Fuel distribution pipe

Abstract

A fuel distribution pipe that distributes fuel supplied from a fuel pipe to a plurality of fuel injection devices is provided with a pipe member that forms a storage space that stores the fuel inside, and a connection member that is inserted into and joined to a front end portion of the pipe member and is formed with a through hole that is connected to the storage space. The connection member has an intermediate diameter portion that is adjacent to the storage space, and a small diameter portion that is disposed at a position on the side opposite the storage space from the intermediate diameter portion. The intermediate diameter portion has an inner diameter that is larger than the inner diameter of the small diameter portion and smaller than the inner diameter of the pipe member.

Description

Technical Field

[0001] One aspect of the present invention relates to a fuel distribution pipe for distributing fuel to a plurality of fuel injection devices. Background Art

[0002] In direct injection engines and other applications, a fuel distribution pipe is used to distribute and supply high-pressure fuel compressed by a high-pressure pump to multiple fuel injection devices. Patent Document 1 describes a fuel delivery pipe that connects fuel supply paths (fuel piping) and distributes fuel to multiple injectors. This fuel delivery pipe has a throttle orifice formed at the tip of a main bore (storage space) formed within the fuel delivery pipe to reduce pulsation.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-097690

[0004] Some fuel distribution pipes include a pipe member that defines a storage space for storing fuel, and a connecting member that is inserted and connected to the front end of the pipe member and has an inner diameter smaller than that of the pipe member. In such fuel distribution pipes, when the fuel pressure increases, the pipe member is susceptible to expansion due to the fuel pressure. However, the front end of the pipe member, into which the connecting member is inserted and connected, is stiffened by the connecting member, thus hindering expansion. Therefore, only the central portion of the pipe member, where the storage space is formed, is susceptible to expansion. As a result, high stress may be generated at the interface between the central portion and the front end of the pipe member, accelerating metal fatigue and shortening its service life.

[0005] One option is to increase the wall thickness of the pipe to prevent it from expanding due to fuel pressure. However, increasing the wall thickness of the pipe increases the weight and cost of the fuel distribution pipe. Furthermore, if the outer diameter of the pipe increases due to the increased wall thickness, the layout flexibility of the fuel distribution pipe decreases. If the inner diameter of the pipe decreases due to the increased wall thickness, the radiated sound generated by the pulsation of the fuel caused by the operation of the high-pressure pump increases. Summary of the Invention

[0006] Therefore, an object of one aspect of the present invention is to provide a fuel delivery pipe that can allow expansion of a pipe member and reduce stress generated in the pipe member.

[0007] The fuel distribution pipe involved in one aspect of the present invention is a fuel distribution pipe that distributes the fuel supplied from the fuel distribution pipe to multiple fuel injection devices, and comprises: a pipe component, which forms a storage space for storing fuel inside; and a connecting component, which is inserted into and coupled to the front end portion of the pipe component and forms a through hole connected to the storage space, the connecting component having: an intermediate diameter portion adjacent to the storage space; and a small diameter portion, which is arranged at a position on the side opposite to the storage space than the intermediate diameter portion, and the intermediate diameter portion has an inner diameter that is larger than the inner diameter of the small diameter portion and smaller than the inner diameter of the pipe component.

[0008] In this fuel distribution pipe, the connecting member, which is inserted into and joined to the front end of the tube member, has an intermediate diameter portion adjacent to the reservoir space and a smaller diameter portion located on the opposite side of the intermediate diameter portion from the reservoir space. The intermediate diameter portion has an inner diameter smaller than the inner diameter of the tube member and larger than the inner diameter of the smaller diameter portion. In other words, the rigidity of the intermediate diameter portion adjacent to the reservoir space is lower than that of the smaller diameter portion. Therefore, when subjected to fuel pressure, the intermediate diameter portion of the connecting member is more likely to expand in accordance with the central portion of the tube member forming the reservoir space. This reduces stress generated at the interface between the central portion and the front end of the tube member.

[0009] A cross section of the storage space perpendicular to the central axis of the tube member may be substantially uniform across the entire region in the direction in which the tube member extends. In this fuel distribution pipe, a cross section passing through the storage space perpendicular to the central axis of the tube member is substantially uniform across the entire region in the direction in which the tube member extends. This can suppress the occurrence of localized stress concentration when the tube member expands due to fuel pressure.

[0010] The connecting member may further include a tapered portion, the tapered portion connecting the intermediate diameter portion and the small diameter portion and having an inner diameter that decreases from the intermediate diameter portion toward the small diameter portion. In this fuel distribution pipe, the tapered portion formed in the connecting member, the tapered portion connecting the intermediate diameter portion and the small diameter portion and having an inner diameter that decreases from the intermediate diameter portion toward the small diameter portion, can more easily follow the expansion of the central portion of the pipe member that forms the storage space.

[0011] The angle formed by the inner circumferential surface of the tapered portion in a reference cross-section including the central axis of the tube member may be greater than or equal to 110° and less than or equal to 160°. In this fuel distribution pipe, by having the angle formed by the inner circumferential surface of the tapered portion in a reference cross-section including the central axis of the tube member be greater than or equal to 110° and less than or equal to 160°, the connecting member can be prevented from becoming excessively long and the intermediate diameter portion of the connecting member can be appropriately expanded.

[0012] The length of the intermediate diameter portion in the direction in which the tube member extends may be shorter than the insertion length of the connecting member into the tube member and longer than the wall thickness of the intermediate diameter portion. In this fuel delivery pipe, by having the length of the intermediate diameter portion in the direction in which the tube member extends be shorter than the insertion length of the connecting member into the tube member and longer than the wall thickness of the intermediate diameter portion, the connecting member can be prevented from becoming excessively long and the intermediate diameter portion of the connecting member can be appropriately expanded.

[0013] The wall thickness of the intermediate diameter portion may be not less than 0.3 times and not more than 1.5 times the wall thickness of the tube member. In this fuel distribution pipe, by having the wall thickness of the intermediate diameter portion be not less than 0.3 times and not more than 1.5 times the wall thickness of the tube member, sufficient rigidity of the intermediate diameter portion can be ensured, and the intermediate diameter portion can more easily follow the expansion of the central portion of the tube member forming the storage space.

[0014] Alternatively, the connecting member may be a pipe connecting member connected to the fuel pipe. In this fuel distribution pipe, since the connecting member is the pipe connecting member, the fuel supplied from the fuel pipe can be appropriately supplied to the storage space over a long period of time.

[0015] Alternatively, the inner diameter of the small-diameter portion may be greater than or equal to 1 mm and less than or equal to 11 mm. In this fuel delivery pipe, when the connecting component is a pipe connecting component, the inner diameter of the small-diameter portion may be greater than or equal to 1 mm and less than or equal to 11 mm. This allows fuel supplied from the fuel pipe to be appropriately supplied to the storage space, prevents the fuel delivery pipe from becoming excessively large, and prevents obstruction of fuel flow.

[0016] Alternatively, the connecting member may be a sensor connecting member connected to a fuel pressure sensor that detects the pressure of the fuel stored in the storage space. In this fuel delivery pipe, by virtue of the connecting member being the sensor connecting member, the pressure of the fuel stored in the storage space can be appropriately transmitted to the fuel pressure sensor over a long period of time.

