U.S. patent application number 11/022150 was filed with the patent office on 2005-07-07 for connecting structure of branch connector in fuel pressure accumulating container.
This patent application is currently assigned to Usui Kokusai Sangyo Kaisha Limited. Invention is credited to Usui, Masayoshi.
Application Number | 20050146134 11/022150 |
Document ID | / |
Family ID | 26625167 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050146134 |
Kind Code |
A1 |
Usui, Masayoshi |
July 7, 2005 |
Connecting structure of branch connector in fuel pressure
accumulating container
Abstract
A branch connector in a fuel pressure accumulating container is
joined with a through hole formed on a peripheral wall of the
pressure accumulating container. The branch connector is inserted
deeply into the through hole until the distal end of the branch
connector is projected from the inner peripheral wall surface of
the pressure accumulating container. Thus, the internal pressure
fatigue strength is improved by lowering the maximum stress value
generated at the internal peripheral edge at the lower end of the
branch connector.
Inventors: |
Usui, Masayoshi;
(Numazu-shi, JP) |
Correspondence
Address: |
CASELLA & HESPOS
274 MADISON AVENUE
NEW YORK
NY
10016
|
Assignee: |
Usui Kokusai Sangyo Kaisha
Limited
Sunto-gun
JP
|
Family ID: |
26625167 |
Appl. No.: |
11/022150 |
Filed: |
December 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11022150 |
Dec 23, 2004 |
|
|
|
10320855 |
Dec 16, 2002 |
|
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|
Current U.S.
Class: |
285/192 |
Current CPC
Class: |
F17C 2201/0128 20130101;
F17C 2203/0636 20130101; F17C 2209/228 20130101; F16L 41/08
20130101; F17C 2223/035 20130101; F17C 2203/0643 20130101; F17C
13/002 20130101; F16L 41/082 20130101; F17C 2209/2181 20130101;
F17C 2201/0104 20130101; F02M 69/465 20130101; F17C 2260/011
20130101; F17C 2203/0639 20130101; F17C 2209/224 20130101; F17C
2223/036 20130101; F17C 2201/0138 20130101; F17C 2209/232 20130101;
F17C 2209/221 20130101; F02M 55/025 20130101; F17C 2203/0617
20130101 |
Class at
Publication: |
285/192 |
International
Class: |
F16L 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2001 |
JP |
2001-387366 |
Jan 21, 2002 |
JP |
2002-11772 |
Claims
What is claimed is:
1. A connecting structure for a fuel pressure accumulating
container having a curved peripheral wall with inner and outer
peripheral surfaces, the inner peripheral surface defining an
interior within the fuel pressure accumulating container, the
connecting structure comprising: at least one through hole formed
through the peripheral wall and communicating with the interior,
the through hole being formed into a tapered shape increasing in
diameter toward the inner peripheral surface of the fuel pressure
accumulating container; and a branch connector inserted into the
through hole until a distal end of the branch connector is
projected from the inner peripheral surface of the container and
into the interior of the fuel pressure accumulating container.
2. The connecting structure of claim 1, wherein a length of
projection L of the distal end of the branch connector from the
inner peripheral surface of the fuel pressure accumulating
container is not less than a thickness t of the branch
connector.
3. The connecting structure of claim 1, wherein the branch
connector is provided with an enlarged diameter portion in abutment
with the outer peripheral surface of the fuel pressure accumulating
container.
4. The connecting structure of claim 1, wherein the distal end of
the branch connector has an inner diameter reduced to obtain an
orifice effect.
5. The connecting structure of claim 1, wherein the branch
connector is press-fitted, shrink-fitted, or cool-fitted, before
joining.
6. The connecting structure claim 1, wherein joining means for
joining the branch connector includes brazing or diffusion
bonding.
7. A connecting structure for a fuel pressure accumulating
container having a curved peripheral wall with inner and outer
peripheral surfaces, the inner peripheral surface defining an
interior within the fuel pressure accumulating container, the
connecting structure comprising: at least one through hole formed
through the peripheral wall and communicating with the interior,
the through hole being formed into a tapered shape increasing in
diameter toward the inner peripheral surface of the fuel pressure
accumulating container, and a flat surface provided on the inner
peripheral surface of the peripheral wall so as to be adjacent the
through hole; and a branch connector including a branch pipe and a
branch joint fixture, the branch pipe being inserted into the
through hole until a distal end of the branch pipe is projected
from the flat surface on the inner periphery of the container and
into the interior of the fuel pressure accumulating container.
8. The connecting structure of claim 7, wherein a length of
projection L of the distal end of the branch connector from the
inner peripheral surface of the fuel pressure accumulating
container into the flow path is not less than a thickness t of the
branch connector.
9. The connecting structure of claim 7, wherein the branch
connector is provided with an enlarged diameter portion in abutment
with the outer peripheral surface of the fuel pressure accumulating
container.
10. The connecting structure of claim 7, wherein the distal end of
the branch pipe has an inner diameter reduced to obtain an orifice
effect.
Description
[0001] This application is a divisional of application Ser. No.
10/320,855.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a connecting structure of a
branch connector formed of a branch pipe or a joint fixture in a
cylindrical fuel pressure accumulating container or a spherical
fuel pressure accumulating container such as a high-pressure fuel
manifold and a high-pressure fuel block, and, more specifically, to
a connecting structure of a branch connector in a fuel pressure
accumulating container for supplying a high-pressure fuel not less
than 1000 kgf/cm.sup.2 in a diesel internal combustion engine.
