JP2007056816A - Connection structure for branched connection pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection structure capable of preventing nozzle clogging and fuel leak from an attachment surface even if a connection branch pipe is detached and then reattached. <P>SOLUTION: A through hole connecting to a flow passage in a main pipe is included. An external circumference edge of the through hole is used as a pressure receiving seat surface opening in a conical shape. A coupling fitting formed as a separate body is externally fitted on an outer circumference wall part of a main pipe with surrounding the pressure receiving seat surface. A screw sleeve surrounding the pressure receiving seat surface part and having male screw on an outer circumference is inserted and is engaged with the coupling fitting and is fixed. A pressing seat surface formed on an connection part of a branch pipe is abutted on the pressure receiving seat surface part. A cylindrical sleeve is inserted between the branch pipe and the screw sleeve. A tip of the cylindrical sleeve is abutted on a pressing head part and a box nut which the branch pipe is penetrated through and is built in is fastened. Consequently, the cylindrical sleeve is pushed down by the box nut and the pressing head part is adhered on the pressure receiving seat surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to, for example, a branch in a high-pressure fluid manifold used in a high-pressure fuel manifold, particularly an ultra-high-pressure fuel manifold having a pressure of 100 MPa or more, as a fuel supply path to the engine in various diesel internal combustion engines. The present invention relates to an improvement of a branch pipe connection structure.

In recent years, as this type of connection structure, for example, a branch branch pipe is provided in each of the through-hole portions connected to the internal flow passages provided in the peripheral wall portion of the main pipe through which high-pressure fuel flows along the length direction. A connection structure configured by brazing or welding to each other in the inserted state is known.
However, in such a connection structure, due to the mutual insertion state requiring connection strength and uncertain welding, etc., an ultra-high flow pressure exceeding 100 MPa during use accompanying improvement of the engine mechanism Due to repeated circulation and vibration from the engine, there are problems that fuel leakage and branch branch detachment often occur due to embrittlement of the brazed part or the welded part.

In order to solve this problem, for example, as shown in FIG. 9, a through hole 9 communicating with the internal flow passage 8 is provided in the peripheral wall portion of the main pipe 1 through which high-pressure fuel flows, and the outer peripheral edge of the through hole 9 is provided. Is made into a pressure-receiving seat surface 3 that opens conically, and a separate fitting fitting 11 is fitted on the outer peripheral wall portion of the main pipe 1 so as to surround the pressure-receiving seat surface 3 and branch to the pressure-receiving seat surface 3 portion. In a state where the pressing seat surface 10-1 provided at the tip of the pressing head 10 of the branch pipe 2 is in contact with and engaged, the screw nut of the joint fitting 11 is screwed with the tightening nut 21 incorporated on the branch branch pipe 2 side. A structure has been proposed in which the connection is fastened (see, for example, Patent Document 1).
JP 05-244853 A

  In the connection structure as described above, the connection and fastening functions are sufficient, but the outer wall of the main pipe and the fitting 11 are bent together by the reaction force of the mutual tightening, and enter between the outer wall of the main pipe 1 and the fitting 11. There is a gap 20, and foreign dust may enter and accumulate in the entry gap 20. For this reason, when the connecting branch pipe 2 is removed and attached again, the accumulated foreign dust enters the inside of the main pipe 1 or the pressure receiving seat surface 3 and the like, and the nozzle of the injector is clogged or the fuel leaks from the pressure receiving seat surface. There were concerns about problems such as

