GB2319824A

GB2319824A - Joint structure for a branch connector with a common rail

Info

Publication number: GB2319824A
Application number: GB9724870A
Authority: GB
Inventors: Kikuo Asada
Original assignee: Usui Kokusai Sangyo Kaisha Ltd
Current assignee: Usui Kokusai Sangyo Kaisha Ltd
Priority date: 1996-11-30
Filing date: 1997-11-26
Publication date: 1998-06-03
Anticipated expiration: 2017-11-26
Also published as: DE19753054A1; GB9724870D0; GB2319824B; FR2756610A1; FR2756610B1; DE19753054C2

Abstract

The joint comprises a pressure receiving seat 2 formed in a circumferential face of the rail 1, a branch pipe 3 having a joint head 3-2 at its end shaped to abut the seat of the rail, a joint fitting 4-1 mounted on the rail and a nut 5-1 mating with the joint fitting to secure the branch pipe, the joint fitting being a threaded sleeve whose base end is secured by welding or soldering 6 to the outer circumference of the rail surrounding the seat. The sleeve 4-1 is cylindrical, and may have a flange for fixing to the rail, or has a rectangular external cross-section. The sleeve 4-1 has an internal thread for mating with a male nut 5-1 or an external thread for mating with a cap nut acting on the pipe 3 via a sleeve.

Description

2319824

S P E C 1 P 1 C A T 1 0 N TITLE OF THE INVENTION Joint Structure for Branch Connectors in Common Rails BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a joint structure for a branch connector by a branch pipe or a branch f itting in a common rail such as a highpressure fuel manifold or a block rail in a Diesel internal combustion engine.

Descript on of the Prior Art

In one of this kind of joint structure fora branch connector of the prior art, as shown in Fig. 7, a through hole 11-2 formed in the circumferential wall of a main pipe rail 11 and communicating with an internal conduit 11-1 is formed to have a pressure receiving seat 11-3 opened to the outside, and a ring-shaped joint fitting 13 enclosing the outer circumference of the main pipe rail 11 in the vicinity of the pressure receiving seat is used to bring a pressure seat 12-3, which is formed by a joint head 12-2 of a branch connector 12 tapered by the buckling method, into abutting engagement with the end portion of the pressure receiving seat 11-3, so that the branch pipe 12 is jointed to the main pipe rail 11 by fastening a male nut 14, which is assembled in advance in the branch connector 12, by the pressure below the neck of the joint head 12 into a threaded wall 13-1 protruded from the joint fitting. Here, reference numeral 15

1 designates a sleeve washer.

In this joint structure of the prior, however, the product weight at the connected portion is seriously increased by the use of the aforementioned ring-shaped joint fitting 13 thereby to raise a difficulty that the product weight cannot be reduced. Since the joint fitting is merely fitted on the main pipe rail 11, moreover, its positioning takes a long time, and the joint fitting may be brought out of position in the axial direction by vibrations or impacts. This out-of position invites a slackness to induce a leakage thereby to make the connection unstable. When the branch connector 12 is removed, moreover, another problem may arise in that the joint fitting 13 may move in the axial direction to allow the dust to steal from the outer surface of the main pipe rail 11 into the clearance between the main pipe rail 11 and the joint fitting 13. SUMMARY OF THE INVENTION

The invention has been conceived in view of the aforementioned problems concomitant with the prior art and has an object to provide a joint structure for a branch connector in a common rail, which can be easily manufactured by using a sleeve nipple as the joint fitting in place of the ring-shaped joint fitting of the prior art and by adopting the welding or soldering method for the connection to the main pipe rail, to reduce the product weight, to solve the problem of the out-of position of the joint fitting, to eliminate the leakage or the

2 dust steal, as might otherwise be caused at the connected portion f or a long time, and to ensure a reliable, stable and easy connection.