[0004] 2. Description of the Related Art
[0005] The cylindrical fuel pressure accumulating container having
a cylindrical inner peripheral wall surface includes an cylindrical
container 111 having a flow path 111---1 therein, which corresponds
to the cylindrical fuel pressure container, and branch pipes 112,
which corresponds to the branch connector, connected to the
cylindrical container 111 directly or via a joint fixture or the
like as shown in FIG. 22 as an example. On the other hand, the
spherical fuel pressure accumulating container having at least
partly a spherical inner peripheral wall surface includes a
spherical container 121 having a spherical space 121-1 therein,
which corresponds to the spherical fuel container, and the branch
pipe 112, which corresponds to the branch connector, connected to
the spherical container 121 directly or via a joint fixture or the
like as shown in FIG. 23 as an example. The structure of the
spherical container 121 is such that, as shown in the figure, an
upper half body 121a and a lower half body 121b having
semi-spherical recesses respectively therein are fixedly connected
by a bolt 121c . Reference numeral 121d designates a sealing
packing.
[0006] The connecting structure of the branch connector in the
cylindrical fuel pressure accumulating container show in FIG. 22
includes a connecting structure in which a connecting end 112-1 of
the branch pipe 112, which has the same diameter as the branch pipe
112 itself, is joined (by means of brazing or the like) with
through holes 111-2 communicated with the flow path formed on the
peripheral wall of the cylindrical container 111 in a state of
being fitted therein, and a structure in which the connecting end
114-1 of the branch joint fixture 114 is joined (by means of
brazing or the like) with through hole 111-2 in a state of being
inserted therein, and the branch pipe 112 is connected to branch
joint fixture 114 by a nut 115 as shown in FIG. 24.
[0007] The connecting structure of the branch connector in the
spherical fuel pressure accumulating container shown in FIG. 23
includes a connecting structure in which the connecting end 112-1
of the branch pipe 112, which has the same diameter as the branch
pipe 112 itself, is joined (by means of brazing or the like) with
through holes 112-2 communicated with the space 121-1 formed on the
peripheral wall of the spherical container 121 in a state of being
fitted therein, and a structure in which the connecting end 114-1
of the branch joint fixture 114 is joined (by means of brazing or
the like) with the through hole 121-2, as shown in FIG. 25 in a
state of being fitted therein, and the branch pipe 112 is connected
to branch joint fixture 114 by a nut 115.
[0008] In the case of the connecting structure of the branch
connector in the cylindrical fuel pressure accumulating container,
the distal end of the branch pipe 112 or the branch joint fixture
114 may be fitted into and joined with the through hole 111-2 in
such a manner that the branch pipe 112 or the branch joint fixture
114 is fitted so that the other peripheral edge 112a or 114a of the
branch pipe 112 or the branch joint fixture 114 comes into contact
with the inner wall of the through hole 111-2 and a recess 111-3 is
formed at the opening of the through hole 111-2.
[0009] However, in such connecting structure, a large stress is
generated at the opening end P of the branch connector, such as the
branch pipe 112 and the branch joint fixture 114 communicating with
the pressure accumulating container, due to constantly repeated
abrupt variations in supplied pressure of the high-pressure fluid
not less than 1000 kgf/cm2, and, especially variations in relative
dimensions between the mating members (mating bearing surfaces) due
to vibrations applied by an engine and increase and decrease of
ambient temperature, and thus it is susceptible to cracking
originating from the opening end P, which may results in leakage of
fuel or the like from time to time. In the case of the cylindrical
fuel pressure accumulating container, as shown in FIG. 223, a large
stress is generated at two opening ends P aligned in the axial
direction.
[0010] Therefore, the following countermeasures are generally
taken. In order to increase fatigue strength at the opening end of
the branch connector communicating with the pressure accumulating
container due to internal pressure, a method of employing a
high-strength steel, there are a method of increasing the strength
of material by heat treatment including carbonitriding and the
like, a method of employing a forged type or an assembled type
(eye-joint type) as a pressure accumulating container, and so
on.
[0011] However, with the method of employing high-strength steel as
a branch connector such as the branch pipe and the joint fixture,
there is a problem, in durability since the high-strength steel is
very hard to weld, and cannot be hardened by heat processing. With
the method of enhancing the strength of material by heat treatment
including carbonitriding and the like, there is a drawback in that
the strength cannot be enhanced because brazing filler metal of the
brazed article is deteriorated by heat treatment in a furnace, and
thus it is intolerable to be used in a high-pressure application.
In addition, the forged type or the assembled type is
disadvantageously heavy in weight and expensive.
[0012] In view of the problems of the related art described above,
the invention provides a connecting structure of the branch
connector in the fuel pressure accumulating container capable of
increasing the internal pressure fatigue strength by lowering the
maximum stress value generated at the inner periphery of the lower
end of the branch connector such as the branch pipe and the point
fixture.
SUMMARY OF THE INVENTION
[0013] The invention provides a connecting structure of a branch
connector in a cylindrical fuel pressure accumulating container or
a spherical fuel pressure accumulating container including at least
a through hole formed on an axially extending peripheral wall or on
a peripheral wall of a cylindrical container or a spherical
container that communicates with the internal flow path of a fuel
container having a cylindrical or spherical inner peripheral curved
wall surface, and a branch connector such as a branch pipe and a
branch joint fixture joined with the through hole in a state of
being inserted therein, wherein the branch connector is inserted
deeply until the distal end thereof is projected from the inner
peripheral wall surface of the container into the flow path or into
the container.