[0017] Alternatively, the inner diameter of the small-diameter portion may be 3 mm or more and 9 mm or less. In this fuel rail pipe, when the connecting component is a sensor connecting component, the inner diameter of the small-diameter portion being 3 mm or more and 9 mm or less allows the pressure of the fuel stored in the storage space to be appropriately transmitted to the fuel pressure sensor, thereby preventing the fuel rail pipe from becoming excessively large and preventing the passage of fuel from being obstructed.

[0018] According to one aspect of the present invention, it is possible to allow expansion of the pipe member and reduce stress generated in the pipe member. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic front view of the fuel rail according to the first embodiment.

[0020] Figure 2Yes Figure 1 A schematic cross-sectional view of a portion of a fuel rail is shown.

[0021] Figure 3 It is magnified Figure 2 A schematic cross-sectional view of the periphery of the pipe connection component in FIG.

[0022] Figure 4 It is magnified Figure 2 A schematic cross-sectional view of the periphery of the sensor connecting component in FIG.

[0023] Figure 5 This is a schematic cross-sectional view showing a portion of the fuel delivery pipe of Comparative Example 1.

[0024] Figure 6 It is a schematic cross-sectional view of a fuel rail according to a second embodiment.

[0025] Figure 7 Yes Figure 6 A schematic cross-sectional view of a portion of a fuel rail is shown.

[0026] Figure 8 It is magnified Figure 7 A schematic cross-sectional view of the periphery of the cover member in FIG.

[0027] Figure 9 This is a schematic cross-sectional view showing a portion of the fuel delivery pipe of Comparative Example 2. DETAILED DESCRIPTION

[0028] Hereinafter, a fuel delivery pipe according to an embodiment will be described with reference to the accompanying drawings. In the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0029] [First embodiment]

[0030] Figure 1 It is a schematic perspective view of the fuel rail pipe according to the first embodiment. Figure 2 Yes Figure 1 A schematic cross-sectional view of a portion of the fuel distribution pipe is shown. Figure 1 and Figure 2 As shown, the fuel distribution pipe 1 according to this embodiment distributes and supplies high-pressure fuel compressed by a high-pressure pump (not shown) and supplied from a fuel pipe (not shown) to fuel injection devices (not shown) provided corresponding to each cylinder (not shown) of an engine (not shown). The fuel distribution pipe 1 is also called a fuel injection rail, a fuel delivery pipe, a common rail, etc.

[0031] Fuel distribution pipe 1 includes a pipe member 2, a plurality of housings (Japanese: ハウジング) 3, a pipe connection member 4, and a sensor connection member 5. The drawings show a fuel distribution pipe 1 including four housings 3, but the number of housings 3 is not particularly limited as long as it is two or more.

[0032] The pipe member 2 is a member for storing fuel pumped from a high-pressure pump in a high-pressure state in order to supply fuel to a plurality of fuel injection devices. The pipe member 2 is formed, for example, in the shape of a circular tube extending linearly along the cylinder row direction (crankshaft direction) of the engine. The pipe shape of the pipe member 2 does not necessarily need to be a circular tube extending linearly, and can be set to various shapes. A storage space 21 for storing fuel is formed inside the pipe member 2. As will be described later, on one side of the pipe member 2 ( Figure 1 and Figure 2 The front end portion 22 of the left side of the pipe member 2 is inserted and connected to the pipe connecting component 4, and the other side of the pipe member 2 ( Figure 1 and Figure 2 The front end portion 23 (right side in the figure) of the pipe member 2 is inserted into and joined to the sensor connecting member 5. Therefore, the storage space 21 is formed by the central portion 24 of the pipe member 2, which is not inserted into and joined to the pipe connecting member 4 and the sensor connecting member 5. Furthermore, the pipe member 2 is fixed to the engine via a member such as a stay (not shown).

[0033] A cross-section of the storage space 21 perpendicular to the central axis A of the pipe member 2 is substantially uniform across the entire region along the extension direction B of the pipe member 2. "Substantially uniform" here means allowing for manufacturing errors or tolerances of approximately ±10%, and is not limited to being identical. For example, if the thickness midway between the thickest and thinnest portions of the pipe member 2 is used as the reference thickness, the thickness at any location on the pipe member 2 is within ±10% of the reference thickness. The central axis A of the pipe member 2 is a line passing through the radial center of the pipe member 2 and extending in the extension direction B of the pipe member 2.

[0034] The housing 3 is a component that maintains the fuel injection device airtight and supplies fuel from the storage space 21 of the pipe member 2 to the fuel injection device. The housing 3 is joined to the peripheral surface of the pipe member 2. The housing 3 and the pipe member 2 can be joined by brazing, welding, or the like. The housing 3 is provided corresponding to the fuel injection device.

[0035] Figure 3 It is magnified Figure 2 A schematic cross-sectional view of the periphery of the piping connection components. Figures 1 to 3 As shown, the pipe connecting component 4 is a connecting component connected to the fuel pipe. The pipe connecting component 4 is formed into a cylindrical shape with the central axis A of the pipe component 2 as the center. The front end ( Figures 1 to 3The front end on the left side in the extension direction B of the pipe connecting component 4 is called the outer front end 4a, and the front end on the other side ( Figures 1 to 3 The front end on the right side in the figure) is called the inner front end 4b.

[0036] The pipe connection member 4 is inserted into and joined to the front end portion 22 of the pipe member 2. The pipe connection member 4 and the front end portion 22 of the pipe member 2 can be joined by brazing, welding, etc. In this embodiment, the pipe connection member 4 is joined to the pipe member 2 by brazing.

[0037] The outer circumferential surface of the pipe connecting component 4 includes an external threaded surface 41, an insertion surface 42, and an abutment surface 43. The external threaded surface 41 is formed with external threads for threaded engagement with the fuel pipe. The external threaded surface 41 extends along the extension direction B from the outer front end 4a toward the inner front end 4b. Furthermore, a tapered surface or the like may be formed between the external threaded surface 41 and the outer front end 4a to facilitate threaded engagement with the fuel pipe.

[0038] The insertion surface 42 extends cylindrically along the extension direction B from the inner front end 4b toward the outer front end 4a. The abutment surface 43 rises from the insertion surface 42 toward the radially outer side of the pipe connection component 4 on the outer front end 4a side of the insertion surface 42. Furthermore, with the insertion surface 42 inserted into the front end 22 of the pipe component 2 and the abutment surface 43 abutting the front end surface 25 of the front end 22 of the pipe component 2, the insertion surface 42 is brazed to the front end 22 of the pipe component 2. Alternatively, the abutment surface 43 of the pipe connection component 4 may also be brazed to the front end surface 25 of the pipe component 2. The front end surface 25 of the pipe component 2 is the end surface on the side of the front end 22 of the pipe component 2 in the extension direction B. Furthermore, a tapered surface or the like may be formed between the insertion surface 42 and the inner front end 4b to facilitate insertion of the pipe connection component 4 into the front end 22 of the pipe component 2.

[0039] The outer diameter of the insertion surface 42 before insertion into the front end portion 22 of the pipe member 2 may be larger than the inner diameter of the pipe member 2. Thus, by inserting the insertion surface 42 into the front end portion 22 of the pipe member 2 and brazing, brazing can be performed while the insertion surface 42 is pressed into the front end portion 22 of the pipe member 2. For example, the insertion surface 42 may be knurled to form projections and depressions, with the maximum outer diameter of the projections larger than the inner diameter of the pipe member 2 and the minimum outer diameter of the depressions smaller than the inner diameter of the pipe member 2. This allows the projections to be pressed against the front end portion 22 of the pipe member 2, allowing the brazing material to enter the depressions, thereby enhancing the bond strength between the insertion surface 42 and the front end portion 22 of the pipe member 2.

