Note: Descriptions are shown in the official language in which they were submitted.
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Manifold and Manufacturi.ng Method Thereof
1 . (Background of the Inven-tion)
This invention rela-tes to a manifold which is
branc}led out to connect valves of an internal combustion
engine of an automobile with ei-ther a carbure-tor or a
muffler, and a manufacturing method therefor~
(Related Art Statement)
There is generally known in the art a manifold
for inta~e/exhaust systems of an internal combustion
engine comprising a manifold main body, branched piPeS
connected to .respec-tive cylinders, and flanges for
fixing these branched pipes on cylinder blocks, which
are cast-molded and are further cladded on the outer
periphe~ thereof for reinforcement purpose, particularly
for an exhaus-t manifold which con-tains gases of high
temperature and pressure. The conventional manifold
however, is defective in that the weight of a manifold
itse].f is heavy and adds an extra weight and size to an
in-ternal combustion engine -to thereb.y give limitations
to the engine layou-t design.
I
~Objects and Summary of the Invention)
: :The present inven-tion was conceived to eliminate
these problems encountered in the prior art, and aims to.
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1 provide a manifold which is light in weight and small in
size to reduce the molding cost by structuring it with pipe
members instead of casting.
In order to solve the aforementioned problems, one
aspect of the invention relates to a manifold comprising a
manifold main body constructed with a pipe member, plural
branch pipes pro~ecting from a side of the pipe member, in
the direction perpendicular to the axial line of the pipe
member, and flanges which are attached on the ends of these
branch pipes, which is characterized in that either the
outer peripheries of said branch pipes at ends thereof or
the inner peripheries of the flanges which are inserted into
the ends of the branch pipes are provided with grooves for
preventing ~as from leaking therefrom and grooves for
preventing rotation, and the outer peripheries of the branch
pipes are caulked with pressure over the inner peripheries
of the flan~es.
A second aspect of the invention relates to a
manufacturing method of manifolds comprising the steps of:
forming with the bulging process (hydraulic bulge forming or
bulge working) plural pipes on one side of a pipe member in a
manner to project therefrom in the direction perpendicular to
the axial line of the pipe; forming branch pipes by boring a
hole on ~he ends of each projected pipe formed by ~he
bulging process, and rectifying the periphery to define
. P~ '
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].~ . straiyht pipe projections; of forming circumferential
` ~ grooves for gas leakage prevention and grooves for
rotat:ion preven-tion wi-th either one of -the outer
peripheries of the branch p:ipes at the ends thereof and
the lnner peripher.ies of -the flanges on which the ends
of the branch pipes being cupped, and of forming flanges
by pressing and caulking the peripheries of the branch
pipes at the ends over the inner peri.pheries of the
flange members.
The maniEold constructed as above is remarkably
lighter and smaller than those in the prior art, as the
main body and the branched pipes are formed integrally
Erom a pipe.
As the connecting sec-tions of flanges are caulked
over the ou-ter per:ipheri.es of the branched pipes, no
welding process is needed for fixil1g. Further, as the
grooves are provided :Eor gas leakage prevention, the
maniEold will not leak gases even iE the gas flowing
therein is of high temperature and high pressure like
exhaust gases.
(~rieE Description of the Drawings)
FIG. 1 is a frontal view to show an embodiment of
the manifold according to this invention; FIG~ 2 is a
cross sectional view of a flange of FIG. 1; FIG. 3 is a
partially enlarged cross sectional~view to show the
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1 state of caulking at the gas leakage pre~ention groove section
of FIG. 2; FIG. 4 is a cross-sectional view to show a forming
process of a branch pipe; FIG. 5 is a frontal view to show a
transformation of the manifold; and FIG. 6 is a cross-
sectional view to show an embodiment of the caulking means forthe flange members of FIG. 1.
ETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENT
The present invention will now be described by
referring to the attached drawings.
FIG. 1 shows an embodiment of this invention
manifold applied to an exhaust manifold of an internal
combustion engine wherein branch pipes 2 of a number
corresponding to the number of cylinders of the internal
combustion engine are projected by the bul3ing process from a
side of a pipe member lA, which forms a main body 1 of the
manifold, in the direction perpendicular to the axial line of
the pipe member lA.
