KR100339811B1 - Exhaust gas system of internal combution engine - Google Patents

Abstract

The present invention relates to an exhaust system of an internal combustion engine, and recycles a part of exhaust gas to an intake manifold through which external air passes through an exhaust gas recirculation valve connected to a control device, and passes through a catalytic converter and a silencer mounted on the exhaust pipe. In an exhaust system of an internal combustion engine that discharges purified exhaust gas to the outside, an exhaust manifold having at least one exhaust gas recycling passage through which a part of the exhaust gas passes, the exhaust manifold connected to the exhaust manifold and An exhaust pipe having an associated exhaust gas flow path and an exhaust gas recirculation valve and an exhaust gas flow path connecting the intake manifold and the exhaust gas flow paths, respectively.

Accordingly, the exhaust gas retains heat while passing through the exhaust gas recirculation passage of the exhaust manifold, and when passing through the inner pipe of the exhaust pipe, heat loss is reduced by the exhaust gas flow path, thereby shortening the catalyst of the catalytic converter. It helps to reduce harmful gas during cold start.

Description

EXHAUST GAS SYSTEM OF INTERNAL COMBUTION ENGINE

The present invention relates to an exhaust system of an internal combustion engine, and more particularly, to reduce the heat loss of the exhaust gas generated from the exhaust manifold to the catalytic converter during cold start, when the temperature of the exhaust gas is not sufficiently raised to reduce the catalyst activation time. The present invention relates to an exhaust system of an internal combustion engine which reduces the harmful gas contained in the exhaust gas by shortening.

Existing internal combustion engine exhaust system, as shown in Figure 1, the exhaust manifold (4), exhaust pipe (6) connected to the combustion chamber of the engine 2, catalytic converter coated with a three-way catalyst for exhaust gas purification ( 8) and a silencer 10 for noise reduction.

A three-way catalyst is a device attached to reduce hydrocarbon (HC), nitrogen oxide (NO _X ) and carbon monoxide (CO) which are harmful components in the exhaust gas burned in an engine. Will operate with sufficient efficiency.

It takes some time for the exhaust gases to rise above these temperatures during the initial start-up of the engine, during which a large amount of harmful gases (especially hydrocarbons) are emitted which are not purified by the three-way catalyst.

Therefore, many methods for maximizing the efficiency of the three-way catalyst by increasing the temperature of the exhaust gas during cold start are being studied, one of which is US Patent 5,579,639 of Toyota Motor. As shown in FIG. 2, the pipes having different diameters are doubled to produce the exhaust pipes 6 between the exhaust manifold 4 and the catalytic converter 8 so that the inner pipes 8a and the outer pipes 8b are separated. An air layer is placed in between to reduce the heat loss of the exhaust gas.

In addition, the technical paper SAE980937 of Honda Motor Co., Ltd. is configured not only with the exhaust pipe but also with the exhaust manifold to reduce the heat loss of the exhaust gas.

On the other hand, the general exhaust gas recirculation apparatus used in the conventional engine is equipped with the exhaust gas recirculation valve 16 between the exhaust manifold 12 (or exhaust port) and the intake manifold 14 as shown in FIG. By opening the exhaust gas recirculation valve 16 in accordance with the difference between the exhaust pressure and the intake pressure under a specific partial load operating condition is a device for recirculating the exhaust gas burned by the engine 18. Recently, the operation of the exhaust gas recirculation valve 16 is a system controlled by the engine control apparatus 20 in which an optimum exhaust gas recirculation condition is input according to each engine operating condition.

However, among the conventional techniques described above, the double pipe exhaust pipe and the exhaust manifold reduce the heat capacity of the metal constituting the inner wall and form an air layer having low thermal conductivity between the pipes so that the engine exhaust gas is catalyzed from the exhaust manifold. Although the heat loss of the exhaust gas is reduced to the converter, during the initial cold start of the engine, the air layer formed between the pipes is also at a low temperature, so the temperature of the metal surface constituting the inner wall of the inner pipe increases during cold start. A degree of heat loss occurs. In order to minimize the heat loss, it is possible to consider the method of making the heat transfer as fast as possible by making the thickness of the metal surface constituting the inner wall as much as possible, but it is difficult to produce the exhaust manifold and the exhaust pipe, and the manufacturing cost increases. do.

