Injector holder, delivery pipe, and method for manufacturing a delivery pipe

Abstract

To provide an injector holder that can achieve both low-cost manufacturing and improved mechanical strength. [Solution] The injector holder 20 for holding the injector that discharges fuel supplied from the discharge hole 12 of the fuel pipe 10, which is the main body of the delivery pipe 1, is a bottomed cylindrical metal press-formed product having a cylindrical portion 31 and a bottom portion 41, the inside of which of the cylindrical portion 31 is a space for inserting the injector, and a through hole 42 for communicating with the discharge hole 12 is formed in the bottom portion 41, and the holder holder 30 comprises a cylindrical reinforcing sleeve 50 which is separate from the holder holder 30 and has an inner diameter sized to fit over the cylindrical portion 31.

Description

Technical Field

[0001] The present invention relates to an injector holder, a delivery pipe including the injector holder, and a method for manufacturing the delivery pipe.

Background Art

[0002] In an engine fuel supply system, fuel pumped from a fuel tank is supplied to an injector through a delivery pipe, and the fuel is injected from the injector into an intake port or combustion chamber of the engine. The delivery pipe mainly includes a fuel pipe and an injector holder provided integrally or integrally with the fuel pipe. The injector holder has a space for inserting the injector. The space communicates with the inside of the fuel pipe and pressurized fuel is supplied thereto. Therefore, the injector holder needs to have sufficient mechanical strength to withstand the pressure of the fuel supplied to the injector.

[0003] In recent years, with the increase in the pressure of the fuel supplied to the injector, improvement of the mechanical strength of the injector holder has been demanded. When the injector holder is constituted by a press-formed product formed from a metal flat plate material (see Patent Document 1), it can be manufactured at low cost, but there is a problem that the mechanical strength is insufficient. On the other hand, increasing the thickness of the metal flat plate material, which is the raw material for press forming, is also conceivable, but since the material of the flat plate material and the materials constituting the punch and die for press forming are limited, the cost becomes high and there is a problem that press forming itself is difficult. On the other hand, there is an injector holder having a thick wall formed by a casting or forging (see Patent Document 2). However, in the case of castings and forgings, there is a problem that a large amount of machining is required, resulting in high costs.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Therefore, in view of the above circumstances, the present invention aims to provide an injector holder that can achieve both low-cost manufacturing and improved mechanical strength, a delivery pipe equipped with the same, and a method for manufacturing the same. [Means for solving the problem]

[0006] To solve the above problems, the injector holder according to the present invention is "This is an injector holder for holding the injector that discharges fuel supplied from the discharge hole of the fuel piping, which is the main body of the delivery pipe." A metal press-formed product having a cylindrical section and a bottom section, wherein the inside of the cylindrical section is a space for inserting an injector, and a through hole for communicating with the discharge hole is formed in the bottom section, A reinforcing sleeve, which is cylindrical and separate from the holder body, and has an inner diameter that is sized to fit onto the cylindrical portion, It is "equipped with."

[0007] In this configuration, the injector holder comprises a bottomed cylindrical holder body and a cylindrical reinforcing sleeve. The holder body has an internal space into which the injector is inserted, and pressurized fuel is introduced into that internal space. Therefore, the cylindrical part of the holder body needs to withstand the pressure of the pressurized fuel acting from the inside, and its mechanical strength needs to be increased in order to increase the pressure of the injected fuel. In contrast, in this configuration, the reinforcing sleeve has an inner diameter that is sized to fit onto the cylindrical part of the holder body, so by fitting the reinforcing sleeve onto the cylindrical part, a double structure is created, and the mechanical strength of the injector holder can be increased.

[0008] Furthermore, the holder body is a metal press-formed product. If the mechanical strength of the holder body itself were to be increased, it would be necessary to increase the thickness of the metal plate material used as the raw material for press forming. This would limit the materials that can be used for both the plate material and the punches and dies used in press forming, resulting in high costs and making press forming difficult. In contrast, with this configuration, even if the holder body is a press-formed product manufactured at low cost from thin plate material using conventional press forming equipment, the mechanical strength of the injector holder can be increased by creating a double structure of the holder body and reinforcing sleeve at the wall where the pressure of the pressurized fuel is applied.

[0009] The holder body is a bottomed cylindrical shape with a cylindrical section and a bottom, but it is not always used with the bottom facing downwards. The holder body, along with the fuel lines and injectors, is mounted in an appropriate position depending on the engine being used, so the direction the bottom faces changes depending on the engine.

