaust gas flowing through it is It reaches the exhaust collection chamber in a high temperature state. Therefore, the temperature of the exhaust gas introduced into the catalytic converter is sufficiently high, and the catalyst always efficiently performs its exhaust purification function.

Furthermore, even if the exhaust gas flowing through the rear exhaust pipe does not contain secondary air, it is combined with high-temperature exhaust gas containing secondary air from the front exhaust pipe in the downstream exhaust collection chamber and exhausted. Since it is guided to the catalytic converter in the muffler, combustible harmful components etc. are sufficiently oxidized there.

Moreover, since the secondary air supply system is configured not to communicate with the rear exhaust port on the rear engine block side, the overall structure of the secondary air supply system is simplified accordingly.

(3) Examples Examples of the present invention will be described below with reference to the drawings.

In Figure 1, the motorcycle body frame F
front and rear engine blocks in the longitudinal direction.
A V-type engine E is installed in which Bf and Br are arranged in a V-shape.
is arranged, and an air cleaner is installed at the outer end of this intake system 1.
AC is connected.

As shown in Figure 3, the front cylinder block Bf
includes two cylinders 2, 2 arranged in parallel orthogonally to the longitudinal direction of the vehicle body frame F.

A front exhaust port 4 that communicates with each cylinder 2 via an exhaust valve 3 is opened on the front surface of the front cylinder block Bf.
The front end of a front exhaust pipe 5 made of a double pipe is connected. This front exhaust pipe 5 passes under the engine E and extends rearward. The rear cylinder block Br also includes two cylinders 6, 6 arranged in parallel orthogonally to the longitudinal direction of the vehicle body frame F. A rear exhaust port 8 communicating with each cylinder 6 via an exhaust valve 7 is opened on the rear surface of the rear cylinder block Br, and the front end of a rear exhaust pipe 9 made of a single pipe is connected to this exhaust port 8. This rear exhaust pipe 9
is extended downward through the rear side of engine E.

An exhaust collection chamber 10 is disposed at the rear lower side of the engine E, and the two inlets 11 and 12 of the chamber 10 are connected to the front and rear exhaust pipes 5,
The open ends of 9 are connected. Exhaust collection chamber 10
is formed long in the lateral direction (direction perpendicular to the plane of the drawings 1 and 2), and a pair of exhaust mufflers Mf is connected to the outlet 13 on the rear surface of both left and right ends thereof. A monolithic catalytic converter 14 is built into the front part of each exhaust pipe muffler Mf.

As shown in Figure 3, the front engine block
A secondary air passage 17 is integrally formed on the side of the cylinder head 15 of Bf, one end of this passage 17 is communicated with the vicinity of the exhaust valve 3 of the exhaust port 4, and the other end is connected to the outlet 18 of the reed valve L. will be communicated to.
The reed valve L is provided on the rear side of the cylinder block 16 of the engine block Bf, that is, on the side of the V-shaped space.

Next, to explain the structure of this reed valve L, a valve portion 19 is formed on the rear surface of the cylinder block 16, and a reed valve body 2 is formed in a recessed portion of this valve portion 19.
0 is fitted through a heat-resistant packing material 21, and this reed valve body 20 is fixed by a valve cap 22 fixed on the valve portion 19. Lead valve body 20
A valve hole 23 is opened in the center thereof, and a lead 24 for opening and closing the valve port 23 is fixedly attached thereto. The reed valve body 20 divides the valve chamber 25 into an upstream chamber u and a downstream chamber d, and a secondary air distribution pipe 26 is communicated with the upstream chamber u, and the downstream chamber d is connected to the upstream chamber u.
The secondary air passage 17 is communicated with. The other end of the secondary air distribution pipe 26 is connected to the outlet 2 of the joint 27.
The secondary air supply main pipe 30 is connected to the inlet 29 of the joint 27, and the pipe 30 is connected to the air cleaner Ac via an air control valve V. The air control valve V has a conventionally known structure, and is closed in a low throttle opening range such as during deceleration operation including idling operation of the engine. The secondary air passage 17, the reed valve L, the secondary air distribution pipe 26, the joint 27, the secondary air supply main pipe 30, the air control valve V, and the air cleaner Ac cooperate with each other to close the front exhaust port 4. Secondary air supply system of the present invention for supplying secondary air to
It constitutes AS.

Next, the operation of the embodiment of the present invention will be explained.

When engine E is operated now, the exhaust from the front engine block Bf is routed through the front exhaust pipe 5, and the exhaust from the rear engine block Br is routed through the rear exhaust pipe 9, as shown by the arrows in Figure 2. It flows into the exhaust collection chamber 10, from there it flows into the exhaust muffler Mf, where it is purified by the catalytic converter 14 and released into the atmosphere.

