JP2002364461A - Exhaust gas recirculation device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device for an internal combustion engine capable of performing recirculation of exhaust gas regardless of an engine load state. SOLUTION: An end of an exhaust gas circulation pipe 4 is protruded inward from a side surface of an exhaust passage 2 connected to an engine body 1, and the end of the exhaust gas circulation pipe 4 is bent to an exhaust port side at a central part of the exhaust passage 2 so that an opening 4a of the end of the exhaust gas circulation pipe 4 faces the exhaust port side. The other end of the exhaust gas circulation pipe 4 communicates with an intake passage 3 connected to the engine body 1. Under an engine operational state, dynamic pressure as well as static pressure is applied to the opening 4a of the end of the exhaust gas circulation pipe 4 in the exhaust passage. The opening 4 positions at a central of a cross section, wherein flow velocity of the exhaust gas is the highest in the exhaust passage. Therefore, the quantity of the exhaust gas taken into the exhaust gas circulation pipe 4 is the largest, and recirculation of the exhaust gas can be effectively performed.

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 system for an internal combustion engine configured to recirculate a part of exhaust gas from an engine to an intake side.

[0002]

2. Description of the Related Art Conventionally, engines mounted on automobiles include:
Part of the exhaust gas is recirculated to the intake side to lower the combustion temperature,
There is a structure in which an EGR pipe (exhaust gas recirculation pipe) is provided in order to reduce NOx. As shown in FIG. 4, an engine body 1 is provided with an exhaust passage 2 and an intake passage 3. E to bypass the engine body 1
One end of the GR pipe 4 is connected to an opening formed on the side surface of the exhaust passage 2, the other end of the EGR pipe 4 is connected to the intake passage 3, and a part of the exhaust gas passes through the EGR pipe 4,
The air is recirculated to the intake passage 3 via the EGR valve 5.

The recirculation of the exhaust gas is performed by a differential pressure between the exhaust gas in the exhaust passage 2 and the intake air in the intake passage 3.

[0004] In addition, EGR is also used in diesel engines.
It is proposed to provide a pipe (Japanese Utility Model Laid-Open No. 3-12225).
It is also considered that when installing an EGR pipe, measures to deal with particulates peculiar to fuel are taken (see Japanese Patent Application Laid-Open No. 9-126063).

[0005]

By the way, in the conventional engine, when the engine is in a low load state,
Although the differential pressure required for exhaust gas recirculation occurs, when the engine is under a high load, the differential pressure required for exhaust gas recirculation is not sufficiently generated, and exhaust gas recirculation is performed efficiently. I can't do it. Therefore, it has been desired that the exhaust gas recirculation works efficiently regardless of the operating state of the engine.

An object of the present invention is to provide an exhaust gas recirculation device for an internal combustion engine that can recirculate exhaust gas regardless of the load condition of the engine.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, one end of an exhaust gas recirculation pipe projects from a side of an exhaust passage connected to an engine body. In addition, an end opening of the exhaust gas recirculation pipe is directed toward the exhaust port, and the other end of the exhaust gas recirculation pipe is connected to an intake passage connected to an engine body.

According to a second aspect of the present invention, in the first aspect of the present invention, an end portion of the exhaust gas recirculation pipe protruding into the exhaust passage is bent toward the exhaust port at the center of the exhaust passage, and the exhaust gas recirculation is performed. The end opening of the pipe is directed toward the exhaust port.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The exhaust gas recirculation device shown in FIG. 1A is a device in which an intake passage 3 connected to an engine body 1 and an exhaust passage 2 are connected by an EGR pipe 4.
An EGR valve 5 is provided in the EGR pipe 4. The exhaust passage 2 has an opening on a side surface thereof. The EGR pipe 4 is inserted through the opening, and is bent along the inner wall surface of the exhaust passage 2 so as to face the exhaust gas flow direction. It is facing almost upstream.

By doing so, the exhaust gas discharged from the engine body 1 flows down in the exhaust passage 2, but at this time, the pressure at the tip opening 4 a of the EGR pipe 4 is increased by the dynamic pressure. As a result, the pressure difference between the intake air in the intake passage 3 and the intake air increases, so that the exhaust gas can be efficiently recirculated even when the engine is under a high load.

