JP2010159675A - Manufacturing method for common rail - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a common rail capable of improving the productivity as to the configuration of fixing an inner cylinder part to an outer cylinder part. <P>SOLUTION: The manufacturing method for the common rail comprising a rail body 40 having a hollow part 41, a crossing hole part 51 opened to the hollow part 41 in the direction orthogonal to the longitudinal direction of the rail body 40, an outer cylinder part 50 connected with a fuel piping 60 at the end part opposite to the hollow part 41, and a cylinder shaped inner cylinder part 70 provided inside the crossed hole part 51 comprises an assembly step of assembling the inner cylinder part 70 to the inside of the crossed hole part 51 of the outer cylinder part 50, and a fluid pressure applying step of introducing a liquid to an inner wall 72 of the inner cylinder part 70 and generating plastic deformation of the inner wall 72 by the internal pressure of the liquid at the inner cylinder part 70 and the outer cylinder part 50 assembled in the assembly step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a common rail, and is used, for example, in an accumulator fuel injection device for an internal combustion engine, and is suitable for application to a method for producing a common rail that accumulates fuel and distributes fuel to each cylinder.

  Conventionally, as a common rail, a rail having a rail body having a hollow portion for storing fuel therein and having an intersection hole opening in the hollow portion in a direction orthogonal to the longitudinal direction of the rail body is known ( Patent Document 1). In this type of common rail, there is one in which a cylindrical bush is installed in the cross hole.

  In the apparatus disclosed in Patent Document 1 as one type of manufacturing method of such a common rail, an “inner cylinder member” such as a bush is press-fitted into an intersecting hole portion of an “outer cylinder member” such as a rail body, thereby The “cylinder member” and the “outer cylinder member” are fixed. In this technique, a communication hole having a smaller diameter than the diameter of the cross hole portion can be provided separately from the rail body.

JP 2001-280217 A

  In the prior art according to Patent Document 1, since the communication hole is provided in the “inner cylinder member” which is a member different from the rail body, it is easy to change the shape and position of the communication hole. However, in the prior art, since the “inner cylinder member” and the “outer cylinder member” are fixed by fitting and fixing by press-fitting, both the “inner cylinder member” and the “outer cylinder member” are fitted. Since it is difficult to manage the parts accuracy and press-fitting load related to the above, there is a concern that the productivity will be lowered.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a method of manufacturing a common rail capable of improving productivity with respect to a configuration in which an inner cylindrical member is fixed in an outer cylindrical member. .

  In order to achieve the above object, the present invention comprises the following technical means.

That is, in the first aspect of the present invention, the rail main body having a hollow portion, the cross hole portion opening in the hollow portion in a direction orthogonal to the longitudinal direction of the rail main body, and the end opposite to the hollow portion are provided. In a method of manufacturing a common rail, comprising an outer cylindrical portion to which fuel piping is connected to a portion, and an inner cylindrical portion provided inside the intersecting hole portion and exhibiting a cylindrical shape,
In the assembly process of assembling the inner cylinder part inside the cross hole part of the outer cylinder part, and in the inner cylinder part and the outer cylinder part assembled in the assembly process, the liquid is introduced into the inner wall of the inner cylinder part, And a hydraulic load step of plastically deforming the inner wall with the internal pressure of the liquid.

  According to this, in the hydraulic load process, liquid is introduced into the inner wall of the inner cylinder part in the inner cylinder part and the outer cylinder part assembled by the assembly process, and the inner wall is plasticized by pressing the inner wall with the internal pressure of the liquid. Transformed. According to the plastic deformation action of the inner wall due to such a hydraulic pressure, even when the outer wall of the inner cylinder portion is not a plastic deformation area but an elastic deformation area, the inner cylinder is released after releasing the hydraulic load on the inner wall. Since the outer wall of the part is enlarged in diameter relative to that before the hydraulic load, the outer wall of the inner cylinder part that is enlarged with respect to the inner wall of the cross hole part of the outer cylinder part can be fixed.

Therefore, in the previous assembly process, the fitting between the inner wall of the cross hole portion of the outer cylinder part and the outer wall of the inner cylinder part is set to a fitting state such as an interference fit for press-fitting as in the prior art. There is no need to do so, and a loose fit such as a clearance fit can be set. As a result, it is not necessary to manage the parts accuracy and press-fitting load related to the fitting based on the press-fitting. According to the above-described invention, the parts accuracy and press-fitting related to the fitting based on the press-fitting are required. Since it is possible to complete the configuration in which the inner cylinder member is fixed in the outer cylinder member without managing the load and the like, productivity can be improved.

  The invention according to claim 2 is characterized in that, in the assembling step, the inner cylindrical portion protrudes toward the hollow portion with respect to the intersecting hole portion of the outer cylindrical portion and is temporarily locked.

