JPH0979043A - Exhaust gas purification device for internal combustion engine with supercharger - Google Patents

Abstract

(57) An object of the present invention is to provide an exhaust emission control device for an internal combustion engine with a supercharger, which allows each exhaust turbocharger to function well without overrotating. A pair of exhaust turbochargers 10, 12
An exhaust gas purification apparatus for an internal combustion engine with a supercharger, the exhaust gas inflow side of each exhaust turbocharger 10, 12 being connected to a common exhaust gas inflow passage 22, and the exhaust gas outflow side of each exhaust turbocharger 10, 12 Are connected to separate exhaust outflow passages 14 and 16, a catalyst 18 is arranged in one exhaust outflow passage 14, and a flow passage resistance means 20 having a flow passage resistance equal to that of the catalyst 18 in the other exhaust outflow passage 16 is provided.
It is characterized by having.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust emission control device for an internal combustion engine with a supercharger.

[0002]

2. Description of the Related Art An exhaust system provided with a catalyst for purifying exhaust gas discharged from an internal combustion engine is known. For example, an exhaust system for an internal combustion engine with a supercharger disclosed in Japanese Patent Laid-Open No. 4-12132 includes a pair of exhaust turbochargers, that is, a main exhaust turbocharger and an auxiliary exhaust turbocharger. In such an exhaust device, only the main exhaust turbocharger is operated when the load is low, and both exhaust turbochargers are operated when the load is high, so that air intake is efficiently performed under various load conditions. The exhaust inflow sides of both exhaust turbochargers are connected to a common exhaust manifold, and the exhaust outflow sides of each exhaust turbocharger join downstream and are connected to a common exhaust duct. A main catalyst for purifying exhaust gas is arranged in the common exhaust duct. However, immediately after the internal combustion engine is started, the temperature of the main catalyst is low and has not reached the catalyst activation temperature.
Good purification action cannot be expected. Therefore, it has been proposed to arrange a pre-catalyst having a higher warm-up property than the main catalyst in the internal combustion engine. This pre-catalyst is arranged in the exhaust duct near the engine body, preferably near the downstream of the exhaust manifold and upstream of the confluence point on the main exhaust turbocharger side.

[0003]

Generally, since a pair of exhaust turbochargers have the same shape and the same characteristics, the air is sucked most efficiently at a half of the maximum exhaust gas amount. However, as described above, in the conventional exhaust system, the exhaust gas flows into both the exhaust turbochargers when the load is high. At this time, the pre-catalyst arranged downstream of the main exhaust turbocharger acts as a resistance to the flow of the exhaust gas, so that a back pressure difference occurs between the main exhaust turbocharger and the auxiliary exhaust turbocharger and flows into the auxiliary exhaust turbocharger. The amount of exhaust gas is larger than the amount that flows into the main exhaust turbocharger. However, when the maximum exhaust gas amount is exhausted from the engine body, the auxiliary exhaust turbocharger will over-rotate and the intake air amount will be less than expected, and the main exhaust turbocharger will have less intake air amount than expected due to insufficient rotation. . Therefore, it is an object of the present invention to provide an exhaust emission control device that allows each exhaust turbocharger to function well without excessive rotation in any operating state of the engine body.

[0004]

An exhaust gas purification device according to the present invention as set forth in claim 1 is an exhaust gas purification device for an internal combustion engine with a supercharger, which comprises a pair of exhaust gas turbochargers.
The exhaust inflow side of each exhaust turbocharger is connected to a common exhaust inflow passage, the exhaust outflow side of each exhaust turbocharger is connected to a separate exhaust outflow passage, and a catalyst is arranged in one exhaust outflow passage and the other The exhaust gas outlet passage is provided with a flow path resistance means having a flow path resistance equal to that of the catalyst. By arranging the flow path resistance means having the same flow path resistance as the catalyst arranged in one exhaust outflow passage in the other exhaust outflow passage, the same amount of exhaust gas flows in both exhaust outflow passages.

