JP2009052452A - Method of sealing high-pressure fuel injection tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of sealing a high-pressure fuel injection tube capable of preventing a seat surface from being deformed or damaged when an automatic frettage treatment or the like is applied thereto. <P>SOLUTION: In this method of sealing when a high pressure is applied into the high-pressure fuel injection tube having a connection head part on which the seat surface is formed, the underhead rear surface of the connection head part is brought into contact with a stay block. The seat surface deformation prevention surface of a seat surface deformation prevention member having the seat surface deformation prevention surface formed in a recessed shape adaptable to at least the shape of the seat surface and a through hole in the center axial direction is brought into contact with the seat surface for sealing. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention provides a high-pressure fuel injection pipe having a high pressure when manufacturing a high-pressure fuel injection pipe made of a thick thin steel pipe having a relatively small diameter, which is used, for example, as a fuel supply path in a diesel internal combustion engine. The present invention relates to a method for sealing a connection head when applying an internal pressure.

  Conventionally, as this type of high-pressure fuel injection pipe, for example, as shown in FIG. 9, a spherical sheet surface 23 and a sheet surface 23 are formed at a connection end portion of a thick thin steel pipe 21 having a relatively small diameter. A connecting head 22 formed by an annular flange portion 25 provided at an interval in the axial direction from the center and a conical surface 24 that is continuous with the seat surface 23 and tapers toward the tip to the annular flange portion 25. What has is known (refer FIG. 4 of patent document 1). In the figure, 26 is a pocket generated by press molding of the connecting head.

The high pressure fuel injection pipe having such a structure is subjected to an internal pressure application operation such as a pressure resistance test at the time of manufacture. This pressure resistance test includes, for example, an autofrettage process performed to improve internal pressure fatigue strength. In general, the pressure resistance test of the high-pressure fuel injection pipe including the auto-frettage process is performed by applying a high pressure to the pipe with the connection head of the high-pressure fuel injection pipe sealed.
As a pressure-resistant inspection method for a high-pressure fuel injection pipe that has been conventionally performed, for example, a method shown in FIG. 10 is known (see Patent Document 2). This method includes a mating member 30 in which a cylindrical portion 31 having a conical surface 32 is formed in an opening, and a connection head of a high-pressure fuel injection pipe 33 inserted in the cylindrical portion 31 of the mating member 30. An intermediate member 35 having an annular protrusion 37 formed coaxially with the tube axis so as to surround the opening of the high pressure fuel injection pipe 33 on the end face 36 substantially parallel to the end face of the high pressure fuel injection pipe 33; This is a method that is performed using a pressing device including a cap nut 38 for pressing the connection head 34 against the mating member 30. That is, this method is a method in which the end surface 36 other than the seal surface 39 of the connection head 34 of the high-pressure fuel injection pipe 33 is brought into pressure contact with the annular protrusion 37 of the intermediate member 35 incorporated in the counterpart member 30 and sealed.
JP 2001-280217 A German patent DE 195 31 743 C1

However, the sealing method of the high-pressure fuel injection pipe by the conventional pressing device described above is sealed at a surface other than the seat surface of the connection head of the high-pressure fuel injection pipe, In order to prevent leakage when the pressure exceeds 5000 kgf / cm ² as in the case of auto-fretting processing, the annular protrusion of the intermediate member is connected to the end face of the connecting head of the high-pressure fuel injection pipe. It is necessary to push deeply and deeply, and as a result, a gap is formed between the conical surface on the counterpart member side and the seat surface of the connection head, so that the seat surface of the connection head is not restrained at all. For this reason, there is a possibility that the sheet surface shape may be deformed and the sheet surface shape may be distorted, or a foreign object may enter the gap and cause a wrinkle on the sheet surface.

  The present invention has been made to solve the above-described problems, and an attempt is made to propose a sealing method for a high-pressure fuel injection pipe that can prevent deformation of the seat surface and wrinkling of the seat surface when performing auto-frettage processing or the like. To do.