  In such an invention, even if the fitting between the inner wall of the intersecting hole portion of the outer tubular portion and the outer wall of the inner tubular portion is set in a loose fitting state, the inner tubular portion is in the intersecting hole portion in the assembly process. Since it is assembled inside, there is a concern that the inner cylinder part moves from the cross hole part of the outer cylinder part. However, in the assembling step according to the second aspect of the present invention, the inner cylindrical portion is projected and locked to the hollow portion side with respect to the intersecting hole portion of the outer tubular portion. Can be assembled to prevent relative movement.

  Moreover, according to the invention described in claim 2, since the inner cylinder part is temporarily locked to the outer cylinder part in the assembling step, the jig is temporarily inserted into the hollow part. The end portion protruding toward the hollow portion of the inner cylinder portion can be easily locked.

Further, in the invention according to claim 3, in the method of manufacturing a common rail having a rail main body having a hollow portion and provided with an intersecting hole portion opening in the hollow portion in a direction orthogonal to the longitudinal direction of the rail main body,
A double cylinder part forming step in which the rail body is formed by an inner cylinder part that defines a hollow part and at least an opening of the cross hole part, and an outer cylinder part provided outside the inner cylinder part; In the assembly process of assembling inside the outer cylinder part, and in the inner cylinder part and the outer cylinder part assembled in the assembly process, the liquid is introduced into the inner wall of the inner cylinder part, and the inner wall is plasticized by the internal pressure of the liquid And a hydraulic load step to be deformed.

  According to this, in the hydraulic load process, liquid is introduced into the inner wall of the inner cylinder part in the inner cylinder part and the outer cylinder part assembled by the assembly process, and the inner wall is plasticized by pressing the inner wall with the internal pressure of the liquid. Transformed. According to the plastic deformation action of the inner wall due to such a hydraulic pressure, the outer wall of the inner cylinder portion is expanded in diameter after the hydraulic load on the inner wall is released, so that the inner wall of the outer cylinder portion is expanded. On the other hand, the outer wall of the inner cylindrical portion whose diameter is increased can be fixed.

  Therefore, in the previous assembly process, the fit between the inner wall of the cross hole portion of the outer cylinder part and the outer wall of the inner cylinder part can be set in a loose fit state such as a gap fit, so press-fit is assumed. It is not necessary to manage the parts accuracy and press-fitting load related to the fitting.

  Moreover, according to the invention described in claim 3, in the previous double tube portion forming step, the inner tube portion and the outer tube portion are formed as separate members in the rail body, so that the stress is easily concentrated in the inner tube portion. Processing of the inner cylindrical portion around the opening of the hole portion is facilitated.

  According to the third aspect of the invention described above, the configuration in which the inner cylindrical member is fixed in the outer cylindrical member is completed without the need for management of component accuracy and press-fitting load related to fitting on the premise of press fitting. Therefore, productivity can be improved.

  The invention according to claim 4 is characterized in that, in the assembling step, the positions of the cross hole portions are matched in the inner cylinder portion and the outer cylinder portion to be temporarily locked.

  According to the invention described in claim 4, in the assembly process, since the positions of the cross hole portions are matched and locked in the inner cylinder portion and the outer cylinder portion, in the actual use environment of the common rail, the hollow portion of the rail body and Of the intersecting hole portion, the portion of the inner cylindrical portion around the opening of the intersecting hole portion is an area where stress is easily concentrated. Such a region where stress is easily concentrated may cause a decrease in durability.

  However, in the hydraulic pressure loading process according to the invention described in claim 4, by applying a plastic deformation action to the inner wall of the inner cylindrical portion, compressive residual stress is applied to the portion of the inner cylindrical portion around the opening of the cross hole portion. It will be. According to the compressive residual stress action in the region where stress is likely to concentrate, the maximum stress can be reduced, so that the durability can be improved.

  According to the fourth aspect of the present invention, the durability and productivity can be improved at the same time by performing the hydraulic load process.

  In the invention according to claim 5, the assembling step has a locking step of locking the inner cylindrical portion and the outer cylindrical portion by attaching a sealing jig to at least the inner cylindrical portion. It is characterized by.

  According to this, in an engagement process, an inner cylinder part and an outer cylinder part are latched by attaching a sealing jig to at least an inner cylinder part in an assembly process. According to this, the size of the liquid volume in the inner cylinder part that receives the internal pressure of the liquid in the subsequent hydraulic pressure loading process is limited. Therefore, while suppressing the energy consumption of the internal pressure generating source that forms the internal pressure, the liquid pressure in the inner cylinder part sealed with the sealing jig is increased, and a plastic deformation region corresponding to the liquid pressure is formed on the inner wall. Can do.

  In the invention according to claim 6, after the inner cylinder part is fixed in the outer cylinder part by the internal pressure of the liquid in the hydraulic load step, the sealing jig is removed from the inner cylinder part, thereby A release step for releasing the temporary locking is provided.

