JPH0452417Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust gas purification device for a V-type internal combustion engine that is mounted horizontally in an engine room at the front of a vehicle.

[Conventional technology] Conventionally, a V
A structure in which an internal combustion engine is mounted horizontally on a vehicle is well known. When connecting a catalytic converter to such a V-type internal combustion engine, normally exhaust manifolds 3a and 3b are connected to both banks 2a and 2b of the V-type internal combustion engine 1, respectively, as shown in FIG. After exhaust pipes 4a and 4b connected to manifolds 3a and 3b are joined at a gathering section 5, a catalytic converter 6 is disposed on the downstream side of the gathering section 5. Since the exhaust pipe extends toward the rear of the vehicle, the exhaust passage on the front side of the vehicle among the exhaust passages leading to the collecting portion 5 is inevitably longer than the exhaust passage on the rear side.

[Problems to be solved by the invention] However, in the conventional structure as described above,
Of the exhaust pipes connected to each exhaust manifold 3a, 3b, the exhaust pipe 4a located on the front side of the vehicle is longer than the exhaust pipe 4b located on the rear side.
Heat release from the exhaust gas in the front exhaust pipe 4a becomes greater than that in the rear side, and the temperature of the exhaust gas reaching the catalytic converter 6 decreases accordingly.
In addition, since the front exhaust pipe 4a is more strongly affected by the driving wind etc. than the rear exhaust pipe 4b, from this aspect as well, heat is released to the atmosphere more than the rear exhaust pipe 4b, which reaches the catalytic converter 6. The overall temperature of the exhaust gas decreases. When the exhaust gas temperature decreases,
When the engine is cold started, the temperature of the catalyst is delayed during warm-up, etc., resulting in a problem that the purifying action of the catalyst cannot be sufficiently obtained.

To solve this problem, a structure has been proposed in which a small catalytic converter, generally called a start cap, is provided only in the exhaust pipe located at the front of the vehicle (Japanese Patent Application Laid-open No. 196918/1983). With this structure, the exhaust gas flowing through the front exhaust pipe is warmed by the reaction heat of the starter cat's catalyst.
Although the temperature of the exhaust gas reaching the main catalytic converter 6 is improved, it is still not sufficient in terms of rapid catalyst temperature rise of the catalytic converter 6.

The present invention focuses on the limitations of the prior art as described above, and aims to make it possible to raise the temperature of the catalyst of a catalytic converter more efficiently and quickly.

[Means for Solving the Problems] The exhaust gas purification device for an internal combustion engine of the present invention, which meets this objective, has an exhaust manifold installed in each bank of a V-type internal combustion engine mounted horizontally to the vehicle at the front of the vehicle. In an exhaust gas purification device for an internal combustion engine, the exhaust gas purification device for an internal combustion engine has exhaust pipes connected to the exhaust manifolds, the exhaust pipes are merged at a collecting part, and a catalytic converter is disposed downstream of the collecting part. Of the side exhaust pipes, a start cap is provided only on the front exhaust pipe that is connected to the front exhaust manifold, and the above-mentioned collecting section is located at a position where the exhaust gas flowing inside each pipe is substantially immediately upstream of the catalytic converter. Constructed in a double pipe structure that merges, the outer pipe of the double pipe structure is connected to the front exhaust pipe, and the inner pipe of the double pipe structure is connected to the rear exhaust pipe connected to the rear exhaust manifold. It consists of

It is desirable that the inner tube of the double-tube structure protrudes into the converter case of the catalytic converter, and that the exhaust gas in the inner tube is guided to a position immediately upstream of the catalyst inlet.

[Operation] In such an exhaust gas purification device, the exhaust gas from the front bank of the engine passes through the start cap containing a small catalyst, and therefore becomes high in temperature due to the heat of reaction with the catalyst. Since this start cat is installed relatively close to the engine, it can be warmed up in a short time and its catalyst can also be activated in a short time. Exhaust gas from the rear exhaust pipe flows through the inner pipe in the double pipe section, and the heated exhaust gas from the front exhaust pipe flows inside the outer pipe so as to surround the inner pipe. The exhaust gas from the rear exhaust pipe is kept at a relatively high temperature because the length of the rear exhaust pipe is relatively short and is not easily affected by the traveling wind. Therefore, the exhaust gas from the rear exhaust pipe that flows inside the inner pipe has the high-temperature exhaust gas that has passed through the start cap flowing to its outer circumferential side, so its temperature drop is suppressed and reaches the catalytic converter in a high-temperature state. . The exhaust gas from this inner pipe will concentrate and flow into the center of the catalyst of the catalytic converter.
A heat spot is generated in the center of the catalyst, and the catalyst is efficiently warmed up from the center. Moreover, at this time, since the exhaust gas from the rear exhaust pipe also contains unburned components, the catalytic reaction of the unburned components is added, and the reaction heat further efficiently and rapidly moves the catalyst from the center. heated.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

