FUEL DISTRIBUTION PIPE

Abstract

A fuel distribution pipe that distributes and supplies fuel from a fuel line to a plurality of fuel injection devices includes a pipe member configured to form a storage space for storing fuel therein and a connecting member inserted into and attached to a portion of the tip end of the pipe member and having a through-hole connected to the storage space. The connecting member has an intermediate-diameter portion adjacent to the storage space and a small-diameter portion positioned on a side opposite the storage space with respect to the intermediate-diameter portion. The intermediate-diameter portion has an inside diameter that is larger than the inside diameter of the small-diameter portion and smaller than the inside diameter of the pipe member.

Description

FUEL DISTRIBUTION PIPE FIELD OF INVENTION

[0001] One aspect of the present invention relates to a fuel distribution tube that distributes and supplies fuel to a plurality of fuel injection devices. BACKGROUND OF THE INVENTION

[0002] In a direct injection engine or similar, a fuel distribution tube is used to distribute and supply high-pressure fuel compressed by a high-pressure pump to a plurality of fuel injection devices. Patent Literature 1 describes a fuel distribution tube to which a fuel supply path (fuel line) is connected for distributing and supplying fuel to a plurality of injectors. In the fuel distribution tube, an orifice is formed to reduce pulsation in a portion of the tip of a main tube orifice (a storage space) formed within the fuel distribution tube. List of Appointments Patent Literature

[0003] Patent Literature 1: Unexamined Japanese Patent Publication No. 2012-097690 BRIEF DESCRIPTION OF THE INVENTION Technical Problem

[0004] The fuel distribution pipe includes a pipe member that forms a storage space for holding fuel and a connecting member that is inserted into and joined to a portion of the tip of the pipe member and has a smaller inside diameter than the inside diameter of the pipe member. In this fuel distribution pipe, when the fuel is pressurized, the pipe member tends to expand due to the fuel pressure. However, because the portion of the tip of the pipe member into which the connecting member is inserted and joined has greater rigidity due to the connecting member, and expansion is inhibited, only a central portion forming the storage space of the pipe member tends to expand.As a result, high stress is generated in a boundary portion between the central portion and the tip portion of the pipe member, which can accelerate metal fatigue and shorten its lifespan.

[0005] Here, it is conceivable to increase the wall thickness of the pipe member so that it does not expand due to fuel pressure. However, increasing the wall thickness of the pipe member increases the weight and cost of the fuel distribution pipe. Furthermore, when the external diameter of the pipe member increases due to the increased wall thickness, the degrees of freedom in the fuel distribution pipe arrangement decrease. When the internal diameter of the pipe member becomes smaller due to the increased wall thickness, noise emissions increase due to fuel pulsation caused by high-pressure pump operation.

[0006] Thus, one objective of an aspect of the present invention is to provide a fuel distribution tube capable of reducing the stress generated in the pipe member while allowing the pipe member to expand. Solution to the Problem

[0007] A fuel distribution pipe according to an aspect of the present invention is a fuel distribution pipe that distributes and supplies fuel supplied from a fuel pipe to a plurality of fuel injection devices, including a pipe member configured to form a storage space for storing the fuel therein and a connecting member inserted into and attached to a portion of the tip end of the pipe member and having a through-hole connected to the storage space,where the connecting member has an intermediate diameter portion adjacent to the storage space and a small diameter portion disposed on a side opposite the storage space with respect to the intermediate diameter portion, and the intermediate diameter portion has an internal diameter that is larger than an internal diameter of the small diameter portion and smaller than an internal diameter of the pipe member.

[0008] In the fuel distribution pipe, the connecting member inserted into and attached to the end portion of the pipe member has an intermediate-diameter portion adjacent to the storage space and a small-diameter portion arranged on the opposite side of the storage space. The intermediate-diameter portion has an internal diameter that is smaller than the internal diameter of the pipe member and larger than the internal diameter of the small-diameter portion. Therefore, in the connecting member, the stiffness of the intermediate-diameter portion adjacent to the storage space is less than the stiffness of the small-diameter portion. Consequently, when fuel pressure is applied, the intermediate-diameter portion of the connecting member expands readily, extending beyond the central portion of the pipe member to form the storage space.In this way, the stress generated in a boundary portion between the central portion and the tip portion of the pipe member is avoided.

[0009] A cross-section of the storage space perpendicular to a central axis of the pipe member may be substantially the same throughout the region of the pipe member in an extension direction. In this fuel distribution pipe, since the cross-section of the storage space perpendicular to the central axis of the pipe member is substantially the same throughout the region of the pipe member in the extension direction, local stress concentration braking may occur when the pipe member expands due to fuel pressure.

[0010] The connecting member further has a tapered-diameter portion connected to the intermediate-diameter portion and the small-diameter portion, having an internal diameter that decreases from one side of the intermediate-diameter portion to one side of the small-diameter portion. In the fuel distribution pipe, since the tapered-diameter portion connected to the intermediate-diameter portion and the small-diameter portion, and having an internal diameter that decreases from the side of the intermediate-diameter portion to the side of the small-diameter portion, is formed in the connecting member, the intermediate-diameter portion can be made to expand more easily after the central portion of the pipe member, forming the storage space.

[0011] An angle formed by an internal peripheral surface of the tapered diameter portion in a reference cross-section including the centerline of the pipe member may be 110° or more and 160° or less. In the fuel distribution pipe, since the angle formed by the internal peripheral surface of the tapered diameter portion in the reference cross-section including the centerline of the pipe member is 110° or more and 160° or less, it is possible to prevent the connecting member from becoming too large by expanding the intermediate diameter portion of the connecting member appropriately.

[0012] In the extension direction of the pipe member, the length of the intermediate diameter portion may be shorter than the insertion length of the connecting member into the pipe member and longer than the thickness of the intermediate diameter portion. In the fuel distribution pipe, since the length of the intermediate diameter portion in the extension direction of the pipe member is shorter than the insertion length of the connecting member into the pipe member and longer than the thickness of the intermediate diameter portion, it is possible to prevent the connecting member from becoming too large and to expand the intermediate diameter portion of the connecting member appropriately.

[0013] The thickness of the intermediate diameter portion may be 0.3 times or more and 1.5 times or less than the thickness of the pipe member. In the fuel distribution pipe, since the thickness of the intermediate diameter portion is 0.3 times or more and 1.5 times or less than the thickness of the pipe member, even if the stiffness of the intermediate diameter portion is sufficiently ensured, the intermediate diameter portion may expand even more readily after the central portion forms the storage space of the pipe member.

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

[0015] The internal diameter of the small-diameter portion may be 1 mm or more and 11 mm or less. In the fuel distribution pipe, when the connecting member is a pipe connecting member, the internal diameter of the small-diameter portion is 1 mm or more and 11 mm or less, thus preventing the fuel distribution pipe from becoming too large while ensuring that the fuel supplied from the fuel pipe is properly delivered to the storage space and preventing obstruction of the fuel flow.

[0016] 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 the fuel distribution line, since the connecting member is the sensor connecting member, the pressure of the fuel stored in the storage space can be appropriately transmitted to the fuel pressure sensor over an extended period of time.