In order to solve the above-described problems, the present invention provides a connection structure in which a plurality of branch branch pipes are connected to a peripheral wall portion of a main pipe through which a high-pressure fluid flows so as to extend in the length direction. The wall portion has through-hole portions connected to the flow passage inside the main pipe, and the outer periphery of each of the through-holes serves as a pressure-receiving seat surface that opens conically, and surrounds the pressure-receiving seat surface portion and A joint fitting made of a separate body is externally fitted to the outer peripheral wall portion, and further, a screw sleeve having a male screw surrounding the pressure-receiving seating surface portion is screwed into the joint fitting, and its tip is brought into contact with the main pipe. The joint fitting is fixed to the main pipe, and a pressure seat surface formed at the connection end of the branch branch pipe is brought into contact with the pressure receiving seat surface section, and a cap nut externally inserted into the branch branch pipe is inserted into the screw. By screwing into the thread of the sleeve, the cap nut is fastened and the cap nut is screwed. By pressing the push head through the nut by fastening the sleeve and the pressing seat surface adopts a connecting structure of a branch branch pipe in the high-pressure fluid manifold connected constituted by close contact with the pressure receiving seat surface.
If such a connection structure is adopted, a screw sleeve is inserted between the outer diameter of the main pipe and the fitting, so that even if the outer diameter of the main pipe is bent due to the reaction force of tightening, an insertion fitting gap is generated. Therefore, foreign dust does not accumulate. For this reason, even when the connecting branch pipe is removed and reattached for inspection and maintenance, foreign dust does not enter the inside of the main pipe or the connecting seat surface, etc., preventing nozzle clogging or fuel leakage from the mounting seat surface. It becomes possible.

In the connection structure of the present invention, it is preferable that a counterbore surface is provided on the outer peripheral wall portion of the main pipe so as to surround the pressure-receiving seat surface, and the tip end portion of the screw sleeve is brought into contact with the counterbore surface.
With such a structure, the outer peripheral wall of the main pipe and the tip of the screw sleeve are in close contact with each other, so there is no gap even if the branches are fastened, and there is no room for dust to enter and accumulate. preferable.

In addition, it is preferable to use a pressure bearing surface whose apex angle is slightly smaller than that of the pressure receiving seat surface.
With such a structure, the pressure seating surface is pressed against the pressure-receiving seating surface to form an annular seal line, which makes it possible to completely prevent fuel leakage.

In the connection structure of the present invention, the screw sleeve preferably having a hexagonal flange portion can be used.
With such a structure, when the joint fitting is fastened and fixed to the main pipe with the screw sleeve, it can be easily and reliably fastened and fixed with a tightening wrench or wrench.
Further, the counterbore surface can be formed of a flat surface and a conical surface perpendicular thereto.
If this structure is adopted, the counterbore surface can be easily formed only by plane cutting.
Alternatively, the counterbore surface formed from a flat surface and a conical surface with a tapered tip can be used.
With such a structure, the formation of the counterbore surface is somewhat difficult, but the screw sleeve can be securely adhered to the counterbore surface.

In the connection structure of the present invention, it is preferable to use one in which the tip of the screw sleeve has a conical surface and the conical surface is formed at the same apex angle as the conical surface of the counterbore surface.
With such a structure, the tip of the screw sleeve can be securely adhered to the counterbore surface, so that it is possible to completely prevent dust from entering.

Furthermore, in the connection structure of the present invention, the joint fitting may be formed by forging a steel material, or a block in which a thread is formed on a U-bent steel strip will be welded. It may be formed by bonding by attaching or the like.
If the latter is used, there is an advantage that it is very easy to create a fitting fitting even when a large number of branch branch pipes are connected to the main pipe.

  According to the present invention, since the sleeve is in close contact with the counterbore surface of the main pipe, dust can enter the gap between the main pipe and the fitting fitting during use or when removing the branch branch pipe for maintenance. There is an advantage that there is no fear of causing nozzle clogging of the injector and fuel leakage from the pressure receiving seat surface.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an external perspective view showing a branched branch pipe portion of a high-pressure fluid manifold using the connection structure of the present invention. 2 shows a cross-sectional view through the branch branch portion of the high-pressure fluid manifold shown in FIG.
The high-pressure fluid manifold shown in FIG. 1 is a high-pressure fuel manifold arranged near the engine as a fuel supply path to the engine, for example, in a diesel internal combustion engine, and is a main pipe made of a thick-walled steel pipe that circulates the high-pressure fuel. A through-hole that is continuous with the internal flow passage 8 is provided in the peripheral wall 1 and the branch branch pipe 2 is attached thereto. The branch branch pipe 2 is connected and fixed to the main pipe 1 by a cap nut 13 that is bent around the screw sleeve 5 and the peripheral wall of the main pipe 1. A plurality of such branch branch pipes 2 are connected along the length direction of the main pipe 1, for example, by adding the number of supply pipes from the pump to the number of cylinders of the internal combustion engine.

