Fuel injection device

Abstract

To provide a fuel injection device that can suppress corrosion of a nozzle body.SOLUTION: A fuel injection device includes: a backup ring 80 installed to a retaining nut groove 55; an O-ring 91 installed on a side of an injection hole 23 in an axial direction relative to the backup ring 80 on a radial outer side of a nozzle body 20 and on a radial inner side relative to the backup ring 80; and a gasket 92 installed on a side of the injection hole 23 in an axial direction relative to the retaining nut groove 55, the backup ring 80, and the O-ring 91 on the radial outer side of the nozzle body 20 so as to come into contact with an end surface of a retaining nut 50 on the side of the injection hole 23.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fuel injection device. [Background technology]

[0002] In recent years, as a countermeasure against corrosion occurring in the nozzle body of a fuel injection device due to the increased use of EGR in response to exhaust gas regulations, the nozzle body has been subjected to corrosion-resistant treatments such as plating. However, in conventional fuel injection devices, even if the base of the nozzle body is plated, there is a concern that the stress on the R portion of the base of the nozzle body will be high when the retaining nut is tightened, causing the plating to crack. Therefore, the base of the nozzle body that has not been subjected to corrosion prevention measures such as plating has low corrosion resistance. Therefore, combustion gas (acid) penetrates around the base of the nozzle body, and condensation water is generated, causing corrosion at the base of the nozzle body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent No. 2321521 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in the fuel injection device disclosed in Patent Document 1, an O-ring is provided between the nozzle body, retaining nut, and gasket to prevent the base of the nozzle body from coming into contact with corrosive liquid, thereby preventing combustion gas from entering the area around the base of the nozzle body. In the fuel injection device disclosed in Patent Document 1, the retaining nut that holds the nozzle body is fastened to the injector body by a nut thread, thereby determining the axial positions of the retaining nut and the injector body. The nozzle body is fixed to the injector body with a pin or the like. This can cause axial misalignment between the retaining nut and the nozzle body, making it difficult to maintain a constant radial compression rate of the O-ring around the entire circumference. This can make it difficult to prevent combustion gas from entering the area around the base of the nozzle body.

[0005] An object of the present invention is to provide a fuel injection device that can suppress corrosion of the nozzle body. [Means for solving the problem]

[0006] The fuel injection device according to the present invention includes a nozzle body (20), a nozzle needle (30), an injector body (40), a cylindrical retaining nut (50), an annular backup ring (80), an annular O-ring (91), and an annular gasket (92). The nozzle body has a nozzle chamber (200) into which fuel flows, a nozzle hole (23) communicating with the nozzle chamber and for injecting fuel, and a locking portion (24) formed on the outer peripheral wall. The nozzle needle is reciprocally movable within the nozzle chamber, and opens and closes the space between the nozzle chamber and the nozzle hole, thereby turning on and off the injection of fuel from the nozzle hole.

[0007] The injector body is provided on the opposite side of the nozzle body from the injection hole, and has a fuel passage (401) through which fuel flows into the nozzle chamber, and a body thread portion (42) formed on the outer peripheral wall. The retaining nut is provided radially outward of the nozzle body and the injector body, and has a nut thread portion (53) that screws onto the body thread portion, a locked portion (54) that locks with the locking portion, and an annular retaining nut groove portion (55) that is recessed radially outward from the inner peripheral wall at the end on the injection hole side, and is capable of generating an axial force between the nozzle body and the injector body in a direction that brings them closer to each other.

[0008] The backup ring is provided in the retaining nut groove. The O-ring is provided radially outside the nozzle body, on the axial nozzle hole side of the backup ring and radially inside the backup ring. The gasket is provided radially outside the nozzle body, on the axial nozzle hole side of the retaining nut groove, backup ring, and O-ring, so as to contact the nozzle hole side end face of the retaining nut.