[0040] A through hole 44 is formed on the inner peripheral surface of the pipe connecting member 4 for supplying high-pressure fuel supplied from the fuel pipe to the storage space 21. The through hole 44 is adjacent to the storage space 21 and extends in the extending direction B centered on the central axis A of the pipe member 2.

[0041] The pipe connection component 4 includes an intermediate diameter portion 45, a small diameter portion 46, and a tapered portion 47. The intermediate diameter portion 45 is a portion of the pipe connection component 4 adjacent to the storage space 21. The small diameter portion 46 is a portion of the pipe connection component 4 located on the side opposite the storage space 21 relative to the intermediate diameter portion 45. The tapered portion 47 is a portion of the pipe connection component 4 located between the intermediate diameter portion 45 and the small diameter portion 46 and connected to the intermediate diameter portion 45 and the small diameter portion 46. The intermediate diameter portion 45, the tapered portion 47, and at least a portion of the small diameter portion 46 form the insertion surface 42. In other words, the insertion surface 42 is formed by the outer peripheral surface of the intermediate diameter portion 45, the outer peripheral surface of the tapered portion 47, and at least a portion of the outer peripheral surface of the small diameter portion 46.

[0042] The inner diameter D2 of the small diameter portion 46 is smaller than the inner diameter D1 of the pipe member 2. In the present embodiment, the inner diameter D2 of the small diameter portion 46 is the smallest inner diameter in the through hole 44.

[0043] The inner diameter D1 of the tube member 2 is not particularly limited. For example, to suppress the radiated sound generated by the pulsation of the fuel caused by the operation of the high-pressure pump, the inner diameter D1 of the tube member 2 may be 10 mm or greater, preferably 11 mm or greater, and more preferably 12 mm or greater. Furthermore, to prevent the fuel distribution pipe 1 from becoming excessively large, the inner diameter D1 of the tube member 2 may be 16 mm or less, preferably 15 mm or less, and more preferably 14 mm or less. These maximum and minimum values ​​can be appropriately combined. For example, the inner diameter D1 of the tube member 2 may be 10 mm or greater and 16 mm or less, preferably 11 mm or greater and 15 mm or less, and more preferably 12 mm or greater and 14 mm or less.

[0044] The inner diameter D2 of the small-diameter portion 46 is not particularly limited. For example, to prevent obstruction of fuel flow, the inner diameter D2 of the small-diameter portion 46 may be 1 mm or greater, preferably 2 mm or greater, and more preferably 3 mm or greater. Furthermore, to prevent the fuel distribution pipe 1 from becoming excessively large, the inner diameter D2 of the small-diameter portion 46 may be 11 mm or less, preferably 10 mm or less, and more preferably 9 mm or less. These maximum and minimum values ​​can be appropriately combined. For example, the inner diameter D2 of the small-diameter portion 46 may be 1 mm or greater and 11 mm or less, preferably 2 mm or greater and 10 mm or less, and more preferably 3 mm or greater and 9 mm or less.

[0045] The inner diameter D3 of the intermediate diameter portion 45 is larger than the inner diameter D2 of the small diameter portion 46 and smaller than the inner diameter D1 of the tube member 2. Therefore, in the pipe connecting member 4, the rigidity of the intermediate diameter portion 45 adjacent to the storage space 21 is lower than the rigidity of the small diameter portion 46. Consequently, in the pipe connecting member 4, if the central portion 24 of the tube member 2 expands due to the pressure of the fuel, the intermediate diameter portion 45 of the pipe connecting member 4 also readily expands in accordance with the central portion 24 of the tube member 2.

[0046] The inner diameter D3 of the intermediate diameter portion 45 is not particularly limited as long as it satisfies the above conditions. For example, to ensure sufficient rigidity of the intermediate diameter portion 45, the inner diameter D3 of the intermediate diameter portion 45 may be larger than the orifice diameter and of a size such that it does not substantially function as an orifice in relation to the small diameter portion 46 (a size such that an orifice effect is substantially absent), for example, larger than 1 mm, preferably larger than 2 mm, and more preferably larger than 3 mm. Furthermore, to facilitate expansion of the central portion 24 of the pipe member 2, the inner diameter D3 of the intermediate diameter portion 45 may be smaller than 14 mm, preferably smaller than 13 mm, and more preferably smaller than 12 mm. These maximum and minimum values ​​can be appropriately combined. For example, the inner diameter D1 of the pipe member 2 may be larger than 1 mm and smaller than 14 mm, preferably larger than 2 mm and smaller than 13 mm, and more preferably larger than 3 mm and smaller than 12 mm.

[0047] The length L1 of the intermediate diameter portion 45 in the extension direction B may be shorter than the insertion length L2 of the pipe connecting component 4 into the pipe component 2. The insertion length L2 of the pipe connecting component 4 into the pipe component 2 is the length of the insertion surface 42 in the extension direction B. Furthermore, the length L1 of the intermediate diameter portion 45 in the extension direction B may be longer than the wall thickness T1 of the intermediate diameter portion 45.

[0048] The wall thickness T1 of the intermediate diameter portion 45 is not particularly limited. For example, to ensure sufficient rigidity of the intermediate diameter portion 45, the wall thickness T1 of the intermediate diameter portion 45 may be 0.3 times or greater, preferably 0.7 times or greater, and more preferably 0.9 times or greater, of the wall thickness T2 of the pipe member 2. Furthermore, to facilitate expansion of the central portion 24 of the pipe member 2, the wall thickness T1 of the intermediate diameter portion 45 may be 1.5 times or less, preferably 1.3 times or less, and more preferably 1.1 times or less, of the wall thickness T2 of the pipe member 2. These maximum and minimum values ​​can be appropriately combined. For example, the wall thickness T1 of the intermediate diameter portion 45 may be 0.3 times or greater and 1.5 times or less, preferably 0.7 times or greater and 1.3 times or less, and more preferably 0.9 times or greater and 1.1 times or less, of the wall thickness T2 of the pipe member 2.

[0049] The tapered portion 47 connects the intermediate diameter portion 45 and the small diameter portion 46. The inner diameter of the tapered portion 47 decreases from the intermediate diameter portion 45 side (inner front end 4b side) toward the small diameter portion 46 side (outer front end 4a side).

[0050] In the reference section containing the central axis A ( Figure 2 and Figure 3 In the cross-section shown), the inner circumferential surface of the tapered portion 47 can extend linearly from the intermediate diameter portion 45 to the small diameter portion 46, can extend curvedly from the intermediate diameter portion 45 to the small diameter portion 46, or can extend curvedly from the intermediate diameter portion 45 to the small diameter portion 46.

[0051] The angle θ1 formed by the inner circumferential surface of the tapered portion 47 in the reference cross-section including the central axis A is not particularly limited. For example, to prevent the pipe connecting component 4 from becoming excessively long, the angle θ1 may be 110° or greater, preferably 113° or greater, and more preferably 115° or greater. Furthermore, to facilitate expansion of the intermediate diameter portion 45 of the sensor connecting component 5 along the central portion 24 of the tube component 2, the angle θ1 may be 160° or less, preferably 155° or less, and more preferably 150° or less. These maximum and minimum values ​​can be appropriately combined; for example, the angle θ1 may be 110° or greater and 160° or less, preferably 113° or greater and 155° or less, and more preferably 115° or greater and 150° or less. In addition, when the inner circumferential surface of the tapered portion 47 does not extend in a straight line from the intermediate diameter portion 45 to the small diameter portion 46, the angle θ1 formed by the inner circumferential surface of the tapered portion 47 in the reference section including the center axis A is the angle formed by an imaginary line connecting the front end of the inner circumferential surface of the tapered portion 47 on the intermediate diameter portion 45 side and the front end on the small diameter portion 46 side.