[0017] The internal diameter of the small diameter portion may be 3 mm or more and 9 mm or less. In the fuel distribution tube, when the connecting member is a sensor connecting member, the internal diameter of the small diameter portion is 3 mm or more and 9 mm or less, thus preventing the fuel distribution tube from becoming too large while ensuring that the pressure of the fuel stored in the storage space is properly transmitted to the fuel pressure sensor and preventing obstruction of the fuel flow. Advantageous Effects of the Invention

[0018] According to one aspect of the present invention, the stress generated in the pipe member can be reduced while allowing the pipe member to expand. BRIEF DESCRIPTION OF THE FIGURES

[0019] Figure 1 is a schematic front view of a fuel distribution tube according to a first modality. Figure 2 is a schematic cross-sectional view, showing a portion of the fuel distribution tube shown in Figure 1. Figure 3 is a schematic cross-sectional view, enlarging the periphery of a pipe connection member in Figure 2. Figure 4 is a schematic cross-sectional view, which enlarges the periphery of the sensor connection member in Figure 2. Figure 5 is a schematic cross-sectional view, showing a portion of a fuel distribution pipe from Comparative Example 1. Figure 6 is a schematic cross-sectional view of a fuel distribution pipe according to a second modality. Figure 7 is a schematic cross-sectional view, showing a portion of the fuel distribution tube shown in Figure 6. Figure 8 is a schematic cross-sectional view, enlarging the periphery of a cover member in Figure 7. Figure 9 is a schematic cross-sectional view, showing a portion of a fuel distribution pipe from Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0020] A fuel distribution pipe according to a specific configuration will be described below with reference to the Figures. In each Figure, the same or corresponding elements are denoted by the same reference numbers, and overlapping descriptions will be avoided.

[0021] First modality Figure 1 is a schematic perspective view of a fuel distribution pipe according to a first embodiment. Figure 2 is a schematic cross-sectional view showing a portion of the fuel distribution pipe shown in Figure 1. As shown in Figures 1 and 2, the fuel distribution pipe 1 according to the present embodiment distributes and supplies high-pressure fuel compressed by a high-pressure pump (not shown) and supplied from a fuel line (not shown) to a fuel injection device (not shown) provided, corresponding to each cylinder (not shown) of an engine (not shown). The fuel distribution pipe 1 is also referred to as a fuel injection rail, a fuel distribution pipe, a common rail, or similarly.

[0022] The fuel distribution tube 1 includes a pipe member 2, a plurality of housings 3, a pipe connection member 4, and a sensor connection member 5. Although the Figure shows the fuel distribution tube 1 including four housings 3, the number of housings 3 is not particularly limited as long as it is two or more.

[0023] Pipe member 2 is a member for storing fuel pumped from a high-pressure pump in a high-pressure state to supply fuel to a plurality of fuel injection devices. Pipe member 2 is formed, for example, in the form of a circular tube extending linearly in one direction of a cylinder bank (one direction of a crankshaft) of an engine. The tube shape of pipe member 2 does not necessarily have to be the shape of a linearly extending circular tube and may be of various shapes. A storage space 21 for storing fuel is formed within pipe member 2.As described below, the pipe connection member 4 is inserted into and joined to a portion of the tip end 22 on one side (the left side in Figures 1 and 2) of pipe member 2, and the sensor connection member 5 is inserted into and joined to a portion of the tip end 23 on the other side (the right side in Figures 1 and 2) of pipe member 2. Therefore, the storage space 21 is formed by a central portion 24 of pipe member 2 into which the pipe connection member 4 and the sensor connection member 5 are not inserted and joined. Pipe member 2 is attached to the motor by means of a tie-back-like member (not shown).

[0024] A cross-section of storage space 21 orthogonal to a centerline A of pipe member 2 is substantially the same throughout the region of pipe member 2 in an extension direction B. Here, “substantially the same” is not limited to being exactly the same, but means that manufacturing errors or tolerances of approximately ±10% are allowed. For example, when an intermediate plate thickness between the thickest and thinnest portions of pipe member 2 is used as a reference plate thickness, a plate thickness at any position on pipe member 2 is within ±10% of the reference plate thickness. The centerline A of pipe member 2 is a line passing through a radial center of pipe member 2 and extending in the extension direction B of pipe member 2.

[0025] Housing 3 is a member for maintaining the airtightness of the fuel injection device and supplying fuel from the storage space 21 of pipe member 2 to the fuel injection device. Housing 3 is attached to a peripheral surface of pipe member 2. The connection of housing 3 to pipe member 2 may be formed by brazing, welding, or similar means. Housing 3 is provided in accordance with the fuel injection device.

[0026] Figure 3 is a schematic cross-sectional view, enlarging the periphery of the pipe fitting member in Figure 2. As shown in Figures 1–3, pipe fitting member 4 is a fitting connected to a fuel pipe. Pipe fitting member 4 is formed in a tubular shape around the central axis A of pipe fitting member 2. One tip end on one side of pipe fitting member 4 in the extension direction B (one tip end on the left side in Figures 1–3) is referred to as an outer tip end 4a, and one tip end on the other side of pipe fitting member 4 in the extension direction B (one tip end on the right side in Figures 1–3) is referred to as an inner tip end 4b.

[0027] The pipe fitting 4 is inserted into and joined to the tip end portion 22 of pipe fitting 2. The connection of the pipe fitting 4 to the tip end portion 22 of pipe fitting 2 may be made by brazing, welding, or similar means. In the present embodiment, the pipe fitting 4 is joined to the pipe fitting 2 by brazing.

[0028] An external peripheral surface of the pipe connection member 4 has a male threaded surface 41, an insertion surface 42, and a contact surface 43. The male threaded surface 41 forms a male thread for screwing on the fuel tube. The male threaded surface 41 extends in the extension direction B from the outer end of tip 4a to the inner end of tip 4b. A tapered or similar surface may be formed between the male threaded surface 41 and the outer end of tip 4a for easy screwing on of the fuel tube.

[0029] The insertion surface 42 extends in a cylindrical shape in the extension direction B from the inner end of the tip 4b to the outer end of the tip 4a. The contact surface 43 rises radially outward from the pipe fitting member 4 from the insertion surface 42 over the outer end side of the tip 4a of the insertion surface 42. Thus, in a state in which the insertion surface 42 is inserted into the tip end portion 22 of the pipe member 2 and the contact surface 43 is in contact with a tip end surface 25 of the tip end portion 22 of the pipe member 2, the insertion surface 42 is brazed to the tip end portion 22 of the pipe member 2.The contact surface 43 of the pipe fitting member 4 can also be brazed to the tip end surface 25 of the pipe fitting member 2. The tip end surface 25 of the pipe fitting member 2 is an end surface on the side of the tip end portion 22 of the pipe fitting member 2 in the extension direction B. Alternatively, a tapered or similar surface can be formed between the insertion surface 42 and the inner end of the tip 4b to facilitate insertion of the pipe fitting member 4 into the tip end portion 22 of the pipe fitting member 2.

[0030] An outside diameter of the insertion surface 42, before the insertion surface 42 is inserted into the tip end portion 22 of the pipe member 2, may be larger than an inside diameter of the pipe member 2. The insertion surface 42 is thus brazed into a press-fit state in the tip end portion 22 of the pipe member 2 by inserting the insertion surface 42 into the tip end portion 22 of the pipe member 2 and brazing it. For example, irregularities may be formed on the insertion surface 42 by knurling or similar means such that the maximum outside diameter of the projection is greater than the inside diameter of the pipe member 2 and the minimum outside diameter of the cavity is less than the inside diameter of the pipe member 2.Thus, since the protruding portion is pressed against the tip end portion 22 of pipe member 2 and the brazing material enters the recessed portion, the stiffness of a joint from the insertion surface 42 to the tip end portion 22 of pipe member 2 can be increased.