[0009] In this invention, the O-ring is located radially outside the nozzle body, axially closer to the injection hole than the backup ring, and radially inside the backup ring. Therefore, even if axial misalignment occurs between the retaining nut and the nozzle body when the retaining nut is fastened to the injector body, the effect of this axial misalignment on the O-ring can be reduced, and the radial compression rate of the O-ring can be expected to be kept constant around the entire circumference. This prevents combustion gas from entering the area around the base of the nozzle body. As a result, corrosion of the nozzle body can be suppressed even if corrosion prevention measures such as plating are not applied to the base of the nozzle body. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a fuel injection device according to a first embodiment. [Figure 2] 1 is a cross-sectional view showing a part of a fuel injection device according to a first embodiment. [Figure 3]3 is a cross-sectional view showing a backup ring, an O-ring, a gasket, and their surroundings of the fuel injection device according to the first embodiment. FIG. [Figure 4] FIG. 10 is a cross-sectional view showing a backup ring, an O-ring, a gasket, and their vicinity in a fuel injection device according to a second embodiment. [Figure 5] FIG. 10 is a cross-sectional view showing a backup ring, an O-ring, a gasket, and their vicinity in a fuel injection device according to a third embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a backup ring, an O-ring, a gasket, and their vicinity in a fuel injection device according to a fourth embodiment. [Figure 7] FIG. 10 is a cross-sectional view showing a backup ring, an O-ring, a gasket, and their vicinity in a fuel injection device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, fuel injection devices according to a number of embodiments will be described with reference to the drawings. Note that substantially the same components in the number of embodiments will be denoted by the same reference numerals, and descriptions thereof will be omitted. <1> A number enclosed in "<" and ">" indicates the beginning of the section describing the content of the invention (including related matters) claimed in the claim of the paragraph number (at the time of filing) corresponding to the number.

[0012] (First embodiment) A fuel injection device of a first embodiment is shown in Fig. 1. The fuel injection device 1 is applied to, for example, a four-cylinder diesel engine mounted on a vehicle (not shown). The fuel injection device 1 is provided in each cylinder and connected to a common rail 2 that stores diesel oil as pressurized fuel. The fuel injection device 1 injects high-pressure fuel supplied from the common rail 2 into the combustion chamber of each cylinder. In other words, the fuel injection device 1 is a fuel injection device that injects high-pressure fuel stored in the common rail 2, which serves as an "accumulator pipe," into the diesel engine, which serves as an "internal combustion engine."

[0013] <1> 1 and 2, the fuel injection device 1 includes a nozzle body 20, a nozzle needle 30, an injector body 40, a cylindrical retaining nut 50, an annular backup ring 80, an annular O-ring 91, an annular gasket 92, etc. The nozzle body 20 has a nozzle chamber 200 into which fuel flows, an injection hole 23 that communicates with the nozzle chamber 200 and injects fuel, and a locking portion 24 formed on the outer peripheral wall. The nozzle needle 30 is provided so as to be able to reciprocate within the nozzle chamber 200, and opens and closes the space between the nozzle chamber 200 and the injection hole 23 to on and off the injection of fuel from the injection hole 23.

[0014] Injector body 40 is provided on the opposite side of nozzle body 20 from injection hole 23, and has a high-pressure fuel passage 401 as a "fuel passage" through which fuel flows into nozzle chamber 200, and a body thread portion 42 formed on the outer peripheral wall. Retaining nut 50 is provided radially outward of nozzle body 20 and injector body 40, and has a nut thread portion 53 that threads onto body thread portion 42, an engaged portion 54 that engages with engaging portion 24, and an annular retaining nut groove portion 55 that is recessed radially outward from the inner peripheral wall at the end on the injection hole 23 side, and is capable of generating an axial force between nozzle body 20 and injector body 40 in a direction that brings them closer to each other.

[0015] The backup ring 80 is provided in the retaining nut groove 55. The O-ring 91 is provided on the radial outside of the nozzle body 20, on the axial side of the backup ring 80 facing the injection hole 23, and on the radial inside of the backup ring 80. The gasket 92 is provided on the radial outside of the nozzle body 20, on the axial side of the injection hole 23 facing the retaining nut groove 55, the backup ring 80, and the O-ring 91, so as to contact the end face of the retaining nut 50 facing the injection hole 23.

[0016] <2> A radial gap Sr1 is formed between the backup ring 80 and the retaining nut groove 55. An axial gap Sa1 is formed between the backup ring 80 and the gasket 92 (see FIG. 3).