[0052] Figure 4 It is magnified Figure 2 A schematic cross-sectional view of the periphery of the sensor connection component in FIG. Figure 1 、 Figure 2 as well as Figure 4 As shown, the sensor connecting member 5 is a connecting member connected to a fuel pressure sensor (not shown) that detects the pressure of the fuel stored in the storage space 21. The sensor connecting member 5 is formed into a cylindrical shape centered on the central axis A of the pipe member 2. The front end ( Figure 1 、 Figure 2 as well as Figure 4 The front end on the left side in the figure is called the inner front end 5a, and the front end on the other side in the extending direction B of the sensor connecting component 5 ( Figure 1 、 Figure 2 as well as Figure 4 The front end on the right side in FIG) is called the outer front end 5b.

[0053] The sensor connecting member 5 is inserted into and joined to the distal end portion 23 of the pipe member 2. The sensor connecting member 5 and the distal end portion 23 of the pipe member 2 can be joined by brazing, welding, etc. In this embodiment, the sensor connecting member 5 is joined to the pipe member 2 by brazing.

[0054] The outer peripheral surface of the sensor connecting member 5 has an insertion surface 51 and a contact surface 52 .

[0055] The insertion surface 51 extends cylindrically from the inner front end 5a toward the outer front end 5b along the extension direction B. The abutment surface 52 rises from the insertion surface 51 toward the radially outer side of the sensor connecting component 5 on the outer front end 5b side of the insertion surface 51. Furthermore, with the insertion surface 51 inserted into the front end 23 of the pipe member 2 and the abutment surface 52 abutting the front end surface 26 of the front end 23 of the pipe member 2, the insertion surface 51 is brazed to the front end 23 of the pipe member 2. Alternatively, the abutment surface 52 of the sensor connecting component 5 may also be brazed to the front end surface 26 of the pipe member 2. The front end surface 26 of the pipe member 2 is the end surface on the side of the front end 23 of the pipe member 2 in the extension direction B. Furthermore, a tapered surface or the like may be formed between the insertion surface 51 and the inner front end 5a to facilitate insertion of the sensor connecting component 5 into the front end 23 of the pipe member 2.

[0056] The outer diameter of the insertion surface 51 before insertion into the front end portion 23 of the pipe member 2 may be larger than the inner diameter of the pipe member 2. Thus, by inserting the insertion surface 51 into the front end portion 23 of the pipe member 2 and brazing, brazing can be performed while the insertion surface 51 is pressed into the front end portion 23 of the pipe member 2. For example, the insertion surface 51 may be knurled to form projections and depressions, with the maximum outer diameter of the projections larger than the inner diameter of the pipe member 2 and the minimum outer diameter of the depressions smaller than the inner diameter of the pipe member 2. This allows the projections to be pressed against the front end portion 23 of the pipe member 2, allowing the brazing material to enter the depressions, thereby enhancing the bond strength between the insertion surface 51 and the front end portion 23 of the pipe member 2.

[0057] The sensor connecting member 5 has a through hole 53 formed on its inner peripheral surface for supplying high-pressure fuel supplied from the fuel pipe to the storage space 21. The through hole 53 is adjacent to the storage space 21 and extends in the extending direction B centered on the central axis A of the tube member 2.

[0058] The sensor connecting member 5 includes an intermediate diameter portion 54, a small diameter portion 55, a tapered portion 56, and a sensor connecting portion 57. The intermediate diameter portion 54 is the portion of the sensor connecting member 5 adjacent to the reservoir 21. The small diameter portion 55 is the portion of the sensor connecting member 5 located on the side opposite the reservoir 21 relative to the intermediate diameter portion 54. The tapered portion 56 is the portion of the sensor connecting member 5 located between the intermediate diameter portion 54 and the small diameter portion 55, connecting them. The sensor connecting portion 57 is the portion of the sensor connecting member 5 located on the side opposite the reservoir 21 of the small diameter portion 55. The intermediate diameter portion 54, the tapered portion 56, and at least a portion of the small diameter portion 55 form the insertion surface 51. Specifically, the insertion surface 51 is formed by the outer circumferential surface of the intermediate diameter portion 54, the outer circumferential surface of the tapered portion 56, and at least a portion of the outer circumferential surface of the small diameter portion 55.

[0059] The inner diameter D4 of the small diameter portion 55 is smaller than the inner diameter D1 of the pipe member 2. In the present embodiment, the inner diameter D4 of the small diameter portion 55 is the smallest inner diameter in the through hole 53.

[0060] The inner diameter D4 of the small-diameter portion 55 is not particularly limited. For example, to ensure that the pressure of the fuel stored in the storage space 21 can be appropriately transmitted to the fuel pressure sensor, the inner diameter D4 of the small-diameter portion 55 may be 3 mm or greater, preferably 3.5 mm or greater, and more preferably 4 mm or greater. Furthermore, to prevent the fuel rail 1 from becoming excessively large, the inner diameter D4 of the small-diameter portion 55 may be 9 mm or less, preferably 7 mm or less, and more preferably 5 mm or less. These maximum and minimum values ​​can be appropriately combined. For example, the inner diameter D4 of the small-diameter portion 55 may be 3 mm or greater and 9 mm or less, preferably 3.5 mm or greater and 7 mm or less, and more preferably 4 mm or greater and 5 mm or less.

[0061] The inner diameter D5 of the intermediate diameter portion 54 is larger than the inner diameter D4 of the small diameter portion 55 and smaller than the inner diameter D1 of the tube member 2. Therefore, in the sensor connecting member 5, the rigidity of the intermediate diameter portion 54 adjacent to the storage space 21 is lower than the rigidity of the small diameter portion 55. Consequently, in the sensor connecting member 5, if the central portion 24 of the tube member 2 expands due to the pressure of the fuel, the intermediate diameter portion 54 of the sensor connecting member 5 also readily expands in accordance with the central portion 24 of the tube member 2.

[0062] The inner diameter D5 of the intermediate diameter portion 54 is not particularly limited as long as it satisfies the above conditions. For example, to ensure sufficient rigidity of the intermediate diameter portion 54, the inner diameter D5 of the intermediate diameter portion 54 may be larger than the orifice diameter and of a size such that it does not substantially function as an orifice in relation to the small diameter portion 55 (a size such that an orifice effect is substantially absent), for example, larger than 3 mm, preferably larger than 3.5 mm, and more preferably larger than 4 mm. Furthermore, to facilitate expansion of the central portion 24 of the pipe member 2, the inner diameter D5 of the intermediate diameter portion 54 may be smaller than 14 mm, preferably smaller than 13 mm, and more preferably smaller than 12 mm. These maximum and minimum values ​​can be appropriately combined. For example, the inner diameter D5 of the intermediate diameter portion 54 may be larger than 3 mm and smaller than 14 mm, preferably larger than 3.5 mm and smaller than 13 mm, and more preferably larger than 4 mm and smaller than 12 mm.

[0063] The length L3 of the intermediate diameter portion 54 in the extension direction B may be shorter than the insertion length L4 of the sensor connecting member 5 into the tube member 2. The insertion length L4 of the sensor connecting member 5 into the tube member 2 is the length of the insertion surface 51 in the extension direction B. Furthermore, the length L3 of the intermediate diameter portion 54 in the extension direction B may be longer than the wall thickness T3 of the intermediate diameter portion 54.