[0031] The inner peripheral surface of the pipe connecting member 4 forms a through hole 44 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 extension direction B around the centerline A of the pipe member 2.

[0032] The pipe fitting member 4 has an intermediate diameter portion 45, a small diameter portion 46, and a tapered diameter portion 47. The intermediate diameter portion 45 is a part of the pipe fitting member 4 adjacent to the storage space 21. The small diameter portion 46 is a part of the pipe fitting member 4 located on the opposite side of the storage space 21 with respect to the intermediate diameter portion 45. The tapered diameter portion 47 is a part of the pipe fitting member 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 diameter portion 47, and at least a portion of the small diameter portion 46 form the insertion surface 42.That is, the insertion surface 42 is formed by an external peripheral surface of the intermediate diameter portion 45, an external peripheral surface of the tapered diameter portion 47, and an external peripheral surface of at least a part of the small diameter portion 46.

[0033] An internal diameter D2 of the small diameter portion 46 is less than an internal diameter D1 of the pipe member 2. In the present embodiment, the internal diameter D2 of the small diameter portion 46 is the smallest internal diameter of the through hole 44.

[0034] The internal diameter D1 of pipe member 2 is not particularly limited. For example, to avoid noise generated by fuel pulsation caused by the operation of the high-pressure pump, the internal diameter D1 of pipe member 2 may be 10 mm or more, preferably 11 mm or more, and more preferably 12 mm or more. To prevent the fuel distribution pipe 1 from becoming too large, the internal diameter D1 of pipe member 2 may be 16 mm or less, preferably 15 mm or less, and more preferably 14 mm or less. The maximum and minimum values ​​may be combined as appropriate; for example, the internal diameter D1 of pipe member 2 may be 10 mm or more and 16 mm or less, preferably 11 mm or more and 15 mm or less, and more preferably 12 mm or more and 14 mm or less.

[0035] The internal diameter D2 of the small-diameter portion 46 is not particularly limited. For example, from the point of view of preventing obstruction of the fuel passage, the internal diameter D2 of the small-diameter portion 46 may be 1 mm or more, preferably 2 mm or more, and more preferably 3 mm or more. Furthermore, from the point of view of preventing the fuel distribution tube 1 from becoming too large, the internal diameter D2 of the small-diameter portion 46 may be 11 mm or less, preferably 2 mm or less, and more preferably 9 mm or less. The maximum and minimum values ​​thereof may be combined as appropriate, and, for example, the internal diameter D2 of the small-diameter portion 46 may be 1 mm or more and 11 mm or less, preferably 2 mm or more and 10 mm or less, and more preferably 3 mm or more and 9 mm or less.

[0036] An internal diameter D3 of the intermediate diameter portion 45 is larger than the internal diameter D2 of the small diameter portion 46 and smaller than the internal diameter D1 of pipe member 2. Therefore, in pipe connecting member 4, a stiffness of the intermediate diameter portion 45 adjacent to the storage space 21 is less than a stiffness of the small diameter portion 46. Thus, in pipe connecting member 4, when the central portion 24 of pipe member 2 expands due to fuel pressure, the intermediate diameter portion 45 of pipe connecting member 4 also tends to expand after the central portion 24 of pipe member 2.

[0037] The internal diameter D3 of the intermediate diameter portion 45 is not particularly restricted as long as it satisfies the above conditions. For example, from the standpoint of ensuring sufficient stiffness of the intermediate diameter portion 45, the internal diameter D3 of the intermediate diameter portion 45 is larger than a hole diameter and may be of a size that does not substantially function as a hole relative to the small diameter portion 46 (a size that does not substantially have a hole effect), for example, greater than 1 mm, preferably greater than 2 mm, and more preferably greater than 3 mm. Furthermore, from the standpoint of ease of expansion after the central portion 24 of the pipe member 2, the internal diameter D3 of the intermediate diameter portion 45 may be less than 14 mm, preferably less than 13 mm, and more preferably less than 12 mm.The maximum and minimum values ​​thereof may be combined as appropriate, and the internal diameter D1 of pipe member 2 may, for example, be greater than 1 mm and less than 14 mm, preferably greater than 2 mm and less than 13 mm, and more preferably greater than 3 mm and less than 12 mm.

[0038] In the extension direction B, a length L1 of the intermediate diameter portion 45 may be shorter than an insertion length L2 of the pipe connection member 4 in the pipe member 2. The insertion length L2 of the pipe connection member 4 in the pipe member 2 is a length of the insertion surface 42 in the extension direction B. Also, the length L1 of the intermediate diameter portion 45 in the extension direction B may be longer than a thickness T1 of the intermediate diameter portion 45.

[0039] The T1 thickness of the intermediate diameter portion 45 is not particularly limited. For example, from the standpoint of ensuring sufficient stiffness of the intermediate diameter portion 45, the thickness T1 of the intermediate diameter portion 45 can be 0.3 times or more, preferably 0.7 times or more, and more preferably 0.9 times or more, the thickness T2 of pipe member 2. Furthermore, from the standpoint of ease of expansion after the central portion 24 of pipe member 2, the thickness T1 of the intermediate diameter portion 45 can be 1.5 times or less, preferably 1.3 times or less, and more preferably 1.1 times or less, the thickness T2 of pipe member 2. The maximum and minimum values ​​thereof can be combined as appropriate, and, for example, the thickness T1 of the intermediate diameter portion 45 can be 0.3 times or more and 1.5 times or less, preferably 0.7 times or more and 1.3 times or less, and more preferably 0.9 times or more and 1.1 times or less the thickness T2 of pipe member 2.

[0040] The tapered diameter portion 47 connects to the intermediate diameter portion 45 and the small diameter portion 46. An internal diameter of the tapered diameter portion 47 decreases from the side of the intermediate diameter portion 45 (the side of the inner end of tip 4b) to the side of the small diameter portion 46 (the side of the outer end of tip 4a).

[0041] In a reference cross section (the cross section shown in Figures 2 and 3) which includes the central axis A, the inner peripheral surface of the tapered diameter portion 47 may extend linearly from the intermediate diameter portion 45 to the small diameter portion 46, may extend in a curved shape from the intermediate diameter portion 45 to the small diameter portion 46, or may bend and extend from the intermediate diameter portion 45 to the small diameter portion 46.

[0042] An angle 01 formed by the inner peripheral surface of the tapered diameter portion 47 in the reference cross-section including the central axis A is not particularly restricted. For example, from the standpoint of preventing the pipe connection member 4 from becoming too large, the angle 01 may be 110° or more, preferably 113° or more, and more preferably 115° or more. Furthermore, from the standpoint of allowing the intermediate diameter portion 45 of the sensor connection member 5 to expand easily beyond the central portion 24 of the pipe member 2, the angle 01 may be 160° or less, preferably 155° or less, and more preferably 150° or less. The maximum and minimum values ​​of these can be combined as appropriate and, for example, angle 01 can be 110° or more and 160° or less, preferably 113° or more and 155° or less and more preferably 115° or more and 150° or less.When the inner peripheral surface of the tapered diameter portion 47 does not extend linearly from the intermediate diameter portion 45 to the small diameter portion 46, the angle 01 formed by the inner peripheral surface of the tapered diameter portion 47 in the reference cross section including the central axis A is an angle formed by an imaginary line connecting one end of the tip of the inner peripheral surface of the tapered diameter portion 47 on the side of the intermediate diameter portion 45 and one end of the tip of the same on the side of the small diameter portion 46.