[0010] The delivery pipe according to the present invention is "A delivery pipe for holding the injector and supplying fuel to the injector, A fuel pipe consisting of a metal pipe with a circular cross-section, and having discharge holes drilled through its side circumferential wall, A metal press-formed product having a cylindrical section and a bottom section, the holder body having a cylindrical section with a bottom section and a space for inserting an injector inside the cylindrical section, and a through hole formed in the bottom section, The holder comprises a cylindrical reinforcing sleeve, which is separate from the holder body and is fitted onto the cylindrical portion and joined to the outer surface of the cylindrical portion, The holder body is joined to the fuel piping with the through hole communicating with the discharge hole.

[0011] This configuration is a delivery pipe equipped with the injector holder described above. With this configuration, the wall of the injector holder that is subjected to the pressure of pressurized fuel has a double structure consisting of the holder body and a reinforcing sleeve, thereby increasing its mechanical strength and enabling the supply of high-pressure fuel to the injector.

[0012] The delivery pipe according to the present invention has the above configuration in addition to the above configuration, The bottom portion may have a curved surface that conforms to the circumferential surface of the fuel pipe.

[0013] In this configuration, the bottom has a curved surface that conforms to the side surface of the fuel pipe. By joining the curved surface to the side surface, the joining area between the holder body and the fuel pipe can be maximized, resulting in a strong bond between the two. If the bottom were flat, in order to join the holder body and the fuel pipe over a large area, it would be necessary to process a portion of the fuel pipe, which is a pipe with a circular cross-section, to make it flat. In contrast, with this configuration, there is no need to process the fuel pipe when making this joint. Furthermore, since the holder body is formed by press working, it is easy to incorporate a process of forming the curved surface by press working as part of the forming process. Therefore, it is possible to firmly join the holder body and the fuel pipe while keeping the processing cost for this joining low.

[0014] The method for manufacturing a delivery pipe according to the present invention is a method for manufacturing a delivery pipe having the above configuration, "A cylindrical joining projection is formed on the bottom by burring, which protrudes from the periphery of the through hole toward the opposite side from the cylindrical portion." The holder body is temporarily secured to the fuel pipe by inserting the connecting projection into the discharge hole, thereby connecting the through hole and the discharge hole.

[0015] In this configuration, the cylindrical joining protrusion protruding from the periphery of the through hole at the bottom is inserted into the discharge hole, and the holder body is temporarily fixed to the fuel pipe in a state where the through hole and the discharge hole communicate with each other. Thereby, it is possible to prevent the positions of the holder body and the fuel pipe from shifting when joining the holder body and the fuel pipe.

[0016] The manufacturing method of the delivery pipe according to the present invention is a manufacturing method of the delivery pipe having the above configuration, "On the peripheral portion of the through hole at the bottom, a welding protrusion protruding on the side opposite to the cylindrical portion is formed, By inserting a pin-shaped jig into the through hole and the discharge hole, in a state where the through hole and the discharge hole are aligned so as to communicate with each other, the welding protrusion is welded to the side peripheral surface of the fuel pipe by projection welding, thereby temporarily fixing the holder body to the fuel pipe."

[0017] In this configuration, the method of aligning the holder body and the fuel pipe so that the through hole and the discharge hole communicate with each other is different from the manufacturing method of the delivery pipe described above. In this configuration, by inserting a pin-shaped jig into both the through hole and the discharge hole, the holder body and the fuel pipe are aligned so that both holes communicate with each other. In that state, the welding protrusion formed on the peripheral portion of the through hole at the bottom is welded to the side peripheral surface of the fuel pipe by projection welding, and the holder body is temporarily fixed to the fuel pipe. After being temporarily fixed, the pin-shaped jig may be removed. By such a method, it is also possible to prevent the positions of the holder body and the fuel pipe from shifting when joining them.

Effects of the Invention

[0018] As described above, according to the present invention, it is possible to provide an injector holder that can achieve both low-cost manufacturing and improvement of mechanical strength, a delivery pipe including the same, and a manufacturing method thereof.

