Apparatus for cooling exhaust

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0110069 filed in the Korean Intellectual Property Office on Nov. 8, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to an apparatus for cooling exhaust gas. More particularly, the present invention relates to an apparatus for cooling exhaust gas in an exhaust gas recirculation system.

(b) Description of the Related Art

Generally, an exhaust gas recirculation system introduces a portion of the exhaust gases discharged from an engine to a combustion chamber after mixing intake air therewith for reducing nitrogen oxide NOx content of the exhaust gases.

An exhaust gas cooling apparatus for cooling exhaust gas is disposed to the exhaust gas recirculation system.

Conventional apparatus for cooling the exhaust gas is made of a stainless steel material that has high heat resistance to high temperature exhaust gas.

However, because the stainless steel material has a high density, weight of the exhaust gas recirculation system increases.

In addition, because the stainless steel material is relatively expensive, manufacturing costs increases.

Furthermore, due to a limited thermal conductivity of the stainless steel, apparatus volume needs to be increased.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide an apparatus for cooling exhaust gas that can overcome the problems associated with conventional systems.

An exemplary embodiment of the present invention provides an apparatus for cooling exhaust gas cooling the exhaust gas re-circulated, comprising an exhaust gas passage in which the exhaust gas flows, at least one first cooling portion comprising a coolant inlet and an exhaust gas inlet for cooling the exhaust gas, and at least one second cooling portion comprising a coolant outlet and an exhaust gas outlet for cooling the exhaust gas cooled from the first cooling portion, wherein the first cooling portion and the second cooling portion are made of different materials each other.

Preferably, the heat conductivity of the first cooling portion and the heat conductivity of the second cooling portion are different.

The first cooling portion may include a plurality of first plates contacting coolant, a plurality of second plates disposed in the first plates, and a fin made of a steel material and disposed between the second plates.

The second cooling portion may include a plurality of first plates contacting coolant, a plurality of second plates disposed in the first plates, and a fin made of a steel material and disposed between the second plates.

A gasket may suitably be disposed between the first cooling portion and the second cooling portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an apparatus for cooling exhaust gas according to an exemplary embodiment of the present invention.

FIG. 2 shows a first cooling portion and a second cooling portion of an apparatus for cooling exhaust gas according to an exemplary embodiment of the present invention.

FIG. 3 shows a view that a first cooling portion and a second cooling portion are separated according to an exemplary embodiment of the present invention.

Reference numerals set forth in the Drawings includes reference to the following elements as further discussed below:

• • 101: the first cooling portion
  • 103: the second cooling portion
  • 105: exhaust gas inlet
  • 107: coolant inlet
  • 109: exhaust gas outlet
  • 111: coolant outlet
  • 113: coolant passage
  • 201: the first plate
  • 203: the second plate
  • 205: steel material fin
  • 207: aluminum material fin
  • 209: exhaust gas passage

DETAILED DESCRIPTION

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 1 shows an apparatus for cooling exhaust gas according to an exemplary embodiment of the present invention, FIG. 2 shows a first cooling portion and a second cooling portion of an apparatus for cooling exhaust gas according to an exemplary embodiment of the present invention, and FIG. 3 shows a view that a first cooling portion and a second cooling portion are separated according to an exemplary embodiment of the present invention.

As shown in FIG. 1 and FIG. 2, an apparatus for cooling exhaust gas includes an exhaust gas passage 209, at least one first cooling portion 101, and at least one second cooling portion 103.

The exhaust gas flows in the exhaust gas passage 209.

The first cooling portion 101 includes a coolant inlet 107 and an exhaust gas inlet 105 and cools the exhaust gas.

The second cooling portion 103 includes a coolant outlet 111 and an exhaust gas outlet 109 and cools the exhaust gas cooled from the first cooling portion 101.

That is, the exhaust gas inflows through the exhaust gas inlet 105 and is exhausted through the exhaust gas outlet 109. (referring to solid line arrow).

In addition, coolant inflows through the coolant inlet 107 and is exhausted through the coolant outlet 111.

Preferably, the first cooling portion 101 and the second cooling portion 103 can be made of different material.

That is, the coolant and the exhaust gas inflow through the first cooling portion 101 and are then supplied to the second cooling portion 103.

Suitably, the heat conductivity of the first cooling portion 101 and the heat conductivity of the second cooling portion 103 may be different.

More suitably, according to an exemplary embodiment of the present invention, the heat conductivity of the first cooling portion 101 may be lower than that of the second cooling portion 103.

That is, the exhaust gas of higher temperature is cooled in the first cooling portion 101. The exhaust gas cooled in the first cooling portion 101 is then cooled in the second cooling portion 103.

Referring to FIG. 2, the first cooling portion 101 includes a plurality of first plates 201, a plurality of second plates 203, and a fin 205.

The first plates 201 contact the coolant, the second plates 203 are disposed in the first plates 201, and the exhaust gas flows the second plates.

The fin 205 is disposed to absorb the heat of the exhaust gas of the second plate 203 and made of steel material.

As shown in FIG. 1 and FIG. 3, the apparatus for cooling the exhaust gas includes a plurality of first cooling portions 101 and a plurality of second cooling portions 103.

Because the coolant flows between a plurality of the first cooling portions 101 and the exhaust gas flows in the first cooling portion 101, heat exchange between the exhaust gas and the coolant is realized.

In particular, referring to FIG. 2, the coolant flows outside the first plates 201 and the exhaust gas flows between the second plates 203.

Heat exchange between exhaust gas and coolant is realized by the fin 205 of the first cooling portion and the fin 207 of the second cooling portion.

Although the first cooling portion 101 and the second cooling portion 103 have the same shape, they have fins of different material.

Particularly, the fin 205 of the first cooling portion 101 may be made of the steel material and the fin 207 of the second cooling portion 103 may be made of an aluminum material.

The hot exhaust gas is cooled by in the first cooling portion 101 including the steel material fin 205 having an excellent heat resistant performance to a temperature that can be applied to the fin of aluminum material.

The exhaust gas is then re-cooled in the second cooling portion 103 including the fin 207 made of the aluminum material.

As shown in FIG. 3, because the first cooling portion 101 and the second cooling portion 103 are made of different materials, it is impossible that the first cooling portion 101 and the second cooling portion 103 are connected by a method such as welding or brazing.

Rather, the first cooling portion 101 and the second cooling portion 103 can be coupled, for example, by bolt (not shown).

Preferably, for preventing a leakage of the exhaust gas or the coolant, a gasket 301 may be disposed between the first cooling portion 101 and the second cooling portion 103.

The heat conductivity of aluminum material is higher than that of stainless steel material. Aluminum material is less expensive than stainless steel material. Also, aluminum material is lighter than stainless steel material. As a result, the present invention can overcome the problems of conventional systems by reducing manufacturing costs and the apparatus volume and weight.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.