[0043] Figure 4 is a schematic cross-sectional view, enlarging the periphery of the sensor connecting member in Figure 2. As shown in Figures 1, 2, and 4, 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 storage space 21. The sensor connecting member 5 is formed in a tubular shape around the central axis A of the pipe member 2. One end of the tip of the sensor connecting member 5 on one side in the extension direction B (one end of the tip on the left side in Figures 1, 2, and 4) is referred to as an inner tip end 5a, and one end of the tip of the sensor connecting member 5 on the other side in the extension direction B (one end of the tip on the right side in Figures 1, 2, and 4) is referred to as an outer tip end 5b.

[0044] The sensor connection member 5 is inserted into and joined to the tip end portion 23 of the pipe member 2. The connection of the sensor connection member 5 to the tip end portion 23 of the pipe member 2 may be effected by brazing, soldering, or similar means. In the present embodiment, the sensor connection member 5 is joined to the pipe member 2 by brazing.

[0045] An external peripheral surface of the sensor connecting member 5 has an insertion surface 51 and a contact surface 52.

[0046] The insertion surface 51 extends in the extension direction B from the inner end of tip 5a to the outer end of tip 5b in a cylindrical shape. The contact surface 52 extends radially outward from the sensor connecting member 5 from the insertion surface 51 over the outer end side of tip 5b of the insertion surface 51. Thus, in a state in which the insertion surface 51 is inserted into the tip end portion 23 of the pipe member 2 and the contact surface 52 is in contact with a tip end surface 26 of the tip end portion 23 of the pipe member 2, the insertion surface 51 is brazed to the tip end portion 23 of the pipe member 2.The contact surface 52 of the sensor connection member 5 can also be brazed to the tip end surface 26 of the pipe member 2. The tip end surface 26 of the pipe member 2 is a pipe member 2 end surface on the side of the tip end portion 23 in the extension direction B. In addition, a tapered or similar surface can be formed between the insertion surface 51 and the inner end of the tip 5a to easily insert the sensor connection member 5 into the tip end portion 23 of the pipe member 2.

[0047] An outside diameter of the insertion surface 51 before being inserted into the tip end portion 23 of pipe member 2 may be larger than the inside diameter of pipe member 2. In this way, the insertion surface 51 is brazed by inserting the insertion surface 51 into the tip end portion 23 of pipe member 2 and is brazed while being press-fitted into the tip end portion 23 of pipe member 2. For example, irregularities may be formed on the insertion surface 51 by knurling or the like so that the maximum outside diameter of the projection is larger than the inside diameter of pipe member 2 and the minimum outside diameter of the cavity is smaller than the inside diameter of pipe member 2.Thus, since the protruding portion is pressed against the tip end portion 23 of pipe member 2 and the entire brazing material against the recessed portion, the stiffness of the bond from the insertion surface 51 to the tip end portion 23 of pipe member 2 can be increased.

[0048] An internal peripheral surface of the sensor connecting member 5 forms a through hole 53 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 extension direction B around the center axis A of the pipe member 2.

[0049] The sensor connection member 5 has an intermediate diameter portion 54, a small diameter portion 55, a tapered diameter portion 56, and a sensor connection portion 57. The intermediate diameter portion 54 is a part of the sensor connection member 5 adjacent to the storage space 21. The small diameter portion 55 is a part of the sensor connection member 5 located on the side opposite the storage space 21 with respect to the intermediate diameter portion 54. The tapered diameter portion is a part of the sensor connection member 5 located between the intermediate diameter portion 54 and the small diameter portion 55 and connected to the intermediate diameter portion 54 and the small diameter portion 55. The sensor connection portion 57 is a part of the sensor connection member 5 located on the side opposite the small diameter portion 55 with respect to the storage space 21.The intermediate diameter portion 54, the tapered diameter portion 56, and at least a part of the small diameter portion 55 form the insertion surface 51. That is, the insertion surface 51 is formed by an external peripheral surface of the intermediate diameter portion 54, an external peripheral surface of the tapered diameter portion 56, and at least a part of an external peripheral surface of the small diameter portion 55.

[0050] An internal diameter D4 of the small diameter portion 55 is smaller than the internal diameter D1 of the pipe member 2. In the present embodiment, the internal diameter D4 of the small diameter portion 55 is the smallest internal diameter of the through hole 53.

[0051] The internal diameter D4 of the small-diameter portion 55 is not particularly limited. For example, from the standpoint of being able to properly transmit the pressure of the fuel stored in the storage space 21 to the fuel pressure sensor, the internal diameter D4 of the small-diameter portion 55 may be 3 mm or more, preferably 3.5 mm or more, and more preferably 4 mm or more. Furthermore, from the standpoint of preventing the fuel distribution tube 1 from becoming too large, the internal 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. The maximum and minimum values ​​thereof may be combined as appropriate, and, for example, the internal diameter D4 of the small-diameter portion 55 may be 3 mm or more and 9 mm or less, preferably 3 mm or less.5 mm or more and 7 mm or less and preferably 4 mm or more and 5 mm or less.

[0052] An internal diameter D5 of the intermediate diameter portion 54 is larger than the internal diameter D4 of the small diameter portion 55 and smaller than the internal diameter D1 of the pipe member 2. Therefore, in the sensor connection member 5, the stiffness of the intermediate diameter portion 54 adjacent to the storage space 21 is less than the stiffness of the small diameter portion 55. Thus, in the sensor connection member 5, when the center portion 24 of the pipe member 2 expands due to fuel pressure, the intermediate diameter portion 54 of the sensor connection member 5 also tends to expand after the center portion 24 of the pipe member 2.

[0053] The internal diameter D5 of the intermediate diameter portion 54 is not particularly restricted as long as it satisfies the above conditions. For example, from the standpoint of ensuring sufficient stiffness of the intermediate diameter portion 54, the internal diameter D5 of the intermediate diameter portion 54 is larger than the orifice diameter and may be of a size that does not substantially function as an orifice relative to the small diameter portion 55 (a size that does not substantially have an orifice effect), for example, greater than 3 mm, preferably greater than 3.5 mm, and more preferably greater than 4 mm. Furthermore, from the standpoint of ease of expansion after the central portion 24 of the pipe member 2, the internal diameter D5 of the intermediate diameter portion 54 may be less than 14 mm, preferably less than 13 mm, and more preferably less than 12 mm.The maximum and minimum values ​​thereof may be combined as appropriate and, for example, the internal diameter D5 of the intermediate diameter portion 54 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.

[0054] In the extension direction B, a length L3 of the intermediate diameter portion 54 may be shorter than an insertion length L4 of the sensor connection member 5 in the pipe member 2. The insertion length L4 of the sensor connection member 5 in the pipe member 2 is a length of the insertion surface 51 in the extension direction B. Also, the length L3 of the intermediate diameter portion 54 in the extension direction B may be longer than a thickness T3 of the intermediate diameter portion 54.