[0014] The invention provides a connecting structure of a branch
connector in a cylindrical fuel pressure accumulating container or
a spherical fuel pressure accumulating container comprising at
least a through hole formed on an axially extending cylindrical
peripheral wall surface or a spherical peripheral wall of a
cylindrical container or a spherical container in a cylindrical
fuel container that communicate with the flow path of a fuel
container having at least partly a cylindrical inner peripheral
wall surface or a spherical fuel container having at least partly a
spherical inner peripheral curved wall surface, and a branch
connector including a branch pipe or a branch joint fixture being
jointed wish the through hole in a state of being inserted into tho
through hole wherein a flat surface is formed on the inner
peripheral wall surface at least at the axial position of the
through hole in abutment with the through hole, and the branch
connector is inserted deeply into the through hole until the distal
end thereof is projected from the inner peripheral wall surface
into the flow path or into the container.
[0015] According to the invention, the length of the distal end of
the branch connector from the inner peripheral wall surface of the
pressure accumulating container into the flow path is preferably
not less than the thickness t of the branch connector, the branch
connector is preferably formed with a integrally formed or a
separately formed enlarge diameter portion at the position that
comes into abutment with the outer peripheral surface of the
pressure accumulating container, the distal end portion of the
branch connector such as the branch pipe or the branch join,
fixture is preferably reduced in inner diameter to obtain the
orifice effect, and the through hole preferably has a tapered shape
that increases in diameter toward the inner peripheral surface of
the pressure accumulating container.
[0016] The invention further provide a connecting structure of the
branch connector in the cylindrical or the spherical fuel pressure
accumulating container including a burring wall formed at the inner
opening end of the through hole, wherein the branch connector is
inserted deeply into the through hole until the distal end thereof
is projected from the burring wall into the flow path, and wherein
a flat surface continuing into the burring wall on the inner
peripheral wall surface around the base portion of the burring wall
being provided.
[0017] In the invention, the branch connector may be joined by
brazing, or diffusion bonding after the branch connector is
press-fitted, shrink-fitted, or cool-fitted.
[0018] The terms, "cylindrical fuel container" and "spherical fuel
container" used in the invention mean that the shapes of the inner
peripheral surface of the pressure accumulating containers are
cylindrical and spherical, respectively, and do not express the
appearance of the pressure accumulating containers. It is needless
to say that there are pressure accumulating containers having
almost the similar shapes as those of the inner peripheral
surfaces.
[0019] In other words, the invention is intended to lower the
maximum value of tensile stress generated at the inner peripheral
edge of the lower end of the branch connector such as the branch
pipe and the joint fixture by inserting the distal end of the
branch connector deeply through the inner peripheral wall surface
of the cylindrical container or the spherical container until it is
projected into the flow path so that a fatigue stress generated at
the peripheral edge at the lower end of the branch connector such
as the branch pipe and the joint fixture is reduced by
counterbalancing the internal pressure and the external pressure
applied to the projected portion. The joint portion (brazed portion
or the portion joined by diffusion bonding) between the branch
connector and the cylindrical container or the spherical container
is applied with a pressure from the side of the flow path of the
branch connector through the wall of the branch connector to
strengthen the joint portion.
[0020] The invention is further intended to prevent generation of
stress-concentrated point such as conventional point P (in the case
of the cylindrical container it may be generated along the axial
direction and thus it has directionality, while in case of the
spherical container, it way be generated over a whole periphery of
the through hole because it has no directionality) by employing a
system to provide the flat surface on the inner peripheral wall
surface of the cylindrical container or the spherical container so
as to be in abutment with the join through hole, and connect the
branch connector into the through hole formed so as to be in
abutment with the flat surface.
[0021] The invention is still further intended to reduce a fatigue
stress generated at the inner peripheral edge at the lower end of
the branch connector such as the branch pipe and the joint fixture
by inserting the distal end of the blanch connector deeply through
the flat inner peripheral wall surface of the cylindrical container
or the spherical container until it is projected into the flow path
and counterbalancing the internal pressure and the external
pressure applied to the projected portion, and to lower the maximum
value of tensile stress generated at the inner peripheral edge of
the lower end of the branch connector such as the branch pipe or
the joint fixture by the action of stress decentralization
associated with the shape effect of the flat inner peripheral wall
surface.
[0022] In the invention, the length L of the projection of the
distal end of the branch connector from the inner peripheral wall
surface of the pressure accumulating container into the flow path
may be short. However, actually, the length is preferably not less
than the thickness t of the branch connector in order to generate
the external pressure as much as the internal pressure at the
projection for balancing them. In other words, the reason is that
it is preferable to set the length L of the projection to the value
not less than the thickness t of the branch connector in order to
reduce the fatigue stress generated at the inner peripheral edge of
the lower end of the branch connector by balancing the internal
pressure applied to the branch connector and the external pressure
applied to the projection. The upper limit value of the length L of
the projection is to be determined appropriately by taking the
internal diameter, the thickness, and the like of the cylindrical
container or the spherical container into account.
[0023] In the case of the cylindrical fuel container, a dimension W
of the flat surface in the direction orthogonal to the axis is
preferably larger than half a diameter d of the through hole, and
not more than twice the diameter d of the through hole. On the
other hand, in the case of the spherical fuel container, a
dimension Y of the flat surface in the direction of radius of the
through hole is preferably larger than 1.1d times a diameter d of
the through hole and not more than twice the diameter d of the
through hole. The reason is that if the dimension W of the flat
surface in the direction orthogonal to the axis in the case of the
cylindrical fuel container, and the dimension Y of the flat surface
in the direction of diameter of the through hole in the case of the
spherical fuel container, is less than half a diameter d of the
through hole and less than 1.1d, respectively, the flat surface is
too small to achieve sufficient action to decentralize a stress. On
the other hand, the dimension W in the direction orthogonal to the
axis and the dimension Y in the direction of the diameter of the
through hole exceed twice the diameter d of the through hole,
respectively, there is no difference in effects, and it is
difficult to mold.