Further, the exhaust pulsation generated in the exhaust port 4 by opening and closing the exhaust valve 3 acts on the reed valve L through the secondary air passage 17, and the reed 24 of the reed valve L is opened intermittently. As a result, the secondary air from the air cleaner AC is transferred to the air control valve V, the secondary air supply main pipe 3
0 to the joint 27, and from there, the air is sucked into the exhaust port 4 through each secondary air distribution pipe 26, reed valve L, and secondary air passage 17. The secondary air that has flowed into the exhaust port 4 is mixed with the exhaust gas, and the unburned components and incompletely burned components contained therein are quickly oxidized in the exhaust port 4 and the front exhaust pipe 5, and the reaction heat is The exhaust gas flowing inside the front exhaust pipe 5 can be heated.

Therefore, the front exhaust pipe 5 is long, and even when the wind hits the exhaust pipe 5, the exhaust gas flowing through the pipe 5 flows to the exhaust collection chamber 10 while maintaining a high temperature due to the reaction heat, while the rear exhaust pipe The exhaust pipe 9 is difficult to be hit by the running wind and is shorter than the front exhaust pipe 5, so the exhaust gas flowing through the pipe 5 flows to the exhaust collecting chamber 10 while maintaining high temperature. Exhaust gases from the rear exhaust pipes 5 and 9 join together without causing a temperature drop and flow into the catalytic converter 14 from there. Inside the catalytic converter 14, the purification reaction is promoted by the inflow of high temperature exhaust gas.

If the front exhaust pipe 5 is made into a double pipe as in this embodiment, the high temperature of the exhaust gas flowing through the pipe 5 can be maintained more effectively.

C. Effects of the Invention As described above, according to the present invention, the front exhaust pipe connected to the front exhaust port opened at the front of the front engine block of a V-type engine is extended rearward through the underside of the engine. In addition, the rear exhaust pipe connected to the rear exhaust port opened on the rear surface of the rear engine block is formed to be shorter than the front exhaust pipe, and is extended downward through the rear side of the engine, so that it is connected to the downstream side of the front and rear exhaust pipes. For exhaust purification for supplying secondary air only to the front exhaust port of the front and rear exhaust ports in a motorcycle whose open end is connected to an exhaust muffler with a built-in catalytic converter via an exhaust collection chamber. Because the secondary air supply system is connected, even though the front exhaust pipe is relatively long and is easily cooled by the wind while driving, the exhaust gas flowing there can undergo oxidation reactions caused by the secondary air supply. Due to the accelerating effect, the exhaust gas can reach the exhaust collection chamber in a high temperature state.On the other hand, the rear exhaust pipe is relatively short and located behind the rear engine block, so it is difficult to be cooled by the running wind. Therefore, even if the exhaust gas flowing there is not supplied with secondary air, it can reach the exhaust collection chamber in the same high temperature state, and as a result, the temperature of the exhaust gas introduced into the catalytic converter is sufficiently high. Since it is expensive, there is no risk of reducing the exhaust purification efficiency of the catalyst.

Furthermore, even if the exhaust gas flowing through the rear exhaust pipe does not contain secondary air, it merges with the high-temperature exhaust gas containing secondary air from the front exhaust pipe in the downstream exhaust collection chamber. Since it is guided to the catalytic converter, combustible and harmful components are sufficiently oxidized there.
Therefore, even if there is no supply of secondary air to the rear exhaust port, no problem arises in terms of exhaust gas purification.

Furthermore, since the configuration does not allow the secondary air supply system to communicate with the rear exhaust port on the rear engine block side, the overall structure of the secondary air supply system can be simplified, reducing the number of parts and making it possible to reduce the number of parts that can be processed on the rear engine block. It is possible to reduce man-hours,
This can greatly contribute to cost reduction, and maintenance of the secondary air supply system is also simplified.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of a motorcycle equipped with the device of the present invention, and FIG.
The figure is a partially cutaway side view of the engine mounted on the motorcycle, and FIG. 3 is an enlarged sectional view taken along the line of FIG. 2. AS...Secondary air supply system for exhaust purification, Bf, Br...
Front and rear engine blocks, F...body frame,
Mf...exhaust muffler, 4, 8...front, rear exhaust port,
5, 9...Front and rear exhaust pipes, 10...Exhaust collection chamber, 14...Catalytic converter.

Claims (1)

[Claims] 1 A V-shaped body frame F in which front and rear engine blocks Bf and Br are arranged in a V-shape in the longitudinal direction.
A front exhaust pipe 5 connected to a front exhaust port 4 opened at the front of the front engine block Bf is extended rearward through the lower side of the engine E, and A rear exhaust pipe 9 connected to a rear exhaust port 8 opened on the rear surface of the engine block Br is formed to be shorter than the front exhaust pipe 5 and extends downward through the rear side of the engine E. The downstream opening ends of the rear exhaust pipes 5 and 9 are connected through the exhaust collection chamber 10,
In a motorcycle connected to an exhaust muffler Mf having a built-in catalytic converter 14, an exhaust purification secondary air purifier for supplying secondary air only to the front exhaust port 4 among the front and rear exhaust ports 4 and 8. An exhaust gas purification device for an engine in a motorcycle, characterized by communicating an air supply system AS.