[0055] The thickness T3 of the intermediate diameter portion 54 is not particularly restricted. For example, a range of thickness T3 of the intermediate diameter portion 54 may be the same as a range of thickness T1 of the intermediate diameter portion 45 of the pipe fitting member 4. The thickness T3 of the intermediate diameter portion 54 may be the same as or different from the thickness T1 of the intermediate diameter portion 45 of the pipe fitting member 4.

[0056] The tapered diameter portion 56 connects to the intermediate diameter portion 54 and the small diameter portion 55. The internal diameter of the tapered diameter portion 56 decreases from the side of the intermediate diameter portion 54 (the side of the inner end of tip 5a) to the side of the small diameter portion 55 (the side of the outer end of tip 5b).

[0057] In the reference cross section (the cross section shown in Figures 2 and 4) which includes the central axis A, an internal peripheral surface of the tapered diameter portion 56 may extend linearly from the intermediate diameter portion 54 to the small diameter portion 55, may extend in a curved shape from the intermediate diameter portion 54 to the small diameter portion 55, or may bend and extend from the intermediate diameter portion 54 to the small diameter portion 55.

[0058] An angle 02 formed by the inner peripheral surface of the tapered diameter 56 portion in the reference cross-section including the centerline A is not particularly restricted. For example, a range of angle 02 formed by the inner peripheral surface of the tapered diameter 56 portion may be the same as the range of angle 01 formed by the inner peripheral surface of the tapered diameter 47 portion of the pipe fitting 4. The angle 02 formed by the inner peripheral surface of the tapered diameter 56 portion may be the same as or different from the angle 01 formed by the inner peripheral surface of the tapered diameter 47 portion of the pipe fitting 4.When the inner peripheral surface of the tapered diameter portion 56 does not extend linearly from the intermediate diameter portion 54 to the small diameter portion 55, the angle 02 formed by the inner peripheral surface of the tapered diameter portion 56 in the reference cross section including the central axis A is an angle formed by an imaginary line connecting the tip end of the inner peripheral surface of the tapered diameter portion 56 on the side of the intermediate diameter portion 54 and the tip end of the same on the side of the small diameter portion 55.

[0059] The fuel pressure sensor connects to the sensor connection portion 57. The fuel pressure sensor connects to the sensor connection portion 57 to detect the pressure of the fuel stored in the storage space 21 through the small-diameter portion 55. An internal peripheral surface of the sensor connection portion 57 has a female threaded surface 57a to which the fuel pressure sensor is screwed on and a sensor contact surface 57b with which the fuel pressure sensor is in contact with the female threaded surface 57a. The female threaded surface 57a forms a female thread for screwing on the fuel pressure sensor. The female threaded surface 57a extends in the extension direction B from the outer end of tip 5b to the inner end of tip 5a.A tapered or similar surface may be formed between the female threaded surface 57a and the outer end of the tip 5b to facilitate threading of the fuel pressure sensor. The sensor contact surface 57b is adjacent to the small-diameter portion 55. The sensor contact surface 57b is formed in a tapered shape such that its inner diameter decreases from the outer end of the tip 5b to the inner end of the tip 5a, in accordance with the shape of the fuel pressure sensor.

[0060] Here, a fuel distribution pipe 101 of Comparative Example 1 will be described with reference to Figure 5. The fuel distribution pipe 101 of Comparative Example 1 shown in Figure 5 includes a pipe member 102 similar to pipe member 2, a pipe connection member 104 corresponding to pipe connection member 4, and a sensor connection member 105 corresponding to sensor connection member 5. The pipe connection member 104 has a small diameter portion 146 that has the same internal diameter as the small diameter portion 46 instead of the intermediate diameter portion 45, the small diameter portion 46, and the tapered diameter portion 47 of pipe connection member 4.The sensor connection member 105 has a small diameter portion 155 that has the same internal diameter as the small diameter portion 55 instead of the intermediate diameter portion 54, the small diameter portion 55, and the tapered diameter portion 56 of the sensor connection member 5.

[0061] In the fuel distribution pipe 101 of Comparative Example 1 configured in this manner, when the pressure of the fuel supplied to the storage space 121 is received, the stiffness of a portion of the tip end 122 of the pipe member 102 into which the pipe connecting member 104 is inserted and joined is increased due to the small-diameter portion 146 of the pipe connecting member 104, thereby inhibiting expansion. Similarly, the stiffness of a portion of the tip end 123 of the pipe member 102 to which the sensor connecting member 105 is joined is increased due to the small-diameter portion 155 of the sensor connecting member 105, thereby inhibiting expansion.As a result, only a central portion 124 of the pipe member 102 tends to expand, thereby generating high stress in a boundary portion 127 between the central portion 124 of the pipe member 102 and a portion of its tip end 122, and a boundary portion 128 between the central portion of the pipe member 102 and a portion of its tip end 123. This can accelerate metal fatigue and shorten its service life.

[0062] On the other hand, in the fuel distribution pipe 1 according to the present embodiment, the pipe connection member 4 is inserted into and joined to the tip end portion 22 of pipe member 2. The intermediate diameter portion 45 adjacent to the storage space 21 and the small diameter portion 46 located on the opposite side of the storage space 21 with respect to the intermediate diameter portion 45 have an internal diameter D3 that is smaller than the internal diameter D1 of pipe member 2 and larger than the internal diameter D2 of the small diameter portion 46. That is to say, in the pipe connection member 4, the stiffness of the intermediate diameter portion 45 adjacent to the storage space 21 is less than the stiffness of the small diameter portion 46.Therefore, when fuel pressure is received, the intermediate diameter portion 45 of the pipe connecting member 4 also expands easily after the central portion 24, forming the storage space 21 of the pipe member 2. In this way, the stress generated in the boundary portion 27 between the central portion 24 and the tip end portion 22 of the pipe member 2 is avoided.Similarly, the sensor connection member 5 is inserted and joined to the tip end portion 23 of the pipe member 2. It has the intermediate diameter portion 54 adjacent to the storage space 21 and the small diameter portion 55 located on the opposite side of the storage space 21 with respect to the intermediate diameter portion 54. The intermediate diameter portion 54 has an internal diameter D5 that is smaller than the internal diameter D1 of the pipe member 2 and larger than the internal diameter D4 of the small diameter portion 55. That is, in the sensor connection member 5, the stiffness of the intermediate diameter portion 54 adjacent to the storage space 21 is less than the stiffness of the small diameter portion 55.Therefore, when fuel pressure is received, the intermediate diameter portion 54 of the sensor connecting member 5 can also easily expand beyond the central portion 24, forming the storage space 21 of the pipe member 2. In this way, the stress generated in the boundary portion 28 between the central portion 24 and the tip end portion 23 of the pipe member 2 is avoided.

[0063] Furthermore, in fuel distribution pipe 1, since a cross section perpendicular to the central axis A of pipe member 2 of storage space 21 is substantially the same throughout the region of pipe member 2 in the extension direction B, when pipe member 2 expands due to fuel pressure, it is possible to avoid the occurrence of local stress concentration.

