JPH03177695A - Branch connected body connecting structure in high pressure fuel rail - Google Patents

Abstract

PURPOSE:To prevent the pressing seat face of a pressing head part from biting into the pipe outer face side opening end part of a pressure receiving seat face by forming the pipe outer face side opening end part of the pressure receiving seat face on the fuel rail side into an approximately circular-arc face. CONSTITUTION:A pressure receiving seat face 2 is formed into a rotated face rotated around the axis of a through hole, and a pressing head part 4 is formed into a rotated face with its contact line with the pressure receiving seat face 2 to be circular. Circular-arc faces 2-2 are formed at least on both longitudinal sides of the fuel rail outer face side opening end part of the pressure receiving seat face 2, and the pressing head part 4 is irregularly fitted at the pressure receiving seat face 2, thus connecting a branch connected body fixedly at the fuel rail. Accordingly, at the time of press-fitting the pressing head part 4 of the branch connecting body at the pressure receiving seat face 2, the pressing seat face 4-1 of the pressing head part 4 is prevented from biting into the outer face side edge part of the pressure receiving seat face 2, thereby preventing the generation of a gap between the pressing seat face 4-1 of the pressing head part 4 and the pressing receiving seat face 2.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a connection structure for branch connections such as branch pipes and branch fittings in fuel rails such as high-pressure fuel manifolds and high-pressure fuel blocks. In particular, the present invention relates to a connection structure of a branch connection body in a high pressure fuel rail of 100,100 O/- or more, which serves as a fuel supply path to a diesel internal combustion engine.

(Prior art) Fig. 8 shows the connection structure of a branch connection body in a manifold pipe as a conventional fuel rail, for example, a branch pipe, in which a hole is drilled into the high-pressure fuel main pipe 11 in a direction perpendicular to the pipe axis. There is a structure in which a branch pipe 13 is inserted into the straight hole 12 and welded to each other for connection.

However, in such a connection structure, 100100O/af
Due to the repeated supply of ultra-high flow pressure for more than 100 yen, as well as vibrations from the engine, fuel scattering often occurs due to embrittlement of the welded part 14, and in some cases, separation of the branch pipe 13 may occur. There is also.

To solve this problem, instead of the connection structure described above,
The applicant has proposed a connection structure that mechanically connects a main pipe and a branch pipe by a concave-convex fitting method.

The connection structure according to this proposal is as shown in Figure 9.
1 is an inverted conical branch hole 16, the inner peripheral surface of the branch hole is a pressure receiving surface, and a truncated conical pressure head is formed at the connecting end of the branch pipe 17. In this method, the portion 18 is press-fitted to the pressure-receiving seat surface 16 via a bowl-shaped seal member 19, and tightened with a nut 20.

(Problems to be Solved by the Invention) In the case of such a concave-convex fitting type connection structure, the sealing effect is greater than that shown in FIG. 8, but as shown in FIG. As time passes, the bowl-shaped sealing member 19 bites into the tube outer edge portion 21 of the pressure-receiving seat 16 and is pulled and deformed by the pressing head 18, so that a gap may occur between the seal member 19 and the pressure-receiving seat. Furthermore, as shown in FIG. 11, due to the inclination or eccentricity of the pressing head 18, one side of the pressing head 18 is deformed by digging into the tube outer surface side edge portion 21, and the pressing head 18 on the opposite side presses into the branch hole 16. This causes a gap to form, and even if the nut 20 is screwed together and the tightening torque is increased, a uniform surface pressure cannot be obtained.

This means that the torque of tightening with the nut 20 is
This is because the edge portion 21 on the outer surface side of the tube on one side of the tube 8 is bitten and does not work normally as an axial force (thrust force).

In this way, in FIGS. 10 and 11, it is possible that surface pressure is not obtained or a gap occurs between the sealing member 19 and the pressure receiving surface or between the pressing surface and the pressure receiving surface of the pressing head 18. In this case, fuel may scatter from the gap or the like, causing leakage, and in some cases, the branch pipe 17 may come off.

In view of the above-mentioned circumstances, the present invention prevents deformation due to the pressing seat surface of the pressing head or the sealing member biting into the edge portion on the outer surface side of the main pipe in the concave-convex fitting type connection structure, and The purpose of this paper is to propose a connection structure for a branch connection body that provides a sealing effect.