  A sealing method for a high-pressure fuel injection pipe according to the present invention is a sealing method for applying a high pressure to the inside of a high-pressure fuel injection pipe having a connection head on which a seat surface is formed. The seat surface of the seat surface deformation preventing member having a seat surface deformation preventing surface that is in contact with the stay block and has a concave shape substantially matching at least the sheet surface shape and having a through-hole in the tube axis direction in the shaft core In the sealing method when applying a high pressure to the inside of the high-pressure fuel injection pipe having a connection head portion on which the seat surface is also formed, the deformation preventing surface is brought into contact with the seat surface and sealed. A back surface of the neck of the connection head is brought into contact with a stay block and has a seat surface deformation preventing surface having a recess shape substantially matching the seat surface shape and a tube at the shaft core. The seat surface deformation preventing member of the sheet surface deformation preventing member having a through hole in the direction is brought into contact with the sheet surface, and then inserted into the sheet surface deformation preventing member, and the seal plug having a cone-shaped protrusion at the end The cone-shaped protrusion is inserted into the connection head end face opening and pressed to seal, and further, a high pressure is applied to the inside of the high pressure fuel injection pipe having the connection head similarly formed with a seat surface. In this case, the back surface of the neck lower portion of the connection head is brought into contact with the stay block, and has a seat surface deformation preventing surface having a concave shape substantially matching at least the shape of the seat surface, and a tube shaft on the shaft core. The sheet surface deformation preventing surface of the sheet surface deformation preventing member having a through hole in the direction is brought into contact with the sheet surface, and then inserted into the sheet surface deformation preventing member, and the end surface of the injection pipe is A seal plug having an annular protrusion formed coaxially with the tube axis so as to surround the mouth portion is pressed against the end face of the connection head, and is entrapped to be sealed. In the sealing method when applying a high pressure to the inside of the high-pressure fuel injection pipe having the connection head formed with the connection head, the back of the neck lower part of the connection head is brought into contact with the stay block, and at least substantially the seat surface shape. The sheet surface deformation preventing surface of a sheet surface deformation preventing member having a sheet surface deformation preventing surface exhibiting a matching concave shape and having a through-hole in the tube axis direction at the shaft core is brought into contact with the sheet surface, and then the connection An annular projection, which is formed in advance coaxially with the tube axis so as to surround the opening of the injection tube, is pressed against the end surface of the seal plug inserted into the sleeve-shaped sheet surface deformation prevention member. And sealing.

A sleeve-shaped member can be used as the sheet surface deformation preventing member in the sealing method of the present invention. In addition, when a high pressure is applied to the inside of the high-pressure fuel injection pipe, it is preferable that the seat surface is pressed in the axial direction by the seat surface deformation preventing member and / or the stay block. Still further, the sealing method of the present invention includes a soft metal for protecting the sheet surface between the sheet surface deformation preventing surface and the sheet surface of the sheet surface deformation preventing member, or preventing the sheet surface deformation. It is a preferable aspect to provide a soft metal layer for protecting the sheet surface on the sheet surface deformation preventing surface of the member.
In the sealing method of the present invention, the sheet surface deformation preventing surface of the sheet surface deformation preventing member may have a concave shape that substantially matches a conical surface continuous with the sheet surface. Further, the lower back of the neck of the connecting head may be brought into contact with the stay block via a nut and / or a washer.

In the sealing method of the high-pressure fuel injection pipe according to the present invention, when the sheet surface deformation preventing member is used alone, the sheet surface deformation preventing member is sealed with a sealing function and a sheet surface deformation preventing function. When both the deformation prevention member and the seal plug are used, the sealing is performed with the seal plug, and the sheet surface deformation prevention member only prevents the deformation of the sheet surface, or the sheet surface deformation prevention member has only the function of preventing the deformation of the sheet surface. In addition, it can have a sealing function. And the sealing method of the high-pressure fuel injection pipe according to the present invention having such a function is such that the seat surface is deformed into a sleeve-like seat surface at the time of application of auto-fraget pressure reaching 5,000 to 10,000 kgf / cm ² , for example. Since it is restrained by being in contact with the seat surface deformation preventing surface of the preventing member, the seal plug and the connecting head of the high pressure fuel injection pipe are pressed against each other with a large axial force, and the high pressure in the high pressure fuel injection pipe It is possible to prevent the sheet surface from being deformed even when the auto-fretage pressure is applied. In addition, the sleeve-shaped sheet surface deformation preventing member is brought into contact with the sheet surface, preferably pressed in the tube axis direction, and an axial force is applied to the heel present at the bottom of the pocket of the high pressure fuel injection pipe connecting head. Further, it is possible to prevent the progression of the depth of the wrinkles and the expansion of the connection head opening due to the auto-frettage process. Further, when a high internal pressure is applied to the high-pressure fuel injection pipe, even if the cone-shaped projection of the seal plug is inserted and pressed into the connection head end face opening, or the cone-shaped projection is inserted and pressed, Even if the opening contact surface is deformed, the seat surface is not deformed because the seat surface is in contact with and restrained by the seat surface deformation preventing surface of the sleeve-shaped sheet surface deformation preventing member. Furthermore, even when a high internal pressure is applied to the high pressure fuel injection pipe, the seat surface contacts the sheet surface deformation preventing surface of the sleeve-shaped sheet surface deformation preventing member even if the annular protrusion of the seal plug is pressed and bited into the end surface of the connection head. Since it is constrained by contact, the sheet surface does not deform. Furthermore, even when an annular protrusion formed on the end face of the connection head is pressed or bite into the end face of the seal plug when a high internal pressure is applied to the high pressure fuel injection pipe, the seat face is deformed by the sleeve-like sheet face deformation preventing member. The seat surface is not deformed because it is restrained by contacting with the prevention surface. In the sealing method of the present invention, the sheet surface deformation preventing surface of the sheet surface deformation preventing member has a concave shape that substantially matches the conical surface continuous with the sheet surface, so that the contact with the sheet surface when high internal pressure is applied. The contact / pressing action is stable. Still further, a soft metal for protecting the sheet surface is interposed between the sheet surface deformation preventing surface and the sheet surface of the sheet surface deformation preventing member, or the sheet surface deformation preventing surface of the sheet surface deformation preventing member. By providing a soft metal layer for protecting the sheet surface, the sheet surface can be more reliably protected.
Therefore, according to the method of the present invention, it is possible not only to prevent the deformation of the seat surface and the wrinkle of the seat surface during auto-frettage processing of the high-pressure fuel injection pipe, but also to ensure the stability and reliability of the seal. There is an effect.

