JPS594524B2 - Exhaust system with catalytic converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust system with a catalytic converter that increases the activity of the catalyst, particularly when starting the engine.

It is well known that Co, HC, and NOX are the main harmful components of exhaust gas from internal combustion engines, and that they have an adverse effect on the human body.

Various methods have been proposed as exhaust gas countermeasures to remove these harmful components, and among them, a catalytic converter method that uses a catalyst to convert Co and HC into harmless components is attracting attention as an effective method. Conventionally, when a catalytic converter is installed in the exhaust system of an internal combustion engine, it takes too long for the catalyst to reach its activation temperature from the time the engine is started, and the catalyst does not function during that time, resulting in the generation of Co, HC, etc.
There was a problem that a large amount of was emitted.

Of course, in order to shorten the time it takes for this catalyst to reach its activation temperature, it would be better to place the catalyst closer to the engine exhaust port so that it is heated to a high temperature. The problem with this structure is that the first expansion chamber becomes smaller and the output performance of the engine decreases. The present invention was developed in view of these points, and has an extremely simple configuration in which a catalytic converter is disposed on the side of the expansion chamber.
To provide an exhaust system with a catalytic converter that shortens the time from when the engine starts until the catalyst reaches the activation temperature without any effect on the output performance of the engine.

Hereinafter, its configuration and the like will be explained in detail with reference to embodiments shown in the drawings. Figure 1 shows how the exhaust system according to the present invention is installed on a motorcycle.
This is a partially longitudinal side view of a case in which the engine is used.
Piston Ib) Intake 0 connected to carburetor (not shown)
As is well known, the engine is comprised of a cylinder Ie having an exhaust gas 1c, an exhaust gas 0Id, a crankcase lf, etc.

2 is an exhaust pipe that forms a part of a first expansion chamber 3, which will be described later, and connects this expansion chamber 3 and the engine exhaust 0Id;
is a first expansion chamber formed in the bulging portion 2a of the exhaust pipe 2; one end of the expansion chamber 3 is connected to the engine exhaust 0Id through the exhaust pipe 2, and the other end is connected to the partition plate 4. It is obstructed.

Reference numeral 5 denotes a partition wall which forms the first expansion chamber 3 by isolating the interior of the bulging portion 2a and holds the catalytic converter 6; 7, which separates the catalyst chamber 8 formed by the partition wall 5 from the first expansion chamber 3; This exhaust port 7 is located on the engine side of the first expansion chamber 3, and is located on the side of the first expansion chamber 3 in order to ensure sufficient substantial volume of the first expansion chamber 3. It's open towards you.

Therefore, between the exhaust port 7 and the closed end formed by the partition plate 4, a space is formed that functions as an expansion chamber and is open only to the engine side. A communication chamber 9 communicates the catalyst chamber 8 with a muffler, which will be described later, and is formed by the terminal end of the exhaust pipe 2 and the partition plate 4.

10 is a muffler, and 11 is a muffler tube that holds the muffler 10 and communicates the communication chamber 9 with the muffler 10 through a communication port 12 opened on the side thereof.

13 is an exhaust inner pipe; 14 is a partition member for isolating the catalytic converter 6 and the exhaust pipe 2, and is integral with the partition wall 5.

15 is an exhaust port, 16 is a fuel tank, and 17 is a driver seat.

In the embodiment shown in FIG. 1, an example was shown in which a honeycomb type catalyst was used and the first expansion chamber 3 and the catalyst chamber 8 were formed by the partition wall 5 holding the catalytic converter 6. However, the present invention is not limited to such a structure, and can also be implemented as shown in FIG. 2, for example.

In other words, in Fig. 2, 22 is the exhaust pipe, 23 is the first
An expansion chamber, 24 a partition plate that closes one end of the first expansion chamber and forms a communication chamber 29, 25 a connecting pipe 26 connecting the catalyst chamber 28 and the communication chamber 29, a catalyst using a bead-shaped catalyst carrier; It is a converter.

Therefore, in this embodiment, a catalytic converter 26 is provided in the opening 27 corresponding to the exhaust port 7 of the embodiment shown in FIG. 1, and the structure is not substantially changed. In FIG. 1, reference numeral 30 denotes an inlet port which introduces air from the atmosphere into the secondary air inner pipe 13 through the filter 31 and the check valve 32 using the pulsating negative pressure within the exhaust inner pipe 13. Since the present invention is configured in this way, the combustion gas discharged from the exhaust port 1d passes through the exhaust pipe 2 and is sufficiently expanded within the first expansion chamber 3, and is then discharged from the exhaust port as shown by the arrow in the figure. 7, it passes through the catalytic converter 6, the communication chamber 9, the communication port 12, the muffler pipe 11, and the muffler 10, and is discharged from the exhaust port 15.

It goes without saying that exhaust is similarly performed in the embodiment shown in FIG. As explained above, according to the present invention, a part of the exhaust pipe is bulged out to the side and is divided to form an expansion chamber and a catalyst chamber, and both chambers are formed on the engine side of the expansion chamber. Since the communicating exhaust port is provided, the catalytic converter and the engine exhaust port can be placed close to each other.
Therefore, the exhaust flow is guided to the catalyst while passing through only a portion of the first expansion chamber, so that the time required for the catalyst to reach its activation temperature can be shortened.

Furthermore, even though the catalytic converter is located close to the engine exhaust port, the exhaust port is provided on the side of the expansion chamber on the engine side, so there is no air between the exhaust port and the closed end of the expansion chamber. Sufficient space is created to function as a chamber, so output performance is not affected in any way.
Furthermore, since the expansion chamber is provided on the side of the catalytic converter, even though the catalytic converter becomes high temperature, it is isolated by the expansion chamber, so there is an effect that it is easy to insulate the outside of the exhaust pipe.

Note that in all of the embodiments shown in the figures, exhaust gas is constantly discharged through the catalytic converter, but when there are relatively many harmful components, such as during startup or deceleration, the exhaust gas is passed over the catalyst and the harmful components are removed. It goes without saying that the present invention can be carried out using a bypass type catalytic converter or a catalytic converter with a switching valve that allows exhaust gas to bypass when the engine is running at a constant speed with few components.

[Brief explanation of drawings]

FIG. 1 is a partially longitudinal side view showing one embodiment of an exhaust system with a catalytic converter according to the present invention, and FIG. 2 is a longitudinal side view showing another embodiment. 1...Engine, 1d...Exhaust port, 2
...Exhaust pipe, 3...Expansion chamber, 4...
...Partition plate, 6...Catalytic converter, 7...
...exhaust port, 10...silencer, 11...
...silencer tube.

Claims (1)

[Claims] 1. An expansion chamber with one end connected to an engine exhaust port and the other end closed, an exhaust port provided on the side of the expansion chamber on the engine side, and between the exhaust port and the muffler and on the side of the expansion chamber. An exhaust gas equipped with a catalytic converter, characterized in that a catalytic converter is disposed so as to be located at the end of the expansion chamber, and a space that opens only toward the engine is formed between the exhaust port and the closed end of the expansion chamber. Device.