  According to this, regarding the locking of the inner cylinder part and the outer cylinder part, the inner cylinder part can be temporarily locked and unlocked by attaching and removing the sealing jig to the inner cylinder part. No special processing is required for both the outer cylindrical portion and the outer cylindrical portion.

It is a general-view figure which shows the common rail to which the manufacturing method by 1st Embodiment of this invention is applied. It is the II-II sectional view taken on the line in FIG. It is a schematic diagram which shows the structure of the pressure accumulation type fuel-injection apparatus carrying a common rail. It is a schematic diagram which shows an example of the manufacturing method of the common rail by 1st Embodiment. It is the VV sectional view taken on the line in FIG. It is a schematic diagram which shows an example of the manufacturing method of the common rail concerning 2nd Embodiment. It is the VII-VII sectional view taken on the line in FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the component corresponding in each embodiment.

(First embodiment)
1-3 have shown the common rail which applies an example of the manufacturing method of the common rail by embodiment of this invention. 4 and 5 show an example of a method for manufacturing a common rail.

  As shown in FIGS. 1 and 3, the accumulator fuel injection device 10 includes a common rail 30, a fuel injection pump 11, and a fuel injection valve 12. The fuel injection pump 11 sucks fuel from the fuel tank 13 via the suction passage 14. The fuel injection pump 11 pressurizes the sucked fuel to a predetermined pressure and supplies it to the common rail 30. The surplus fuel in the fuel injection pump 11 is discharged to the fuel tank 13 via the discharge passage 15. The fuel injection pump 11 supplies pressurized fuel to the common rail 30 via a supply pipe 16 serving as a “supply passage”. The common rail 30 stores the fuel pressurized by the fuel injection pump 11 so as to be maintained at a predetermined pressure, and distributes the fuel to the fuel injection valves 12 mounted in each cylinder of the engine (not shown).

  A pressure sensor 31 is provided on the common rail 30. The pressure sensor 31 detects the pressure of the fuel stored in the common rail 30. The pressure sensor 31 is connected to an electronic control device (not shown). The electronic control device adjusts the flow rate of the fuel discharged from the fuel injection pump 11 based on the pressure of the fuel in the common rail 30 detected by the pressure sensor 31. The common rail 30 is provided with a pressure control valve 32. The pressure control valve 32 opens when the fuel pressure stored in the common rail 30 becomes greater than a predetermined value. The fuel discharged from the common rail 30 by opening the pressure control valve 32 is returned to the fuel tank 13 via the discharge passage 15.

  The pressure sensor 31 and the pressure control valve 32 are attached to both shaft ends of the rail body 40 of the common rail 30 by a joining means such as screw fastening. In this embodiment, the pressure sensor 31 and the pressure control valve 32 are provided with male screw portions (not shown), and the male screw portion and the female screw portion that can be screwed are provided at both shaft end portions of the common rail 30.

  As shown in FIGS. 1 and 2, the common rail 30 includes a rail body 40 and a pipe connection portion 50 as an “outer cylinder portion”. The rail body 40 is formed in a hollow cylindrical shape. As shown in FIG. 1, the plurality of pipe connection portions 50 protrude radially outward from the rail body 40. In the present embodiment, five pipe connection portions 50 are provided along the longitudinal direction of the container body 40 (the left-right direction in the drawing). A supply pipe 16 connected to the fuel injection pump 11 is connected to one of the five pipe connections 50. Fuel pipes 60 connected to the fuel injection valves 12 are connected to the remaining four pipe connection parts 50.

  As shown in FIG. 2, the cylindrical rail body 40 has a hollow portion 41 formed therein. The hollow portion 41 extends in the longitudinal direction of the rail body 40. The pipe connection portion 50 protrudes outward in the orthogonal direction orthogonal to the longitudinal direction of the rail body 40. In the present embodiment, the pipe connection portion 50 is formed as a single member integrally with the rail body 40. The pipe connection part 50 has a seat surface part 59 at the end opposite to the hollow part 41. In the seat surface portion 59, the inner wall of the pipe connection portion 50 is formed in a truncated cone shape whose inner diameter decreases toward the hollow portion 41 side.

  The pipe connecting portion 50 includes an intersecting hole portion 51 that communicates with the pipe connecting portion 50 on the inner peripheral side. The intersecting hole portion 51 has one opening connected to the hollow portion 41 and the other opening connected to the pipe. The connecting portion 50 opens to the seating surface portion 59 at the end opposite to the rail body 40. In other words, the cross hole portion 51 penetrates the pipe connection portion 50 and the rail body 40 and is connected to the hollow portion 41.

  The intersecting hole portion 51 is formed with substantially the same inner diameter from the end portion on the hollow portion 41 side to the end portion on the opposite side to the hollow portion 41. In the present embodiment, as shown in FIG. 2, the central axis of the cross hole 51 is arranged so as to coincide with the central axis of the rail body 40 and the hollow part 41 (perpendicular to the paper surface in the drawing). However, the central axis of the cross hole 51 may be offset so as to deviate from the central axis of the hollow portion 41. Regardless of the arrangement, the inner wall portion around the opening on the hollow portion 41 side of the cross hole portion 51 is a region where stress is easily concentrated by the pressure of the fuel stored in the common rail 30 during operation of the accumulator fuel injector 10. It becomes.