  1 is a longitudinal sectional view showing a first embodiment of a sealing method for a high-pressure fuel injection pipe according to the present invention, FIG. 2 is a longitudinal sectional view showing the second embodiment, and FIG. 3 is a longitudinal section showing the third embodiment. FIG. 5 is a longitudinal sectional view showing the fourth embodiment, FIG. 5 is a longitudinal sectional view showing the fifth embodiment, FIG. 6 is a longitudinal sectional view showing the sixth embodiment, and FIG. FIG. 8 is a longitudinal sectional view showing various sectional shapes of the connecting head of the high pressure fuel injection pipe according to the present invention, 1A to 1E are high pressure fuel injection pipes, and 2A to 2E are seats. Surface deformation prevention member, 2A-1 to 2E-1 are seat surface deformation prevention surfaces, 3A to 3D are seal plugs, 4A to 4E are stay blocks, 5 is a nut, 6A is a sleeve-like washer, 6B is a ring-like washer, 7 Is a soft metal.

That is, the high-pressure fuel injection pipe sealing method (first embodiment) shown in FIG. 1 is an example of a sealing method that obtains both the sealing and the seat surface deformation prevention function simultaneously by using only the seat surface deformation preventing member. A spherical sheet surface 1A-3 and an annular flange portion 1A provided at an interval in the axial direction from the sheet surface 1A-3 at the connection end of the thick thin steel pipe 1A-1 having a small diameter -4 and a conical surface 1A-2 formed from a conical surface 1A-5 that is continuous with the seat surface 1A-3 and tapers toward the tip to the annular flange portion 1A-4, and is connected to the connection head 1A-2. The back surface of the annular flange portion 1A-4 of the connecting head portion 1A-2 of the high pressure fuel injection pipe 1A having the pocket 1A-6 on the inner peripheral surface of the head portion 1A-2 is brought into contact with the stay block 4A, and the seat The sheet surface 1 on the surface facing the surface 1A-3 -3 having an arcuate sheet surface deformation preventing surface 2A-1 having a concave shape substantially matching the shape of -3, and having a through-hole 2A-2 in the tube axis direction at the shaft core. With the arcuate sheet surface deformation preventing surface 2A-1 of the member 2A in contact with the sheet surface 1A-3, the sheet surface deformation preventing member 2A and / or the stay block 4A are pressed in the tube axis direction. The sheet surface deformation preventing surface 2A-1 of the sheet surface deformation preventing member 2A is pressed against the sheet surface 1A-3 and sealed.
In the case of this sealing method, an autofraget pressure is applied to the high-pressure fuel injection pipe 1A from the through hole 2A-2 of the seat surface deformation preventing member 2A. At this time, the seat surface 1A-3 becomes the seat surface deformation preventing member 2A. Therefore, the seat surface 1A-3 is hardly deformed, and the seat surface deformation preventing member 2A and / or the high-pressure fuel injection pipe 1A is not deformed. The surface pressure required for the high pressure seal is obtained by being pressed in the direction of the tube axis, and the shaft (not shown) is provided at the bottom of the pocket 1A-6 of the high pressure fuel injection tube connection head 1A-2. As a result of the force being applied, the progression of the depth of the heel and the expansion of the connecting head opening 1A-7 are prevented as a result of the autofrettage process.