Brief Description of the Drawings

[0019] [Figure 1]Exploded perspective view of the delivery pipe which is the first embodiment of the present invention. [Figure 2] Fig. 2(a) is a cross-sectional view of the delivery pipe of Fig. 1, Fig. 2(b) is a perspective view of the holder body in the delivery pipe of Fig. 1, and Fig. 2(c) is a cross-sectional view of the holder body of Fig. 2(b). [Figure 3] Fig. 3(a) is a cross-sectional view for explaining the process of forming a bottomed cylindrical workpiece from a flat metal sheet, Fig. 3(b) is a cross-sectional view for explaining the process of making the bottom of the bottomed cylindrical workpiece a curved surface, Fig. 3(c) is a cross-sectional view for explaining the process of forming a pilot hole at the bottom, and Fig. 3(d) is a cross-sectional view for explaining the process of forming a joining projection at the bottom by burring. [Figure 4] Fig. 4(a) is a perspective view showing the state where the injector holder is set on the positioning jig, Fig. 4(b) is a plan view of the state of Fig. 4(a), and Fig. 4(c) is a cross-sectional view showing the temporary fixing state between the holder body and the fuel pipe. [Figure 5] Fig. 5(a) is a cross-sectional view of the delivery pipe which is the second embodiment of the present invention, Fig. 5(b) is a perspective view of the holder body in the delivery pipe of Fig. 5(a), Fig. 5(c) is a plan view of the holder body of Fig. 5(b), Fig. 5(d) is a cross-sectional view taken along the line A-A in Fig. 5(c), and Fig. 5(e) is a cross-sectional view for explaining the process of forming a welding projection at the bottom of the bottomed cylindrical workpiece. [Figure 6] Fig. 6(a) is a perspective view showing the state where the injector holder of Fig. 5(a) is set on the positioning jig, and Fig. 6(b) is a cross-sectional view for explaining the process of welding the welding projection of the holder body to the fuel pipe by projection welding.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, an injector holder which is a specific embodiment of the present invention, a delivery pipe including the same, and a manufacturing method thereof will be described with reference to the drawings.

[0021] First, the delivery pipe 1 of the first embodiment will be described with reference to Figures 1 to 4. The delivery pipe 1 is for supplying fuel to an injector (not shown) and comprises a fuel pipe 10 and an injector holder 20. Multiple injector holders 20 are arranged at intervals along the longitudinal direction of the fuel pipe 10 (three are shown here as an example).

[0022] The fuel piping 10 is the main body of the delivery pipe 1 and consists of a metal pipe with a circular cross-section. The inside of the fuel piping 10 is a fuel supply passage 11 through which pressurized fuel is supplied. Multiple discharge holes 12 are provided through the side surface 13 of the fuel piping 10. Each discharge hole 12 communicates with the fuel supply passage 11. The side surface 13 of the fuel piping 10 is set to have sufficient mechanical strength to withstand the pressure of the pressurized fuel filling the fuel supply passage 11.

[0023] The injector holder 20 is for holding the injector, and one is provided for each discharge hole 12. Each injector holder 20 comprises a holder body 30 and a reinforcing sleeve 50. The holder body 30 is a bottomed cylindrical metal press-formed product having a cylindrical portion 31 and a bottom portion 41. The inside of the cylindrical portion 31 is a space for inserting the injector. The cylindrical portion 31 has a flange portion 33 that protrudes outward from the opening edge opposite the bottom portion 41, and a positioning notch 34 in which a part of the flange portion 33 is cut out in an arc shape. Figure 2(a) is a cross-sectional view of the delivery pipe cut in a plane perpendicular to the axial direction of the fuel piping 10 and passing through the central axis of the cylindrical portion 31, and Figure 2(c) is a cross-sectional view of the injector holder 20 cut in a plane passing through the positioning notch 34 and the central axis of the cylindrical portion 31.

[0024] The bottom portion 41 has a through hole 42 that penetrates the bottom portion 41, and a cylindrical connecting projection 43 that protrudes from the periphery of the through hole 42 on the side opposite to the cylindrical portion 31. The connecting projection 43 is fitted into the discharge hole 12 of the fuel pipe 10, so the through hole 42 is in communication with the discharge hole 12.

[0025] The bottom portion 41 has a curved surface 44 that conforms to the side surface 13 of the fuel pipe 10. The holder body 30 is integrated with the fuel pipe 10 by joining the curved surface 44 to the side surface 13 with the through hole 42 communicating with the discharge hole 12. In this embodiment, the curved surface 44 is brazed to the side surface 13.

[0026] The reinforcing sleeve 50 is a separate cylindrical part from the holder body 30, and in this embodiment, it is a metal press-formed product. A first introduction portion 51 is formed on one opening periphery of the reinforcing sleeve 50, with a chamfered edge to round the corner. Similarly, a second introduction portion 52 is formed on the other opening periphery of the reinforcing sleeve 50, with a chamfered edge to round the corner.

[0027] The reinforcing sleeve 50 has an inner diameter sized to fit onto the cylindrical portion 31, and is joined to the outer circumferential surface of the cylindrical portion 31 when fitted onto it. As a result, the side circumferential wall of the injector holder 20 has a double structure consisting of the cylindrical portion 31 of the holder body 30 and the reinforcing sleeve 50. In this embodiment, the reinforcing sleeve 50 is brazed to the outer circumferential surface of the cylindrical portion 31.