  On the outer wall of the pipe connection portion 50, a male screw portion 53 for connecting to either the fuel pipe 60 or the supply pipe 16 is formed. A connection nut (not shown) as a connection component on the piping side is attached to the male screw portion 53. A male screw part 53 and a female screw part that can be screwed are formed on the inner wall of the connection nut. The connection nut is engaged with the main body of the pipe, and the main body of the pipe is a cylindrical pipe that forms a fuel passage therein. The main body of the specific pipe has a connection head that presses against the seat surface portion 59 at the end on the common rail 30 side.

  A bush 70 as an “inner cylinder part” is accommodated in the cross hole 51 of the pipe connection part 50. The bush 70 is formed in a cylindrical shape and narrows the flow path diameter between the cross hole 51 and the hollow portion 41. The pressure pulsation propagated to the cross hole 51 via the fuel pipe 60 is attenuated by the bush 70, thereby suppressing the pressure fluctuation in the hollow part 41 due to the pressure pulsation. By such a bush 70, the influence of pressure pulsation on the fuel supplied from the common rail 30 to the fuel injection valve is suppressed.

  Moreover, in this embodiment, the bush 70 is arrange | positioned so that it may protrude in the hollow part 41 side.

  The basic configuration of the common rail 30 has been described above. Hereinafter, the manufacturing method of the common rail of 1st Embodiment is demonstrated based on FIG.

(Production method)
(Formation process)
In the forming process, all the elements 40, 50, and 70 are made of metal. The rail body 40 and the pipe connection part 50 are integrally formed by hot forging or the like. And the inner walls 42 and 52 which divide and form the hollow part 41 and the cross hole part 51 in the said integrated elements 40 and 50 are formed by cutting. In this process, the bush 70 is formed in a cylindrical shape by cutting or pressing as a separate member from the pipe connecting portion 50. At this time, the outer diameter of the bush 70 is formed to be smaller than the inner diameter of the inner wall 52 of the intersecting hole portion 51, that is, to have a diameter that is a clearance fit.
(Assembly process)
The assembly process is a pre-process for performing a hydraulic load process described later. Therefore, here, this is not the final assembly process in which the pressure sensor 31 and the pressure control valve 32 are attached to both shaft ends of the rail body 40.

  In this assembling step, the bush 70 is inserted into the intersecting hole 51 of the pipe connecting portion 50, and the bush 70 is locked at a predetermined position with respect to the intersecting hole 51. Specifically, a jig (hereinafter, first sealing jig) 81 shown in FIGS. 4 and 5 is used. The first sealing jig 81 has a rod shape. In this step, the sealing jig 81 is inserted into the hollow portion 41 of the rail body 40, and one bushing 70 is supported by the first sealing jig 81 to hollow the bush 70 with respect to the cross hole 51. It locks in the position which protrudes to the part 41 side.

The first sealing jig 81 preferably includes a curved surface portion 81 a along the inner wall 42 of the hollow portion 41 and a flat portion 81 b in contact with the shaft end portion of the bush 70 in the outer peripheral direction. Thus, when the flat portion 81b and the end surface of the one shaft end of the bush 70 are brought into contact with each other, the curved surface portion 81a is supported by the inner wall 42 of the hollow portion 41. The contact state in contact with the end face of the portion can be stably secured. Thereby, the contact state between the end surface of the one end portion of the bush 70 and the flat portion 81b of the first sealing jig 81 can be obtained by surface contact, but the bush 70 is pressed against the first sealing jig 81. It becomes possible to keep airtight according to the magnitude of the force.
(Hydraulic load process)
In the hydraulic pressure loading step, the hydraulic fluid is introduced into the bush 70, and the internal pressure due to the hydraulic pressure of the hydraulic fluid is pressed against the inner wall 72 of the bush 70. In this step, the inner wall 72 of the bush 70 is applied with the internal pressure. Is plastically deformed. The working fluid corresponds to the liquid recited in the claims.

  In the hydraulic pressure loading step, a second sealing jig 82 that seals the other shaft end portion of the bush 70 and a high-pressure generation source 90 as an “operating hydraulic pressure generation source” are used.

  The distal end portion of the second sealing jig 82 has a convex conical surface portion, and the conical surface portion functions as a pressing surface that presses against the corner portion (edge) of the inner wall 72 of the bush 70 in a sealable manner. To do. In addition, the front-end | tip part of the 2nd sealing jig 82 is not restricted to what has a conical surface like the said conical surface part, You may have a spherical surface. Even if it is the 2nd sealing jig 82 which exhibits any shape, the inner wall space 71 of the inner wall 72 of the bush 70 is sealed by combining with the 1st sealing jig 81.