1 and 2 show an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention. In the figure, 11 indicates a vehicle, and a V-type internal combustion engine 1 is installed in an engine compartment 12 at the front of the vehicle 11.
3 is mounted horizontally on the vehicle 11.

A front exhaust manifold 16a and a rear exhaust manifold 16b are connected to each cylinder head 15a, 15b of each bank 14a, 14b of the V-type internal combustion engine 13, respectively. Front exhaust manifold 1
6a is connected to a front exhaust pipe 17a that extends downward, then bends and extends toward the rear of the vehicle, and the rear exhaust manifold 16b has a
A rear exhaust pipe 17b extending downward is connected. The front exhaust pipe 17a and the rear exhaust pipe 1
7b, the pipes themselves merge at a gathering part 18 and extend toward the rear of the vehicle as an exhaust pipe 19. exhaust pipe 19
A catalytic converter 20 is connected to the catalytic converter 20, and an exhaust pipe 21 extends from the catalytic converter 20 to the rear of the vehicle. As shown in FIG. 2, the catalytic converter 20 has a built-in catalyst (catalyst carrier) 22, and the catalyst 22 is held by a retainer 23 and a mesh wire 24.

A start cap 25, which is a small catalytic converter, is interposed in the middle of the front exhaust pipe 17a, and a small catalyst (not shown) is accommodated within the start cap 25. The gathering part 18
The exhaust pipe 19 from the exhaust pipe 19 to the catalytic converter 20 has a double pipe structure as shown in FIG.
The front exhaust pipe 17a is connected to the outer pipe 19a of this double pipe structure via the pipe of the gathering part 18, and the inner pipe 19
A rear exhaust pipe 17b is connected to b. In this embodiment, the rear exhaust pipe 17b and the inner pipe 19b are configured as an integral curved pipe. Since the outer pipe 19a and the inner pipe 19b each extend to a position immediately upstream of the catalytic converter 20, the exhaust gases flowing within each pipe substantially merge at the position immediately upstream of the catalytic converter 20. In this embodiment, the inner pipe 19b further extends into the converter case 26 of the catalytic converter 20, and opens at a position immediately upstream of the center of the inlet of the catalyst 22.

The operation of the embodiment device configured as described above will be explained.

When the engine is cold-started, exhaust gas from the front bank passes through a small catalyst in the start cap 25 and is then guided from the collecting section 18 to the outer pipe 19a of the double-pipe structure, and then to the catalytic converter 20. It will be destroyed. Since the start cat 25 is close to the front exhaust manifold 16a, its small catalyst is warmed up and activated in a short time. The exhaust gas passing through this small catalyst is
The temperature is raised by the reaction heat of the catalyst, and reaches the exhaust pipe 19 at a much higher temperature than without the small catalyst.

The exhaust gas from the rear bank does not have a temperature increasing effect due to the heat of catalytic reaction in this part because a start cap is not disposed in the exhaust pipe 17b, but the rear exhaust pipe 17b is shorter than the front exhaust pipe 17a, and Since it is difficult for the vehicle to be hit by wind, the temperature of the exhaust gas passing through the interior is maintained at a relatively high temperature, and reaches the exhaust pipe 19 in this high temperature state.

The exhaust pipe 19 has a double pipe structure, with the inner pipe 1
Exhaust gas from the rear exhaust pipe 17b flows through the outer pipe 9b, and exhaust gas from the front exhaust pipe 17a flows through the outer pipe 19a. The exhaust gas flowing through the inner pipe 19b passes through the small catalyst on the outer circumferential side of the exhaust gas, which becomes high in temperature.
leading to.