[0064] Furthermore, in the fuel distribution pipe 1, since the tapered diameter portion 47 connected to the intermediate diameter portion 45 and the small diameter portion 46, and having an internal diameter that decreases from the side of the intermediate diameter portion 45 to the side of the small diameter portion 46, is formed in the pipe connecting member 4, the intermediate diameter portion 45 can be made to expand more easily after the center portion 24, forming the storage space 21 of the pipe member 2. In this way, the stress generated in the boundary portion 27 between the center portion 24 and the tip end portion 22 of the pipe member 2 is further avoided.Similarly, since the tapered diameter portion 56 connected to the intermediate diameter portion 54 and the small diameter portion 55, and having an internal diameter that decreases from the side of the intermediate diameter portion 54 to the side of the small diameter portion 55, is formed in the sensor connection member 5, the intermediate diameter portion 54 can be made to expand more easily after the central portion 24, forming the storage space 21 of the pipe member 2. In this way, the stress generated in the boundary portion 28 between the central portion 24 and the tip end portion 23 of the pipe member 2 is further avoided.

[0065] Furthermore, in the fuel distribution tube 1, since the angles 01 and 02 formed by the internal peripheral surfaces of the tapered diameter portion 47 and the tapered diameter portion 56 in the reference cross section including the centerline A of the pipe member 2 are 110° or more and 160° or less, excessive elongation of the pipe connection member 4 and the sensor connection member 5 can be avoided, and the intermediate diameter portion 45 of the pipe connection member 4 and the intermediate diameter portion 54 of the sensor connection member 5 can be appropriately expanded.

[0066] Furthermore, in fuel distribution tube 1, since the pipe connection member 4 and the sensor connection member 5 are joined while being inserted into the tip end portions 22 and 23 of pipe member 2, the pipe connection member 4 and the sensor connection member 5 can be firmly attached to pipe member 2.

[0067] Furthermore, in fuel distribution pipe 1, since the length L1 of the intermediate diameter portion 45 in the extension direction B of pipe member 2 is shorter than the insertion length L2 of the pipe connection member 4 in pipe member 2 and longer than the thickness T1 of the intermediate diameter portion 45, it is possible to prevent the pipe connection member 4 from becoming too large and to expand the intermediate diameter portion 45 of the pipe connection member 4 appropriately.Similarly, since the length L3 of the intermediate diameter portion 54 in the extension direction B of pipe member 2 is shorter than the insertion length L4 of the sensor connection member 5 in pipe member 2 and longer than the thickness T3 of the intermediate diameter portion 54, it is possible to prevent the sensor connection member 5 from becoming too large and to expand the intermediate diameter portion 54 of the sensor connection member 5 appropriately.

[0068] Furthermore, in the fuel distribution pipe 1, since the thickness T1 of the intermediate diameter portion 45 is 0.3 times or more and 1.5 times or less, preferably 0.7 times or more and 1.3 times or less, and more preferably 0.9 times or more and 1.1 times or less, the thickness T2 of the pipe member 2, the intermediate diameter portion 45 can be more easily expanded to follow the central portion 24 forming the storage space 21 of the pipe member 2 while sufficiently ensuring the rigidity of the intermediate diameter portion 45. Similarly, since the thickness T3 of the intermediate diameter portion 54 is 0.3 times or more and 1.5 times or less, preferably 0.7 times or more and 1.3 times or less, and more preferably 0.9 times or more and 1.1 times or less the thickness T2 of pipe member 2, the intermediate diameter portion 54 can be more easily expanded to follow the central portion 24 forming the storage space 21 of pipe member 2 while sufficiently ensuring the rigidity of the intermediate diameter portion 54.

[0069] Furthermore, in the fuel distribution pipe 1, since the pipe connection member 4 has the intermediate diameter portion 45, the fuel supplied from the fuel pipe can be properly supplied to the storage space over an extended period of time. Similarly, since the sensor connection member 5 has the intermediate diameter portion 54, the pressure of the fuel stored in the storage space 21 can be properly transmitted to the fuel pressure sensor over an extended period of time.

[0070] Furthermore, in the fuel distribution tube, since the internal diameter D2 of the small-diameter portion 46 is 1 mm or more and 11 mm or less, preferably 2 mm or more and 10 mm or less, and more preferably 3 mm or more and 9 mm or less, it is possible to prevent the fuel distribution tube 1 from becoming too large while ensuring that the fuel supplied from the fuel tube is properly delivered to the storage space 21 and preventing the fuel flow from being obstructed. Similarly, since the internal diameter D4 of the small-diameter portion 55 is 3 mm or more and 9 mm or less, preferably 3 mm or more.5 mm or more and 7 mm or less and preferably 4 mm or more and 5 mm or less, it is possible to prevent the fuel distribution tube 1 from becoming too large while the pressure of the fuel stored in the storage space 21 is properly transmitted to the fuel pressure sensor and it is possible to prevent the fuel passage from being obstructed.

[0071] Second modality A second embodiment will now be described. The second embodiment is essentially the same as the first embodiment, the only difference being that the sensor connection member is attached to the peripheral surface of the pipe member, and a cap member is attached to the end portion of the pipe member's tip instead of the sensor connection member. Therefore, the following description will focus solely on the differences in the first embodiment, omitting the description of the first embodiment itself.

[0072] Figure 6 is a schematic perspective view of a fuel distribution pipe according to the second embodiment. Figure 7 is a schematic cross-sectional view showing a portion of the fuel distribution pipe shown in Figure 6. As shown in Figures 6 and 7, the fuel distribution pipe 1A according to the present embodiment includes a pipe member 2, a plurality of housings 3, a pipe connection member 4, a sensor connection member 5A, and a cap member 6.

[0073] Sensor connection member 5A is a connection member connected to a fuel pressure sensor (not shown) that detects the pressure of the fuel stored in storage space 21, like sensor connection member 5 of the first modality. Sensor connection member 5A is attached to the peripheral surface of pipe member 2. The connection of sensor connection member 5A to the peripheral surface of pipe member 2 may be made by brazing, welding, or similar means.

[0074] The cap member 6 is inserted into and joined to the tip end portion 23 of the pipe member 2 on the other side (the right side in Figures 6 and 7) instead of the sensor connection member 5 of the first mode. Therefore, the storage space 21 is formed by the center portion 24 of the pipe member 2 into which the pipe connection member 4 and the cap member 6 are not inserted and joined.

[0075] Figure 8 is a schematic cross-sectional view, enlarging the periphery of the cap member in Figure 7. As shown in Figures 6 to 8, the cap member 6 is a connecting member that closes off the other side of the pipe member 2. The cap member 6 is formed in a plug shape around the centerline A of the pipe member 2. One end of the tip of the cap member 6 on one side in the extension direction B (a left tip end in Figures 6 to 8) is referred to as an inner tip end 6a, and one end of the tip of the cap member 6 on the other side in the extension direction B (a right tip end in Figures 6 to 8) is referred to as an outer tip end 6b.

[0076] The cap member 6 is inserted into and joined to the tip end portion 23 of pipe member 2. The connection of the cap member 6 to the tip end portion 23 of pipe member 2 may be made by brazing, welding, or similar means. In the present embodiment, the cap member 6 is joined to pipe member 2 by brazing.

[0077] An external peripheral surface of the cap member 6 has an insertion surface 61 and a contact surface 62.