The high pressure fuel injection pipe sealing method (second embodiment) shown in FIG. 2 is an example of a sealing method using both a seat surface deformation preventing member and a seal plug. This method is basically a sealing method. Is performed by a seal plug, and the seat surface deformation preventing member is a method for preventing the deformation of the seat surface. When applying a high pressure to the inside of the high pressure fuel injection tube 1B, the connection head of the high pressure fuel injection tube 1B is used. A seal plug 3A having a cone-shaped protrusion 3A-2 on the surface facing the end surface opening 1B-7 of the portion 1B-2 is inserted into a sleeve-shaped sheet surface deformation preventing member 2B similar to the above, and the In this method, the cone-shaped protrusion 3A-2 of the seal plug 3A is inserted into the connecting head end face opening 1B-7 and pressed to be sealed.
That is, similar to the one shown in FIG. 1, a spherical sheet surface 1B-3 and a shaft core from the sheet surface 1B-3 are connected to the connection end of a thick thin steel pipe 1B-1 having a relatively small diameter. An annular flange portion 1B-4 provided at intervals in the direction, and a conical surface 1B-5 that is continuous with the seat surface 1B-3 and tapers toward the tip to the annular flange portion 1B-4. The back surface of the annular flange portion 1B-4 of the connecting head 1B-2 of the high pressure fuel injection pipe 1B having the connecting head 1B-2 having the pocket 1B-6 on the inner peripheral surface is brought into contact with the stay block 4B; Furthermore, the sheet surface 1B-3 has an arcuate sheet surface deformation preventing surface 2B-1 that has a concave shape substantially matching the shape of the sheet surface 1B-3 on the surface facing the sheet surface 1B-3, and the axial center of the tube surface direction is the tube axis direction. A sleeve-shaped sheet surface deformation preventing member having a through hole 2B-2 The arcuate sheet surface deformation preventing surface 2B-1 of B is brought into contact with the sheet surface 1B-3, and then cone-shaped protrusions are formed on the surface facing the end surface opening 1B-7 of the connection head 1B-2. The seal plug 3A having 3A-2 is inserted in the through hole 2B-2 of the sheet surface deformation preventing member 2B, and the sheet surface deformation preventing member 2B and the seal plug 3A are pressed, or the sheet surface deformation preventing member. 2B and the seal plug 3A are fixed, the high pressure fuel injection pipe 1B is pressed by the stay block 4B, or the seat surface deformation preventing member 2B, the seal plug 3A and the stay block 4B are pressed against each other to In this method, the cone-shaped protrusion 3A-2 is inserted into the connecting head end face opening 1B-7, pressed, and sealed.
In the case of this sealing method, autofrettage pressure is applied to the high-pressure fuel injection pipe 1B from the through hole 3A-1 of the seal plug 3A. At this time, the seat surface 1B-3 is an arc shape of the seat surface deformation preventing member 2B. Since the sheet surface deformation preventing surface 2B-1 is restrained, the cone-shaped protrusion 3A-2 of the seal plug 3A is inserted into the connection head opening 1B-7 and pressed to connect the connection head opening 1B-7. The sheet surface 1B-3 is hardly deformed even if the expanding force is applied to the sheet, and the sheet surface deformation preventing member 2B and / or the high-pressure fuel injection pipe 1B are pressed in the tube axis direction also in this embodiment. As a result, an axial force is applied to the heel (not shown) at the bottom of the pocket 1B-6 of the high-pressure fuel injection pipe connection head 1B-2. Depth progression and connection head Widening of the opening 1B-7 is prevented.

The sealing method (third embodiment) of the high-pressure fuel injection pipe shown in FIG. 3 is a sealing method using both the seat surface deformation preventing member and the sealing plug, as in the sealing method of FIG. A sheet surface deformation preventing member 2C having a sheet surface deformation preventing surface 2C-1 having a concave shape substantially matching the sheet surface 1C-3 and the conical surface 1C-5 connected to the sheet surface, and a seal plug 3B. This is an example of a sealing method. A spherical sheet surface 1C-3 is connected to a connecting end of a thick thin steel pipe 1C-1 having a relatively small diameter, and the axial direction from the sheet surface 1C-3. An annular flange portion 1C-4 provided at intervals, a conical surface 1C-5 that continues to the seat surface 1C-3 and tapers toward the tip to the annular flange portion 1C-4, and the annular flange portion 1C. Convex formed on the back of -4 Of the high pressure fuel injection pipe 1C having a pocket 1C-7 on the inner peripheral surface of the connection head 1C-2. The convex spherical surface 1C-6 on the back surface of the annular flange portion 1C-4 is brought into contact with the stay block 4C, and further the seat surface 1C-3 of the connecting head 1C-2 and the conical surface 1C-5 connected to the seat surface. The sheet surface 1C-3 and the conical surface 1C-5 that continues to the sheet surface have a recess surface 2C-1 that has a concave shape that substantially coincides with the sheet surface 1C-3. The sheet surface deformation preventing surface 2C-1 of the sleeve-shaped sheet surface deformation preventing member 2C having the through hole 2C-2 is brought into contact with the sheet surface 1C-3 and the conical surface 1C-5 connected to the sheet surface. Then, the end face opening 1C-8 of the connection head 1C-2 The seal plug 3B having a conical protrusion 3B-2 on the opposite surface is inserted into the through hole 2C-2 of the sheet surface deformation preventing member 2C, and the sheet surface deformation preventing member 2C and the seal plug 3B are pressed. Alternatively, the high pressure fuel injection pipe 1C is pressed by the stay block 4C while the seat surface deformation preventing member 2C and the seal plug 3B are fixed, or the seat surface deformation preventing member 2C, the seal plug 3B and the stay block 4C are mutually connected. The cone-shaped projection 3B-2 of the seal plug 3B is inserted into the connecting head end face opening 1C-7 and pressed to seal the seal plug 3B.
In the case of this sealing method, autofrettage pressure is applied to the high-pressure fuel injection pipe 1C from the through hole 3B-1 of the seal plug 3B. At this time, the seat surface 1C-3 and the conical surface 1C- connected to the seat surface are provided. 5 is restrained by the sheet surface deformation preventing surface 2C-1 of the sheet surface deformation preventing member 2C, so that the cone-shaped protrusion 3B-2 of the seal plug 3B is inserted and pressed into the connection head opening 1C-8. Even if the expansion force acts on the connection head opening 1C-8, the seat surface 1C-3 hardly deforms. Also in this embodiment, the seat surface deformation preventing member 2C and / or the high-pressure fuel is used. As a result of the injection tube 1C being pressed in the tube axis direction, axial force is applied to the ridge (not shown) present at the bottom of the pocket 1C-7 of the high pressure fuel injection tube connection head 1C-2, Auto Fletage Expansion of the connecting head opening 1C-8 is prevented progression of the depth of wrinkles flaws associated with.