The branch pipes 2 are formed as shown in FIG. 4
with the bulging process in a manner that a pipe member lB is
projected from a side of the pipe member lA. After performing
the bulging process, a hole lD having a diameter slightly
smaller than the internal diameter of the pro~ected pipe lB is
bored on the end surface lC of the pipe ~, and the
circumference lE of the hole lD is rectified to be
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l straight with a burrning die and cylindrical rod as shown
with the dot-and-dash line.
The branch pipe 2 is formed by bending a pipe
member lA in advance and then bulging the bent portions to
S enlarge the diameters. As shown in FIG. 5, however, all the
branch pipes 2 may be formed by the bulging process.
The branch pipes 2 are attached at the ends
thereof with flan~es 3 for connection with cylinder blocks.
The flanges 3 are fixed on the branch pipes by
caulking (pressure fitting) so as to be as shown in FIG.
2. More particularly, grooves 4 for gas leakage prevention
and grooves 5 for rotation prevention are formed on one of
the interface of the branch pipe 2 and the flange 3A which
has the higher hardness (in the Figure, on the outer
periphery of a hranch pipe 2 at one end thereof) to caulk
them together. As shown in FIG. 3 the grooves for gas
leakage prevention are grooved in a plural number and in
parallel to each other in circumferential direction of the
outer periphery of the end portion of pipe 2 to have a
serrated cross section.
The grooves for rotation prevention are provided
in a plural number on the outer periphery of a branch pipe 2
; in the axial direction or formed spirally or knurled
thereon.
In caulking, as shown in FIG. 6, a flange 3A is
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1 placed fir~ly at a prede-term:ined position be-tween
holders 6 7 and an end of a branch pipe 2 is inserted
at the center thereoE so that the branch pipe 2 may be
Eixed immovably in -the ax:ia:L. direction with a fixing
rneans (not shown~. A rod 8 is then forcibly inserted
into -the branch pipe 2 Erom one end thereof -to expand
the end portion thereof and caulk -them as shown ln Eig.
2.
As shown in enlargement in FIG. 3 the ridges~of
the grooves~for gas leakage prevention are forced into
the internal periphery of the flange 3A and both
members are closely at-tached to each other. As this
close attachment is generated on the plural r.idges and
grooves and as adjacent yrooves are completely
independent of each other axially the yas can fully be
prevented .Erom leaklng f.rom the pipe.
As the ridges of the grooves 5 for rotation
prevention are similarly forced in-to the internal
peripheral surface of the flange member 3A~ the parts
are also fixed integrally in rotation.
A flange member 3~ is bored with bolt holes of a
predetermined number -to be attached to a cylinder block
with bol-ts or other appropriate means.
(Effect of the Invention)
2.5 As described in de-tail in the foregoing
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statement, the main body and branch pipes of the manifold of
the invention ls integrally formed with a single pipe member
and therefore the total weight can be remarkably reduced
from the conventional manifolds which are cast-formed.
AS this manifold is manufactured by bulging a pipe
without using the casting process, it can be manufactured at
lower cost and in smaller size.
As this maniold can be made smaller and compact,
conditions heretofore restricting the layout design of an
internal combustion engine may be removed to greatly
facilitate the design.
As the flange and branch pipe are fixed by
caulking, they can be attached to a cylinder block in a
manner similar to the prior art. Since the flange is
caulked via the grooves for gas leakage prevention, even if
gas flows through the manifold at high temperature and under
high pressure like an exhaust manifold, there is no
possibility of gas lealcing from the manifold. As the
grooves for rotation prevention are provided, the connection
between the flanges and branch pipes are further reinforced
to ensure a solid and firm attachment as in the case of cast
manifolds.
According to this manifold manufacturing method
according to the invention, as branch pipes are formed with
the bulging process, the manufacturing does not require
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1 the welding process and the produc-tivity is thereEore
improved. Moreover, i.t is easy -to Eorm the connect:ion
of branch pipes smoothly to .Eacili-tate the flow of the
gas and to achieve other various advantages.
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