In order to achieve the above-specified object, there is provided a joint structure for a branch connector in a common rail, comprising: a main pipe rail having a conduit therein on its axis and a plurality of through holes formed in its circumferential wall at an axial spacing, each of the through holes having a pressure receiving seat formed on the circumferential face thereof and opened to the outside; a branch connector having a conduit to communicate with the conduit of the main pipe rail and including a joint head formed at the end thereof and forming a pressure seat so that the branch connector is engaged with the main pipe rail by bringing the pressure seat thereof into abutment against the pressure receiving seat of the main pipe rail; a joint fitting mounted on the main pipe rail; and a nut assembled in advance in the branch connector and fastened into the joint fitting against the pressure of the joint head thereby to joint the branch connector to the main pipe, wherein the joint fitting is made of a cylindrical sleeve nipple having a threaded face so that the branch connector is jointed to the main pipe rail by jointing the base end of the sleeve nipple to the outer circumference of the main pipe rail in the vicinity of the pressure receiving f ace. In a j oint structure f or a branch connector in a common rail, moreover, a cap nut assembled in 3 advance in the branch connector is fastened into the joint fitting against the pressure of the joint head thereby to joint the branch connector to the main pipe, wherein the joint fitting is made of a cylindrical sleeve nipple having a threaded face in its outer circumference so that the branch connector is jointed to the main pipe rail by jointing the base end of the sleeve nipple to the outer circumference of the main pipe rail in the vicinity of the pressure receiving face. Still moreover, each of the cylindrical sleeve nipple having the threaded face in its inner circumference and the cylindrical sleeve nipple having the threaded face in its outer circumference has a jointing flange at its base end. In addition, each of the cylindrical sleeve nipple having the threaded face in its inner circumference and the cylindrical sleeve nipple having the threaded face in its outer circumference is so connected at its base end to the main pipe rail as to ride over the outer circumference of the main pipe rail.

With the construction thus far described, the invention can be easily practiced by the joint -structure according to the welding or soldering joint method using the cylindrical sleeve nipple which is projected from a portion of the outer circumference of the main pipe rail. The connected portion can be reduced in size and weight and made compact, and the sleeve nipple can be prevented from going out of position so that the leakage and the steal of dust, as might otherwise be invited by a slackness in the connected portion, can be prevented for a long 4 time thereby to ensure a stable and easy connection. By providing the jointing flange portion at the base end of the cylindrical sleeve nipple and by connecting the base end of the cylindrical sleeve nipple to the main pipe rail while riding over the outer circumf erence of the main pipe rail in the vicinity of the pressure receiving seat, moreover, the joint area between the base end and the outer circumference of the main pipe rail can be increased to improve the joint strength. When the soldering method is adopted, not only the individual sleeve nipples but also the brackets and the seal portions at the main pipe rail ends can be jointed as a whole. When the branch connector is to be removed, too, the cylindrical sleeve nipple can be prevented from moving axially or circumferentially thereby to completely prevent the steal of the dust from the outer circumference of the main pipe rail into the sleeve nipple.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an enlarged section of a joint portion and shows a joint structure for a branch connector in a common rail in accordance with a first embodiment of the invention; Fig. 2 is a section taken along line II - II of Fig. 1; Fig. 3 corresponds to Fig. 1 but shows a second embodiment of the invention; Figs. 4A and 4B are partial sections showing examples of the structure of the base end of a sleeve nipple in accordance with a third embodiment of the invention, and respectively present an example, in which a flange having a small width is formed at the base end of the sleeve nipple, and an example in which a f lange having a large width is formed at the base end of the sleeve nipple; Fig. 5 is a section showing a structure of the base end of the sleeve nipple in accordance with a fourth embodiment of the invention; Figs. 6A and 6B show an example of the joint structure of another sleeve nipple of the invention, and respectively present a top plan view of a sleeve nipple joint portion and a section taken along line VI - VI of Fig. 6A; and Fig. 7 is a partially cut-away enlarged section showing the joint structure of the prior art for a branch connector in the common rail.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described with reference to Figs. 1 to 6. Reference numeral 1 designates a main pipe rail as the common rail; numeral 2 designates a pressure receiving seat; numeral 3 designates a branch connector; numerals 4-1, 4-1a and 4-1b designate internally threaded sleeve nipples; numeral 4-2 designates an externally threaded sleeve nipple; numerals 5-1 and 5-2 designate a male nut and a cap nut, respectively; and numeral 6 designates a welded overlay or a solder fillet.