The high pressure fuel injection pipe sealing method (fourth embodiment) shown in FIG. 4 is a sealing method using both the seat surface deformation preventing member and the seal plug, similar to the sealing method shown in FIGS. The seal plug 3C having an annular protrusion 3C-2 formed coaxially with the tube axis so as to surround the opening 1D-7 of the high-pressure fuel injection pipe, the seat surface 1D-3 of the connection head, and the seat surface A sleeve-like sheet surface deformation preventing member 2D having a sheet surface deformation preventing surface 2D-1 having a concave shape substantially matching the conical surface 1D-5 is used, and the annular protrusion 3C-2 of the seal plug 3C is used as a high-pressure fuel. This is an example of a method of pressing and biting into the end face of the connecting head 1D-2 of the injection pipe 1D and sealing it, and like the one shown in FIG. 1, a thick thin steel pipe 1D-1 having a relatively small diameter. Spherical sheet at the connection end of 1D-3, an annular flange portion 1D-4 provided at an interval from the seat surface 1D-3 in the axial direction, and the leading end of the seat surface 1D-3 to the annular flange portion 1D-4. An annular flange portion of the connection head 1D-2 of the high-pressure fuel injection pipe 1D having a connection head 1D-2 having a conical surface 1D-5 tapered and having a pocket 1D-6 on the inner peripheral surface The back surface of 1D-4 is brought into contact with the stay block 4D via the sleeve-like washer 6A, and the surface of the connecting head 1D-2 facing the seat surface 1D-3 and the conical surface 1D-5 connected to the seat surface. The sheet surface 1D-3 and the conical surface 1D-5 connected to the sheet surface have a recessed surface substantially in conformity with the sheet surface deformation preventing surface 2D-1, and a through-hole 2D- Sleeve-like sheet surface deformation having 2 The sheet surface deformation preventing surface 2D-1 of the stop member 2D is brought into contact with the sheet surface 1D-3 and the conical surface 1D-5 connected to the sheet surface, and then the surface facing the end surface of the connection head 1D-2 A seal plug 3C having an annular projection 3C-2 formed coaxially with the tube axis so as to surround the opening 1D-7 of the injection tube is inserted into the through hole 2D-2 of the sheet surface deformation preventing member 2D. The high pressure fuel injection pipe 1D is pressed by the stay block 4D while the seat surface deformation preventing member 2D and the seal plug 3C are pressed, or the seat surface deformation preventing member 2D and the seal plug 3C are fixed, or the seat The surface deformation preventing member 2D, the seal plug 3C, and the stay block 4D are pressed against each other to press and bite the annular protrusion 3C-2 of the seal plug 3C into the end face of the connection head 1D-2. This is a sealing method.
In the case of this sealing method, autofrettage pressure is applied to the high-pressure fuel injection pipe 1D from the through hole 3C-1 of the seal plug 3C. At this time, the seat surface 1D-3 and the conical surface 1D- connected to the seat surface are provided. 5 is restrained by the sheet surface deformation preventing surface 2D-1 of the sheet surface deformation preventing member 2D. Therefore, even if the annular protrusion 3C-2 of the seal plug 3C is pressed and bite into the end surface of the connection head 1D-2. The seat surface 1D-3 is hardly deformed. Also in this embodiment, the seat surface deformation preventing member 2D and / or the high-pressure fuel injection pipe 1D are pressed in the tube axis direction, thereby connecting the high-pressure fuel injection pipe. As a result of the axial force applied to the heel (not shown) at the bottom of the pocket 1D-6 of the head 1D-2, the progression of the depth of the heel and the connection head opening associated with the autofrettage process 1D-7 Expansion is prevented.
Here, the annular projection 3C-2 of the seal plug 3C is shown as a single (one), but the annular projection 3C-2 formed coaxially with the tube axis is double (two) or It goes without saying that Mie (Article 3) may be used.