[0078] The insertion surface 61 extends in the extension direction B from the inner end of tip 6a to the outer end of tip 6b in a cylindrical shape. The contact surface 62 extends radially outward from the cap member 6 from the insertion surface 61 over the outer end side of tip 6b of the insertion surface 61. Thus, in a state in which the insertion surface 61 is inserted into the tip end portion 23 of the pipe member 2 and the contact surface 62 is in contact with the tip end surface 26 of the tip end portion 23 of the pipe member 2, the insertion surface 61 is brazed to the tip end portion 23 of the pipe member 2. The contact surface 62 of the cap member 6 may also be brazed to the tip end surface 26 of the pipe member 2.Alternatively, a tapered or similar surface may be formed between the insertion surface 61 and the inner end of the tip 4b to easily insert the cap member 6 into the tip end portion 23 of the pipe member 2.

[0079] An outside diameter of the insertion surface 61 before the insertion surface 61 is inserted into the tip end portion 23 of the pipe member 2 may be larger than the inside diameter of the pipe member 2. The insertion surface 61 is thus brazed by inserting the insertion surface 61 into the tip end portion 23 of the pipe member 2 and brazing it in a press-fit state. For example, irregularities may be formed on the insertion surface 61 by knurling or the like, such that the maximum outside diameter of the projection is larger than the inside diameter of the pipe member 2 and the minimum outside diameter of the cavity is smaller than the inside diameter of the pipe member 2.Thus, since the protruding portion is pressed against the tip end portion 23 of pipe member 2 and the brazing material enters the recessed portion, the stiffness of the bond from the insertion surface 61 to the tip end portion 23 of pipe member 2 can be increased.

[0080] A recessed portion 63 is formed adjacent to the storage space 21 and recessed from the inner end of tip 6a to the outer end of tip 6b in the cap member 6. The cap member 6 has a perforated portion 64, a tapered diameter portion 65, and a closed portion 66.

[0081] The perforated portion 64 is part of the cap member 6 with a recessed portion 63 formed adjacent to the storage space 21. The tapered-diameter portion 65 is part of the cap member 6 in which the recessed portion 63 is formed adjacent to the perforated portion 64 on the side opposite the storage space 21. The closed portion 66 is part of the cap member 6 in which the recessed portion 63 is not formed adjacent to the tapered-diameter portion 65 on the side opposite the storage space 21. The perforated portion 64 and at least a portion of the tapered-diameter portion 65 form the insertion surface 61. That is, the insertion surface 61 is formed by an external peripheral surface of the perforated portion 64 and at least a portion of an external peripheral surface of the tapered-diameter portion 65. At least a portion of the closed portion 66 may form the insertion surface. insertion 61.In this case, the insertion surface 61 is formed by the external peripheral surface of the perforated portion 64, the external peripheral surface of the tapered diameter portion 65, and the external peripheral surface of at least a part of the closed portion 66.

[0082] In the cap member 6, the stiffness of each of the perforated portion 64 adjacent to the storage space 21 and the tapered diameter portion 65 adjacent to the perforated portion 64 are less stiff than the closed portion 66 due to the recessed portion 63. Therefore, when fuel pressure is received, the center portion 24 of the pipe member 2 expands and the perforated portion 64 of the cap member 6 also expands readily after the center portion 24 of the pipe member 2.

[0083] An internal diameter D6 of the perforated portion 64 is smaller than the internal diameter D1 of pipe member 2. The internal diameter D6 of the perforated portion 64 is not particularly limited as long as it satisfies the above conditions. For example, from the standpoint of ensuring sufficient stiffness of the perforated portion 64, the internal 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. Also, from the standpoint of ease of expansion after the central portion 24 of pipe member 2, the internal 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. The maximum and minimum values ​​thereof may be combined as appropriate, and, for example, the internal diameter D6 of the perforated portion 64 may be greater than 3 mm and less than 14 mm, preferably greater than 3 mm.5 mm and less than 13 mm and preferably greater than 4 mm and less than 12 mm.

[0084] In the extension direction B, a length L5 of the perforated portion 64 may be shorter than an insertion length L6 of the cap member 6 in the pipe member 2. The insertion length L6 of the cap member 6 in the pipe member 2 is a length of the insertion surface 61 in the extension direction B. Also, the length L5 of the perforated portion 64 in the extension direction B may be longer than a thickness T4 of the perforated portion 64.

[0085] The thickness T4 of the perforated portion 64 is not particularly restricted. For example, a range of thickness T4 of the perforated portion 64 may be the same as the range of thickness T1 of the intermediate diameter 45 portion of the pipe fitting member 4. The thickness T4 of the perforated portion 64 may be the same as or different from the thickness T1 of the intermediate diameter 45 portion of the pipe fitting member 4.

[0086] The tapered diameter portion 65 connects to the perforated portion 64 and the closed portion 66. An internal diameter of the tapered diameter portion 65 decreases from the side of the perforated portion 64 (the side of the inner end of the tip 6a) to the side of the closed portion 66 (the side of the outer end of the tip 6b).

[0087] In a reference cross section (a cross section shown in Figures 7 and 8) including the central axis A, an internal peripheral surface of the tapered diameter portion 65 may extend linearly from the perforated portion 64 to the closed portion 66, may extend in a curved shape from the perforated portion 64 to the closed portion 66, or may bend and extend from the perforated portion 64 to the closed portion 66.

[0088] An angle 03 formed by the inner peripheral surface of the tapered diameter 65 portion in the reference cross-section including the centerline A is not particularly restricted. For example, a range of angle 03 formed by the inner peripheral surface of the tapered diameter 65 portion may be the same as the range of angle 01 formed by the inner peripheral surface of the tapered diameter 47 portion of the pipe fitting 4. The angle 03 formed by the inner peripheral surface of the tapered diameter 65 portion may be the same as or different from the angle 01 formed by the inner peripheral surface of the tapered diameter 47 portion of the pipe fitting 4.When the inner peripheral surface of the tapered diameter portion 65 does not extend linearly from the perforated portion 64 to the closed portion 66, the angle 03 formed by the inner peripheral surface of the tapered diameter portion 65 in the reference cross section including the central axis A is an angle formed by an imaginary line connecting one end of the tip of the inner peripheral surface of the tapered diameter portion 32 on the side of the perforated portion 64 and one end of the tip of the same on the side of the closed portion 66.

[0089] Here, a fuel distribution pipe 101A of Comparative Example 2 will be described with reference to Figure 9. The fuel distribution pipe 101A of Comparative Example 2 shown in Figure 9 includes a pipe member 102 similar to pipe member 2, a pipe fitting member 104 corresponding to pipe fitting member 4, and a cap member 106 corresponding to cap member 6. In the fuel distribution pipe 101A of Comparative Example 2, the pipe fitting member 104 has a small diameter portion 146 that has the same inside diameter as the small diameter portion 46 instead of the intermediate diameter portion 45, the small diameter portion 46, and the tapered diameter portion 47 of the pipe fitting member 4.The cap member 106 has a closed portion 166 in which the recessed portion 63 of cap member 6 is not formed instead of the perforated portion 64, the tapered diameter portion 65, and the closed portion 66 of cap member 6.