(Means for Solving the Problems) The object is to form through holes at a plurality of positions in the axial direction in the peripheral wall of a flow passage formed in the axial direction in the fuel rail and through which high-pressure fuel flows; A pressure receiving surface with an enlarged opening in the circumferential direction is formed in the fuel rail so that the branch connecting bodies each having a flow path communicating with the flow path are arranged in series, and the pressure receiving surface is provided with a pressure receiving surface having an enlarged opening in the circumferential direction. A connection structure for a branch connection body in a high-pressure fuel rail in which the branch connection body is fixed to the fuel rail by abutting and engaging a pressing head formed at a connection end with the fuel rail, and the pressure receiving seat is fixed to the fuel rail. a surface is formed as a rotating surface centered on the axis of the through hole, the pressing head is formed as a rotating surface whose contact line with the rotating surface is circular, and the pressure receiving surface is on the outer surface of the fuel rail. This is achieved by forming substantially arcuate surfaces on at least both sides of the opening end in the longitudinal direction, fitting the pressing head into the pressure receiving surface with a concave-convex fit, and connecting and fixing the branch connecting body to the fuel rail. be done.

(Function) With this configuration, the outer open end of the pressure receiving surface of the fuel rail is a substantially arc-shaped surface with no corners, and the pressing head of the branch connection body is press-fitted to the pressure receiving surface. If you let
The pressing seat surface of the pressing head does not dig into the outer edge portion of the pressure receiving surface, so that no gap is created between the pressing surface and the pressure receiving surface of the pressing head.

In other words, since there is no biting into the pressing bearing surface of the pressing head of the branch connecting body or the sealing member, the surface pressure on the sealing surface increases evenly and sufficiently. The thrust force associated with tightening is sufficiently transmitted to the sheet surface, and high sealing performance is obtained, which has the excellent effect of being able to withstand rapid and frequent repeated pressure fluctuations of ultra-high flow pressure. play.

As a mechanical means for connecting the branch connection body to the fuel rail, for example, a joint fitting is externally fitted on the fuel rail side so as to surround the pressure receiving surface, and a pressing head on the branch connection body side is internally fitted into the joint fitting. In this state, it is possible to adopt a method in which a nut assembled on the branch connection body side is internally screwed into the joint fitting and tightened.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a) and 1(b) are diagrams for explaining the ↑ embodiment of the present invention, and FIG. 1(a) is a longitudinal sectional front view of the main part, and FIG.
B) is an enlarged explanatory view of the pressure-receiving seat surface. As shown in Fig. 1, in the first embodiment, a main pipe (2) is used as a fuel manifold, which is made of a relatively thick metal pipe with an outer diameter of 20 mm and a wall thickness of 6 mm, through which high-pressure fuel flows as a fuel rail. It is being A flow passage 1a is formed in this main pipe (in the axial direction), and through holes 1b are formed in the flow passage 1a at multiple locations in the axial direction (see Fig. 1). - Only the through hole 1b is shown>.The end side of the through hole 1b has an enlarged opening in the radial direction of the main pipe 1, and a conical surface that rotates around the axis of the through hole 1b. A substantially conical pressure receiving surface 2 is formed, which is a rotating surface such as an arcuate surface, an ellipsoid of revolution, a hyperbolic surface of revolution, a parabolic surface of revolution, or the like.

A joint fitting 6 is provided to the main pipe 1 so as to surround the pressure receiving surface 2, and the joint fitting 6 has a screw hole 6a formed therein.

In the second embodiment, a branch pipe 3 having a pressing head 4 formed at the end thereof is used as the branch connection body.
Press the pressing bearing surface 4-1 of the pressing head 4 against the pressure receiving surface 2 through the bowl-shaped sealing member 5, and tighten with the fastening nut 7 through the washer 8 in the screw hole 6a. is located.

This pressing seat surface 4-1 is a rotating surface similar to the pressure receiving surface 2,
If the pressing seat surface 4-1 of the pressing head 4 is a conical surface, and the pressure receiving surface 2 is a conical surface, it will come into band-like surface contact with the pressing seating surface 4-1 and with other concave rotating surfaces. Then, the pressing seat surface 4-1
First, there is a line contact, and when tightening a nut, etc., as the torque increases, a narrow band-like surface contact is obtained. Furthermore, if the pressing seat surface 4-1 of the pressing head 4 is a convex rotating surface, a line contact will first occur regardless of the shape of the pressure receiving surface 2, and when tightening a nut, etc., as the torque increases, a narrow strip-shaped surface contact will occur. can get.