An exhaust gas purifying apparatus for an internal combustion engine with a supercharger according to a second aspect of the present invention is the exhaust gas purifying apparatus for an internal combustion engine with a supercharger according to the first aspect, wherein the flow path resistance means is a catalyst. It is characterized by being. By arranging the catalyst having the same flow resistance as the catalyst arranged in one exhaust outflow passage in the other exhaust outflow passage, the same amount of exhaust gas flows in both exhaust outflow passages, and the other exhaust outflow passage Purifies the exhaust gas flowing through the passage.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a system diagram of an internal combustion engine with a supercharger including an exhaust emission control device of the present invention, specifically, a twin turbo engine equipped with a pair of superchargers. 10 is a main exhaust turbocharger, 12 is a sub exhaust turbocharger arranged in parallel with the main exhaust turbocharger 10,
14 is a main exhaust duct having an exhaust outflow passage connected to the exhaust outflow side of the main exhaust turbocharger, 16 is an auxiliary exhaust duct having an exhaust outflow passage connected to the exhaust outflow side of the auxiliary exhaust turbocharger 12, and 18 is Reference numeral 20 denotes a first pre-catalyst arranged in the main exhaust duct 14 downstream of the main exhaust turbocharger 10, and 20 denotes the auxiliary exhaust turbocharger 12.
Is a second pre-catalyst arranged in the auxiliary exhaust duct 16 downstream of as a flow path resistance means.

An exhaust manifold 2 having a common exhaust inflow passage on the exhaust inflow side of both exhaust turbochargers 10 and 12.
2, the exhaust manifold 22 is connected to the engine body 24.
(See FIG. 2). Both exhaust ducts 14, 1
6 are connected downstream, and the main catalyst 26 is arranged downstream of this connection point. Both exhaust turbocharger 1
Nos. 0 and 12 have the same shape and the same characteristics, and the ones having the maximum intake air amount when rotated at ½ of the maximum exhaust gas amount discharged by the engine body are used. Exhaust gas amount exceeding this predetermined amount is exhaust turbocharger 1
Exhaust turbocharger 10, 1 when flowing into 0, 12
2 rotates excessively, and the intake air amount decreases. Both first pre-catalysts 18 and 20 have the same shape and the same characteristics, and therefore have the same flow passage resistance to the exhaust gas flowing through the exhaust passage.

An exhaust switching valve 28 is provided in the auxiliary exhaust duct 16 between the auxiliary exhaust turbocharger 12 and the second precatalyst 20.
Is provided, and an auxiliary exhaust turbocharger 12 is also provided.
A bypass passage 30 that extends from the auxiliary exhaust duct 16 between the exhaust switching valve 28 and the main exhaust duct 14 between the main exhaust turbocharger 10 and the first precatalyst 18 is provided. Also, excessive exhaust gas is the main exhaust turbocharger 1.
In order to prevent inflow to 0, a bypass pipe 32 extending from the exhaust manifold 22 to the main exhaust duct 14 between the main exhaust turbocharger 10 and the first precatalyst 18 is provided, and the bypass pipe 32 is provided with a supercharger. A waste gate valve 33 is installed to prevent the pressure from rising above a predetermined pressure. By opening this waste gate valve 33, excess exhaust gas is released.

When the exhaust gas is discharged from the engine body, the exhaust gas flows into the exhaust turbochargers 10 and 12 via the exhaust manifold 24. At this time, the pre-catalyst 1 having the same flow resistance is provided in each of the exhaust ducts 14 and 16.
Since 8 and 20 are arranged, the amount of exhaust gas flowing into each exhaust turbocharger 10 and 12 is also equal. Therefore, even if the amount of exhaust gas from the engine body is the largest, the amount of exhaust gas flowing into each exhaust turbocharger is one half of the maximum amount of exhaust gas, which does not exceed the predetermined range.
The intake air amount by each exhaust turbocharger 10, 12 is maximized without the exhaust turbocharger being over-rotated.