The exhaust gas in the inner pipe 19b is transferred to the catalytic converter 2
0 flows into the center of the inlet side of the catalyst 22. In particular, since the inner tube 19b protrudes into the converter case 26, the open end thereof is efficiently guided to the center of the catalyst 22 without being mixed with the exhaust gas in the outer tube. Since the exhaust gas in the inner tube 19b is maintained at a high temperature, a heat spot is generated at the center of the catalyst 22 due to the inflow of the exhaust gas, and the center is effectively heated. And inner pipe 19b
Since the exhaust gas that has been guided inside has not passed through the catalyst, unburned components remain, and with the addition of the catalytic reaction of the unburned components, the catalyst 22 is efficiently heated from the center. Its temperature rises rapidly. By quickly warming up the catalyst 22, a predetermined exhaust gas purification performance can be obtained in a short time.

In addition, in the exhaust pipe 19 having a double pipe structure, it is possible to flow the exhaust gas from the rear exhaust pipe to the outer pipe side and the exhaust gas from the front exhaust pipe to the inner pipe side, but in that case, the catalyst 22 The exhaust gas in the inner pipe that flows into the center has already passed through the start cat and has less unburned components in the gas, so the heat of catalytic reaction in the catalyst 22 as described above is reduced, and as a result, the amount of heat is reduced compared to the case of the above embodiment. Also, catalyst warm-up tends to be delayed. Therefore, as in the present invention, it is better to specify the connection structure between the inner pipe, outer pipe, and front and rear exhaust pipes.

[Effects of the invention] As explained above, when using the exhaust gas purification device for an internal combustion engine of the present invention, a start cap is provided in the front exhaust pipe, the exhaust gas flowing in the exhaust pipe is heated to a high temperature, and the catalyst is removed from the collecting part. The structure up to the converter has a double pipe structure, with exhaust gas from the rear exhaust pipe flowing into the inner pipe and exhaust gas from the front exhaust pipe flowing into the outer pipe, raising the temperature of the exhaust gas flowing into the center of the catalyst of the catalytic converter. Since the temperature can be maintained, the catalyst of the catalytic converter can be efficiently and quickly warmed up from the center, and the catalytic converter can exhibit a predetermined exhaust gas purification performance in a short time. Furthermore, since the exhaust gases from the front and rear exhaust pipes do not merge upstream directly upstream of the catalytic converter, the exhaust pulsation effect of the engine is strengthened, and as a result, the output and fuel efficiency of the engine can be improved.

Furthermore, since the start cat is installed only in the long front exhaust pipe, the degree of uneven length of the exhaust pipe from the perspective of exhaust sound is reduced, which reduces unpleasant engine exhaust sound components caused by uneven exhaust pulsation. Effects can also be obtained.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention, Fig. 2 is an enlarged vertical sectional view of the catalytic converter and its surroundings of the device shown in Fig. 1, and Fig. 3 is a conventional exhaust gas purification device. FIG. 2 is an overall side view of the gas purification device. 11...Vehicle, 12...Engine room, 13
...V-type internal combustion engine, 14a, 14b...bank,
15a, 15b...Cylinder head, 16a, 1
6b...exhaust manifold, 17a...front exhaust pipe, 17b...rear exhaust pipe, 18...collection part, 1
9...Exhaust pipe, 19a...Outer pipe, 19b...Inner pipe, 20...Catalytic converter, 22...Catalyst, 2
5...Start cat, 26...Converter case.

Claims (1)

[Scope of utility model registration request] An exhaust manifold is connected to each bank of a V-type internal combustion engine that is mounted horizontally to the vehicle at the front of the vehicle, an exhaust pipe is connected to each exhaust manifold, and the exhaust pipes are joined at a collecting part, and In the exhaust gas purification device for an internal combustion engine, in which a catalytic converter is arranged downstream of the collecting part, a start cap is provided only in the front exhaust pipe connected to the front exhaust manifold among the exhaust pipes upstream of the collecting part,
and the collecting part is configured to have a double pipe structure in which the exhaust gas flowing in each pipe substantially joins at a position immediately upstream of the catalytic converter, and an outer pipe of the double pipe structure is connected to the front exhaust pipe. 1. An exhaust gas purification device for an internal combustion engine, characterized in that an inner pipe with a double pipe structure is connected to a rear exhaust pipe connected to a rear exhaust manifold.