[0064] The wall thickness T3 of the intermediate diameter portion 54 is not particularly limited. For example, the range of the wall thickness T3 of the intermediate diameter portion 54 may be the same as the range of the wall thickness T1 of the intermediate diameter portion 45 of the pipe connecting component 4. Furthermore, the wall thickness T3 of the intermediate diameter portion 54 may be the same as or different from the wall thickness T1 of the intermediate diameter portion 45 of the pipe connecting component 4.

[0065] The tapered portion 56 connects the intermediate diameter portion 54 and the small diameter portion 55. The inner diameter of the tapered portion 56 decreases from the intermediate diameter portion 54 side (inner front end 5a side) toward the small diameter portion 55 side (outer front end 5b side).

[0066] In the reference section containing the central axis A ( Figure 2 and Figure 4 In the cross-section shown), the inner circumferential surface of the tapered portion 56 can extend linearly from the intermediate diameter portion 54 to the small diameter portion 55, can extend curvedly from the intermediate diameter portion 54 to the small diameter portion 55, or can extend curvedly from the intermediate diameter portion 54 to the small diameter portion 55.

[0067] The angle θ2 formed by the inner circumferential surface of the tapered portion 56 in the reference cross-section including the central axis A is not particularly limited. For example, the range of the angle θ2 formed by the inner circumferential surface of the tapered portion 56 may be the same as the range of the angle θ1 formed by the inner circumferential surface of the tapered portion 47 of the pipe connecting component 4. Furthermore, the angle θ2 formed by the inner circumferential surface of the tapered portion 56 may be the same as or different from the angle θ1 formed by the inner circumferential surface of the tapered portion 47 of the pipe connecting component 4. Furthermore, in the case where the inner circumferential surface of the tapered portion 56 does not extend linearly from the intermediate diameter portion 54 to the small diameter portion 55, the angle θ2 formed by the inner circumferential surface of the tapered portion 56 in the reference cross-section including the central axis A is the angle formed by an imaginary line connecting the front end of the inner circumferential surface of the tapered portion 56 on the intermediate diameter portion 54 side and the front end on the small diameter portion 55 side.

[0068] A fuel pressure sensor is connected to the sensor connection portion 57. Connected to the sensor connection portion 57, the fuel pressure sensor detects the pressure of the fuel stored in the storage space 21 via the small-diameter portion 55. The inner circumferential surface of the sensor connection portion 57 includes an internal threaded surface 57a, with which the fuel pressure sensor is threadedly engaged, and a sensor abutment surface 57b, with which the fuel pressure sensor, which is threadedly engaged with the internal threaded surface 57a, abuts. The internal threaded surface 57a is formed with internal threads for threading the fuel pressure sensor. The internal threaded surface 57a extends along the extension direction B from the outer front end 5b toward the inner front end 5a. Alternatively, a tapered surface or the like may be formed between the internal threaded surface 57a and the outer front end 5b to facilitate threaded engagement of the fuel pressure sensor. The sensor abutment surface 57b is adjacent to the small-diameter portion 55. The sensor abutment surface 57b is tapered, with the inner diameter decreasing from the outer front end 5b toward the inner front end 5a, in accordance with the shape of the fuel pressure sensor.

[0069] Here, refer to Figure 5 , the fuel distribution pipe 101 of Comparative Example 1 will be described. Figure 5 Fuel distribution pipe 101 of Comparative Example 1 shown includes: pipe member 102, similar to pipe member 2; pipe connection member 104, corresponding to pipe connection member 4; and sensor connection member 105, corresponding to sensor connection member 5. Pipe connection member 104 includes a small-diameter portion 146 having the same inner diameter as small-diameter portion 46, replacing intermediate-diameter portion 45, small-diameter portion 46, and tapered portion 47 of pipe connection member 4. Sensor connection member 105 includes a small-diameter portion 155 having the same inner diameter as small-diameter portion 55, replacing intermediate-diameter portion 54, small-diameter portion 55, and tapered portion 56 of sensor connection member 5.

[0070] In the fuel distribution pipe 101 of Comparative Example 1 thus constructed, when subjected to the pressure of the fuel supplied to the storage space 121, the front end portion 122 of the pipe member 102, which is inserted into and joined to the supply pipe connecting member 104, is stiffened by the small-diameter portion 146 of the pipe connecting member 104, thereby inhibiting its expansion. Similarly, the front end portion 123 of the pipe member 102, which is joined to the sensor connecting member 105, is stiffened by the small-diameter portion 155 of the sensor connecting member 105, thereby inhibiting its expansion. As a result, only the central portion 124 of the pipe member 102 is susceptible to expansion, generating high stress at the boundary 127 between the central portion 124 and the front end portion 122, and at the boundary 128 between the central portion 124 and the front end portion 123 of the pipe member 102. This can accelerate metal fatigue and shorten its service life.

[0071] In contrast, in the fuel delivery pipe 1 according to this embodiment, the pipe connecting member 4, which is inserted into and joined to the distal end portion 22 of the pipe member 2, has an intermediate diameter portion 45 adjacent to the storage space 21 and a smaller diameter portion 46 located on the opposite side of the intermediate diameter portion 45 from the storage space 21. The intermediate diameter portion 45 has an inner diameter D3 that is smaller than the inner diameter D1 of the pipe member 2 and larger than the inner diameter D2 of the smaller diameter portion 46. In other words, the rigidity of the intermediate diameter portion 45 adjacent to the storage space 21 is lower than that of the smaller diameter portion 46. Therefore, when subjected to fuel pressure, the intermediate diameter portion 45 of the pipe connecting member 4 easily expands, following the central portion 24 of the pipe member 2 that forms the storage space 21. This suppresses stress generated at the boundary 27 between the central portion 24 and the distal end portion 22 of the pipe member 2. Similarly, the sensor connecting member 5, which is inserted into and joined to the distal end portion 23 of the tube member 2, has an intermediate diameter portion 54 adjacent to the reservoir space 21 and a smaller diameter portion 55 located on the opposite side of the intermediate diameter portion 54 from the reservoir space 21. The intermediate diameter portion 54 has an inner diameter D5 that is smaller than the inner diameter D1 of the tube member 2 and larger than the inner diameter D4 of the smaller diameter portion 55. In other words, the rigidity of the intermediate diameter portion 54 adjacent to the reservoir space 21 is lower than that of the smaller diameter portion 55. Therefore, when subjected to fuel pressure, the intermediate diameter portion 54 of the sensor connecting member 5 tends to expand in accordance with the central portion 24 of the tube member 2 that forms the reservoir space 21. This suppresses stress generated at the boundary 28 between the central portion 24 and the distal end portion 23 of the tube member 2.

[0072] Furthermore, in this fuel distribution pipe 1, a cross section perpendicular to the central axis A of the pipe member 2 and passing through the storage space 21 is substantially uniform throughout the entire region in the extension direction B of the pipe member 2. This can suppress the occurrence of local stress concentration when the pipe member 2 expands due to the pressure of the fuel.