Further, by constructing the exhaust gas purification device as described above, it is possible to efficiently purify the exhaust gas in any operating state of the engine body. In the internal combustion engine having the above-described configuration, in order to improve the air intake efficiency by the exhaust turbochargers 10 and 12, the exhaust gas switching amount 28 and the bypass passage 28 are small because the amount of exhaust gas is small at the time of low load.
The bypass valve 34 provided in the exhaust gas is closed so that all the exhaust gas flows only into the main exhaust turbocharger 10, and when the load is high, the exhaust switching valve 28 is opened so that the exhaust gas is discharged to both the exhaust turbochargers 10 and 12. It is supposed to flow in. If the high-load operation is performed immediately after the internal combustion engine is started, the exhaust gas flows into both the exhaust turbochargers 10 and 12. In this case, if the pre-catalyst is provided only on one side (main exhaust duct side) as in the conventional exhaust emission control device, exhaust gas will flow through the sub exhaust duct to the main catalyst that has not been sufficiently warmed up. Exhaust gas that has not been purified is released to the atmosphere. However, in the exhaust gas purifying apparatus of the present invention, the exhaust gas is sufficiently purified because the pre-catalysts 18, 20 having high warm-up property are arranged in both the exhaust ducts 14, 16. Further, in the present invention, it is not necessary to provide a control means for adjusting each exhaust gas inflow amount as in an exhaust device having two different exhaust turbochargers, so that the structure is simplified.

In the above embodiment, the second pre-catalyst, which is the same as the first pre-catalyst, is arranged in the sub-exhaust duct, but this does not limit the present invention. The duct diameter may be reduced to increase the flow path resistance of the auxiliary exhaust duct.

[0012]

As described above, according to the exhaust gas purifying apparatus for an internal combustion engine with a supercharger of claim 1 of the present invention, since the flow path resistances in both the exhaust gas outflow passages are equal, the exhaust gas flowing into each exhaust turbocharger is Equal and maximum exhaust gas amount of 2 at maximum
It is one-half and is within a predetermined range in which each exhaust turbocharger functions at maximum efficiency, and it is possible to suck air efficiently.

Further, according to the exhaust gas purifying apparatus for an internal combustion engine with a supercharger of the second aspect of the present invention, since the flow path resistances in both the exhaust gas outflow passages are equal, the exhaust gas flowing into each exhaust turbocharger is equal and the maximum. However, it is half of the maximum exhaust gas amount, and it is within the predetermined range in which each exhaust turbocharger functions at maximum efficiency, and it is possible to suck air efficiently, and because the catalyst is placed in both exhaust outflow passages, good exhaust The gas can be purified.

[Brief description of drawings]

FIG. 1 is a system diagram of an internal combustion engine with a supercharger including an exhaust emission control device of the present invention.

FIG. 2 is a schematic diagram showing an exhaust manifold connected to each exhaust turbocharger and an engine body.

[Explanation of symbols]

 10 ... Main exhaust turbocharger 12 ... Sub exhaust turbocharger 14 ... Main exhaust duct 16 ... Sub exhaust duct 18 ... First pre-catalyst 20 ... Second pre-catalyst 22 ... Exhaust manifold

Claims (2)

[Claims] 1. An exhaust emission control device for an internal combustion engine with a supercharger, comprising a pair of exhaust turbochargers, wherein the exhaust inflow side of each exhaust turbocharger is connected to a common exhaust inflow passage, The exhaust outflow sides are connected to separate exhaust outflow passages, the catalyst is arranged in one exhaust outflow passage, and the other exhaust outflow passage is provided with flow passage resistance means having a flow passage resistance equal to that of the catalyst. An exhaust purification system for internal combustion engines with a supercharger. 2. The exhaust gas purifying apparatus for an internal combustion engine with a supercharger according to claim 1, wherein the flow path resistance means is a catalyst.