In addition, the harmful gas reduction method using the exhaust gas recirculation valve does not reduce the harmful gas generated at the initial start of the engine.

In order to solve these problems, the present invention reduces the heat loss of the exhaust gas generated from the exhaust manifold to the catalytic converter during cold start when the temperature of the exhaust gas is not sufficiently raised, thereby reducing the catalyst activation time. It is an object to provide an exhaust system of an internal combustion engine that reduces harmful gases.

1 is a schematic diagram showing an exhaust system of a general internal combustion engine;

2 is a cross-sectional view schematically showing an exhaust pipe having a double wall associated with an exhaust manifold installed in a conventional internal combustion engine;

3 is a schematic diagram showing an exhaust system of a conventional internal combustion engine;

4 is a schematic diagram showing an exhaust system of an internal combustion engine according to a preferred embodiment of the present invention;

5 is a perspective view showing an exhaust manifold of the present invention;

FIG. 6 is a view seen from A of FIG. 5;

Figure 7 shows the connection of the exhaust manifold and the exhaust pipe of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

34: exhaust manifold 35: exhaust gas recirculation passage

36: exhaust pipe 36a: inner pipe

36b: Outer pipe 36c: Exhaust gas flow path

38: Catalyst converter 40: Silencer

42: controller 44: exhaust gas recirculation valve

46: exhaust gas flow path

The present invention devised to achieve the above object is to recycle a part of the exhaust gas to the intake manifold through which the outside air is passed by using the exhaust gas recirculation valve connected to the control device, and through the catalytic converter and silencer mounted on the exhaust pipe In an exhaust system of an internal combustion engine that discharges purified exhaust gas to the outside, an exhaust manifold having at least one exhaust gas recycling passage through which a part of the exhaust gas passes, the exhaust manifold connected to the exhaust manifold and An exhaust pipe having an associated exhaust gas flow path and an exhaust gas recirculation valve and an exhaust gas flow path connecting the intake manifold and the exhaust gas flow paths, respectively.

Here, the exhaust gas flow path is preferably formed between the inner pipe and the outer pipe having a different diameter in the exhaust pipe.

In addition, the exhaust gas recirculation passage is preferably formed in the distribution pipe of the exhaust manifold to communicate with the end of the integrated pipe.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 4 is a schematic diagram showing an exhaust system of an internal combustion engine according to a preferred embodiment of the present invention, FIG. 5 is a perspective view showing an exhaust manifold of the present invention, and FIG. 6 is a view seen from A of FIG. 7 is a view showing a connection portion of the exhaust manifold and the exhaust pipe of the present invention.

As can be seen in Figure 4, the exhaust system of the present invention comprises an intake manifold 32 and an exhaust manifold 34 associated with the combustion chamber of the engine 30, an exhaust pipe 36 connected to the exhaust manifold 34, It consists of a catalytic converter 38 connected to the exhaust pipe 36 and a recirculation valve 44 connected to the muffler 40 and the control device 42.

5 and 6, in the exhaust manifold 34, the distribution pipes 34a connected to each combustion chamber are formed as one integrated pipe 34b, and the distribution pipe 34a and the integrated pipe 34b are formed. At the end, a flange 34c is formed.

As the exhaust gas recirculation passage 35 is formed in at least one of the distribution pipes 34a and at least one of the distribution pipes 34a communicates with the end of the integrated pipe 34b, the exhaust gas recirculation passage 35 passes through the exhaust gas recirculation passage 35. The exhaust gas is maintained at a temperature by the exhaust gas passing through the distribution pipe 34a so that cooling is minimized while reaching the exhaust pipe 36.