[0073] Furthermore, in this fuel distribution pipe 1, a tapered portion 47 is formed on the pipe connecting member 4. This tapered portion 47 connects to the intermediate diameter portion 45 and the small diameter portion 46 and has an inner diameter that decreases from the intermediate diameter portion 45 toward the small diameter portion 46. This allows the intermediate diameter portion 45 to more easily follow the expansion of the central portion 24 forming the storage space 21 of the pipe member 2. This further reduces stress generated at the boundary 27 between the central portion 24 and the distal end portion 22 of the pipe member 2. Similarly, a tapered portion 56 is formed on the sensor connecting member 5. This tapered portion 56 connects to the intermediate diameter portion 54 and the small diameter portion 55 and has an inner diameter that decreases from the intermediate diameter portion 54 toward the small diameter portion 55. This allows the intermediate diameter portion 54 to more easily follow the expansion of the central portion 24 forming the storage space 21 of the pipe member 2. This further reduces stress generated at the boundary 28 between the central portion 24 and the distal end portion 23 of the pipe member 2.

[0074] Furthermore, in this fuel distribution pipe 1, by setting the angles θ1 and θ2 formed by the inner circumferential surfaces of the tapered portion 47 and the tapered portion 56 in a reference cross-section including the central axis A of the pipe member 2 to be not less than 110° and not more than 160°, it is possible to prevent the piping connection member 4 and the sensor connection member 5 from becoming excessively long, and to appropriately expand the intermediate diameter portion 45 of the piping connection member 4 and the intermediate diameter portion 54 of the sensor connection member 5.

[0075] Furthermore, in the fuel delivery pipe 1 , the pipe connecting member 4 and the sensor connecting member 5 are joined to the distal end portion 22 and the distal end portion 23 of the pipe member 2 in the inserted state, so that the pipe connecting member 4 and the sensor connecting member 5 can be firmly joined to the pipe member 2 .

[0076] Furthermore, in this fuel distribution pipe 1, since the length L1 of the intermediate diameter portion 45 in the extension direction B of the pipe member 2 is shorter than the insertion length L2 of the pipe connecting member 4 into the pipe member 2 and longer than the wall thickness T1 of the intermediate diameter portion 45, it is possible to prevent the pipe connecting member 4 from becoming excessively long and to appropriately expand the intermediate diameter portion 45 of the pipe connecting member 4. Similarly, since the length L3 of the intermediate diameter portion 54 in the extension direction B of the pipe member 2 is shorter than the insertion length L4 of the sensor connecting member 5 into the pipe member 2 and longer than the wall thickness T3 of the intermediate diameter portion 54, it is possible to prevent the sensor connecting member 5 from becoming excessively long and to appropriately expand the intermediate diameter portion 54 of the sensor connecting member 5.

[0077] Furthermore, in this fuel distribution pipe 1, by having the wall thickness T1 of the intermediate diameter portion 45 be no less than 0.3 times and no more than 1.5 times, preferably no less than 0.7 times and no more than 1.3 times, and more preferably no less than 0.9 times and no more than 1.1 times, the rigidity of the intermediate diameter portion 45 is ensured sufficiently, and the intermediate diameter portion 45 is more easily able to follow the expansion of the central portion 24 of the pipe member 2 forming the storage space 21. Similarly, by having the wall thickness T3 of the intermediate diameter portion 54 be no less than 0.3 times and no more than 1.5 times, preferably no less than 0.7 times and no more than 1.3 times, and more preferably no less than 0.9 times and no more than 1.1 times, the rigidity of the intermediate diameter portion 54 is ensured sufficiently, and the expansion of the central portion 24 of the pipe member 2 forming the storage space 21 is more easily able to follow the expansion of the central portion 24 of the pipe member 2 forming the storage space 21.

[0078] Furthermore, in this fuel rail 1, the presence of intermediate diameter portion 45 in pipe connecting member 4 allows fuel supplied from the fuel pipe to be appropriately supplied to the storage space over a long period of time. Similarly, the presence of intermediate diameter portion 54 in sensor connecting member 5 allows the pressure of the fuel stored in storage space 21 to be appropriately transmitted to the fuel pressure sensor over a long period of time.

[0079] Furthermore, in this fuel rail pipe, by having an inner diameter D2 of small-diameter portion 46 of 1 mm to 11 mm, preferably 2 mm to 10 mm, and more preferably 3 mm to 9 mm, the fuel supplied from the fuel pipe can be appropriately supplied to storage space 21, while preventing the fuel rail pipe 1 from becoming excessively large and obstructing the flow of fuel. Similarly, by having an inner diameter D4 of small-diameter portion 55 of 3 mm to 9 mm, preferably 3.5 mm to 7 mm, and more preferably 4 mm to 5 mm, the pressure of the fuel stored in storage space 21 can be appropriately transmitted to the fuel pressure sensor, while preventing the fuel rail pipe 1 from becoming excessively large and obstructing the flow of fuel.

[0080] [Second embodiment]

[0081] Next, the second embodiment will be described. The second embodiment is fundamentally the same as the first embodiment, differing only in that a sensor connecting member is joined to the circumferential surface of the tube member, and a cap member is joined to the distal end of the tube member, replacing the sensor connecting member. Therefore, the following description will focus on only those matters that differ from the first embodiment, and any descriptions that overlap with the first embodiment will be omitted.

[0082] Figure 6 It is a schematic perspective view of a fuel rail according to a second embodiment. Figure 7 Yes Figure 6 A schematic cross-sectional view of a portion of the fuel distribution pipe is shown. Figure 6and Figure 7 As shown, a fuel delivery pipe 1A according to the present embodiment includes a pipe member 2 , a plurality of housings 3 , a pipe connecting member 4 , a sensor connecting member 5A, and a cover member 6 .

[0083] Similar to the sensor connecting member 5 of the first embodiment, the sensor connecting member 5A is a connecting member connected to a fuel pressure sensor (not shown) that detects the pressure of the fuel stored in the storage space 21. The sensor connecting member 5A is joined to the peripheral surface of the pipe member 2. The sensor connecting member 5A and the peripheral surface of the pipe member 2 are joined by brazing, welding, or the like.

[0084] The cover member 6 is inserted into and joined to the other side of the tube member 2 ( Figure 6 and Figure 7 The front end portion 23 (on the right side in FIG) replaces the sensor connection member 5 of the first embodiment. Therefore, the storage space 21 is formed by the central portion 24 of the tube member 2 where the pipe connection member 4 and the cover member 6 are not inserted and joined.

[0085] Figure 8 It is magnified Figure 7 A schematic cross-sectional view of the periphery of the cover member in FIG. Figures 6 to 8 As shown, the cover member 6 is a connecting member that closes the other side of the pipe member 2. The cover member 6 is formed into a cap shape centered on the central axis A of the pipe member 2. The front end ( Figures 6 to 8 The front end on the left side of the cover member 6 is referred to as the inner front end 6a, and the front end on the other side in the extending direction B of the cover member 6 ( Figures 6 to 8 The front end on the right side in FIG) is called the outer front end 6b.

[0086] The cover member 6 is inserted into and joined to the front end portion 23 of the pipe member 2. The cover member 6 and the front end portion 23 of the pipe member 2 can be joined by brazing, welding, etc. In this embodiment, the cover member 6 is joined to the pipe member 2 by brazing.

[0087] The outer peripheral surface of the cover member 6 has an insertion surface 61 and a contact surface 62 .