[0017] <3> The inner peripheral wall of the backup ring 80 contacts the outer peripheral wall of the nozzle body 20 (see FIG. 3).

[0018] <5> The backup ring 80 has an annular contact surface 801 that contacts the O-ring 91 at a location opposite the injection hole 23, and a cylindrical contact surface 802 that contacts the O-ring 91 at a radially outer location (see FIG. 3).

[0019] The configuration of the fuel injection device 1 will be described in more detail below.

[0020] 2, the nozzle body 20 has a nozzle cylinder portion 21, a nozzle bottom portion 22, an injection hole 23, and a locking portion 24. The nozzle cylinder portion 21 is formed of, for example, metal. The nozzle cylinder portion 21 has a nozzle small diameter portion 211, a nozzle medium diameter portion 212, and a nozzle large diameter portion 213.

[0021] The nozzle small diameter portion 211 is formed in a substantially cylindrical shape. The nozzle medium diameter portion 212 is formed in a substantially cylindrical shape integrally with the nozzle small diameter portion 211 so as to be connected to one end of the nozzle small diameter portion 211. The nozzle medium diameter portion 212 has an outer diameter larger than that of the nozzle small diameter portion 211. The nozzle medium diameter portion 212 has an inner diameter equal to that of the nozzle small diameter portion 211. The outer peripheral walls of the nozzle small diameter portion 211 and the nozzle medium diameter portion 212 are connected by a tapered wall surface (see FIGS. 2 and 3).

[0022] The large nozzle diameter portion 213 is formed integrally with the medium nozzle diameter portion 212 in a substantially cylindrical shape so as to connect to one end of the medium nozzle diameter portion 212. The outer diameter of the large nozzle diameter portion 213 is larger than the outer diameter of the medium nozzle diameter portion 212. The inner diameter of the large nozzle diameter portion 213 is larger than the inner diameter of the medium nozzle diameter portion 212. The inner peripheral walls of the medium nozzle diameter portion 212 and the large nozzle diameter portion 213 are connected by a tapered wall surface. The outer peripheral walls of the medium nozzle diameter portion 212 and the large nozzle diameter portion 213 are connected by a flat, annular nozzle step surface 214. The locking portion 24 is formed on the nozzle step surface 214 (see FIGS. 2 and 3).

[0023] The nozzle bottom portion 22 is formed integrally with the nozzle cylinder portion 21 so as to close the end of the nozzle small diameter portion 211 of the nozzle cylinder portion 21 opposite to the nozzle medium diameter portion 212. The injection hole 23 is formed to penetrate the nozzle bottom portion 22. For example, a plurality of injection holes 23 are formed at equal intervals in the circumferential direction of the nozzle bottom portion 22. The inner wall of the nozzle bottom portion 22 upstream of the injection hole 23 forms a tapered valve seat 220. The nozzle chamber 200 is formed inside the nozzle cylinder portion 21 and the nozzle bottom portion 22, and is in communication with the injection hole 23.

[0024] The nozzle needle 30 has a needle body 31 and a flange 32. The needle body 31 is formed into a rod shape from, for example, metal. The needle body 31 is provided in the nozzle chamber 200 so as to be able to move back and forth in the axial direction. The needle body 31 is provided in the nozzle chamber 200 so that one end can abut against or move away from the valve seat 220. Hereinafter, the direction in which the needle body 31 abuts against the valve seat 220 will be referred to as the "valve closing direction," and the direction in which the needle body 31 moves away from the valve seat 220 will be referred to as the "valve opening direction," as appropriate.

[0025] The flange 32 is formed into an annular shape from, for example, metal, and is provided at a position a predetermined distance away from the end of the needle body 31 opposite the injection hole 23. When one end of the needle body 31 abuts against the valve seat 220, the flange 32 is located radially inside the end of the nozzle large diameter portion 213 on the nozzle small diameter portion 211 side. In this state, the end face of the other end of the needle body 31 is spaced a predetermined distance toward the injection hole 23 from the end face of the nozzle large diameter portion 213 opposite the nozzle small diameter portion 211.

