JP2002130060A - Egr gas cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR gas cooling device having excellent durability with the small-sized and simple structure capable of efficiently cooling the EGR gas. SOLUTION: A bellows part is arranged at a part of an inner pipe for EGR gas passage for taking a part of the exhaust gas out of an exhaust system of an engine, and an outer pipe for the EGR gas cooling water is arranged in the peripheral surface of the bellows part so as to circulate the engine cooling water. With this structure, a surface area of the bellows part is increased so as to improve the heat efficiency, and a heat exchanger can be miniaturized, and expansion and shrinkage of the piping with a start and a stop of the engine can be effectively absorbed, and a difference of the thermal expansion between each piping to be generated by a temperature difference between the inner pipe of a high temperature part and the outer pipe of the low temperature part can be absorbed by the bellows part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation device (EGR device) for extracting a part of exhaust gas from an exhaust system of an engine, returning the exhaust gas to an intake port of the engine, and adding the mixture to an air-fuel mixture.
The present invention relates to an EGR gas cooling device.

[0002]

2. Description of the Related Art An exhaust gas recirculation system is employed in which a part of exhaust gas is taken out of an exhaust system of an engine and mixed with intake air of the engine to recirculate in a cylinder. The device, the recirculated exhaust gas is called an EGR gas, and the device that cools the EGR gas is called an EGR gas cooling device, respectively). By adding a part of the exhaust gas to the air-fuel mixture, the ratio of inert gas such as nitrogen gas and carbon dioxide gas is increased to suppress the combustion temperature and pressure, and NOx
The purpose of this is to reduce the generation of gas and increase the combustion efficiency. However, if part of the high-temperature exhaust gas is directly mixed with the intake air, the intake air temperature rises, the volumetric efficiency decreases, and the engine output,
Due to problems such as deterioration of performance such as fuel efficiency, EGR
The gas is cooled appropriately, and this EGR
Various gas cooling devices have been proposed. However, the conventional E
The GR gas cooling system is a plate-fin type or multi-tube type heat exchanger. The structure is complex and large, and the difference in temperature between the exhaust gas temperature and the cooling water is large. There is a technical problem that the durability is inferior because the difference in thermal expansion between components constituting each pipe of the exchanger becomes large.

[0003]

SUMMARY OF THE INVENTION In view of the above technical problems, an object of the present invention is to provide an EGR gas cooling apparatus having a small and simple structure capable of efficiently cooling EGR gas and having excellent durability. .

[0004]

In order to achieve the above object, according to the present invention, a bellows portion is provided on a part of an inner pipe for an EGR gas passage obtained by extracting a part of exhaust gas from an exhaust system of an engine. And an outer pipe for EGR gas cooling water having a bellows on its outer peripheral surface.
Cooling water for cooling the engine was circulated. As a result, the surface area of the bellows part is large and the thermal efficiency is improved, the heat exchanger can be downsized, the expansion and contraction of the piping caused by starting and stopping the engine can be effectively absorbed, and the inner pipe in the high temperature part and the outer part in the low temperature part The bellows portion acts to absorb the difference in thermal expansion of each pipe resulting from the temperature difference between the pipes.

According to a second aspect of the present invention, an outer pipe for an EGR gas cooling water having a bellows portion is provided on an outer peripheral surface of an inner pipe for an EGR gas passage from which a part of exhaust gas is extracted from an exhaust system of an engine, Cooling water for cooling the engine was circulated. This effectively absorbs the expansion and contraction of the pipes caused by the start and stop of the engine, and the difference in the thermal expansion of each pipe caused by the temperature difference between the inner pipe in the high-temperature section and the outer pipe in the low-temperature section is reduced by the bellows section of the outer pipe. Acts to absorb.

According to a third aspect of the present invention, a bellows portion is provided in a part of an inner pipe for an EGR gas passage from which a part of exhaust gas is taken out from an exhaust system of an engine, and EGR gas cooling water is provided on an outer peripheral surface thereof. An outer pipe was provided to circulate cooling water for cooling the engine. This increases the surface area of the bellows of the inner pipe, improving thermal efficiency,
The heat exchanger can be miniaturized, effectively absorbing the expansion and contraction of the piping caused by starting and stopping the engine, and the difference in thermal expansion of each piping caused by the temperature difference between the high temperature inner pipe and the low temperature part outer pipe. Acts to be absorbed by the bellows portion of the inner pipe.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention. A bellows portion 11 is provided on a part of the inner pipe 1 through which the EGR gas passes, and an outer pipe 2 is provided on an outer peripheral surface thereof. Is provided. Further, a cooling water inlet 22 and an outlet 23 are provided in the outer pipe, and the cooling water is circulated.

FIG. 2 shows a second embodiment of the present invention. Outer pipe 2 for cooling water having a bellows portion 21 on the outer peripheral surface of inner pipe 1a through which EGR gas passes
Was provided. Others are the same as those of the first embodiment.

FIG. 3 shows a third embodiment of the present invention. A bellows portion 11 was provided on a part of the inner pipe 1 through which the EGR gas passed, and an outer pipe 2a for cooling water was provided on the outer peripheral surface thereof. Others are the same as those of the first embodiment. In any of the first to third aspects of the present invention, the bellows portion may be provided integrally with the pipe, or another bellows pipe may be joined.

[0010]

According to the present invention, the bellows portion is provided in a part of the piping of the EGR gas cooling device, so that the surface area is large, the thermal efficiency is improved, and the simple structure allows for downsizing, which is accompanied by the start and stop of the engine. EGR with excellent durability because it can easily absorb the expansion and contraction of the pipe due to the cooling and heating cycle and absorb the difference in thermal expansion caused by the temperature difference between the inner pipe as the high temperature part and the outer pipe as the low temperature part
It becomes a gas cooling device.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the invention described in claim 1;

FIG. 2 shows an embodiment of the invention described in claim 2;

FIG. 3 shows an embodiment of the invention described in claim 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner pipe 11 Bellows part of inner pipe 2 Outer pipe 21 Bellows part of outer pipe 22 Cooling water inlet 23 Cooling water outlet

Claims (3)

[Claims] 1. An exhaust gas recirculation system for an exhaust gas recirculation system, wherein a part of exhaust gas is taken out of an exhaust system of an engine, cooled, returned to an intake port of the engine, and added to an air-fuel mixture.
An EGR gas cooling apparatus comprising: a bellows portion provided in a part of an inner pipe for an EGR gas passage; and an outer pipe for cooling water having a bellows portion provided on an outer peripheral surface thereof. 2. An exhaust gas cooling system of an exhaust gas recirculation system for removing a part of exhaust gas from an exhaust system of an engine, cooling the exhaust gas, returning the exhaust gas to an intake port of the engine, and adding the mixture to an air-fuel mixture.
An EGR gas cooling device, wherein an outer pipe for cooling water having a bellows portion is disposed on an outer peripheral surface of an inner pipe for an EGR gas passage. 3. An exhaust gas cooling device for an exhaust gas recirculation device for extracting a part of exhaust gas from an exhaust system of an engine, cooling the exhaust gas, returning the exhaust gas to an intake port of the engine, and adding the mixture to an air-fuel mixture.
An EGR gas cooling device, wherein a bellows portion is provided in a part of an inner pipe for an EGR gas passage, and an outer pipe for cooling water is provided on an outer peripheral surface thereof.