[0088] The insertion surface 61 extends cylindrically along the extension direction B from the inner front end 6a toward the outer front end 6b. The abutment surface 62 rises from the insertion surface 61 toward the radially outer side of the cover member 6 on the outer front end 6b side of the insertion surface 61. Furthermore, with the insertion surface 61 inserted into the front end portion 23 of the pipe member 2 and the abutment surface 62 abutting the front end surface 26 of the front end portion 23 of the pipe member 2, the insertion surface 61 is brazed to the front end portion 23 of the pipe member 2. Alternatively, the abutment surface 62 of the cover member 6 may also be brazed to the front end surface 26 of the pipe member 2. Furthermore, a tapered surface or the like may be formed between the insertion surface 61 and the inner front end 4b to facilitate insertion of the cover member 6 into the front end portion 23 of the pipe member 2.

[0089] The outer diameter of the insertion surface 61 before insertion into the front end portion 23 of the pipe member 2 may be larger than the inner diameter of the pipe member 2. Thus, by inserting the insertion surface 61 into the front end portion 23 of the pipe member 2 and brazing, brazing can be performed while the insertion surface 61 is pressed into the front end portion 23 of the pipe member 2. For example, the insertion surface 61 may be knurled to form projections and depressions, with the maximum outer diameter of the projections larger than the inner diameter of the pipe member 2 and the minimum outer diameter of the depressions smaller than the inner diameter of the pipe member 2. This allows the projections to be pressed against the front end portion 23 of the pipe member 2, allowing the brazing material to enter the depressions, thereby enhancing the bond strength between the insertion surface 61 and the front end portion 23 of the pipe member 2.

[0090] The lid member 6 has a recessed portion 63 that is adjacent to the storage space 21 and is recessed from the inner front end 6a toward the outer front end 6b. The lid member 6 includes a hole portion 64, a tapered portion 65, and a closing portion 66.

[0091] The hole portion 64 is a portion of the cover member 6 that is adjacent to the storage space 21 and forms the recess 63. The tapered portion 65 is a portion of the cover member 6 that is adjacent to the side opposite to the storage space 21 side of the hole portion 64 and forms the recess 63. The closed portion 66 is a portion of the cover member 6 that is adjacent to the side opposite to the storage space 21 side of the tapered portion 65 and does not form the recess 63. The hole portion 64 and at least a portion of the tapered portion 65 form the insertion surface 61. That is, the insertion surface 61 is formed by the outer peripheral surface of the hole portion 64 and the outer peripheral surface of at least a portion of the tapered portion 65. In addition, at least a portion of the closed portion 66 may also form the insertion surface 61. In this case, the insertion surface 61 is formed by the outer peripheral surface of the hole portion 64, the outer peripheral surface of the tapered portion 65, and the outer peripheral surface of at least a portion of the closed portion 66.

[0092] In the cover member 6, due to the recessed portion 63, the rigidity of the perforated portion 64 adjacent to the storage space 21 and the tapered portion 65 adjacent to the perforated portion 64 is lower than the rigidity of the sealing portion 66. Therefore, when the central portion 24 of the tube member 2 expands under the pressure of the fuel, the perforated portion 64 of the cover member 6 also tends to expand in accordance with the central portion 24 of the tube member 2.

[0093] The inner diameter D6 of the perforated portion 64 is smaller than the inner diameter D1 of the tube member 2. The inner diameter D6 of the perforated portion 64 is not particularly limited as long as it satisfies the above-mentioned conditions. For example, to ensure sufficient rigidity of the perforated portion 64, the inner diameter D6 of the perforated portion 64 may be greater than 3 mm, preferably greater than 3.5 mm, and more preferably greater than 4 mm. Furthermore, to facilitate expansion of the central portion 24 of the tube member 2, the inner diameter D6 of the perforated portion 64 may be less than 14 mm, preferably less than 13 mm, and more preferably less than 12 mm. These maximum and minimum values ​​can be appropriately combined. For example, the inner diameter D6 of the perforated portion 64 may be greater than 3 mm and less than 14 mm, preferably greater than 3.5 mm and less than 13 mm, and more preferably greater than 4 mm and less than 12 mm.

[0094] The length L5 of the hole portion 64 in the extension direction B may be shorter than the insertion length L6 of the cover member 6 into the tube member 2. The insertion length L6 of the cover member 6 into the tube member 2 is the length of the insertion surface 61 in the extension direction B. Furthermore, the length L5 of the hole portion 64 in the extension direction B may be longer than the wall thickness T4 of the hole portion 64.

[0095] The wall thickness T4 of the hole portion 64 is not particularly limited. For example, the wall thickness T4 of the hole portion 64 may be within the same range as the wall thickness T1 of the intermediate diameter portion 45 of the pipe connecting component 4. Furthermore, the wall thickness T4 of the hole portion 64 may be the same as or different from the wall thickness T1 of the intermediate diameter portion 45 of the pipe connecting component 4.

[0096] The tapered portion 65 is connected to the hole portion 64 and the closed portion 66. The inner diameter of the tapered portion 65 decreases from the hole portion 64 side (inner front end 6a side) toward the closed portion 66 side (outer front end 6b side).

[0097] In the reference section containing the central axis A ( Figure 7 and Figure 8 In the cross-section shown), the inner circumferential surface of the tapered portion 65 can extend linearly from the porous portion 64 to the closed portion 66, can extend curvedly from the porous portion 64 to the closed portion 66, or can extend curvedly from the porous portion 64 to the closed portion 66.

[0098] The angle θ3 formed by the inner circumferential surface of the tapered portion 65 in the reference cross-section including the central axis A is not particularly limited. For example, the range of the angle θ3 formed by the inner circumferential surface of the tapered portion 65 may be the same as the range of the angle θ1 formed by the inner circumferential surface of the tapered portion 47 of the pipe connecting component 4. In addition, the angle θ3 formed by the inner circumferential surface of the tapered portion 65 may be the same as or different from the angle θ1 formed by the inner circumferential surface of the tapered portion 47 of the pipe connecting component 4. In addition, in the case where the inner circumferential surface of the tapered portion 65 does not extend linearly from the hole portion 64 to the closed portion 66, the angle θ3 formed by the inner circumferential surface of the tapered portion 65 in the reference cross-section including the central axis A is the angle formed by an imaginary line connecting the front end of the inner circumferential surface of the tapered portion 32 on the hole portion 64 side and the front end on the closed portion 66 side.

[0099] Here, refer to Figure 9 , the fuel distribution pipe 101A of Comparative Example 2 will be described. Figure 9 Fuel delivery pipe 101A of Comparative Example 2 shown includes: pipe member 102, similar to pipe member 2; pipe connection member 104, corresponding to pipe connection member 4; and cap member 106, corresponding to cap member 6. In fuel delivery pipe 101A of Comparative Example 2, pipe connection member 104 includes a small-diameter portion 146 having the same inner diameter as small-diameter portion 46, replacing intermediate-diameter portion 45, small-diameter portion 46, and tapered portion 47 of pipe connection member 4. Cap member 106 includes a closing portion 166, which, in place of the perforated portion 64, tapered portion 65, and closing portion 66 of cap member 6, lacks the recessed portion 63 of cap member 6.

[0100] In the fuel distribution pipe 101A of Comparative Example 2, constructed in this manner, when subjected to the pressure of the fuel supplied to the storage space 121, the front end portion 122 of the tube member 102, which is inserted and joined to the pipe connection member 104, is stiffened by the small-diameter portion 146 of the pipe connection member 104, thereby inhibiting expansion. Similarly, the front end portion 123 of the tube member 102, which is joined to the cap member 106, is stiffened by the sealing portion 166 of the cap member 106, thereby inhibiting expansion. As a result, only the central portion 124 of the tube member 102 is susceptible to expansion, generating high stress at the boundary 127 between the central portion 124 and the front end portion 122, and at the boundary 129 between the central portion 124 and the front end portion 123 of the tube member 102. This may accelerate metal fatigue and shorten the service life.