[0028] Next, the manufacturing method of the delivery pipe 1 will be explained with reference to Figures 2 to 4. The delivery pipe 1 is manufactured by first manufacturing the holder body 30 and the reinforcing sleeve 50, and then assembling the holder body 30, the reinforcing sleeve 50, and the fuel pipe 10. First, the manufacturing method of the holder body 30 will be explained. The manufacturing method of the holder body 30 comprises a drawing process, a curved section forming process, a cutting process, a pilot hole forming process, and a burring forming process.

[0029] In the deep drawing process, a bottomed cylindrical workpiece 100 is formed from a thin metal plate (not shown) through several steps of plastic deformation of the metal using a punch and die, as shown in Figure 3(a). The bottomed cylindrical workpiece 100 has one end of the cylindrical portion 101 closed at the bottom portion 102, and a protruding portion 103 extending outward from the other end.

[0030] In the curved section forming process, the bottom 102 of the bottomed cylindrical workpiece 100 shown in Figure 3(a) is pressed between the upper punch 201 and the lower punch 202, as shown in Figure 3(b). The surface of the upper punch 201 that contacts the bottom 102 is the same curved surface as the side circumferential surface 13 of the fuel pipe 10 (see Figure 2(a)). As a result of this process, the entire bottom 102 is curved downwards, forming a bottom 41 having a curved surface 44 that conforms to the side circumferential surface 13 of the fuel pipe 10.

[0031] Simultaneously, in the curved portion forming process, the cylindrical portion 101 of the bottomed cylindrical workpiece 100 is sandwiched between the lower punch 202 and the die 203, as shown in Figure 3(b), and a force is applied inward to the portion of the cylindrical portion 101, excluding the portion close to the protruding portion 103. As a result, a cylindrical portion 31 having a stepped outer surface is formed from the cylindrical portion 101, that is, a cylindrical portion 31 having a reduced diameter first cylindrical portion 35 on the bottom 41 side and a second cylindrical portion 36 with a slightly larger outer diameter than the first cylindrical portion 35 on the protruding portion 103 side (see Figure 2(b)). The first cylindrical portion 35 and the second cylindrical portion 36 are arranged coaxially.

[0032] In the cutting process, in order to form the flange portion 33 and the positioning notch 34 (see Figure 2(b)) from the protruding portion 103 of the bottomed cylindrical workpiece that has undergone the curved portion forming process, the excess portion of the protruding portion 103 is cut off using a punch and die.

[0033] In the pilot hole forming process, a pilot hole 104 is formed in the bottom 41 of the bottomed cylindrical workpiece that has undergone the cutting process. In this process, as shown in Figure 3(c), with the bottom 41 fixed by a cylindrical piercing die 213, the piercing punch 211 is advanced along a guide 212 placed inside the cylindrical part 31, thereby forming the pilot hole 104 in the bottom 41.

[0034] In the burring process, a through hole 42 and a joining projection 43 are formed in the bottom portion 41 of the bottomed cylindrical workpiece that has undergone the pilot hole forming process. In this process, as shown in Figure 3(d), a cylindrical burring die 223 is brought into contact with the bottom portion 41 slightly outside the opening edge of the pilot hole 104, and the burring punch 221 is advanced along a guide 222 positioned inside the cylindrical portion 31, thereby pushing the burring punch 221 into the pilot hole 104. As a result, the pilot hole 104 is widened to become a through hole 42, and its opening edge is pushed up on the opposite side from the cylindrical portion 31, forming a cylindrical joining projection 43.

[0035] Furthermore, by using a burring die 223 that has a portion protruding along the inner circumferential surface at its tip, a circumferential groove 37 (see Figures 2(b) and 2(c)) is formed at the base of the joining projection 43 at the bottom 41.

[0036] Through the above processes, the holder body 30 (see Figure 2) is formed from a thin metal plate. In its standalone state before being assembled to the fuel pipe 10, the outer diameter of the joining projection 43 of the holder body 30 is set to be only slightly larger than the inner diameter of the discharge hole 12 of the fuel pipe 10.

[0037] Next, the manufacturing method of the reinforcing sleeve 50 will be described. The manufacturing method of the reinforcing sleeve 50 comprises a cylindrical member forming step, a first introduction part forming step, and a second introduction part forming step. The cylindrical member forming step is a step of forming a cylindrical workpiece in which the outer diameter and inner diameter are each the same. In this embodiment, it is a press forming step, but it can also be an extrusion forming step.