The main pipe rail 1 as the common rail is made of a relatively thick and slender metal pipe having a diameter of about 20 mm 6 and a thickness of about 6 mm, for example. This main pipe rail 1 has a conduit 1-1 therein on its axis and a plurality of through holes 1-2 which are formed in its circumf erential wall at an axial spacing, and each of which is opened to the outside to f orm the pressure receiving face 2 on its circumference and communicating with the conduit 101.

On the other hand, the branch connector 3 is made of a branch pipe or a branch fitting and has therein a conduit 3-1 to communicate with the conduit 1-1. This branch connector 3 has at its end a tapered joint head 3-2 which is radially expanded by the buckling method to form a pressure seat 3-3.

In the invention, the joint fitting of the branch connector is constructed of either the internally threaded cylindrical sleeve nipple 4- 1 having a circular contour of a diameter to enclose the pressure receiving seat 2 or the externally threaded cylindrical sleeve nipple 4-2 having a circular contour. This sleeve nipple 4-1 or 4-2 is welded or soldered so concentrically of the pressure receiving seat 2 to the main pipe rail 1 outside of the pressure receiving seat 2 as to enclose the seat 2.

Specifically, in the joint structure for a branch connector in the common rail according to a f irst embodiment of the invention shown in Figs. 1 and 2, the cylindrical sleeve nipple 4-1 having on its inner circumference a threaded face 5-1a to be screwed on the male nut 5-1 assembled in advance with the branch connector 3 is employed as the joint fitting and is welded or soldered at 7 its base end so concentrically of the pressure receiving face 2 to the outer circumference of the main pipe rail 1 in the vicinity of the pressure receiving face 2 as to enclose the pressure receiving face 2, and the pressure face 3-3 formed by the joint head 3-2 of the branch connector 3 is brought into abutting engagement with the pressure receiving face 2 of the main pipe rail 1, so that the branch connector 3 is jointed to the main pipe rail 1 by fastening the male nut 5-1 into the sleeve nipple 4-1.

In the joint structure for a branch connector in the common rail according to a second embodiment of the invention shown in Fig. 3, on the other hand, the joint fitting of the branch connector is exemplified by the externally threaded cylindrical sleeve nipple 4-2 having a diameter to enclose the pressure receiving seat 2 and is welded or soldered, as in the aforementioned internally threaded sleeve nipple 4 1, at its base end so concentrically of the pressure receiving face 2 to the outer circumference of the main pipe rail 1 in the vicinity of the pressure receiving f ace 2 as to enclose the pressure receiving face 2, and the pressure face 3-3 formed by the joint head 3-2 of the branch connector 3 is brought into abutting engagement with the pressure receiving face 2 of the main pipe rail 1, so that the branch connector 3 is jointed to the main pipe rail 1 by fastening the cap nut 5-2 into the sleeve nipple 4-2. Reference numeral 7 designates a sleeve washer.

8 In the invention, as described above, the sleeve nipple 4-1 or 4-2 and the main pipe rail 1 are firmly jointed by the welding or soldering method so that the sleeve nipple 4-1 or 4-2 can be prevented from chattering and axially or circumferentially moving.

In the invention, moreover, both the internally threaded cylindrical sleeve nipple 4-1 and the externally threaded cylindrical sleeve nipple 42 exemplifying the joint fitting are jointed directly to the main pipe rail 1 by the welding or soldering method. When the welding method is adopted for the joint, the connected portion of the branch connector 3 is troubled by the thermal influences. However, the sleeve nipple 4-1 or 4-2 is welded, as shown, with the welded overlay 6 at the outer circumference of its base end so that no problem arises, because the influence of the welding heat will not extend so far as to the vicinities of a starting position (X of the internal pressure fatigue of the conduit 1-1 of the main pipe rail 1 and a seal line position P between the pressure seat 3-3 of the joint head 32 of the branch connector 3 and the pressure receiving face 2 of the main pipe rail 1. When the soldering method is adopted, on the other hand, the thermal influence extends to the vicinities of the starting point CC of the internal pressure fatigue and the seal line position P. In this case, however, a material less reluctant to receive the thermal influence may be selected for the main pipe rail 1 or the sleeve nipple 4-1 or 4-2. If the 9 soldering method is adopted, moreover, the sleeve nipple can be jointed as a whole to the main pipe rail so that another ef f ect of making the main pipe rail easily can be achieved.