As shown in FIG. 7, the exhaust pipe 36 is a pipe in which two pipes having different diameters are doubled, and an exhaust gas flow path 36c is formed between the inner pipe 36a and the outer pipe 36b.

The exhaust pipe 36 and the intake manifold 32 are connected to the exhaust gas flow passage 46. Since the exhaust pipe 36 is in contact with the air with the exhaust gas flow passage 46 interposed therebetween, the exhaust gas flow passage 46 is provided. The recycled exhaust gas entering the intake manifold 32 is cooled by air.

In addition, the exhaust gas recirculation valve 44 installed in the middle of the exhaust gas passage 46 discharges the valve according to the amount of opening of the throttle valve (not shown) at rotations other than idle and warm-up of the engine 30 as is well known. The gas recirculation valve 44 is opened to recirculate a part of the exhaust gas to the outside of the engine 30 to lower the combustion temperature while minimizing the decrease in output as much as possible.

The exhaust system of the internal combustion engine which is a preferred embodiment of the present invention configured as described above exhibits the following operation.

During the initial cold start of the engine 30, when the ignition is generated in the outside air and the fuel introduced into the combustion chamber, the exhaust gas is formed, and the exhaust gas is catalyzed through the exhaust pipe manifold 34 and the inner pipe 36a of the exhaust pipe 36. The transducer 38 is reached.

At this time, a part of the exhaust gas reaches the catalytic converter 38 through the exhaust gas recirculation passage 35 and the exhaust gas passage 36c of the exhaust pipe 36, and the exhaust gas connected to the control device 42 at that moment. The recirculation valve 44 is operated by the pressure difference in the exhaust pipe 36 and the intake manifold 32 so that a part of the exhaust gas in the exhaust gas passage 36c is bypassed, and the exhaust gas passage 46 and the exhaust gas are exhausted. The intake manifold 32 is supplied via the recirculation valve 44. Here, the exhaust pipe 36 serves to reduce the heat loss of the exhaust gas.

A portion of the exhaust gas introduced into the intake manifold 32 is mixed with the outside air and introduced into the combustion chamber together with the fuel. At this time, since the exhaust gas introduced into the intake manifold 32 is cooled by passing through the exhaust gas movement path 46, the exhaust gas is relatively cooled compared to the outside air introduced into the combustion chamber.

As can be seen from the above operation, the exhaust gas is reduced heat loss by a part of the exhaust gas passing through the exhaust gas recirculation passage 35 and the exhaust gas flow path 36c, which helps to shorten the catalyst of the catalytic converter. This reduces the harmful emissions (especially hydrocarbons) during cold start.

Exhaust system exhibiting such a configuration and operation can be applied without the development of exhaust gas recirculation system of the existing engine.

As described above, the exhaust system of the internal combustion engine, which is a preferred embodiment of the present invention, substantially solves the conventional problems.

That is, the exhaust gas preserves heat while passing through the exhaust gas recirculation passage of the exhaust manifold, and when passing through the inner pipe of the exhaust pipe, heat loss is reduced by the exhaust gas flow path, thereby shortening the catalyst of the catalytic converter. Help to reduce harmful gases during cold start.

Claims (3)

The internal combustion engine recirculates a part of the exhaust gas to the intake manifold through which the outside air passes through the exhaust gas recirculation valve connected to the control device, and sends the purified exhaust gas to the outside via the catalytic converter and silencer mounted on the exhaust pipe. In the exhaust system, An exhaust manifold having at least one exhaust gas recirculation passage through which a portion of the exhaust gas passes; An exhaust pipe having an exhaust gas flow passage connected to the exhaust manifold and associated with the exhaust gas recirculation passage; And And an exhaust gas flow passage connecting the exhaust gas recirculation valve, the intake manifold, and the exhaust gas flow path, respectively. The exhaust system of claim 1, wherein the exhaust gas flow path is formed between an inner pipe and an outer pipe having a different diameter in the exhaust pipe. The exhaust system of claim 1, wherein the exhaust gas recirculation passage is formed in a distribution pipe of the exhaust manifold and communicates with an end of an integrated pipe.