[0038] The first and second introduction section forming processes are press forming processes performed by sandwiching a cylindrical workpiece between a punch and a die. In the first introduction section forming process, the opening at one end of the cylindrical workpiece is formed with rounded corners by the shape of the punch and die, thereby forming the first introduction section 51 (see Figure 2(a)). Similarly, in the second introduction section forming process, the opening at the other end of the cylindrical workpiece is formed with rounded corners by the shape of the punch and die, thereby forming the second introduction section 52 (see Figure 2(a)).

[0039] The reinforcing sleeve 50 is formed through the above processes. In its standalone state before being assembled to the holder body 30, the inner diameter of the reinforcing sleeve 50 is set to be slightly larger than the outer diameter of the first cylindrical portion 35 of the holder body 30 and slightly smaller than the outer diameter of the second cylindrical portion 36.

[0040] Next, the assembly method of the holder body 30, the reinforcing sleeve 50, and the fuel pipe 10 will be explained with reference to Figure 4. This assembly method comprises a press-fitting step, a temporary fixing step, and a joining step.

[0041] Prior to the press-fitting process, the holder body 30 is set on the positioning jig 230 as shown in Figures 4(a) and 4(b). The positioning jig 230 has a base 231, an insert 232, and an anti-rotation pin 233. The base 231 is a block-shaped member with a smooth horizontal surface on its upper surface. The holder body 30 is placed on the upper surface of the base 231 with the flange portion 33 facing downwards. The insert 232 protrudes upward from the upper surface of the base 231 and is inserted into the cylindrical portion 31 to hold the holder body 30 in a direction parallel to the upper surface of the base 231. The anti-rotation pin 233 is a pin that protrudes upward from the upper surface of the base 231 and has a shape and size that fits into the positioning notch 34 of the cylindrical portion 31. With the anti-rotation pin 233 inserted into the positioning notch 34, the holder body 30 is placed on the upper surface of the base 231, thereby holding the holder body 30 so as not to move in the circumferential direction (so as not to rotate around the central axis of the cylindrical portion 31). The same number of holder bodies 30 as are provided on one delivery pipe 1 (three are used as an example here) are set on the positioning jig 230 in the same arrangement and orientation as they are provided on the delivery pipe 1.

[0042] In the press-fitting process, the reinforcing sleeve 50 is press-fitted into the second cylindrical portion 36 of the cylindrical portion 31 of the holder body 30. Since the first cylindrical portion 35 and the second cylindrical portion 36 are arranged coaxially in the cylindrical portion 31, when the reinforcing sleeve 50 is press-fitted into the second cylindrical portion 36, a uniform radial clearance is formed around the entire circumference between the inner surface of the reinforcing sleeve 50 and the outer surface of the first cylindrical portion 35. This clearance is set to a size suitable for the brazing material to penetrate by capillary action in the subsequent joining process.

[0043] In the temporary fastening process, as shown in Figure 4(c), the connecting projection 43 of the holder body 30 is pressed into the discharge hole 12 of the fuel pipe 10. This temporarily fastens the holder body 30 to the fuel pipe 10 with the through hole 42 and the discharge hole 12 in communication.

[0044] In the joining process, first, the holder body 30, the reinforcing sleeve 50 into which the holder body 30 is press-fitted, and the fuel pipe 10 temporarily fixed to the holder body 30 are removed from the positioning jig 230 and placed on a heat-resistant jig. Next, a paste-like brazing material is applied between the periphery of the curved surface 44 of the holder body 30 and the side circumferential surface 13 of the fuel pipe 10, between the first introduction portion 51 of the reinforcing sleeve 50 and the outer circumferential surface of the cylindrical portion 31 of the holder body 30, and between the end of the reinforcing sleeve 50 on the second introduction portion 52 side and the flange portion 33 of the holder body 30. Next, the brazing material is heated and melted, and the molten brazing material is allowed to penetrate by capillary action between the side circumferential surface 13 and the curved surface 44, between the outer circumferential surface of the holder body 30 and the inner circumferential surface of the reinforcing sleeve 50, and between the end of the reinforcing sleeve 50 on the second introduction portion 52 side and the flange portion 33. Afterward, the holder body 30, reinforcing sleeve 50, and fuel pipe 10 are joined together and integrated by cooling and solidifying the brazing material.

[0045] As shown in Figure 2(a), the above manufacturing method yields a delivery pipe 1 having an injector holder 20 with a double-walled side circumferential structure formed by the holder body 30 and the reinforcing sleeve 50. If the reinforcing sleeve 50 were absent, in order to increase the pressure of the injected fuel, it would be necessary to thicken the side circumferential wall to increase the mechanical strength of the injector holder. This would limit the materials available for the flat plate material used as raw material for press forming, as well as the materials for the punch and die used in press forming, resulting in high costs and making press forming itself difficult. In contrast, in this embodiment, the mechanical strength of the injector holder 20 can be increased by the presence of the reinforcing sleeve 50. Therefore, the holder body 30 can be manufactured simply and at low cost using conventional press forming equipment and press forming with thin flat plate material as the raw material.