In a third embodiment of the invention, as shown in Figs. 4A and 4B, the internally threaded sleeve nipple 4-1 or the externally threaded cylindrical sleeve nipple 4-2 is modified at its base end structure to improve the strength by increasing the joint area between the base end and the outer circumference of the main pipe rail 1. When the welding method is adopted for the aforementioned joint, the problem of the thermal influence can be further taken into consideration. The means for avoiding the influence of the thermal heat more perfectly is exemplified, in Fig. 4A, by a structure in which a welding flange 4a having a small width to be melted away at the welding time is formed at the base end of the sleeve nipple 4-1 or 4-2 or, in Fig. 4B, by a construction in which a welding flange 4b having a large width is formed at the base end of the sleeve nipple 4-1 or 4-2. By forming the welding flange 4a or 4b at the base end of the sleeve nipple 4-1 or 4-2, more specifically, the distance to the welding portion from the starting position (X of the internal pressure fatigue or from the seal line position 0 of the seat face is elongated so that the influence of the welding heat can be avoided more perfectly than in the sleeve nipple having no welding flange. When the soldering method is adopted for the joint, on the other hand, its operation can be more facilitated by the soldering f lange portion 4a having a small width or the soldering f lange portion 4b having a large width, and the soldering strength can also be improved.

In a fourth embodiment of the invention, as shown in Fig. 5, the construction of the base end of the internally threaded cylindrical sleeve nipple 4-1a is made such that the base end rides over the main pipe rail 1. In the case of this structure, as with the flanged sleeve nipple shown in Fig. 4, it is also possible to avoid the influence of the welding head, to facilitate the soldering operation and to enhance the soldering strength. This structure can naturally be applied to the case in which the cylindrical sleeve nipple 4- 4-1a is externally threaded.

Here, the foregoing embodiments shown in Figs. 1 to 5 have been exemplified by the sleeve nipples having circular contours. However, the internally threaded cylindrical sleeve nipple should not limit its contour to the circular shape but may be replaced by the sleeve nipple 4- 1b having a rectangular contour, as shown in Figs. 6A and 6B. This rectangular sleeve nipple 4-1b can naturally achieve effects similar to those of the circular one.

In a joint structure for a branch connector in a common rail in accordance with the invention, as has been described hereinbefore, the joint fitting of the branch connector is replaced by the cylindrical sleeve nipple, and this sleeve nipple is projected from a portion of the outer circumference of the 11 main pipe rail by using the welding or soldering joint structure, so that the joint connector is connected to the main pipe rail by screwing and fastening the male nut, as assembled in advance with the branch connector, into the sleeve nipple. The connected portion can be reduced in size and weight and made compact, and the sleeve nipple can be prevented from going out of position so that the leakage and the steal of dust, as might otherwise be invited by a slackness in the connected portion, can be prevented for a long time thereby to ensure a stable and easy connection. Thus, it is possible to provide a remarkably useful joint structure for a branch connector in a common rail.

12

Claims

CLAIMS:

1. A joint structure for a branch connector in a common rail, comprising:

a main pipe rail having a conduit therein on its axis and a plurality of through holes formed in its circumferential wall at an axial spacing, each of said through holes having a pressure receiving seat formed on the circumferential face thereof and opened to the outside; a branch connector having a conduit to communicate with the conduit of said main pipe rail and including a joint head formed at the end thereof and forming a pressure seat so that said branch connector is engaged with said main pipe rail by bringing the pressure seat thereof into abutment against the pressure receiving seat of said main pipe rail; a joint fitting mounted on said main pipe rail; and nut means assembled in advance in said branch connector and fastened into said joint fitting against the pressure of said joint head thereby to joint said branch connector to said main pipe, wherein said joint fitting is made of a cylindrical sleeve nipple having a threaded face so that said branch connector is jointed to said main pipe rail by jointing the base end of said sleeve nipple to the outer circumference of said main pipe rail in the vicinity of said pressure receiving face.