  The high pressure generation source 90 includes a pressure-increasing piston (not shown) that supplies hydraulic fluid to the inner wall space 71 of the bush 70 and reduces the volume of the sealed inner wall space 71 to increase the pressure of the hydraulic fluid. Yes. The high pressure generation source 90 and the second sealing jig 82 are connected by a hydraulic fluid supply passage 91, and the volume of the hydraulic fluid supply passage 91 is included in the volume of the inner wall space 71.

  The hydraulic fluid supply passage 91 preferably suppresses the volume by reducing the cross-sectional area and the passage length of the hydraulic fluid supply passage 91.

  The hydraulic fluid uses hydraulic fluid such as oil. When such hydraulic oil is pressurized, the fluidity is lowered and it is difficult to flow. When the fluidity is excessively lowered, there is a concern that the hydraulic fluid pressure generated on the high pressure generation source 90 side and the actual hydraulic fluid pressure actually generated in the inner wall space 71 are excessively shifted. Therefore, it is preferable to use the specific hydraulic oil whose fluidity is not excessively lowered in the hydraulic pressure range for forming the target internal pressure among the hydraulic oils as described above.

  Next, in the present embodiment, the hydraulic load step includes a hydraulic fluid filling step, a hydraulic fluid pressurizing step, and a releasing step.

  In the hydraulic fluid filling step, the hydraulic fluid is fed from the high-pressure generating source 90 to the inner wall space 71 of the bush 70 to release air from the inner wall space 71 and fill the inner wall space 71 with the hydraulic fluid. Specifically, in the hydraulic fluid filling step, the surface of the bush 70 and the first sealing jig 81 is set by setting the pressing force of the second sealing jig 82 against the other shaft end of the bush 70 relatively low. The contact state due to the contact is in a state in which the hydraulic fluid can easily flow out. As a result, the hydraulic fluid that has flowed into the inner wall space 71 via the second sealing jig 82 flows out from the other shaft end side of the bush 70 to the outside, so that air is vented together with the outflow of the hydraulic fluid. .

  In the hydraulic fluid filling step, when the hydraulic fluid filling is completed by air bleeding, the set force for forming the target internal pressure is secured by increasing the pressing force by the second sealing jig 82. To do.

  In the hydraulic fluid pressurization step, the hydraulic fluid pressure in the inner wall space 71 of the bush 70 is increased to the target hydraulic fluid pressure that is the target internal pressure by operating the pressure increasing piston of the high pressure generation source 90. Thereby, the inner wall 72 is plastically deformed by pressing the inner wall 72 with the target hydraulic pressure, and the respective diameters of the inner wall 72 and the outer wall 73 are expanded.

  At this time, even if the entire region of the bush 70 is not plastically deformed, the plastic deformation layer may be present in a part of the region. In other words, the plastic deformation layer expands in the radial direction from the inner wall 72 to the outer wall 73 in accordance with the magnitude of the inner pressure, but the plastic deformation layer is formed on the inner wall 72 side, and the outer wall There may be a region that remains the elastic deformation layer on the 73 side. This is because the outer diameter of the outer wall 73 of the bush 70 is larger than the outer diameter before the hydraulic load even after releasing the hydraulic pressure load on the inner wall 72 due to the target hydraulic pressure.

  By performing the hydraulic load processing in such a hydraulic fluid pressurizing step, the fitting state of the outer diameter of the outer wall 73 of the bush 70 with respect to the inner diameter of the inner wall 52 of the cross hole 51 is changed from the gap fit before the hydraulic pressure loading. Converted to an interference fit after hydraulic loading. Thereby, the outer wall 73 of the bush 70 can be fixed to the inner wall 52 of the pipe connection part 50 after the hydraulic load.

  As a result, it is not necessary to set the fitting relationship between the bush 70 and the pipe connection portion 50 to an interference fit that assumes press-fitting in the forming process as in the prior art. It is not necessary to manage parts accuracy and press-fitting load.

  In the releasing step, the hydraulic load applied to the inner wall space 71 of the bush 70 is released, and the first sealing jig 81 and the second sealing jig 82 are removed from the bush 70.

  In the present embodiment described above, the configuration in which the bush 70 is fixed in the intersecting hole portion 51 of the pipe connection portion 50 is completed without the management of the component accuracy and the press-fit load related to the fitting on the premise of press fitting. Therefore, productivity can be improved.

  Moreover, in this embodiment demonstrated above, the fitting state in the bush 70 and the piping connection part 50 after a formation process is set to the loose fitting state called clearance fit. Therefore, if the bush 70 is simply inserted into the intersecting hole 51 of the pipe connecting portion 50 in the assembling process, the bush 70 may move from the intersecting hole 51 and fall off. However, in this embodiment, since the bush 70 is supported by the first sealing jig 81, the first sealing jig 81 can be assembled to prevent relative movement between the cross hole 51 and the bush 70.