In the first embodiment, as shown in the construction drawing (B) and FIG. 2 (A), a substantially arc-shaped surface 2- 2 is formed over the entire circumference, but in the present invention, it is an essential condition that it is formed at least on both sides of the outer open end of the pressure receiving surface in the longitudinal direction as shown in FIG. 2 (b). . The outline of this approximately arcuate surface 2-2 is not only a simple curve as shown in Figure 3 (A), but also a series of straight lines in multiple stages as shown in Figure 3 (B), or a straight line as shown in Figure 3 (C). The substantially arcuate surface 2-2 may be discontinuous with respect to the pressure receiving surface 2 and the outer surface of the main pipe 1. In any case, when assembling, press the seat surface 4-
1 or the sealing member 5 is set to such an extent that it does not bite. The joint member 6 is made of a short toric body or a rectangular ring body, and surrounds the pressure-receiving seat surface 2 and is fitted onto the main pipe (2).

When connecting the branch pipe 3 to the main pipe 1, the pressing head 4 of the branch pipe 3 is inserted into the screw hole 6a of the joint fitting 6, and the pressing head 4 of the branch pipe 3 is inserted into the pressure receiving surface 2 through the bowl-shaped seal member 5. When fitted,
The fastening nut 7 installed on the branch pipe side is internally screwed into the joint fitting 6 to tighten it.

At that time, as the nut 7 is tightened, the sealing member 5 is pressed between the pressing head 4 and the pressure-receiving seat surface 2, but the open end of the pressure-receiving seat surface 2 on the outside of the tube has a substantially arc-shaped surface. 2-2
Since the seal member 5 is formed of The surface pressure between the two increases evenly and sufficiently, resulting in a complete seal.

It goes without saying that the present invention has the same effect even when the sealing member 5 is not provided, and in this case, the sealing between the pressure receiving surface 2 and the pressing surface 4-1 is completely achieved. .

On the other hand, the seal member 5 is preferably made of a relatively soft metal material such as indium, silver, copper, brass, or aluminum.

FIG. 4 is a longitudinal sectional front view of the main part of the second embodiment, in which the flow passage 1a of the main pipe 1 is eccentrically bored in the main pipe 1 without providing a joint fitting, and the thick wall of the main pipe 1 is eccentrically bored. A through-hole 1b communicating with the flow path 1a, a pressure-receiving seat surface 2, and a screw hole 6a are provided in the portion.

A nut 7 is directly screwed into this screw hole 6a.

According to the second embodiment, when assembling the branch connection body, there is no need for centering work between the main pipe and the joint fitting, and the number of parts can be reduced to make the whole structure compact and compact. The configuration, operation, and effects of other parts of the second embodiment are the same as those of the first embodiment already described.

FIG. 5 is a longitudinal sectional front view of the main part of the third embodiment, in which the branch connection body is composed of a branch fitting 5.
Mains are used for the fuel rail. In order to avoid interference with other parts caused by large curvature when bending branch pipes, this embodiment is suitable for cases where branch fittings such as elbows are used, equal seat valves, damping valves, delivery valves, etc. This was done in consideration of the case where a branch fitting with a mechanism such as a discharge valve installed therein is used. In the third embodiment, the branch connection body connected to the main pipe 1 is composed of a branch fitting 5'', and one end of the branch fitting 5'' has a pressing head 4 formed with a rotating surface similar to the previous embodiment. The screw wall 2 provided on the outer periphery of the branch fitting 5
1 into the screw hole 6a of the joint fitting 6, the branch fitting 5° is brought into abutting engagement with the pressure receiving surface 2 of the main pipe 1.

On the other hand, a branch pipe 3' is connected to the other end of the branch fitting 5°, which is fixed by screwing a cap nut 23 through a sleeve 22.

According to this third embodiment, branch pipes 3° can be led out parallel to the longitudinal direction of the main pipe 1.

FIG. 6 is a longitudinal sectional front view of the main part of the fourth embodiment, in which a branch branch pipe 3, which is a branch connection body, is connected to a main pipe 1, which is a fuel rail, by a cap nut 24. . A cylindrical protrusion 25 is formed in the center of the cap nut 24, and as the inner circumferential screw 24 of the cap nut 24 is screwed into the outer circumferential screw 16 of the joint fitting 6, this protrusion 25 The annular protrusion 20a is pressed downward via the washer 26 to bring the pressing seat surface 4-1 of the pressing head 4 into abutting engagement with the pressure receiving surface 2.