[0101] In contrast, in the fuel delivery pipe 1A according to this embodiment, the pipe connecting member 4, which is inserted into and joined to the distal end portion 22 of the pipe member 2, has an intermediate diameter portion 45 adjacent to the reservoir space 21 and a smaller diameter portion 46 located on the opposite side of the intermediate diameter portion 45 from the reservoir space 21. The intermediate diameter portion 45 has an inner diameter D3 that is smaller than the inner diameter D1 of the pipe member 2 and larger than the inner diameter D2 of the smaller diameter portion 46. In other words, the rigidity of the intermediate diameter portion 45 adjacent to the reservoir space 21 is lower than that of the smaller diameter portion 46. Therefore, when subjected to fuel pressure, the intermediate diameter portion 45 of the pipe connecting member 4 easily expands, following the central portion 24 of the pipe member 2 that forms the reservoir space 21. This suppresses stress generated at the boundary 27 between the central portion 24 and the distal end portion 22 of the pipe member 2. Similarly, the cover member 6, which is inserted into and joined to the front end portion 23 of the tube member 2, has a perforated portion 64 adjacent to the reservoir 21 and forming a recessed portion 63. Specifically, the rigidity of the perforated portion 64 adjacent to the reservoir 21 is lower than that of the sealing portion 66 of the cover member 6. Therefore, when subjected to fuel pressure, the perforated portion 64 of the cover member 6 tends to expand in accordance with the central portion 24 of the tube member 2, which forms the reservoir 21. This suppresses stress generated at the boundary 29 between the central portion 24 and the front end portion 23 of the tube member 2.

[0102] Furthermore, in this fuel distribution pipe 1A, a tapered portion 65 is formed in the cap member 6. This tapered portion 65 is connected to the side of the perforated portion 64 opposite the storage space 21 side and has an inner diameter that decreases from the inner front end 6a side toward the outer front end 6b side. This allows the perforated portion 64 to more easily expand in accordance with the central portion 24 of the pipe member 2 that forms the storage space 21. This further reduces the stress generated at the boundary 29 between the central portion 24 and the front end 23 of the pipe member 2.

[0103] As mentioned above, although the preferred embodiment of one aspect of the present invention has been described, one aspect of the present invention is not limited to the above embodiment.

[0104] For example, while the above embodiments describe examples of connecting components using a pipe connecting component and a sensor connecting component, the connecting component may also be a connecting component that includes both a pipe connecting component and a sensor connecting component. Furthermore, while the second embodiment describes an example in which the sensor connecting component is joined to the circumferential surface of the pipe component, the pipe connecting component is joined to the front end of one side of the pipe component, and the cover component is joined to the front end of the other side of the pipe component, the pipe connecting component may also be joined to the circumferential surface of the pipe component, the sensor connecting component may be joined to the front end of one side of the pipe component, and the cover component may be joined to the front end of the other side of the pipe component. Furthermore, as a reference example, connecting components such as the pipe connecting component and the sensor connecting component may also be joined to the circumferential surface of the pipe component, and the cover component may be joined to the front end of one side of the pipe component and the front end of the other side of the pipe component.

[0105] Industrial applicability

[0106] One aspect of the present invention can be used as a fuel distribution pipe for distributing and supplying fuel to a plurality of fuel injection devices.

[0107] Description of Reference Numerals

[0108] 1…Fuel distribution pipe; 1A…Fuel distribution pipe; 2…Pipe member; 21…Storage space; 22…Front end portion; 23…Front end portion; 24…Central portion; 25…Front end surface; 26…Front end surface; 27…Boundary portion; 28…Boundary portion; 29…Boundary portion; 3…Casing; 4…Pipe connecting member; 4a…Outer front end; 4b…Inner front end; 41…External threaded surface; 42…Insertion surface; 43…Abutment surface; 44…Through hole; 45…Intermediate diameter portion; 46…Small diameter portion; 47…Tapered portion; 5…Sensor connecting member; 5A…Sensor connecting member; 5a…Inner front end; 5b…Outer front end; 51…Insertion surface; 52…Abutment surface; 53…Through hole; 54…Intermediate diameter portion; 55…Small diameter portion; 56…Tapered portion; 57…Sensor connecting member; 57a …internal thread surface; 57b…sensor abutment surface; 6…cover component; 6a…inner front end; 6b…outer front end; 61…insertion surface; 62…abutment surface; 63…recessed portion; 64…perforated portion; 65…tapered portion; 66…closed portion; 101…fuel distribution pipe; 101A…fuel distribution pipe; 102…pipe component; 104…piping connection component; 105…sensor connection component; 106…cover component; 121…storage space; 122…front end portion; 123…front end portion; 124…central portion; 127…junction portion; 128…junction portion; 129…junction portion; 146…small diameter portion; 155…small diameter portion; 166…closed portion; A…center axis; B…extension direction; D1–D6…inner diameter; T1–T4…wall thickness; θ1–θ3…angle.

Claims

1. A fuel distribution pipe that distributes fuel supplied from a fuel pipe to a plurality of fuel injection devices, characterized in that: have: a pipe member having a storage space formed therein for storing the fuel; a pipe connecting member, inserted into and joined to a front end portion of one side of the pipe member, formed with a through hole connected to the storage space, the pipe connecting member being connected to the fuel pipe; as well as a sensor connecting member, which is inserted into and joined to the front end portion of the other side of the pipe member and is formed with a through hole connected to the storage space; the sensor connecting member is connected to a fuel pressure sensor, and the fuel pressure sensor detects the pressure of the fuel stored in the storage space; The pipe connecting member and the sensor connecting member have: an intermediate diameter portion adjacent to the storage space; and a small diameter portion arranged at a position on the opposite side of the storage space than the intermediate diameter portion. The intermediate diameter portion has an inner diameter that is larger than the inner diameter of the small diameter portion and smaller than the inner diameter of the pipe member.

2. The fuel distribution pipe according to claim 1, characterized in that A cross section of the storage space perpendicular to the central axis of the pipe member is substantially uniform over the entire region in the extending direction of the pipe member.

3. The fuel distribution pipe according to claim 1 or 2, characterized in that: The pipe connection member and the sensor connection member further include a tapered portion connected to the intermediate diameter portion and the small diameter portion and having an inner diameter that decreases from the intermediate diameter portion side toward the small diameter portion side.

4. The fuel distribution pipe according to claim 3, characterized in that In a reference cross section including the central axis of the pipe member, an angle formed by the inner peripheral surface of the tapered portion is not less than 110° and not more than 160°.

5. The fuel distribution pipe according to claim 1 or 2, characterized in that: In the extending direction of the tube member, the length of the intermediate diameter portion is shorter than the insertion length of the pipe connecting member and the sensor connecting member into the tube member and is longer than the wall thickness of the intermediate diameter portion.

6. The fuel distribution pipe according to claim 1 or 2, characterized in that: The wall thickness of the intermediate diameter portion is not less than 0.3 times and not more than 1.5 times the wall thickness of the pipe member.

7. The fuel distribution pipe according to claim 1 or 2, characterized in that: The inner diameter of the small-diameter portion is not less than 1 mm and not more than 11 mm.

8. The fuel distribution pipe according to claim 1 or 2, characterized in that: The inner diameter of the small-diameter portion is not less than 3 mm and not more than 9 mm.

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