[0024] A method of forming the flat surface that may be employed in
the invention includes a method Of forming a flat surface on the
inner peripheral wall surface by applying a depressing pressure
under the external pressure system, a method of forming a flat
surface on the inner wall surface when forging, and a method of
forming a flat surface during injection molding. In the method of
forming a flat surface on the inner peripheral wall surface by
applying a depressing pressure under the external pressure system,
the flat surface may include an arcuate plane projecting inward.
Therefore, the flat surface in the invention is not limited to a
complete flat surface, and includes various curved shape such as
the arcuate plane, a oval surface, and so on.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a cross sectional view showing a connecting
portion using a branch pipe according to the connecting structure
of a branch connector in a cylindrical fuel container having a
cylindrical inner peripheral wall surface according to a first
embodiment of the invention;
[0026] FIG. 2 is a cross sectional view showing a second embodiment
of the connecting portion also using the branch joint fixture;
[0027] FIG. 3 is a cross sectional view of a connecting portion
using the branch pipe having a flat surface on a part of the
cylindrical inner peripheral wall surface according to a third
embodiment;
[0028] FIG. 4 is a cross sectional view of a connecting portion
using the branch pipe having a slat surface on a part of the
cylindrical inner peripheral wall surface according to a fourth
embodiment;
[0029] FIG. 5 is a cross sectional view of a connecting portion
using the branch joints fixture having a flat surface on a part of
the cylindrical inner peripheral wall surface according to a fifth
embodiment;
[0030] FIG. 6 is a cross sectional view of a connecting portion
using the branch joint fixture having a flat surface on a part of
the cylindrical inner peripheral wall surface according to a sixth
embodiment;
[0031] FIG. 7 is a cross sectional view of a connecting portion in
the connecting structure using the branch connector in a spherical
fuel container having a spherical inner peripheral wall surface
having a flat surface on a part thereon according to a seventh
embodiment;
[0032] FIG. 8 is a cross sectional view of the connecting portion
also using the branch pipe according to a eighth embodiment;
[0033] FIG. 9 is a cross sectional view showing a ninth embodiment
of the connecting portion also using the branch joint fixture;
[0034] FIG. 10 is a cross sectional view showing a tenth embodiment
of the connecting portion also using the branch joint fixture;
[0035] FIG. 11A is an explanatory drawing illustrating a projecting
length L of the branch connector in the cylindrical fuel container
and a spherical fuel container to the interior of the pressure
accumulating container and the action of reducing a fatigue
stress;
[0036] FIG. 11B is an explanatory drawing illustrating a projecting
length L of the branch connector in the cylindrical fuel container
to the interior of the container;
[0037] FIG. 12 is a conceptual diagram illustrating a flat surface
of the cylindrical fuel container having a cylindrical inner
peripheral wail surface therein;
[0038] FIG. 13 is a conceptual diagram illustrating the flat
surface in the spherical fuel container having a spherical inner
peripheral wall surface therein;
[0039] FIG. 14 is a cross sectional view of the connecting portion
using the branch pipe according to another embodiment of the
invention;
[0040] FIG. 15 is a cross sectional view showing still another
embodiment of the connecting portion using the branch pipe;
[0041] FIG. 16 is a cross sectional view showing still another
embodiment of the connecting portion using the branch pipe;
[0042] FIG. 17 is a cross sectional view showing still another
embodiment of the connecting portion using the branch pipe;
[0043] FIG. 18 is a connecting through hole and a branch pipe of
the connecting structure according to another embodiment of the
invention;
[0044] FIG. 19 is an enlarged cross sectional view showing a part
of a connecting structure of the branch pipe or the branch joint
fixture according to the connecting structure of the branch
connector according to the invention;
[0045] FIG. 20 is a cross sectional view ox the connecting portion
using the branch pipe according to a eleventh embodiment of the
invention;
[0046] FIG. 21 is a cross sectional view of the connecting portion
using the branch pipe according to a twelfth embodiment of the
invention;
[0047] FIG. 22A is a partly broken side view of the connecting
structure of the branch connector in the cylindrical fuel container
in the related art;
[0048] FIG. 22B is a cross sectional view taken along the line a-a
in FIG. 22A;
[0049] FIG. 23 is a cross sectional view showing an example of the
connecting stricture of the branch connector of the spherical, fuel
container in the related art;
[0050] FIG. 24 is a drawing of the connecting structure employing a
branch joint fixture as a branch connector in the connecting
structure shown in FIG. 22, which corresponds to FIG. 2;
[0051] FIG. 25 is a drawing of the connecting structure employing a
branch joint fixture as a branch connector in the connecting
structure shown in FIG. 23, which corresponds to FIG. 9; and
[0052] FIG. 26 is an enlarged cross sectional view showing a part
of the connecting structure of the branch pipe or the branch joint
fixture according to the connecting structure in the related
art.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0053] The cylindrical container 1, 11 having the cylindrical inner
peripheral wall surface shown in FIG. 1 to FIG. 6 defines the flow
path 1-1, 11-1 therein, and is formed of a thick steel pipe member
having a diameter in the order of 30 m/m or less such as a
high-pressure piping carbon steel pipe, a stainless steel pipe, or
the like. The cylindrical container 1 shown in FIG. 1 and FIG. 2
has a single through hole 1-2 or a plurality of through holes 1-2
at intervals on the inner surface of the peripheral wall in the
axial direction so as to communicate with the flow path 1-1. The
cylindrical container 1 shown in FIG. 3 to FIG. 6 has a single flat
surface 11-2 or a plurality of flat surfaces 11-2 at intervals on
the inner surface of the peripheral wall in the circumferential or
the axial direction so as to communicate with the flow path 11-1,
and a single or plurality of through holes 11-3 are formed into
abutment with the flat surfaces so that the centers of the through
holes 11-3 substantially coincide with the axial centerlines of the
flat surfaces.