  In addition, the first sealing jig 81 can be temporarily locked and unlocked by attaching to and removing from the bush 70 with respect to the locking between the cross hole 51 and the bush 70. No special processing is required for both 70 and the pipe connection 50.

  In addition, the first sealing jig 81 can easily lock the plurality of bushes 70 and the intersecting hole portions 51 simply by being inserted into the hollow portion 41.

  Further, in the present embodiment described above, the locking between the cross hole 51 and the bush 70 is realized by attaching the first sealing jig 81 and the second sealing jig 82 to the bush 70. The sealing jig 81 and the second sealing jig 82 simultaneously seal both axial ends of the bush 70. According to this, the magnitude | size of the hydraulic fluid volume in the inner wall space 71 which loads hydraulic fluid pressure in a subsequent hydraulic pressure load process can be restrict | limited. Therefore, the hydraulic pressure of the inner wall space 71 sealed by both the sealing jigs 81 and 82 can be effectively increased while suppressing the energy consumption of the pressure generation source 90 that forms the internal pressure and the immediate hydraulic pressure load. A plastic deformation region corresponding to the hydraulic pressure can be formed on the inner wall 72 of the bush 70.

  In addition, it is preferable to use the metal base material whose hardness is low for the bush 70 compared with the metal base material of the pipe connection part 50, ie, the integrated elements 40 and 50. As a result, the bush 70 is easily plastically deformed even at a relatively low hydraulic pressure load. Therefore, since the plastic deformation layer can be expanded with respect to the same hydraulic pressure load, the bush 70 can be easily fixed to the inner wall 52 of the pipe connection portion 50 after the hydraulic pressure load.

(Second Embodiment)
A second embodiment is shown in FIGS. The second embodiment is a modification of the first embodiment. In 2nd Embodiment, an example which makes the rail main body 40 the double cylinder part structure which has the inner side cylinder part 140 and the outer side cylinder part 240 is shown. 6 and 7 show an example of a method for manufacturing a common rail.

  A characteristic manufacturing method of the common rail 30 according to the present embodiment is to integrally fix the inner cylindrical portion 140 and the outer cylindrical portion 240 to each other without press-fitting the inner cylindrical portion 140 and the outer cylindrical portion 240. .

  First, the configuration of the common rail 30 according to the present embodiment will be described below. As shown in FIGS. 6 and 7, the rail body 40 has a cylindrical inner cylindrical portion 140 and an outer cylindrical portion 240 provided outside the inner cylindrical portion 140, and the inner cylindrical portion 140 and the outer cylindrical portion 240. It is formed by a separate member.

  The inner cylinder part 140 defines the hollow part 41 and at least the opening part on the hollow part 41 side in the intersecting hole part 51. Further, as shown in FIGS. 6 and 7, the outer cylindrical portion 240 is formed in each cross hole 51 corresponding to the portion 51 a so as to substantially coincide with the position of the portion 51 a of each cross hole 51 in the inner cylindrical portion 140. The other part 51b is formed.

  Here, in the present embodiment, the bush 70 described in the first embodiment may be provided in the intersecting hole 51, or the bush 70 may not be provided.

Next, a method for manufacturing the common rail 30 according to the present embodiment will be described below.
(Formation process)
In the forming process, both elements 140 and 240 are made of metal. The outer cylinder part 240 is formed by hot forging or the like. And in the outer side cylinder part 240, the inner wall 52 which divides and forms the other part 51b of the cross hole part 51 is formed by cutting. Furthermore, an inner wall 242 that accommodates the inner cylinder part 140 inside is formed in the outer cylinder part 240 by cutting.

  In this step, the inner cylinder portion 140 is formed by a removal process such as a cutting process. In the inner cylinder part 140, the hollow part 41 and the inner wall 52 which partitions and forms the part 51a which comprises the said opening part side of the cross hole part 51 are formed by cutting. At this time, the outer diameter of the inner cylindrical portion 140 is formed to be smaller than the inner diameter of the inner wall 242 of the outer cylindrical portion 240, that is, a diameter that is a clearance fit.

In addition, this formation process is corresponded to the double cylinder part formation process as described in a claim.
(Assembly process)
In the assembling step, the inner cylinder part 140 is inserted into the inner wall 242 of the outer cylinder part 240, and the inner cylinder part 140 is locked to a predetermined position with respect to the outer cylinder part 240. Specifically, sealing jigs 181, 182, and 183 shown in FIGS.

  The front ends of the first sealing jig 181 and the second sealing jig 182 have a convex conical surface portion, and the conical surface portion is at the corner (edge) of the inner wall 42 of the inner cylindrical portion 140. It functions as a pressing surface that presses in a sealable manner. In addition, the third sealing jig 183 has a conical surface portion having a convex shape at the tip portion, and the conical surface portion is formed at a corner portion (edge) of a portion 51 a of the intersecting hole portion 51 of the inner cylindrical portion 140. It functions as a pressing surface that presses in a sealable manner.