As shown in FIG. 2, the cross-sectional structure has a through hole 9 connected to the flow passage 8 inside the main pipe 1 in the outer peripheral wall portion of the main pipe 1, and a conical opening at the outer periphery of the through hole 9. The pressure-receiving seat surface 3 is formed, and a joint fitting 11 made of a separate body is externally attached to the outer peripheral wall portion of the main pipe 1 so as to surround the pressure-receiving seat surface 3 portion.
Further, a screw sleeve 5 having a male screw on the outer periphery is inserted around the pressure receiving seat surface 3 part, and the male screw is screwed into the female screw 4-2 of the fitting 11.
In the example shown in FIG. 2, the inside of the tip of the screw sleeve 5 is formed with a conical surface 5 a having a tapered tip that extends outward and is fitted to a counterbore surface 12 formed on the outer peripheral wall of the main pipe 1. I'm allowed. The counterbore surface 12 formed on the outer peripheral wall portion of the main pipe 1 is composed of a flat surface and a convex conical surface, and the apex angle of the conical surface is the same as the apex angle of the conical surface at the tip of the screw sleeve 5. They are formed at the same angle. Accordingly, when the screw sleeve 5 is screwed into the female screw 4-2 of the fitting 11 and tightened, the fitting 11 is fixed to the outer peripheral wall portion of the main pipe 1 and the tip of the screw sleeve 5 is attached to the counterbore surface 12. It can be brought into close contact with each other.

Further, the pressure-receiving seat surface 3 can be brought into contact with a pressing seat surface 10-1 of the pressing head 10 formed at the connection end of the branch branch pipe 2. The pressing head 10 has a conical surface with an apex slightly smaller than the pressure-receiving seat surface 3, and is configured to have a diameter one step larger than the main body portion of the branch branch pipe 2. A continuous through hole 2a is formed. For this reason, the pressing seat surface 10-1 of the branch branch pipe 2 can be brought into close contact with the pressure receiving seat surface 3 by pressing the cap nut 13 through the cylindrical sleeve 14.
The cap nut 13 has a female screw engraved on the inner surface thereof that engages with a male screw on the outer periphery of the screw sleeve 5. When the cap nut 13 is screwed and tightened to the male screw on the outer periphery of the screw sleeve 5, the cap pressing surface presses the cylindrical sleeve 14, and the cylindrical sleeve 14 presses the pressing head 10 of the branch branch pipe 2 to branch. A branch pipe 2 is fixed to the main pipe 1.
The cylindrical sleeve 14 is firmly fitted and fixed to the branch branch pipe 2 (see Japanese Patent Application Laid-Open No. 2001-82664), is divided into two parts in the axial direction (see Japanese Patent Application Laid-Open No. 2005-9394), (See Utility Model Registration No. 2513684), the cylindrical sleeve 14 may be abolished or shortened, or a washer shape may be provided.

  In this manner, between the branch branch pipe 2 connected and fixed to the main pipe 1, the pressing seat surface 10-1 of the branch branch pipe 2 is brought into close contact with the pressure receiving seat surface 3 of the main pipe 1. Therefore, fuel leakage does not occur even when used for an ultrahigh pressure fuel manifold of 100 MPa or more. Even if the outer surface of the main pipe is bent due to the reaction force of tightening by the fitting and / or the fitting is bent due to the fastening, the screw sleeve is used. There is no fitting gap, and no foreign dust enters or accumulates in the gap. For this reason, even if the connecting branch pipe is removed and reattached at the time of inspection and maintenance, foreign dust may enter the main pipe or the pressure-receiving seat surface and cause clogging of the injector nozzle or fuel leakage from the pressure-receiving seat surface. Absent.