[0046] In practice, assuming the supply of pressurized fuel, the stress on the injector holder was analyzed when a predetermined pressure was applied to the inside of the injector holder 20, which has a double structure consisting of a holder body 30 and a reinforcing sleeve 50, and to the inside of an injector holder consisting only of a holder body 30. As a result, it was confirmed that the injector holder 20 with a double structure had a maximum stress (maximum value of stress applied to the injector holder) reduced by approximately 1 / 3 compared to the injector holder consisting only of a holder body 30, indicating improved mechanical strength.

[0047] Furthermore, in this embodiment, the bottom portion 41 has a curved surface 44 that conforms to the side circumferential surface 13 of the fuel pipe 10. Because the curved surface 44 is joined to the side circumferential surface 13, the joining area between the holder body 30 and the fuel pipe 10 can be made as large as possible, allowing for a strong bond between the two. If the bottom portion 41 were flat, in order to join it with the side circumferential surface 13 of the fuel pipe 10 over a large area, it would be necessary to process the pipe, which has a circular cross-section, to form a partially flat section. In contrast, in this embodiment, the holder body 30 and the fuel pipe 10 can be joined over a large area without the need to process the fuel pipe 10. Also, since the holder body 30 is manufactured by press molding, it is easy to incorporate the process of forming the curved surface 44 into part of the molding process. Therefore, the cost of processing for joining can be kept low while firmly joining the holder body 30 and the fuel pipe 10.

[0048] Furthermore, in this embodiment, since the bottom portion 41 has a curved surface 44 that conforms to the side surface 13 of the fuel pipe 10, if there were no joining projection 43, when joining the holder body 30 to the fuel pipe 10, the bottom portion 41 would move along the side surface 13 of the fuel pipe 10, requiring alignment to connect the discharge hole 12 and the through hole 42. In this embodiment, however, by fitting the cylindrical joining projection 43 that protrudes from the periphery of the through hole 42 of the bottom portion 41 into the discharge hole 12 of the fuel pipe 10, the holder body 30 is temporarily fixed to the fuel pipe 10 while the through hole 42 and the discharge hole 12 are in communication. This prevents misalignment of the holder body 30 and the fuel pipe 10 when they are joined in a later process.

[0049] Furthermore, in this embodiment, the cylindrical portion 31 has a stepped outer surface consisting of a first cylindrical portion 35 and a second cylindrical portion 36, and the first cylindrical portion 35 and the second cylindrical portion 36 are arranged coaxially. When assembling the holder body 30 and the reinforcing sleeve 50, the reinforcing sleeve 50 is press-fitted into the second cylindrical portion 36, thereby forming a uniform clearance between the inner surface of the reinforcing sleeve 50 and the outer surface of the first cylindrical portion 35. As a result, in the joining process, the molten brazing material penetrates evenly around the entire circumference between the reinforcing sleeve 50 and the first cylindrical portion 35, forming a uniform brazing material layer, and allowing the reinforcing sleeve 50 and the holder body 30 to be firmly joined.

[0050] Furthermore, since the reinforcing sleeve 50 has a first introduction portion 51 and a second introduction portion 52 with rounded corners at both ends, brazing material accumulates between these and the cylindrical portion 31, resulting in a strong joint between the holder body 30 and the reinforcing sleeve 50. In addition, a circumferential groove 37 is formed at the base of the joining projection 43 at the bottom portion 41 of the holder body 30, so brazing material also accumulates there. As a result, the joint between the side surface 13 of the fuel pipe 10 and the holder body 30 becomes even stronger.

[0051] Next, the delivery pipe 2 of the second embodiment will be described with reference to Figures 5 and 6. The differences between the delivery pipe 2 and the delivery pipe 1 of the first embodiment are the configuration of the holder body 70 of the injector holder 60 and the method of temporarily fixing the holder body 70 to the fuel pipe 10. In the following, components similar to those in the first embodiment will be denoted by the same reference numerals, and detailed explanations will be omitted. Figures 5(a), 5(d), 5(e), and 6(b) are cross-sectional views taken along the line AA shown in Figure 5(c).