[0054] The spherical container 21 having the spherical inner
peripheral wall surface shown in FIG. 7 to FIG. 10 is formed with a
space 21-1 having a spherical portion of about 25 to 60 m/m in
diameter therein, and the peripheral wall to which the branch pipe
2 or the branch joint fixture 3 is connected is at least about 15
m/m in thickness. The container itself is formed of various types
of steel. Here, a spherical container 21 formed with a single flat
surface 21-2 or a plurality of flat surfaces 21-2 at intervals on
the inner surface of the peripheral wall and with a single or
plurality of through holes 21-3 in abutment with the flat surfaces
is taken as an example.
[0055] On he other hand, the branch connector such as the branch
pipe 2 and the branch joint fixture 3 is formed of the same steel
pipe member or a steel member as the cylindrical container 11 or
the spherical container 21 having pipe diameter in the order of 20
m/m or less. The reference numerals 2-1 and 3-1 designate the flow
paths.
[0056] The connecting structure shown in FIG. 1 is such that the
connecting end 2-2 thereof, which has the same diameter as the
branch pipe 2 itself, is joined (by means of brazing, diffusion
bonding or the like) with the through hole 1-2 formed on the inner
peripheral wall surface of the peripheral wall entending apially of
the cylindrical container 1 having a cylindrical inner peripheral
wall surface defining the flow path 11-1 therein in a state of
being fitted therein.
[0057] In this case, the connecting end 2-2 of the branch pipe 2 is
connected by being inserted deeply into the through hole 1-2 until
the distal end of the branch pipe 2 is projected from an inner
peripheral wall surface 1-1a into the flow path 1-1 to form the
projection 2-3 and joined by means of brazing or diffusion bonding.
In this connecting structure, when forming the projection 2-3 by
inserting the distal end of the branch pipe 2 into the through hole
1-2, the projection 2-3 is formed so that the recess 111-3 as shown
in FIG. 23 is not formed.
[0058] In the connecting structure shown in FIG. 2, the branch
connector is formed of the branch joint fixture 3 instead of the
branch pipe 2, and the branch joint fixture 3 is formed with the
flow path 3-1 at the axle center by boring process such as drilling
and the like, and applied with processes to form the pressure
receiving bearing surface 3-2 opening outwardly in a trumpet shape
on the outer end portion and the threaded wall 3-3, respectively.
The straight cylindrical portion of the branch joint fixture 3 on
the opposite side of the threaded wail 3-3 is joined by means of
brazing or the like by being inserted deeply into the through hole
1-2 in the same manner as the branch pipe 2 until the distal end of
the joint fixture 3 is projected into the flow path 1-1 from the
inner peripheral wall surface 1-1a of the rail to form the
projection 3-4.
[0059] The connecting structure shown in FIG. 3 is formed by
applying a depressing force on the inner peripheral wall surface or
the peripheral wall extending axially of the cylindrical container
11 having a cylindrical inner peripheral wall surface defining the
flow path 11-1 therein under an external pressure system to form
the flat surface 11-2, and forming the through hole 11-3 in
abutment with the flat surface. The branch pipe 2 is to be
connected in such a manner that the connecting end 2-2 thereof,
which has the same diameter as the branch pipe 2 itself, is joined
(by means of brazing, diffusion bonding or the like) with the
through hole 11-3 in a state of being fitted therein. In this case,
the connecting end 2-2 of the branch pipe 2 is connected by being
inserted deeply into the through hole 1-2 until the distal end of
the branch pipe 2 is projected from the flat surface 11-2 into the
flow path 1-1 to form the projection 2-3 and joined with each other
by means of brazing or diffusion bonding.
[0060] The connecting structure shown in FIG. 4 is formed by
providing the flat surface 11-2 on the inner peripheral wall
surface of the peripheral wall extending axially of the cylindrical
container 11 having the cylindrical inner peripheral wall surface
defining the flow path 11-1 therein according to the method of
forming a flat surface on the inner peripheral wall surface during
injection molding. In this case as well, in the same manner as FIG.
3, the connecting end 2-2 thereof, which has the same diameter as
the branch pipe 2 itself, is joined (by means of brazing, diffusion
bonding or the like) with the through hole 11-3 formed in abutment
with the flat surface 11-2 in a state of being fitted therein. In
this case, the connecting end 2-2 of the branch pipe 2 is connected
by being inserted deeply into the through hole 11-3 until the
distal end of the branch pipe 2 is projected from the flat surface
11-2 into the flow path 11-1 to form the projection 2-3 and joined
with each other by means of brazing or diffusion bonding.
[0061] The connecting structure shown in FIG. 5 is constructed of
the branch joint fixture 3 shown in FIG. 2 as the branch connector
instead of the branch pipe 2 described above, and is a system or
connecting the branch pipe 2 to the cylindrical container 11 having
the flat surface 11-2 formed by applying a depressing force under
the external pressure system via the branch joint fixture 3 as in
the case of the cylindrical container 11 shown in FIG. 3. In this
case, the straight cylindrical portion 3-5 of the branch joint
fixture 3 on the opposite side of the threaded wall 3-3 is joined
by means of brazing or the like by being inserted deeply into the
through hole 11-3 formed in abutment with the flat surface 11-2 in
the same manner as the branch pipe 2 until the distal end of the
joint fixture 3 is projected from the flat surface 11-2 into the
flow path 11-1 to form the projection 3-4.