The screw sleeve used in FIG. 2 and the detailed structure of the main pipe are shown in FIG.
As shown in FIG. 3A, the screw sleeve 5 is formed by cutting or rolling male screws 5a and 5b having different diameters on the outer periphery of a steel pipe having a predetermined inner diameter, and a lower end portion of the conical surface 5c extending outward. I am doing.
FIG. 3B shows a cross section of a counterbore surface 12 provided on the main pipe 1 that receives and supports the screw sleeve 5. The counterbore surface 12 is formed by two surfaces, a flat surface 12a and a convex conical surface 12b having a tapered tip. Since the apex angle of the conical surface 12b is the same as the apex angle of the conical surface 5c at the lower end of the screw sleeve 5, the lower end of the screw sleeve 5 is closely supported by the two counterbore surfaces 12a and 12b. can do.
The male screw 5 a is for screwing and fixing to the female screw of the cap nut 13, and the male screw 5 b is screwed to the female screw of the fitting 11 and tightening and fixing the fitting 11 to the main pipe 1. belongs to. The outer diameters of the male screw 5a and the female screw 5b may be the same or different. Moreover, in order to make it easy to use a fastening tool between the male screws 5a and 5b, it is preferable to process it with the planes facing each other.

As the screw sleeve 5, a screw sleeve provided with a hexagonal flange (HEX) 5d at an intermediate portion as shown in FIG. 4 may be used. The size of the HEX 5d may be larger than the outer diameter of the male screws 5a and 5b. When the HEX 5d is provided, the screw sleeve 5 can be easily tightened.
Except for the provision of HEX5d, the structure is the same as in FIG. The lower end portion of the screw sleeve 5 forms a conical surface 5c extending outward as in the above case. When this screw sleeve is used, it is used for a main pipe provided with a counterbore surface formed by two surfaces, a flat surface 12a and a conical surface 12b shown in FIG.

In addition to the above example, the screw sleeve 5 may be a screw sleeve having a shape in which no HEX is provided at the intermediate portion as shown in FIG. 5A and the lower end portion does not have a conical surface extending outward. it can. In this case, the counterbore surface of the main pipe is used for a main pipe provided with a counterbore surface formed of two surfaces, a flat surface 12a and a cylindrical surface 12c as shown in FIG.
Further, the screw sleeve 5 may be a screw sleeve provided with a HEX 5d at an intermediate portion as shown in FIG. 6 and having no conical surface extending outward at the lower end portion. In this case, the counterbore surface of the main pipe is used for a main pipe provided with a counterbore surface formed of two surfaces, a flat surface 12a and a cylindrical surface 12c as shown in FIG.

FIG. 7A is a side view showing an example of the joint fitting 11. This fitting is made of a forged steel or cast steel block having a head portion 11b extending in a direction orthogonal to the cylindrical portion 11a above the cylindrical portion 11a that penetrates the main pipe, and a female screw 11c is formed on the inner wall of the head portion 11b. It is integrally formed by cutting or rolling. FIG. 7B shows a cross section of the joint fitting 11. A female screw 11c for screwing the male screw on the outer peripheral surface of the screw sleeve is cut or rolled inside the head 11b of the joint fitting 11.
FIG. 8A is an external perspective view showing another example of the fitting 11. This fitting 11 is made by welding or brazing a block 11e having a male screw 11c penetrated by cutting or rolling into a U-shaped portion 11d formed by bending a steel strip in accordance with the outer diameter of the main pipe of the high-pressure fluid manifold. It is formed by bonding. FIG.8 (b) has shown the cross section of this coupling metal fitting. A block 11e, in which a female screw 11c is penetrated by cutting or rolling, is welded or brazed to the upper end of a U-shaped portion 11d obtained by processing a steel strip into a U-shape. 11f is a welding beat in the case of welding.
If the joint fitting having such a structure is used, the joint fitting can be easily attached even when many branch branch pipes 2 are arranged in parallel at a narrow interval. In addition, there is an advantage that it is easy to install and remove the fitting.