[0052] The holder body 70 is a bottomed cylindrical metal press-formed product having a cylindrical portion 31 and a bottom portion 71. The bottom portion 71, like the bottom portion 41 of the first embodiment, has a curved surface 44 that conforms to the side circumferential surface 13 of the fuel pipe 10 and a through hole 42b that communicates with the discharge hole 12, but unlike the first embodiment, it does not have a joining projection 43. In its standalone state before the holder body 70 is assembled to the fuel pipe 10, the bottom portion 71 has a welding projection 73 on the periphery of the through hole 42b that protrudes on the side opposite to the cylindrical portion 31. On the side of the bottom portion 71 opposite to the side from which the welding projection 73 protrudes, a recess 74 is formed that is slightly larger than the recess obtained by inverting the welding projection 73. Multiple welding projections 73 are formed around the through hole 42b at intervals (four are shown here as an example).

[0053] The holder body 70 is manufactured by forming a bottomed cylindrical workpiece having a cylindrical portion 31 and a bottom portion 71 through a drawing process, a curved portion forming process, and a cutting process, similar to those in the first embodiment, and then by a through-hole forming process and a projection forming process, which will be described below.

[0054] In the through-hole forming process, the bottom portion 71 is fixed with a cylindrical piercing die, and a piercing punch is advanced along a guide placed inside the cylindrical portion 31 to form a through-hole 42b in the bottom portion 71. The diameter of the through-hole 42b is the same as the diameter of the discharge hole 12 of the fuel piping.

[0055] In the protrusion forming process, as shown in Figure 5(e), with the bottomed cylindrical workpiece held by the die 243, the bottom 71 is sandwiched between a cylindrical upper punch 241 and a cylindrical lower punch 242 coaxial with the upper punch 241, thereby applying an upward pressing force to the bottom 71. A hemispherical protrusion 74p is formed on the surface of the lower punch 242 that contacts the bottom 71, while a recess 73r, which is the inverted shape of a hemisphere, is formed on the surface of the upper punch 241 that contacts the bottom 71. The size of the protrusion 74p is slightly larger than the protrusion which is the inverted shape of the recess 73r. There are the same number of protrusions 74p and recesses 73r (four are shown as an example), and they are arranged so that the positions of the protrusions 74p and recesses 73r overlap when the upper punch 241 and lower punch 242 are viewed from directly above or directly below. By pressing the bottom portion 71 with the lower punch 242 relative to the upper punch 241, the metal pressed by the convex portion 74p moves into the recess 73r, forming a welding projection 73, and the recess 74 remains as a mark left by the convex portion 74p.

[0056] The holder body 70 manufactured as described above is temporarily fixed to the fuel pipe 10 by a temporary fixing process different from that of the first embodiment. The press-fitting process, which precedes the temporary fixing process, and the joining process, which follows it, are the same as in the first embodiment, but the positioning jig 250 used in the press-fitting process and the temporary fixing process is different from the positioning jig 230 of the first embodiment.

[0057] As shown in Figures 6(a) and 6(b), the positioning jig 250 has a base 251, an alignment pin 252, an anti-rotation pin 233, and a lower electrode 253. The base 251 and the anti-rotation pin 233 are the same as the base 231 and anti-rotation pin 233 in the positioning jig 230 of the first embodiment, respectively. The alignment pin 252 is a cylindrical pin extending upward from the base 251, and its diameter is sized to fit perfectly into the through hole 42b and the discharge hole 12. The "alignment pin 252" corresponds to the "pin-shaped jig" of the present invention. The lower electrode 253 is inserted inside the cylindrical portion 31 with the alignment pin 252 inserted through it, and is in contact with the bottom portion 71. The base 251 and the alignment pin 252 are made of a non-conductive material, while the lower electrode 253 is made of a conductive material.

[0058] In the temporary fastening process, as shown in Figure 6(b), the alignment pin 252 is inserted through the through hole 42b and then further inserted through the discharge hole 12. Because the bottom portion 71 has a curved surface 44 that conforms to the side surface 13 of the fuel pipe 10, when joining the holder body 70 to the fuel pipe 10, the bottom portion 71 moves along the side surface 13 of the fuel pipe 10, requiring alignment to connect the discharge hole 12 and the through hole 42b. This alignment is achieved by inserting the alignment pin 252 through both the through hole 42b and the discharge hole 12.

[0059] In this manner, with the through-hole 42b and the discharge hole 12 aligned so that they are in communication, the holder body 70 is temporarily fixed to the fuel pipe 10 by projection welding, which welds the welding projection 73 to the side surface 13 of the fuel pipe 10. In this projection welding, the fuel pipe 10 and its bottom 71 are sandwiched between the upper electrode 254 and the lower electrode 253, and the upper electrode 254 is pushed downward to press the welding projection 73 against the side surface 13 of the fuel pipe 10, while current is passed through the upper electrode 254 and the lower electrode 253. As a result, a large current flows concentratedly through the welding projection 73, which is a part of the metal holder body 70 and is partially in contact with the side surface 13 of the fuel pipe 10, and the heat generated melts the welding projection 73, welding it to the fuel pipe 10.