[0062] The connecting structure shown in FIG. 6 is, as in the case
of the cylindrical container 11 in FIG. 4, a system to connect the
branch pipe 2 to the cylindrical container 11 formed with the flat
surface 11-2 on the cylindrical inner peripheral wall surface
defining the flow path 11-1 therein via the branch joint fixture 3
shown in FIG. 5 by the method of forming the flat surface on the
inner peripheral wall surface during injection molding. In this
case as well, the straight cylindrical portion 3-5 of the branch
joint fixture 3 on the opposite side of the threaded wall 3-3 is
joined by means of brazing or the like by being inserted deeply
into the through hole 11-3 formed in abutment with the flat surface
11-2 in the same manner as the branch pipe 2 until the distal end
of the joint fixture 3 is projected from the flat surface 11-2 into
the flow path 11-1 to form the projection 3-4.
[0063] The construction shown in FIG. 7 is formed with the through
holes 21-3 on the spherical peripheral wall portion of the
spherical container 21 having at least partly a spherical inner
peripheral wall surface defining a spherical space 21-1 therein and
the branch tube 2 is, in the same manner as the connecting
structure shown in FIG. 1, to be connected in such a manner that
the connecting end 2-2 thereof, which has the same diameter as the
branch pipe 2 itself, is joined (by means of brazing, diffusion
bonding or the like) with the respective through holes 21-3 in a
state of being fitted therein. In this case, the connecting end 2-2
of the branch pipe 2 is connected by being inserted deeply into the
respective through holes 21-3 until the distal end of the branch
pipe 2 is projected from the inner peripheral wall surface into the
spherical space 21-1 to form the projection 2-3 and joined with
each other by means of brazing or diffusion bonding.
[0064] The connecting structure shown in FIG. 8 is provided with a
flat surface 21-2 on the inner peripheral wall surface of the
peripheral wall of the spherical container 21 having the spherical
inner peripheral wall surface defining the spherical space 21-1
therein by a method of forming a flat surface on the inner
peripheral wall surface when forging. In this case as well, in the
same manner as FIG. 4, the connecting end 2-2 thereof, which has
the same diameter as the branch pipe 2 itself, is joined (by means
of brazing, diffusion bonding or the like) with the through hole
21-3 formed in abutment with the flat surface 21-2 in a state of
being fitted therein. In this case, the connecting end 2-2 of the
branch pipe 2 is connected by being inserted deeply into the
through hole 21-3 until the distal end of the branch pipe 2 is
projected from the flat surface 21-2 into the spherical space 21-1
to form the projection 2-3 and joined with each other by means of
brazing or diffusion bonding.
[0065] The structure shown in FIG. 9 is constructed of the branch
joint fixture 3 as the branch connector instead of the branch pipe
2 described above. It is a system to connect the branch pipe 2 to
the spherical container 21 with the flat surface 21-2 formed by
applying a depressing force under the external pressure system via
the branch joint fixture 3. In this case as well, as in the
connecting structure shown in FIG. 5 and FIG. 6, the straight
cylindrical portion 3-5 of the branch joint fixture 3 on the
opposite side of the threaded wall 3-3 is joined by means of
brazing or the like by being inserted deeply into the through hole
21-3 formed in abutment with the flat surface 21-2 in the same
manner as the branch pipe 2 until the distal end of the joint
fixture 3 is projected from the flat surface 21-2 into the
spherical space 21-1 to form the projection 3-4.
[0066] The connecting structure shown in. FIG. 10 is, as in the
case of the spherical container 21 shown in FIG. 3, is a system to
connect the branch pipe 2 to the spherical container 21 formed with
a flat surface 21-2 on the spherical inner peripheral wall surface
via the branch joint fixture 3 shown in FIG. 9. In this case as
well, the straight cylindrical portion 3-5 of the branch joint
fixture 3 on the opposite side of the threaded wall 3-3 is joined
by means of brazing or the like by being inserted deeply into the
through hole 21-3 formed in abutment with the flat surface 21-2 in
he same manner as the branch pipe 2 until the distal end of the
joint fixture 3 is projected from the flat surface 21-2 into the
spherical space 21-1 to form the projection 3-4.
[0067] The respective lengths L of the projections 2-3 and 3-4 of
the branch pipe 2 and the branch joint fixture 3 in the connecting
structure shown in FIG. 1 to FIG. 10, are the lengths from the
inner peripheral wall surface 1-1a and from the flat surfaces 11-2,
21-2 as shown in FIG. 11A, or the lengths from the inner peripheral
wall surface shown in FIG. 11B (since the widths or the flat
surface 11-2 in the case of the cylindrical container 1, and the
width of the flat surface 21-2 in the case of the spherical
container may be shorter than the diameters d of the through holes
11-3 and 21-3), and the length L of the projection to the interior
of the pressure accumulating container is preferably not less than
the thickness t of the branch pipe 2 or the branch joint fixture
3.
[0068] FIG. 12 and FIG. 13 are explanatory drawings illustrating
the flat surface of the cylindrical fuel container and the
spherical fuel container, respectively. In other words, since the
stress-concentrated points P may be generated axially of the
cylindrical fuel container, which means that the position thereof
has directionality in the case of the cylindrical fuel container as
described above, the flat surface 11-2 is to be formed at least
axially of the cylindrical container, and dimensions thereof are
such that, as shown in FIG. 12, the maximum dimension W of the flat
surface in the direction orthogonal to the axis is preferably
larger than half the diameter d of the through hole 11-3, and the
minimum dimension w thereof is not more than twice the diameter d
of the through hole 11-3. Accordingly, in the case of the
cylindrical fuel container, the shadowed portion corresponds to the
region to form the flat surface.