FIG. 7 is an explanatory diagram of a fuel block used as a fuel rail of the present invention in place of the main pipe of each embodiment, in which flow passages 31 and 32 through which high-pressure fuel flows are formed in a thick block 30. Attachment holes 33 a ~ communicating with these flow paths
33 d, 34 a to 34 d are formed on the surface of the block 30. These mounting holes 33a...34a.
... are formed with the pressure receiving surfaces described in each embodiment, and screws are formed on the inner circumferential surfaces of the mounting holes 33a to 33d and 34a to 34d.

When using this fuel block 35 as a fuel rail, each mounting hole 33a to 33d, 34a to 3
4d, the branch connection body is secured to the screw on the inner periphery of the mounting hole using a nut.

(Effects of the Invention) As explained above, the connection structure of the branch connection body according to the present invention is such that the opening end of the pressure receiving surface on the fuel rail side on the outside of the tube is formed into a substantially arc-shaped surface. The pressing seat surface of the pressing head is prevented from digging into the open end of the surface on the tube outer surface side. Therefore, there is no gap between the suppressing seating surface and the pressure receiving seating surface, and the surface pressure on the sealing surface increases uniformly, making it possible to completely prevent fuel leakage.

Therefore, the sealing performance does not deteriorate even under vibration conditions caused by repeated circulation of ultra-high flow pressure, and the connection function of the branch connection body is maintained for a long period of time. It is highly safe and reliable as a connection structure for branch connections.

[Brief explanation of drawings]

Figures 1 (a) and (b) are diagrams for explaining the first embodiment of the present invention. Figure 1 (a) is a longitudinal sectional front view of the main part, and Figure 1 (b) is an enlarged view of the pressure-receiving seat surface. Explanatory diagram, Figure 2 (a) and (b)
3(A) to 3(C) are partial enlarged cross-sectional views showing each embodiment of a substantially arc-shaped surface, and FIGS. 4 to 6 are respectively views of the present invention. FIG. 7 is a perspective explanatory view of a fuel block used as the fuel rail of the present invention, and FIGS. 8 and 9 are examples of conventional connection structures. A partially cutaway front view showing
FIGS. 10 and 11 are explanatory views showing modified states of the conventional connection structure. DESCRIPTION OF SYMBOLS 1...Main pipe, 2...Pressure receiving surface, 2-2...Substantially arcuate surface, 3...Branch branch pipe, 4...Press head, 4-1...
...Press bearing surface, 6...Joint fitting, 7...Tightening nut.

Claims (5)

[Claims] (1) Through holes are formed at multiple positions in the axial direction in the peripheral wall of a flow passage formed in the axial direction in the fuel rail and through which high-pressure fuel flows, and each of the through holes has a flow passage communicating with the flow passage. A pressure receiving surface is formed on the fuel rail with an enlarged opening in the circumferential direction so that the branch connecting body is connected to the fuel rail, and a pressure receiving surface is formed on the pressure receiving surface at the connecting end of the branch connecting body with the fuel rail. This is a connection structure for a branch connection body in a high-pressure fuel rail, in which the branch connection body is fixed to the fuel rail by abutting and engaging pressing heads, and the pressure receiving surface is centered on the axis of the through hole. The pressing head is formed on a rotating surface whose contact line with the rotating surface is circular,
Approximately arc-shaped surfaces are formed on at least both sides in the longitudinal direction of the open end on the outer surface side of the fuel rail of the pressure receiving surface, and the pressing head is fitted into the pressure receiving surface with an uneven fit, and the fuel rail A connection structure for a branch connection body in a high-pressure fuel rail, characterized in that the branch connection body is connected and fixed to. (2) In the connection structure of a branch connection body in a high-pressure fuel rail according to claim (1), the fuel rail or the fuel rail is surrounded by a nut incorporated in the branch connection body side or a threaded wall provided on the branch connection body side. 1. A connection structure for a branch connection body in a high-pressure fuel rail, characterized in that the branch connection body is connected to the fuel rail by being fastened to a screw hole of a joint fitting provided as described above. (3) The connection structure for a branch connection body in a high-pressure fuel rail according to claim (1), wherein the pressure receiving surface is a conical surface and the pressing head is formed in a truncated conical shape. (4) The connection structure of a branch connection body in a high-pressure fuel rail according to claim (1), wherein the branch connection body is constituted by a branch branch pipe or a branch metal fitting. (5) The connection structure of a branch connection body in a high-pressure fuel rail according to claim (1), wherein the fuel rail is composed of a fuel manifold or a fuel block.