[0060] As described above, according to the second embodiment, similar to the first embodiment, the mechanical strength of the injector holder 60 can be increased by the presence of the reinforcing sleeve 50, so the holder body 70 can be manufactured simply and at low cost by press molding of a thin flat material using conventional press molding equipment.

[0061] In the second embodiment, the holder body 70 is temporarily fixed to the fuel pipe 10 by inserting the alignment pin 252 into the through hole 42b and the discharge hole 12 to connect them, and then welding the welding projection 73 on the bottom portion 71 to the side surface 13 of the fuel pipe 10 by projection welding. This prevents misalignment of the holder body 70 and the fuel pipe 10 when they are joined in a later process.

[0062] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention, as shown below.

[0063] For example, the above embodiment illustrates a case where three injector holders 20 are provided in the fuel piping 10, but the number of injectors is not limited to this. Also, the above embodiment illustrates a case in which the reinforcing sleeve 50 extends from the flange portion 33 to very close to the side circumferential surface 13, extending almost the entire length of the cylindrical portion 31, but it is not limited to this. The reinforcing sleeve may be provided in a part of the section between the flange portion and the side circumferential surface. Specifically, the part of the cylindrical portion that experiences the highest stress due to the pressure of the pressurized fuel may be partially reinforced with the reinforcing sleeve.

[0064] Furthermore, while the above embodiment illustrates a case where the reinforcing sleeve 50 is press-fitted into a part of the outer circumferential surface of the cylindrical portion 31 (the second cylindrical portion 36) and then brazed, the embodiment is not limited to this. The reinforcing sleeve may be brazed without being press-fitted into the outer circumferential surface of the cylindrical portion. Alternatively, the reinforcing sleeve may be joined only by being press-fitted into the outer circumferential surface of the cylindrical portion, without being brazed. [Explanation of symbols]

[0065] 1,2 Delivery pipe 10 Fuel piping 12 Discharge hole 20.60 Injector Holder 30,70 Holder body 31 Cylindrical section 41,71 bottom 42,42b Through hole 44 Curved surface 50 Reinforcement Sleeves 43 Connection protrusion 73 Welding protrusions 252 Alignment pin (pin-shaped jig)

Claims

1. This is an injector holder for holding the injector that discharges fuel supplied from the discharge hole of the fuel piping, which is the main body of the delivery pipe. A metal press-formed product having a cylindrical section and a bottom section, wherein the inside of the cylindrical section is a space for inserting an injector, and a through hole for communicating with the discharge hole is formed in the bottom section, A reinforcing sleeve, which is cylindrical and separate from the holder body, and has an inner diameter that is sized to fit onto the cylindrical portion, An injector holder characterized by comprising the following:

2. A delivery pipe for holding an injector and supplying fuel to the injector. A fuel pipe consisting of a metal pipe with a circular cross-section, and having discharge holes drilled through its side circumferential wall, A metal press-formed product having a cylindrical section and a bottom section, the holder body having a cylindrical section with a bottom section and a space for inserting an injector inside the cylindrical section, and a through hole formed in the bottom section, The holder comprises a cylindrical reinforcing sleeve, which is separate from the holder body and is fitted onto the cylindrical portion and joined to the outer surface of the cylindrical portion, The holder body is joined to the fuel piping with the through hole communicating with the discharge hole. A delivery pipe characterized by the following features.

3. The bottom portion has a curved surface that conforms to the circumferential surface of the fuel pipe. The delivery pipe according to feature 2.

4. A method for manufacturing a delivery pipe according to claim 2, A cylindrical joining projection is formed on the bottom by burring, projecting from the periphery of the through hole toward the opposite side from the cylindrical portion. By inserting the connecting projection into the discharge hole, the holder body is temporarily secured to the fuel pipe while the through hole and the discharge hole are in communication. A method for manufacturing a delivery pipe characterized by the following:

5. A method for manufacturing a delivery pipe according to claim 2, At the bottom portion, a welding projection is formed on the periphery of the through hole, projecting toward the opposite side from the cylindrical portion. By inserting a pin-shaped jig into the through-hole and the discharge hole, the holder body is temporarily fixed to the fuel pipe by projection welding, while the through-hole and the discharge hole are aligned so that they are in communication, and the welding projection is welded to the side surface of the fuel pipe. A method for manufacturing a delivery pipe characterized by the following:

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