[0069] On the other hand, in the case of the spherical fuel
container, the stress-concentrated point P does not have
directionality, and thus the flat surface 21-2 may be formed
concentrically with the through hole 21-3. The dimensions thereof
are such that, as shown in FIG. 13, the minimum dimension y of the
flat surface in the direction of radius of the through hole is
preferably larger than the 1.1 times the diameter d of the through
hole 21-3, and the maximum dimension Y thereof is not more than
twice the diameter d of the through hole. Therefore, in the case of
the spherical fuel container, the shadowed portion around the
through hole 21-3 is the region to form the flat surface. The flat
surface of the spherical fuel container is almost ring-shaped flat
surface.
[0070] According to the invention, since the distal ends of the
branch pipe 2 and the branch joint fixture 3 are inserted from the
inner peripheral wall surface or the flat surface 11-2 of the
cylindrical containers 1 and 11 and the inner peripheral wall
surface or the flat surface 21-2 of the spherical container 21 into
the flow path 1-1, 11-1 and the spherical space 21-2 respectively
to form the projection 2-3, 3-4 as described above, the internal
pressure shown by an arrow .alpha. is applied to the walls of the
connecting ends of the branch pipe 2 and the branch joint fixture 3
including the projections as shown in FIG. 11,. Simultaneously, the
external pressure (arrow .beta.) that is equivalent to the internal
pressure is applied to the outer wall of the projection 2-3, 3-4.
As a consequence, the internal pressure and the external pressure
are counterbalanced, and thus little tensile stress is generated at
the opening ends of the cylindrical container 1, 11 and the
spherical container 21 of the branch pipe 2 and the branch joint
fixture 3. In addition, since the branch pipe 2 and the branch
joint fixture 3 are secured on the flat surface 11-2, 21-2,
stress-concentrated point is not generated. In addition, the
brazing filler material 16 at the joint portion (or the diffused
joint) between the branch pipe 2 and the branch joint fixture 3 and
the cylindrical container 1, 11 and the spherical container 21 is
increased in drawing resistance by being compressed by the pressure
from the flow path 2-1, 3-1 of the branch pipe 2 or the branch
joint fixture 3 through the wall or the branch pipe 2 or the branch
joint fixture 3.
[0071] The connecting structure shown in FIG. 14 is such that the
integrally formed enlarged diameter portion 2-4 is formed on the
branch pipe 2 at the positions that comes into abutment with the
outer peripheral surface of the cylindrical container 1, 11 and the
spherical container 21 and is joined therewith. In the case of this
branch pipe 2, since a function as a stopper may be provided by the
integrally formed enlarged diameter portion 2-4, by selecting the
position to provide this integrally formed enlarged diameter
portion 2-4, the length of the projection 2-3 inserted through the
through hole 1-2, 11-3, 21-3 of the cylindrical container 1, 11 and
the spherical container 21 may be determined easily and
accurately.
[0072] The connecting structure shown in FIG. 15 is such that the
separately formed enlarged diameter portion 2-5 is fixedly fitted
on the branch pipe 2 at the positions that come into abutment with
the outer peripheral surface of the cylindrical container 1, 11 and
the spherical container 21 and joined therebetween instead of the
integrally formed enlarged diameter portion 2-4 shown in FIG. 14.
In this case as well, as in the connecting structure shown in FIG.
14, by selecting the position to provide the separately formed
enlarged diameter portion 2-5, the length of the projection 2-3 of
the branch pipe 12 formed in the flow path 1-1 by being inserted
through the through hole 1-2, 11-3, 21-3 of the spherical container
21 may be determined easily and accurately. The means for fixing
the separately formed enlarged diameter portion 2-5 includes
brazing, diffusion bonding, welding, and so on.
[0073] In the connecting structure shown in FIG. 16 and FIG. 17,
the orifices 2a and 2b are formed on the distal end or the
projection 2-3 off the branch side 2 for ensuring smooth flow of
fluid and preventing pulsation due to injection to the engine
respectively. The branch pipe 2 shown in FIG. 16 is formed with the
orifice 2a by reducing the diameter of the flow path 2-1 it the
distal end while maintaining the outer diameter as it is, and the
branch pipe 2 shown in FIG. 17 is formed with the orifice 2b by
reducing the diameter of the low path 2-1 at the distal end with
the outer diameter reduced. Both of these connecting structures are
formed in such a manner that the connecting end 2-2 of the branch
pipe 2 is inserted deeply into the through hole 1-2, 11-3, 21-3
until the distal end of the branch pipe 2 is projected into the
flow path 1-1, 11-1 of the cylindrical container 1, 11 to form the
projection 2-3 and joined with each other by means of brazing or
the like as described above.
[0074] In the connecting structure as shown in FIG. 18, the through
hole 1-2 to be formed with the cylindrical container 1 is replaced
with the tapered through hole 1-3 which increases in diameter
toward the inner peripheral wall surface 1-1a of the rail, and that
corresponds to the branch connector is joined by means of brazing
or the like with the tapered through hole 1-3 in such a manner that
the connecting end 2-2 of the branch pipe 2 is inserted deeply into
the tapered through hole 1-3 until the distal end of the branch
pipe 2 is projected from the inner peripheral wall surface 1-1a of
the rail into the flow path 1-1. In this cases the branch pipe 2 is
press-fitted, shrink-fitted, or cool-fitted into the through hole
1-3 before being joined by brazing with each other.