It is the external appearance perspective view which cut and showed one branch branch pipe part of the high pressure fluid manifold which used the connection structure of this invention. It is a figure which shows the cross section which passes along the branch branch pipe part of the high pressure fluid manifold shown in FIG. It is a figure which shows an example of a screw sleeve, Comprising: (a) shows sectional drawing of a screw sleeve, (b) is sectional drawing of the main pipe | tube connected with this screw sleeve. It is sectional drawing which shows the other example of a screw sleeve. It is a figure which shows another example of a screw sleeve, Comprising: (a) shows sectional drawing of a screw sleeve, (b) is sectional drawing of the main pipe | tube connected with this screw sleeve. It is sectional drawing which shows another example of a screw sleeve. It is a figure which shows an example of a coupling metal fitting, Comprising: (a) shows a side view, (b) shows sectional drawing. It is a figure which shows the other example of a coupling metal fitting, Comprising: (a) shows an external appearance perspective view, (b) shows sectional drawing. It is sectional drawing which shows an example of the connection structure of the branch branch pipe in the conventional high pressure fluid manifold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main pipe 2 Branch branch pipe 3 Pressure-receiving seat surface 5 Screw sleeve 8 Flow path 9 Through-hole 10 Pressing head 10-1 Pressing seat surface 11 Joint metal fitting 12 Decrease surface 13 Cap nut 14 Cylindrical sleeve 20 Entry gap 21 Tightening nut

Claims (9)

  In a connection structure in which a plurality of branch branch pipes are connected to the peripheral wall portion of the main pipe that circulates the high-pressure fluid along the length thereof, the outer peripheral wall section of the main pipe is connected to the flow passage inside the main pipe. Each of the through-holes has a pressure-receiving seat surface that opens in a conical shape at the outer peripheral edge of each through-hole, and a separate joint fitting is attached to the outer peripheral wall portion of the main pipe so as to surround the pressure-receiving seat surface portion. Furthermore, the joint fitting is fixed to the main pipe by screwing a screw sleeve having a male screw surrounding the pressure-receiving seating surface portion and screwing the screw sleeve to the joint pipe and bringing its tip into contact with the main pipe. Further, the pressure bearing surface formed at the connection end of the branch branch pipe is brought into contact with the pressure receiving seat surface part, and the cap nut externally inserted into the branch branch pipe is screwed into the screw thread of the screw sleeve. By tightening the cap nut and fastening the cap nut to the screw sleeve, the nut Connecting structure of the branch branch pipe in the high-pressure fluid manifold and presses the pressing head, characterized in that the pressing seat surface connected constituted by close contact with the pressure receiving seat surface via.   The high-pressure fluid manifold according to claim 1, wherein a counterbore surface is provided on an outer peripheral wall portion of the main pipe so as to surround the pressure-receiving seat surface, and a tip end portion of the screw sleeve is brought into contact with the counterbore surface. The connection structure of the branch branch pipe in a pipe.   The branching branch in the high-pressure fluid manifold according to claim 1 or 2, characterized in that the apex angle of the pressure-receiving seat surface is an inclined surface having an angle equal to or slightly larger than the apex angle of the pressing seat surface. Pipe connection structure.   The connection structure of the branch branch pipe in the high pressure fluid manifold according to any one of claims 1 to 3, wherein the screw sleeve has a hexagonal flange portion.   5. The connection structure of a branch branch pipe in a high-pressure fluid manifold according to any one of claims 1 to 4, wherein the counterbore surface is formed of a flat surface and a cylindrical surface perpendicular thereto.   5. The branch branch pipe connection structure in a high-pressure fluid manifold according to any one of claims 1 to 4, wherein the counterbore surface is formed by a flat surface and a conical surface having a tapered tip.   The high pressure according to any one of claims 1 to 5, wherein a tip end of the screw sleeve has a conical surface, and the conical surface is formed at the same apex angle as the conical surface of the counterbore surface. Connection structure of branch branches in a fluid manifold.   The connection structure of the branch branch pipe in the high-pressure fluid manifold according to any one of claims 1 to 7, wherein the joint metal fitting is formed by forging or casting of a steel material. . 8. The high pressure according to claim 1, wherein the joint fitting is formed by welding or brazing a block in which a female screw is formed on a U-bent steel strip. 9. Connection structure of branch branches in a fluid manifold.

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