[0090] In the fuel distribution pipe 101A of Comparative Example 2 configured in this manner, when the pressure of the fuel supplied to the storage space 121 is received, the stiffness of a portion of the tip end 122 of the pipe member 102 into which the pipe connecting member 104 is inserted and joined is increased due to the small-diameter portion 146 of the pipe connecting member 104, thereby inhibiting expansion. Similarly, the stiffness of a portion of the tip end 123 of the pipe member 102 to which the cap member 106 is connected is increased due to the closed portion 166 of the cap member 106, and expansion is inhibited.As a result, only the central portion 124 of the pipe member 102 expands easily, thereby generating high stress in a boundary portion 127 between the central portion 124 and the tip end portion 122 of the pipe member 102 and a boundary 129 between the central portion 124 of the pipe member 102 and the tip end portion 123. In this way, metal fatigue can be accelerated and the life can be shortened.

[0091] On the other hand, in the fuel distribution pipe 1A according to the present embodiment, the pipe connection member 4 is inserted into and joined to the tip end portion 22 of pipe member 2. It has the intermediate diameter portion 45 adjacent to the storage space 21 and the small diameter portion 46 located on the opposite side of the storage space 21 with respect to the intermediate diameter portion 45. The intermediate diameter portion 45 has an internal diameter D3 that is smaller than the internal diameter D1 of pipe member 2 and larger than the internal diameter D2 of the small diameter portion 46. That is to say, in the pipe connection member 4, the stiffness of the intermediate diameter portion 45 adjacent to the storage space 21 is less than the stiffness of the small diameter portion 46.Therefore, when fuel pressure is applied, the intermediate diameter portion 45 of the pipe connecting member 4 also readily expands beyond the central portion 24, forming the storage space 21 of the pipe member 2. This prevents the stress generated in the boundary portion 27 between the central portion 24 and the tip end portion 22 of the pipe member 2. Similarly, the cap member 6, inserted into and attached to the tip end portion 23 of the pipe member 2, has the perforated portion 64 adjacent to the storage space 21 and the recessed portion 63 formed within it. That is, in the cap member 6, the stiffness of the perforated portion 64 adjacent to the storage space 21 is less than the stiffness of the closed portion 66.Therefore, when fuel pressure is received, the perforated portion 64 of the cap member 6 also expands easily after the center portion 24, forming the storage space 21 of the pipe member 2. In this way, the stress generated in the boundary portion 29 between the center portion 24 and the tip end portion 23 of the pipe member 2 is avoided.

[0092] Furthermore, in the fuel distribution pipe 1A, since the tapered diameter portion 65 connected to the opposite side of the storage space 21 of the perforated portion 64, and having an internal diameter decreasing from the inner end side of the tip 6a to the outer end side of the tip 6b, is formed in the cap member 6, the perforated portion 64 can be made to easily expand past the center portion 24, forming the storage space 21 of the pipe member 2. In this way, the stress generated in the boundary portion 29 between the center portion 24 and the tip end portion 23 of the pipe member 2 is further avoided.

[0093] Although preferred embodiments of an aspect of the present invention have been described above, an aspect of the present invention is not limited to the above embodiments.

[0094] For example, in the above modality, although an example has been described that uses the pipe connection member and the sensor connection member as connection members, the connection members can be a pipe connection member and a sensor connection member.Furthermore, in the second embodiment, although an example has been described in which the sensor connection member is attached to the peripheral surface of the pipe member, the pipe connection member was attached to the tip end portion of the pipe member on one side and the cap member was attached to the tip end of the pipe member on the other side, the pipe connection member can be attached to the peripheral surface of the pipe member, the sensor connection member can be attached to the tip end portion of the pipe member on one side and the cap member can be attached to the tip end portion of the pipe member on the other side.As a reference example, connecting members such as the pipe connecting member and the sensor connecting member can be attached to the peripheral surface of the pipe member, and the cap member can be attached to the tip end portion of the pipe member on one side and the tip end portion of the same on the other side. Industrial Applicability

[0095] One aspect of the present invention can be used as a fuel distribution tube that distributes and supplies fuel to a plurality of fuel injection devices. List of Reference Signs

[0096] 1 Fuel distribution tube 1A Fuel distribution tube Pipe member Storage space Portion of the tip end Portion of the tip end Central portion Surface of the tip Surface of the tip Limit portion Limit portion Limit portion Accommodation Pipe connection member 4a Outer end of the tip 4b Inner end of tip Male threaded surface Insertion surface Contact surface Through hole Portion of intermediate diameter Small diameter portion Portion of tapered diameter Sensor connection member 5A Sensor connection member 5a Inner end of the tip 5b Outer end of the tip Insertion surface Contact surface Through hole Portion of intermediate diameter Small diameter portion Portion of tapered diameter Sensor connection portion 57a Female threaded surface 57b Sensor contact surface Cover member 6a Inner end of the tip 6b Outer end of the tip Insertion surface Contact surface Reduced portion Perforated portion Portion of tapered diameter Closed portion 101 Fuel distribution tube 101A Fuel distribution tube 102 Pipe Member 104 Pipe connection member 105 Sensor connection member 106 Cover Member 121 Storage space 122 Portion of the tip end 123 Portion of the tip end 124 Central portion 127 Limit portion 128 Limit portion 129 Limit portion 146 Portion of small diameter 155 Small diameter portion 166 Closed portion A Central axis B Extension address Internal diameter D1 to D6 Thickness T1 to T4 Angle 01 to 03

Claims

1. A fuel distribution pipe that distributes and supplies fuel from a fuel pipe to a plurality of fuel injection devices, comprising: a pipe member configured to form a storage space for storing the fuel therein; and a connecting member inserted into and attached to a portion of the tip end of the pipe member and having a through-hole connected to the storage space, wherein the connecting member has an intermediate-diameter portion adjacent to the storage space and a small-diameter portion positioned on a side opposite the storage space with respect to the intermediate-diameter portion, and the intermediate-diameter portion has an internal diameter that is larger than an internal diameter of the small-diameter portion and smaller than an internal diameter of the pipe member.

2. The fuel distribution pipe according to claim 1, wherein a cross-section of the storage space perpendicular to a central axis of the pipe member is substantially the same throughout the region of the pipe member in an extension direction.

3. The fuel distribution tube according to claim 1 or 2, wherein the connecting member further has a tapered diameter portion connected to the intermediate diameter portion and the small diameter portion and having an internal diameter that decreases from one side of the intermediate diameter portion to one side of the small diameter portion.

4. The fuel distribution tube according to claim 3, wherein an angle formed by an internal peripheral surface of the tapered diameter portion in a reference cross section including the central axis of the pipe member is 110° or more and 160° or less.

5. The fuel distribution pipe according to any of claims 1 to 4, wherein, in the extension direction of the pipe member, a length of the intermediate diameter portion is shorter than an insertion length of the connecting member in the pipe member and longer than a thickness of the intermediate diameter portion.

6. The fuel distribution tube according to any of claims 1 to 5, wherein the thickness of the intermediate diameter portion is 0.3 times or more and 1.5 times or less a thickness of the pipe member.

7. The fuel distribution pipe according to any of claims 1 to 6, wherein the connecting member is a pipe connecting member connected to the fuel pipe.

8. The fuel distribution tube according to claim 7, wherein the internal diameter of the small diameter portion is 1 mm or more and 11 mm or less.

9. The fuel distribution tube according to any of claims 1 to 6, wherein the connecting member is a sensor connecting member connected to a fuel pressure sensor that detects a pressure of the fuel stored in the storage space.

10. The fuel distribution tube according to claim 9, wherein the internal diameter of the small diameter portion is 3 mm or more and 9 mm or less.

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