[0075] Regarding diameters d.sub.1 and d.sub.2 of the tapered
through hole 1-3 and the thickness 1 of the cylindrical container
1, when the working pressure is 2000 bar, d.sub.1 is 6.35 mm and 1
is 7 mm, for example, d.sub.2is in the order of d.sub.1.div.2-3
.mu.m.
[0076] In this connecting structure, since the through hole 1-3 has
a tapered shape that increases in diameter toward the inner
peripheral wall surface 1-1a of the rail, the diameter of the
branch pipe 2 is increased by the internal pressure applied on the
inner wall of the connecting end 2-2 of the branch pipe 2 and hence
is deformed along the through hole 1-3, and a large drawing
resistance may be obtained.
[0077] In the case of the connecting structure according to the
invention described above, the distal end of the branch pipe 2 or
the branch joint fixture 3 may be joined by being fitted into the
through hole 1-2 so that the outer peripheral edge 2c, 3c of the
branch pipe 2 or the branch joint fixture 3 abuts to the inner
peripheral wall surface of the cylindrical container 1, 11 or the
spherical container 21 as shown in FIG. 19. In this case, the
projection 2-3, 3-4 is formed only in the direction of the axis of
the pipe.
[0078] In the connecting structures of the invention shown in FIG.
1 to FIG. 19, since the distal ends of the branch pipe 2 and the
branch joint fixture 3 are inserted respectively through the inner
peripheral wall surface and the flat surface 11-2 of the
cylindrical containers 1 and 11, and the inner peripheral wall
surface and the flat surface 21-2 of the spherical container 21
into the flow path 1-1, 11-1 and into the spherical space 21-1 to
form the projection 2-3, 3-4, respectively, the internal pressure
(indicated by the arrow .alpha.) and the external pressure
(indicated by the arrow .beta.) are counterbalanced as shown in
FIG. 11. As a consequence, little tensile stress is generated at
the opening end of the cylindrical containers 1, 11 and the
spherical container 21 of the branch pipe 2 and the branch joint
fixture 3, and also a tensile strength applied on the brazing
filler material 16 (or the portion of diffusion bonding) is reduced
so that large drawing resistance may be achieved. Another
embodiment of the invention shown in FIG. 20 and FIG. 21 is a
connecting structure for reducing a tensile strength applied on the
brazing filler material 16 (or diffusion bonding) near the burring
wall 31 by forming a burring wall 31 at the inner opening end or
the through hole of the cylindrical container 1, 11 or the
spherical container 21 instead of the projection 2-3, 3-4 at the
distal end of the branch pipe 2 or the branch joint fixture 3, and
counterbalancing an external pressure (indicated by an arrow
.beta.) applied on the burring wall 31 and the internal pressure
(indicated by an arrow .alpha.) from the branch pipe 2 or the
branch joint fixture 3. In addition, as shown in FIG. 21, reduction
of the tensile strength applied on the brazing filler material (or
diffusion bonding) and further alleviation of concentrated stress
may be achieved by forming a flat surface 32 as shown in FIG. 3 or
FIG. 8 on the inner peripheral wall surface around the base portion
of the burring wall 31.
[0079] A method of forming the burring wall 31 may be a method
including the steps of forming a small hole on the cylindrical
container 11, 1 or on the spherical container 21, and subsequently
driving a punch into the small hole. On the other hand, a method of
forming the flat surface 32 may be the method of forming under the
external pressure system or the method of forming the flat surface
when forging or during injection molding as described above.
[0080] The joining means of the branch connector such as the branch
pipe 2 and the branch joint fixture 3 in the invention is
preferably brazing in the furnace such as copper brazing and nickel
brazing. It is also possible to achieve diffusion bonding by
activating the surface of the through hole 1-2, 11-3, 21-3 and the
branch connector such as the branch pipe 2 and the branch joint
fixture 3 by a process before finishing with high accuracy, and
then preferably, applying meal plate coating such as nickel and
copper, inserting the branch connector into the through hole, and
maintaining it at the diffusing temperature for a sufficient period
of time.
[0081] As described thus far, the connecting structure of the
branch connector in the cylindrical fuel pressure accumulating
container or the spherical fuel pressure accumulating container
according to the invention is a connecting structure in which the
distal end of the branch connector such as the branch pipe and the
branch joint fixture is joined with the pressure accumulating
container by being inserted into the interior thereof and the
projection is secured by brazing. Therefore, the external pressure
that is almost equivalent to the internal pressure is applied on
the outer wall portion of the projection to counterbalance both of
them, and as a consequence, the fatigue stress at the opening, end
P of the pressure accumulating container of the branch connector
may significantly be alleviated, and simultaneously, a large
drawing resistance may be achieved since the brazing filler
material of the joint portion or the diffused joint between the
branch connector and the pressure accumulating container are
compressed by the internal pressure applied on the branch
connector. In addition, since a system of forming a flat surface on
the inner peripheral surface of the cylindrical container or the
spherical container and connecting the branch connector into the
through hole formed in abutment with the flat surface is employed,
generation of a stress-concentrated point such as the point P may
be prevented, and further reduction or the fatigue stress at the
opening end of the pressure accumulating container may be achieved.
Therefore, according to the invention, a connecting structure of
the high-pressure branch connector having a high internal pressure
fatigue characteristics may be provided advantageously at low costs
even with heat treatment such as brazing and diffusion bonding
associated with the manufacturing process.
* * * * *