The sealing method (fifth embodiment) of the high-pressure fuel injection pipe shown in FIG. 5 is sealed by using both the seat surface deformation preventing member and the sealing plug, similarly to the sealing method shown in FIGS. 4 is an example of a method of sealing the annular protrusion 3C-2 in FIG. 4 provided on the high pressure fuel injection pipe side, and the injection pipe is formed on the opening end face of the connection head 1E-2 of the high pressure fuel injection pipe 1E. An annular projection 1E-8 is formed coaxially with the tube axis so as to surround the opening of the tube, and the annular projection 1E-7 is pressed against the end face of the seal plug 3D inserted into the sleeve-like sheet surface deformation preventing member 2E. Alternatively, it is a method of encroaching and sealing.
In other words, a spherical sheet surface 1E-3 and a ring provided at an interval in the axial direction from the sheet surface 1E-3 at the connection end of a thick thin steel pipe 1E-1 having a relatively small diameter. Formed from a flange portion 1E-4 and a conical surface 1E-5 that is continuous with the seat surface 1E-3 and tapers toward the tip to the annular flange portion 1E-4. A pocket 1E-6 is formed on the inner peripheral surface. An annular protrusion 1E-8 is formed coaxially with the tube axis so as to surround the connection head opening 1E-7 on the end surface of the connection head 1E-2 of the high pressure fuel injection pipe 1E having the connection head 1E-2. Pre-form. Then, the back surface of the annular flange portion 1E-4 of the connection head portion 1E-2 of the high pressure fuel injection pipe 1E is brought into contact with the stay block 4E via the ring washer 6B, and the seat of the connection head portion 1E-2. Sheet surface deformation prevention in which the concave surface substantially coincides with the sheet surface 1E-3 and the conical surface 1E-5 connected to the sheet surface on the surface facing the surface 1E-3 and the conical surface 1E-5 connected to the sheet surface The sheet surface deformation preventing surface 2E-1 of the sleeve-shaped sheet surface deformation preventing member 2E having the surface 2E-1 and having a through-hole 2E-2 in the tube axis direction at the shaft core is used as the sheet surface 1E-3. The seal plug 3D having a through hole 3D-1 in the shaft core is inserted into the through hole 2E-2 of the sheet surface deformation preventing member 2E. And sheet surface deformation prevention member E and the seal plug 3D are pressed, or the high pressure fuel injection pipe 1E is pressed by the stay block 4E while the seat surface deformation preventing member 2E and the seal plug 3D are fixed, or the sheet surface deformation preventing member 2E and the seal plug 3D. The stay block 4E is pressed against each other, and an annular projection 1E-8 formed coaxially with the tube axis on the end face of the connection head 1E-2 is pressed or bite into the end face of the seal plug 3D for sealing. It is.
In the case of this sealing method, autofrettage pressure is applied to the high-pressure fuel injection pipe 1E from the through hole 3D-1 of the seal plug 3D. At this time, the seat surface 1E-3 and the conical surface 1E- connected to the seat surface are provided. 5 is restrained by the sheet surface deformation preventing surface 2E-1 of the sheet surface deformation preventing member 2E, so that the sheet surface 1E-3 is hardly deformed, and also in this embodiment, the sheet surface deformation preventing member 2E and / or the high-pressure fuel injection pipe 1E are pressed in the axial direction of the pipe, whereby an axial force is exerted on a rod (not shown) at the bottom of the pocket 1E-6 of the high-pressure fuel injection pipe connection head 1E-2. As a result, the progression of the depth of the heel and the expansion of the connection head opening 1E-7 associated with the autofragement process are prevented.
In this embodiment, the annular protrusion 1E-7 formed coaxially with the tube axis on the connecting head end face is not limited to a single (one), but may be double (two) or triple (three). Needless to say.

  The high pressure fuel injection pipe sealing method (sixth embodiment) shown in FIG. 6 is an example of a method in which the back surface of the annular flange portion of the connection head of the high pressure fuel injection pipe is brought into contact with the stay block via a nut and sealed. As shown in FIG. 2, the back side of the annular flange portion 1B-4 of the connection head portion 1B-2 of the high pressure fuel injection pipe 1B is replaced by a nut 5 instead of a washer. This is a method of sealing against the stay block 4B. Therefore, it goes without saying that the same operational effects as the sealing method shown in FIG. In the case of the present embodiment, a washer similar to the ring-shaped washer 6B shown in FIG. 5 may be interposed between the nut 5 and the annular flange portion 1B-4.