The exhaust gas recirculation device shown in FIG.
The EGR pipe 4 that has entered the exhaust passage 2 is bent at a central position in the exhaust passage 2, and a tip end opening 4 a of the EGR pipe 4 is formed.
Is directed substantially upstream. Symbol r represents the radius of the exhaust passage 2. In practice, as shown in FIGS. 2 and 3,
The EGR pipe 4 is connected to a downstream pipe section 8 where exhaust pipes of respective cylinders of an exhaust manifold 7 having an attachment flange 6 formed on the engine body 1 are combined.

The downstream pipe section 8 of the exhaust manifold 7
Is connected to a catalyst device 9, and an exhaust pipe (not shown) is connected to a rear portion thereof. An opening 8a is formed in a side surface of the downstream pipe portion 8, and a substantially arc-shaped bent pipe 10 extends into the downstream pipe portion 8 from the opening 8a.
a is fixed toward the upstream side with a being located substantially at the center of the downstream pipe portion 8. The bending pipe 10 has a connection fitting 11 fixed thereto, and the EGR pipe 4 is provided with a mounting fitting 12. Then, the EGR pipe 4 is fixed to the downstream pipe portion 8 by attaching the fitting 12 to the connecting fitting 11 of the bent pipe 10. The other end of the EGR pipe 4 is connected to the intake passage 3.
Has been contacted.

As described above, the distal end of the EGR pipe 4, that is, the distal opening 10 a of the bent pipe 10 is connected to the downstream pipe section 8.
Of the EGR pipe 4 is located at the center of the cross section of the exhaust passage 2 where the flow rate of the exhaust gas is the fastest, that is, at the tip opening 4a of the EGR pipe 4. Since a large dynamic pressure of the exhaust gas is applied and the pressure difference between the exhaust gas and the intake air in the intake passage 3 increases, the exhaust gas can be efficiently recirculated even when the engine is under a high load.

[0014]

The present invention is as described above. According to the first aspect of the present invention, the opening of the exhaust gas recirculation pipe in the exhaust passage is directed to the exhaust port side (upstream side). In the operating state, not only static pressure but also dynamic pressure is applied to the opening of the end of the exhaust gas recirculation pipe in the exhaust passage. Therefore, the pressure applied to the opening of the end of the exhaust gas recirculation pipe increases, and the pressure difference with the intake side increases, so that the exhaust gas can be sufficiently recirculated even when the engine is operated under a high load. Thereby, it is possible to efficiently perform the exhaust gas recirculation control.

According to the second aspect of the present invention, the opening of the end of the exhaust gas recirculation pipe in the exhaust passage is located particularly at the center of the cross section where the flow velocity of the exhaust gas is the fastest in the exhaust passage.
The largest amount of exhaust gas can be taken into the exhaust gas recirculation pipe, and the exhaust gas can be efficiently recirculated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an exhaust gas recirculation device for an internal combustion engine according to an embodiment of the present invention, in which exhaust gas intake ports are arranged at a peripheral position (a) and a center position (b).

FIG. 2 is a perspective view showing an exhaust pipe side structure of the exhaust gas recirculation device according to the embodiment of the present invention.

FIG. 3 is a side view of the exhaust gas recirculation device shown in FIG. 2;

FIG. 4 is a schematic view of a conventional exhaust gas recirculation device for an internal combustion engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 2 Exhaust passage 4 Exhaust gas recirculation pipe 4a Tip opening 10 Bending pipe 10a Tip opening

Claims (2)

[Claims] An exhaust gas recirculation pipe has one end protruding from a side surface of an exhaust passage connected to an engine body, and an end opening of the exhaust gas recirculation pipe is directed toward an exhaust port. An exhaust gas recirculation device for an internal combustion engine, wherein the other end of the pipe is connected to an intake passage connected to an engine body. 2. An end of an exhaust gas recirculation pipe protruding into an exhaust passage is bent toward an exhaust port at a center of the exhaust passage, and an end opening of the exhaust gas recirculation pipe is directed toward the exhaust port. The exhaust gas recirculation device for an internal combustion engine according to claim 1, wherein: