Double pipe exhaust manifold

Details Double pipe exhaust manifold Double pipe exhaust manifold

2002-02-28

2003-09-30

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

Common receiver having inlets from plural cylinder

C060S322000

Reexamination Certificate

active

06625979

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a double pipe exhaust manifold which is interposed between an engine and a catalyst and in which an adiabatic outer pipe is disposed around an inner pipe through which exhaust gas passes in a state that a mesh spacer member is interposed between those pipes, whereby an adiabatic space is formed between the inner pipe and the outer pipe.
It is a common practice that the exhaust manifold, as shown in
FIG. 6
, has a double pipe structure including an inner pipe
101
and an adiabatic outer pipe
102
covering the outer periphery of the inner pipe, in order that a catalyst located in the midway of the exhaust system of an engine early exercises its purifying function by rapidly heating up the catalyst to facilitate the purifying performance of the vehicle by utilizing the heat of the exhaust gas. A mesh spacer member
103
is interposed between the inner pipe
101
and the outer pipe
102
to secure the adiabatic space. Since the mesh spacer member
103
is brought into contact with the inner pipe
101
and the outer pipe
102
, a mesh consisting of wires each having a small diameter of about 0.25 mm is used for the mesh spacer member
103
so as to minimize its thermal conduction.
To give the inner pipe
101
a function of absorbing a thermal expansion difference between the inner pipe
101
and the outer pipe
102
, which results from a thermal expansion difference and a thermal expansion coefficient between the inner pipe and the outer pipe, the inner pipe
101
consists of two pipe members coupled so as to allow those members to axially extend and shrink. The mesh spacer member
103
is fixed only to the inner pipe
101
, and the outer pipe
102
and the mesh spacer member
103
are coupled such that those are slidable in the axial direction.
The outer pipe
102
is divided into two pipe members in the radial direction in the light of the assembling of the outer pipe
102
to the inner pipe
101
. To assemble the outer pipe to the inner pipe
101
, the divided outer pipe members
102
a
and
102
b
are both brought into contact with the outer periphery of the mesh spacer member
103
outside the inner pipe
101
. In this state, one side end of the divided outer pipe member
102
a
is put on the corresponding side end of the divided outer pipe member
102
b.
The other side end of the former is also put on the corresponding one of the latter. Those overlapping portions of the divided outer pipe members
102
a
and
102
b
are bonded, by welding
104
, into one cylindrical member. In this way, the outer pipe is assembled to the inner pipe
101
.
In the conventional double pipe exhaust manifold, as described above, in a state that both the divided outer pipe members
102
a
and
102
b
are brought into contact with the outer peripheral surface of the mesh spacer member
103
, those overlapping portions of the outer pipes
102
a
and
102
b
are bonded together by the welding
104
. When the overlapping portions are welded together, a back bead
104
a
of the welding
104
comes in contact with the mesh spacer member
103
. In this condition, the mesh spacer member
103
formed with fine wires of 0.25 mm in diameter is cut by high heat of the back bead
104
a.
As a result, there is the possibility that the mesh of the mesh spacer member starts to be broken from its cut part, and is loosened. The back bead
104
a
may be welded onto the mesh spacer member
103
although the mesh is not cut. In this case, the axially sliding motion of the outer pipe
102
to the inner pipe
101
will be impeded or break the mesh spacer member
103
. The above problems may be solved in a manner that the outward flanges are formed at both side ends of the divided outer pipe members, and those flanges are welded together at the tips of them. In this approach, the outward flanges greatly project to the right and left from the outer pipe. Accordingly, the outside diameter of the exhaust manifold is increased by an amount corresponding to the flange projection. This results in deterioration of the on-board property.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a double pipe exhaust manifold which is able to prevent such an unwanted situation that during the assembling work by the welding of the divided outer pipe members forming the cylindrical outer pipe, the back bead comes in contact with the mesh spacer member, and the mesh spacer member is cut or the mesh spacer member is welded to the outer pipe by high heat of the back bead, without the deterioration of the on-board property.
The aforementioned object is achieved by means of a double pipe exhaust manifold having an inner pipe, a mesh spacer member applied to the outer periphery of the inner pipe, and an outer pipe being disposed around the outer periphery of the mesh spacer member in a state that the outer pipe is axially slidable to the inner pipe, wherein the outer pipe is divided into two pipe members in a radial direction, and one side end of one of the divided pipe members is put on the corresponding one of the other of the divided pipe members, and the other side end of the divided pipe member is put on the corresponding one of the latter divided pipe member in a radial direction, and the overlapping portions are welded together, the improvement being characterized in that the overlapping portions of the pipe members are swollen to the outside to form gaps between the overlapping portions and the mesh spacer member.
Preferably, the inner pipe is thinner than the outer pipe, and the mesh spacer member is fastened to the inner pipe by spot welding.
As described, in the invention, the overlapping portions of the pipe members are swollen to the outside to form gaps between the overlapping portions and the mesh spacer member. Accordingly, it is avoided that the back bead of the welding comes in contact with the mesh spacer member when one side end of one of the divided pipe members is put on the corresponding one of the other of the divided pipe members as radially viewed, and the other side end of the divided pipe member is put on the corresponding one of the latter divided pipe member, and in this state the overlapping portions are welded together.
The double pipe exhaust manifold of the invention successfully prevents such an unwanted situation that the back bead at high temperature comes in contact with the mesh spacer member, and hence the mesh spacer member is cut and the mesh spacer member is welded to the outer pipe.
It suffices that gaps between the overlapping portions and the mesh spacer member are minute (≈2 mm). Accordingly, there is no chance that the outside diameter of the exhaust manifold is increased and the on-board property is deteriorated.
In the preferred embodiment, the inner piper is thinner than the outer pipe, so that the mesh spacer member may be fastened to the inner pipe by spot welding. In the spot welding, temperature during the welding is lower than that in the cladding by welding. Therefore, the mesh spacer member may easily be fastened without the cutting of the mesh of the mesh spacer member.
Since the inner pipe is formed to have a thin thickness, a thermal capacity of it is small. Accordingly, it is prevented that heat is absorbed by the inner pipe and exhaust gas temperature reduces. Further, the outer pipe is formed to have a thick thickness, so that the durability of the double pipe exhaust manifold is increased.


REFERENCES:
patent: 4404992 (1983-09-01), Sasaki et al.
patent: 5004018 (1991-04-01), Bainbridge
patent: 5419127 (1995-05-01), Moore, III
patent: 5682741 (1997-11-01), Augustin et al.
patent: 5761905 (1998-06-01), Yamada et al.
patent: 5953912 (1999-09-01), Kaiho et al.
patent: 6155046 (2000-12-01), Kato et al.
patent: 6245301 (2001-06-01), Stroom et al.
patent: 6247552 (2001-06-01), Kovar et al.
patent: 34 32 744 (1986-03-01), None
patent: 39 22 667 (1990-09-01), None
patent: 199 17 604 (2000-12-01), None
patent: 0 582 985 (1994-02-01), None
patent: 2 122 683 (1994-01-01), None
patent: 58-104318 (19

Affiliated with

Also associated with

Rating

Double pipe exhaust manifold does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Double pipe exhaust manifold, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Double pipe exhaust manifold will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3060278