JP2003293864A - Egr pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EGR pipe, in which thermal stress of an EGR pipe is reduced by a shape of the pipe, and stress concentration on connection portions of flanges is reduced. <P>SOLUTION: The EGR pipe 1 has flanges 2, 2, which are disposed to both ends of the EGR pipe 1 to be respectively connected with an exhaust path and an intake path. One or plurality of bending portion(s) 3a (3b, 3c) is/are formed in the pipe between the flanges 2, 2. Bending tops 4a, 4b, 4c are mutually arranged in line symmetry of a center line A-A connecting centers of the flanges 2, 2, so that contraction and extension caused by exhaust heat or the like applied to the EGR pipe 1 is absorbed by the bending portion(s) 3a (3b, 3c) to reduce the stress concentration of connecting portions of both flanges 2, 2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR pipe for circulating a part of engine exhaust gas to the intake side.

[0002]

2. Description of the Related Art As shown in FIG. 3, an EGR (exhaust gas recirculation system) connects an EGR pipe 13 between an exhaust system passage 11 and an intake system passage 12 of an engine 10 through a flange to exhaust gas. A part of the air is recirculated to the intake system passage 12, mixed with intake air, and re-combusted.

[0003]

DISCLOSURE OF THE INVENTION Conventional EGR pipe 1
Since 3 is a shape that connects the flanges on both ends with a straight line,
Due to the high heat of the exhaust gas, the EGR pipe 13 linearly expands and contracts, and this thermal stress may concentrate on the connecting portion of the flange and adversely affect the connecting portion.

An object of the present invention is to reduce the thermal stress of the EGR pipe by the shape of the pipe, and to alleviate the stress concentration on the connecting portion of the flange.

[0005]

According to the present invention for achieving the above object, as set forth in claim 1, EGR is provided with flanges which are respectively connected to an exhaust system passage and an intake system passage of an engine at both ends. In the pipe, one or a plurality of bent portions are formed in the pipe between the flanges.

According to a second aspect of the present invention, in the EGR pipe, the bending vertices of the plurality of bending portions are arranged symmetrically with respect to the center line connecting the centers of both flanges.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes the entire EGR pipe of the present invention. As shown in FIG. 3, flanges 2 and 2 for connecting to an exhaust system passage 11 and an intake system passage 12 of the engine 10 are provided at both ends of the EGR pipe 1.
Therefore, the EGR pipe 1 of the present invention is
It has a shape in which a corrugated bent portion 3a, 3b, 3c is formed in the pipe between the two.

It is desirable that the vertices 4a, 4b and 4c of the bent portions 3a, 3b and 3c be arranged symmetrically with respect to a center line AA connecting the centers of the flanges 2 and 2. Further, the respective vertices 4a, 4 of the bent portions 3a, 3b, 3c.
Straight portions 5 and 5 connecting b and 4c are bent portions 3a, 3b and 3c.
It is desirable that the bending radius be 1 times or more. Further, it is desirable that the bending angle of the bent portion 3b in the middle portion be 90 ° to 120 °.

Since the present invention has the structure as described above, E
Expansion and contraction due to exhaust heat applied to the GR pipe 1 causes bending portion 3
It is absorbed by a, 3b, and 3c, and stress concentration at the connecting portions of the flanges 2 and 2 is relaxed.

Further, the respective vertices 4a, 4b, 4c of the bent portions 3a, 3b, 3c are arranged in line symmetry with respect to a center line AA connecting the centers of the flanges 2, 2 to disperse stress. Therefore, the stress concentration at the connecting portion between the flanges 2 and 2 can be more effectively relieved.

In addition, the straight line portions 5 and 5 connecting the respective vertices 4a, 4b and 4c of the bent portions 3a, 3b and 3c are bent portions 3.
By setting the bending R of a, 3b, 3c to be at least 1 time and the bending angle of the middle bent portion 3b to be 90 ° to 120 °, the effect of absorbing expansion and contraction due to exhaust heat or the like applied to the EGR pipe 1 can be effectively achieved. can get.

In the embodiment of the present invention shown in the drawings, three bent portions 3a, 3b, 3c are formed, but one or more than three depending on the span between both flanges 2, 2. It is also possible to form a plurality.

[0013]

As described above, according to the present invention, EG
With a simple structure in which a bent portion is formed on the R pipe, thermal stress can be absorbed and stress concentration at the flange connection can be relaxed. Especially, the apex of the bent portion is arranged in line symmetry of the center line connecting the centers of both flanges. By doing so, it is possible to disperse the stress and further reduce the stress concentration in the flange connection portion.

[Brief description of drawings]

FIG. 1 is a plan view of the present invention.

FIG. 2 is a side view of the present invention.

FIG. 3 is a diagram showing a layout of a conventional EGR pipe.

[Explanation of symbols]

1 EGR pipe 2 flange 3a bent part 3b bend 3c bent part 4a vertex 4b vertex 4c vertex 5 Straight section

Claims (2)

[Claims] 1. An EGR pipe having flanges at both ends, which are respectively connected to an exhaust system passage and an intake system passage of an engine, wherein one or more bent portions are formed in the pipe between the flanges. EGR pipe to do. 2. The EGR pipe according to claim 1, wherein the bending vertices of the plurality of bending portions are arranged symmetrically with respect to a center line connecting the centers of both flanges.