  In the cross hole 51, the inner diameter of the portion 51a of the inner cylindrical portion 140 is substantially the same as the inner diameter of the portion 51b of the outer cylindrical portion 240 or slightly smaller than the inner diameter of the portion 51b.

In this step, the first and second sealing jigs 181 and 182 are attached to both axial ends of the inner cylinder 140, and the cross hole 51 of the inner cylinder 140 is formed at the tip of the third sealing jig 183. The portion 51a is supported. By attaching these sealing jigs 181, 182, and 183 to the inner cylindrical portion 140, the inner cylindrical portion 140 so that both portions 51 a and 51 b of the intersecting hole portion 51 of the inner cylindrical portion 140 and the outer cylindrical portion 240 substantially coincide with each other. And the outer cylinder part 240 is latched.
(Hydraulic load process)
The hydraulic load step is a step of introducing hydraulic fluid into the inner cylinder portion 140 and pressing the inner pressure (hydraulic load) due to the hydraulic pressure of the hydraulic fluid against the inner wall 42 of the inner cylinder portion 140. In this step, With the internal pressure, the inner wall 42 of the hollow portion 41 and the inner wall 52 on the part 51a side of the cross hole 51 are plastically deformed in the inner cylindrical portion 140.

  The high pressure generation source 90 is connected to the second sealing jig 182 via the hydraulic fluid supply passage 91, and the hydraulic fluid from the high pressure generation source 90 passes through the second sealing jig 182 and part of the hollow portion 41. It flows into the inner wall space portion on the 51a side. By the combination of the sealing jigs 181, 182, and 183, the hollow portion 41 and the inner wall space portion on the part 51a side are sealed.

  In the hydraulic fluid filling step, the hydraulic fluid is fed from the high-pressure generation source 90 to the hollow portion 41 and the inner wall space portion on the side of the portion 51a of the inner cylinder portion 140, thereby air in the inner wall space portion on the side of the hollow portion 41 and the portion 51a. In addition, the working fluid is filled in the hollow portion 41 and the inner wall space portion on the side of the portion 51a. Specifically, for example, by setting the pressing force of any one specific third sealing jig among the plurality of third sealing jigs 183 to the inner cylindrical portion 140 to be relatively low, the specific third The working fluid can flow out from the periphery of the sealing jig. As a result, the air can be easily removed along with the outflow of the hydraulic fluid.

  In the hydraulic fluid filling step, when filling of the hydraulic fluid by air bleeding is completed, the set value for forming the target internal pressure (hydraulic load) is increased by increasing the pressing force by the specific third sealing jig. Make sure to secure.

  In the hydraulic fluid pressurization step, the hydraulic fluid pressure in the hollow portion 41 of the inner cylindrical portion 140 and the inner wall space portion on the side of the portion 51a is set to a target internal pressure by operating the pressure increasing piston of the high pressure generation source 90. Increase to hydraulic fluid pressure. Thereby, since the outer diameter of the outer wall 143 of the inner cylinder part 140 can be expanded from before the hydraulic pressure load, management of component accuracy and press-fitting load related to fitting on the premise of press-fitting is unnecessary, The structure which adheres the inner cylinder part 140 to the outer cylinder part 240 can be completed.

  At this time, the magnitude of the hydraulic load (internal pressure) to be set is plastic deformation in a part of the region, rather than setting the hydraulic load to such an extent that a plastic deformation layer is formed in the entire region in the inner cylindrical portion 140. It is preferable to set the hydraulic load so that the layer exists. As a result, the inner wall 42 and the inner wall 52 corresponding to the hollow portion 41 and the inner wall space portion on the part 51a side are compressed and retained in the plastic deformation layer by the shrinking action of the elastic deformation layer to be restored after the hydraulic load is released. Stress can be generated.

  In particular, among the inner wall 42 and the inner wall 52, stress concentration tends to occur in the inner wall 42 and the inner wall 52 around the opening on the part 51 a side of the cross hole 51. Such a region where stress is easily concentrated may cause a decrease in durability.

  On the other hand, in the present embodiment, the inner cylinder portion 140 is plastically deformed in the hydraulic load step, thereby generating compressive residual stress in the inner wall 42 and the inner wall 52, and the periphery of the opening portion where the stress is easily concentrated. The compressive residual stress can be applied to the inner wall 42 and the inner wall 52 of the first wall. As a result, the maximum stress generated in the inner wall 42 and the inner wall 52 around the opening in the region where the stress is likely to be concentrated can be reduced by the pre-applied compressive residual stress, so that the durability of the rail body 40 can be improved. .

  Further, in the present embodiment described above, since the inner cylindrical portion 140 and the outer cylindrical portion 240 are formed as separate members in the rail body 40, the forming step is an opening portion in the region where stress concentration is likely to occur in the inner cylindrical portion 140. The peripheral inner wall 42 and inner wall 52 can be easily processed. As a result, regarding the improvement of productivity, the configuration in which the inner cylinder part 140 is fixed in the outer cylinder part 240 is completed without the management of the component accuracy and the press-fitting load related to the fitting on the premise of press-fitting. In addition, productivity can be improved more effectively.