2. A joint structure for a branch connector in a common 13 rail according to Claim 1, wherein said nut means includes a male nut adapted to be screwed in the threaded face of the inner circumference of said cylindrical sleeve nipple.

3. A joint structure for a branch connector in a common rail according to Claim 1, wherein said nut means includes a cap nut adapted to be screwed on the threaded face formed in the outer circumference of said cylindrical sleeve nipple.

4. A joint structure for a branch connector in a common rail according to Claim 1, wherein the base of said sleeve nipple and the outer circumference of said main pipe rail are jointed by the welding or soldering method.

5. A joint structure for a branch connector in a common rail according to Claim 1, wherein each of said cylindrical sleeve nipple having the threaded face in its inner circumference and said cylindrical sleeve nipple having the threaded face in its outer circumference has a jointing flange at its base end.

6. A joint structure for a branch connector in a common rail according to Claim 1, wherein each of said cylindrical sleeve nipple having the threaded face in its inner circumference and said cylindrical sleeve nipple having the threaded face in its outer circumference 14 is so connected at its base end to said main pipe rail as to ride over the outer circumference of said main pipe rail.

7. A joint structure for a branch connector in a common rail according to Claim 1, wherein said cylindrical sleeve nipple has a circular or rectangular contour.

8. A joint structure for a branch connector in a common rail, comprising:

a main pipe rail having a conduit therein on its axis and a plurality of through holes formed in its circumferential wall at an axial spacing, each of said through holes having a pressure receiving seat formed on the circumferential face thereof and opened to the outside; a branch connector having a conduit to communicate with the conduit of said main pipe rail and including a joint head formed at the end thereof and forming a pressure seat so that said branch connector is engaged with said main pipe rail by bringing the pressure seat thereof into abutment against the pressure receiving seat of said main pipe rail; joint fitting mounted on said main pipe rail; and male nut assembled in advance in said branch connector and fastened into said joint fitting against the pressure of said joint head thereby to joint said branch connector to said main pipe, wherein said joint fitting is made of a cylindrical sleeve is nipple having a threaded face in its inner circumference so that said branch connector is jointed to said main pipe rail by jointing the base end of said sleeve nipple to the outer circumference of said main pipe rail in the vicinity of said pressure receiving f ace.

9. A joint structure for a branch connector in a common rail according to Claim 8, wherein said cylindrical sleeve nipple having the threaded face in its inner circumference has a jointing flange at its base end.

10. A joint structure for a branch connector in a common rail according to Claim 8, wherein said cylindrical sleeve nipple having the threaded face in its inner circumference is so connected at its base end to said main pipe rail as to ride over the outer circumference of said main pipe rail.

11. A joint structure for a branch connector in a common rail, comprising:

a main pipe rail having a conduit therein on its axis and a plurality of through holes formed in its circumferential wall at an axial spacing, each of said through holes having a pressure receiving seat formed on the circumferential face thereof and opened to the outside; a branch connector having a conduit to communicate with the conduit of said main pipe rail and including a joint head formed 16 at the end thereof and forming a pressure seat so that said branch connector is engaged with said main pipe rail by bringing the pressure seat thereof into abutment against the pressure receiving seat of said main pipe rail; a joint fitting mounted on said main pipe rail; and a cap nut assembled in advance in said branch connector and fastened into said joint fitting against the pressure of said joint head thereby to joint said branch connector to said main pipe, wherein said joint fitting is made of a cylindrical sleeve nipple having a threaded face in its outer circumference so that saidbranch connector is jointed to saidmainpipe rail by jointing the base end of said sleeve nipple to the outer circumference of said main pipe rail in the vicinity of said pressure receiving face.

12. A joint structure for a branch connector in a common rail according to Claim 11, wherein said cylindrical sleeve nipple having the threaded face in its outer circumference has a jointing flange at its base end.

13. A joint structure for a branch connector in a common rail according to Claim 11, wherein said cylindrical sleeve nipple having the threaded face in its outer circumference is so connected at its base end to said main pipe rail as to ride over the outer circumference 17 18 of said main pipe rail.

14. A joint structure for a branch connector to a common pipe rail substantially as hereinbefore described with reference to and as shown in Figures 1 and 2; Figure 3; Figures 4A and B; Figure 5; or Figures 6A and B.