  Further, in the sealing method of the high pressure fuel injection pipe shown in FIG. 7 (seventh embodiment), a soft metal layer is provided on the sheet surface deformation preventing surface of the sheet surface deformation preventing member in order to protect the seat surface of the connecting head. As an example of the sealing method, a case where the present invention is applied to the sealing method shown in FIG. 2 is shown. In this case, the sleeve-shaped sheet surface deformation preventing member 2B is opposed to the sheet surface 1B-3. A soft metal 7 is attached to the arcuate sheet surface deformation preventing surface 2B-1 that has a concave shape that substantially matches the shape of the sheet surface 1B-3 formed on the surface, and the sheet surface deformation preventing member 2B is attached to the sheet. It abuts on the surface 1B-3. As a method for depositing the soft metal 7 on the arc-shaped sheet surface deformation preventing surface 2B-1, plating, thermal spraying, or the like can be used. In addition, as a soft metal, metals, such as soft iron, Cu, Sn, Al, Bi, Sb, and these alloys can be used.

FIG. 8 is a cross-sectional view of the connecting head portion of the high pressure fuel injection pipe for effectively preventing the deformation of the seat surface and further improving the stability of the seal in the high pressure fuel injection pipe sealing method according to the present invention. In the figure, (a) shows a connecting head having a tip portion formed by a tapered surface G-1a having an angle θ1 of 1 to 10 degrees and a spherical sheet surface G-1b continuous to the tapered surface G-1a. Part G-1, FIG. 5B shows a flat part G-2a from the opening side, a tapered surface G-2b having an angle θ2 of 1 to 10 degrees connected to the flat part G-2a, and the tapered surface G. -2a is a connecting head G-2 formed by a spherical sheet surface G-1c continuous to -2a, and FIG. 5C shows the tip of the annular projection G-3a and the annular projection G-3a from the opening side. A flat portion G-3b and a tapered surface G-3c having an angle θ3 of 1 to 10 degrees connected to the flat portion G-3b; It shows a connecting head G-3 which is formed with a spherical seat surface G-3d continuous with the tapered surface G-3c.
Here, the angles θ1 to θ3 of the taper surfaces G-1a and G-2b and the taper surface G-3c are set to 1 to 10 degrees. If it exceeds 10 degrees, the deformation resistance decreases, but the shape after deformation is not stable, and it is difficult to ensure a uniform seal surface pressure. The angles θ1 to θ3 are preferably 2 to 5 degrees, and the shape of the seal surface after deformation may be stable and a uniform seal surface pressure may be obtained.
In addition, in the high-pressure fuel injection pipe shown in FIGS. 8 (A) to (C), it can be said that appropriate chamfering at the pipe inner diameter inlet of the pipe end is preferable from the viewpoint of preventing the opening end from being narrowed. Not too long.

  The sealing method of the high-pressure fuel injection pipe according to the present invention is constrained by the seat surface being in contact with the seat surface deformation preventing surface of the sleeve-shaped seat surface deformation preventing member, for example, when applying an autofraget pressure. Therefore, it is possible to prevent deformation of the seat surface even if a pressure or expansion force is applied to the connection head portion with a seal plug, or even if a high-pressure autofraget pressure is applied in the high-pressure fuel injection pipe. In addition, the axial force is applied to the bottom of the pocket of the high-pressure fuel injection pipe connection head pocket, so that the progress of the depth of the soot and the connection head opening of the connection head opening are It is possible to prevent expansion, and further, it is possible to prevent deformation of the seat surface when applying a high internal pressure to the high-pressure fuel injection pipe, and in addition, a contact / pressing action with the seat surface when applying a high internal pressure. Is stable Narazu, an excellent effect of being able to protect the seat surface to more securely by soft metal or a soft metal layer to be interposed between the seat surface deformation preventing surface and the seat surface of the seat surface deformation prevention member. Therefore, according to the method of the present invention, not only can the deformation of the seat surface and the wrinkle of the seat surface be prevented during auto-frettage processing of the high-pressure fuel injection pipe, but also the stability and reliability of the seal can be secured. This greatly contributes to the improvement of the internal pressure fatigue strength of the high-pressure fuel injection pipe and the performance of the internal combustion engine in the internal combustion engine.

It is a longitudinal cross-sectional view which shows 1st Example of the sealing method of the high pressure fuel injection pipe which concerns on this invention. It is the longitudinal cross-sectional view which similarly shows 2nd Example. It is a longitudinal section showing the 3rd example similarly. It is a longitudinal section showing the 4th example similarly. It is a longitudinal section showing a 5th example similarly. It is a longitudinal section showing the 6th example similarly. It is a longitudinal section showing the 7th example similarly. FIG. 2 illustrates various cross-sectional shapes of a connection head of a high-pressure fuel injection pipe according to the present invention. (A) shows a connection head having a tip formed by a tapered surface and a spherical sheet surface connected to the tapered surface. FIG. 4B is a cross-sectional view of a main part showing a connecting head formed by a flat part from the opening side, a tapered surface connected to the flat part, and a spherical sheet surface connected to the tapered surface. Fig. 3 (C) shows a connecting head formed with an annular protrusion from the opening side, a flat portion connected to the annular protrusion, a tapered surface connected to the flat portion, and a spherical sheet surface connected to the tapered surface. It is a principal part sectional view shown. It is a longitudinal cross-sectional view which shows an example of the connection head of the conventional high pressure fuel injection pipe. It is a longitudinal cross-sectional view which shows an example of the sealing method of the conventional high pressure fuel injection pipe.