  In addition, the magnitude of the hardness of the metal base material of the inner cylinder part 140 decreases the magnitude of the plastic deformation that occurs as the magnitude of the hardness increases, while increasing the generated compressive residual stress. . Therefore, it is preferable that the hardness of the inner cylinder part 140 is set to a hardness range in which the configuration in which the inner cylinder part 140 and the outer cylinder part 240 are fixed and the magnitude of the compressive residual stress to be applied in advance are compatible.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. .

  (1) In the present embodiment described above, the hydraulic fluid used in the hydraulic load step is hydraulic fluid such as oil. However, the present invention is not limited to this, and any fluid having fluidity in the set hydraulic load range may be used. Any liquid may be used.

  (2) In the first embodiment, the length of the bush 70 as the “inner cylinder part” is set so as to protrude toward the hollow part 41 with respect to the intersecting hole part 51. May be set to a length that fits within the cross hole 51.

  (3) Moreover, in 2nd Embodiment, the internal diameter of the part 51a of the inner side cylinder part 140 and the part 51b of the outer side cylinder part 240 was made into the substantially same diameter in the cross hole part 51. FIG. Not limited to this, the inner diameter of the part 51a of the inner cylinder part 140 may be set smaller than the inner diameter of the part 51b of the outer cylinder part 240 like a throttle part.

  When the inner diameter of the portion 51a of the inner cylindrical portion 140 is set as small as the throttle portion in this way, the pressure pulsation transmitted to the cross hole portion 51 through the fuel pipe 60 is caused by the throttle portion (orifice) function of the portion 51a. By attenuating, the pressure fluctuation in the hollow portion 41 due to the pressure pulsation can be suppressed.

DESCRIPTION OF SYMBOLS 10 Accumulation type fuel injection device 12 Fuel injection valve 16 Supply piping (supply passage)
30 Common rail 31 Pressure sensor 32 Pressure control valve 40 Rail body 41 Hollow part 42 Inner wall 50 Piping connection part (outer cylinder part)
51 Crossing hole part 52 Inner wall 53 Male thread part 59 Seat surface part 60 Fuel piping 70 Bush (inner cylinder part)
71 inner wall space 72 inner wall 81 first sealing jig (sealing jig)
82 Second sealing jig (sealing jig)
90 High pressure source (Internal pressure source)
91 Hydraulic fluid supply passage

Claims (6)

A rail body having a hollow portion, a cross hole portion opening in the hollow portion in a direction orthogonal to the longitudinal direction of the rail body, and a fuel pipe connected to an end opposite to the hollow portion In a method for manufacturing a common rail, comprising an outer cylindrical portion and an inner cylindrical portion provided inside the intersecting hole portion and exhibiting a cylindrical shape,
An assembling step of assembling the inner cylinder part inside the intersecting hole part of the outer cylinder part;
In the inner tube portion and the outer tube portion assembled in the assembly step, a liquid is introduced into the inner wall of the inner tube portion, and the inner wall is plastically deformed by the inner pressure of the liquid; and
A method of manufacturing a common rail, comprising:   2. The common rail according to claim 1, wherein, in the assembling step, the inner cylindrical portion is protruded toward the hollow portion with respect to the intersecting hole portion of the outer cylindrical portion and temporarily locked. Production method. In the method of manufacturing a common rail, which has a rail body having a hollow portion, and is provided with an intersecting hole portion opening in the hollow portion in a direction orthogonal to the longitudinal direction of the rail body,
A double cylinder part forming step in which the rail body is formed by an inner cylinder part that defines the hollow part and at least an opening of the cross hole part, and an outer cylinder part provided outside the inner cylinder part;
An assembling step of assembling the inner cylinder part inside the outer cylinder part;
In the inner tube portion and the outer tube portion assembled in the assembly step, a liquid is introduced into the inner wall of the inner tube portion, and the inner wall is plastically deformed by the inner pressure of the liquid; and
A method of manufacturing a common rail, comprising:   4. The method of manufacturing a common rail according to claim 3, wherein in the assembling step, the positions of the intersecting hole portions are matched in the inner cylindrical portion and the outer cylindrical portion, and are temporarily locked.   The assembly process includes a locking step of locking the inner cylindrical portion and the outer cylindrical portion by attaching a sealing jig to at least the inner cylindrical portion. The manufacturing method of the common rail as described in any one of Claim 4.   After the inner cylinder part is fixed in the outer cylinder part by the internal pressure of the liquid in the hydraulic load step, the sealing jig is removed from the inner cylinder part, thereby temporarily engaging the sealing jig. The method for manufacturing a common rail according to claim 5, further comprising a releasing step for releasing the stop.

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