Explanation of symbols

1A to 1E High pressure fuel injection pipe 2A to 2E Seat surface deformation preventing member 2A-1 to 2E-1 Seat surface deformation preventing surface 3A to 3D Seal plug 4A to 4E Stay block 5 Nut 6A Sleeve washer 6B Ring washer 7 Soft metal

Claims (10)

  In a sealing method for applying a high pressure to the inside of a high-pressure fuel injection pipe having a connection head formed with a seat surface, the back of the neck lower part of the connection head is brought into contact with a stay block, and at least the seat surface shape The sheet surface deformation prevention surface of the sheet surface deformation prevention member having a sheet surface deformation prevention surface having a concave shape substantially matching with the axial center and having a through-hole in the tube axis direction on the shaft core, A sealing method for a high-pressure fuel injection pipe, wherein sealing is performed with the seat surface deformation preventing member.   In a sealing method for applying a high pressure to the inside of a high-pressure fuel injection pipe having a connection head formed with a seat surface, the back of the neck lower part of the connection head is brought into contact with a stay block, and at least the seat surface shape The sheet surface deformation preventing surface of the sheet surface deformation preventing member having a sheet surface deformation preventing surface having a concave shape substantially matching with the axial center and having a through-hole in the tube axis direction at the shaft core, and then contacting the sheet surface A high-pressure fuel injection, wherein the cone-shaped projection of a seal plug inserted into the sheet surface deformation prevention member and having a cone-shaped projection at an end portion is inserted into the connecting head end surface opening portion and pressed to be sealed. Tube sealing method.   In a sealing method for applying a high pressure to the inside of a high-pressure fuel injection pipe having a connection head formed with a seat surface, the back of the neck lower part of the connection head is brought into contact with a stay block, and at least the seat surface shape The sheet surface deformation preventing surface of the sheet surface deformation preventing member having a sheet surface deformation preventing surface having a concave shape substantially matching with the axial center and having a through-hole in the tube axis direction at the shaft core, and then contacting the sheet surface The annular projection of the seal plug having an annular projection that is inserted into the sheet surface deformation prevention member and formed coaxially with the tube axis so as to surround the opening of the injection tube on the end surface is pressed against the end surface of the connection head, A method for sealing a high-pressure fuel injection pipe, characterized by encroaching and sealing.   In a sealing method for applying a high pressure to the inside of a high-pressure fuel injection pipe having a connection head formed with a seat surface, the back of the neck lower part of the connection head is brought into contact with a stay block, and at least the seat surface shape The sheet surface deformation preventing surface of the sheet surface deformation preventing member having a sheet surface deformation preventing surface having a concave shape substantially matching with the axial center and having a through-hole in the tube axis direction at the shaft core, and then contacting the sheet surface An annular protrusion formed coaxially with the tube axis so as to surround the opening of the injection tube is pressed against the end surface of the seal plug inserted into the sleeve-shaped sheet surface deformation preventing member on the opening end surface of the connection head. And sealing the high-pressure fuel injection pipe.   The method for sealing a high-pressure fuel injection pipe according to any one of claims 1 to 4, wherein the seat surface deformation preventing member has a sleeve shape.   6. When applying a high pressure to the inside of the high-pressure fuel injection pipe, the seat surface is pressed in the axial direction by the seat surface deformation preventing member and / or stay block. The high-pressure fuel injection pipe sealing method according to item.   The said sheet surface deformation | transformation prevention surface of the said sheet surface deformation | transformation prevention member has comprised the recessed part shape which substantially corresponds to the conical surface which continues to the said sheet surface, The one of Claim 1 thru | or 6 characterized by the above-mentioned. A method for sealing a high-pressure fuel injection pipe.   8. The soft metal for protecting the sheet surface is interposed between the sheet surface deformation preventing surface and the sheet surface of the sheet surface deformation preventing member, according to claim 1. A method for sealing a high-pressure fuel injection pipe.   The high pressure fuel injection according to any one of claims 1 to 7, wherein a soft metal layer for protecting the seat surface is provided on a seat surface deformation preventing surface of the seat surface deformation preventing member. Tube sealing method.   The method for sealing a high-pressure fuel injection pipe according to any one of claims 1 to 9, wherein the lower back of the neck of the connection head is brought into contact with a stay block via a nut and / or a washer.