[0026] A cylinder 34, a needle spring 33, a control plate 35, and a support spring 36 are provided radially inside the nozzle large diameter portion 213. The cylinder 34 is made of, for example, metal and has a substantially cylindrical shape. The cylinder 34 is provided radially outside the end of the needle body 31 opposite the injection hole 23.

[0027] The inner diameter of the end of the cylinder 34 on the nozzle needle 30 side is slightly larger than the outer diameter of the end of the needle body 31 opposite the injection hole 23. The cylinder 34 is provided so that the inner peripheral wall of the end on the nozzle needle 30 side can slide on the outer peripheral wall of the end of the needle body 31 opposite the injection hole 23, and is movable axially relative to the needle body 31. The outer diameter of the cylinder 34 is smaller than the inner diameter of the nozzle large diameter portion 213. A substantially cylindrical gap is formed between the outer peripheral wall of the cylinder 34 and the inner peripheral wall of the nozzle large diameter portion 213.

[0028] The needle spring 33 is, for example, a coil spring, and is provided radially outside the needle body 31 between the flange 32 and the cylinder 34. One end of the needle spring 33 abuts against the flange 32, and the other end abuts against the cylinder 34. The needle spring 33 has a force that stretches in the axial direction. As a result, the needle spring 33 urges the cylinder 34 in the valve-opening direction relative to the needle body 31.

[0029] The control plate 35 has a plate body 351 and an orifice passage 350. The plate body 351 is formed, for example, from metal in a substantially circular plate shape. The plate body 351 is provided radially inside the end of the cylinder 34 opposite the nozzle needle 30 so as to be able to reciprocate in the axial direction. The orifice passage 350 is formed to penetrate the center of the plate body 351 in the plate thickness direction. The orifice passage 350 is formed in an orifice shape so that the inner diameter of the end opposite the nozzle needle 30 is smaller than the inner diameter of the end on the nozzle needle 30 side.

[0030] The support spring 36 is, for example, a coil spring, and is provided between the end of the needle body 31 opposite the injection hole 23 and the control plate 35. One end of the support spring 36 abuts against the needle body 31, and the other end abuts against a ring member 352 provided on the injection hole 23 side of the control plate 35. The support spring 36 has a force that stretches in the axial direction. As a result, the support spring 36 urges the control plate 35 in the valve-opening direction relative to the needle body 31 and the cylinder 34.

[0031] The intermediate member 60 is provided on the nozzle body 20 on the opposite side to the injection hole 23. The intermediate member 60 has an intermediate member main body 61, a high-pressure fuel passage 601, a supply passage 602, and a discharge passage 603. The intermediate member main body 61 is formed into a substantially circular plate shape from, for example, metal. The end face of the intermediate member main body 61 on the injection hole 23 side is provided to abut against the end face of the nozzle large diameter portion 213 opposite to the nozzle small diameter portion 211.

[0032] The high-pressure fuel passage 601 is formed at an outer edge of the intermediate member body 61 at an angle with respect to the axis of the intermediate member body 61, and connects the end face of the intermediate member body 61 opposite to the nozzle hole 23 with the end face on the nozzle hole 23 side. The supply passage 602 is formed at an angle with respect to the axis of the intermediate member body 61, and connects the end face of the intermediate member body 61 opposite to the nozzle hole 23 with the center of the end face on the nozzle hole 23 side. Here, the end of the supply passage 602 opposite to the nozzle hole 23 is connected to the end of the high-pressure fuel passage 601 opposite to the nozzle hole 23. The discharge passage 603 is formed at an angle with respect to the axis of the intermediate member body 61, and connects the end face of the intermediate member body 61 opposite to the nozzle hole 23 with the center of the end face on the nozzle hole 23 side.

[0033] A guide ring 62 is provided radially outward of the connection between the nozzle large diameter portion 213 and the intermediate member main body 61. The guide ring 62 is formed, for example, from metal in a substantially cylindrical shape. The inner diameter of the guide ring 62 is slightly larger than the outer diameter of the nozzle large diameter portion 213 and the outer diameter of the end of the intermediate member main body 61 on the nozzle large diameter portion 213 side. This prevents radial positional misalignment between the nozzle body 20 and the intermediate member 60.

[0034] The end face of the cylinder 34 opposite to the nozzle hole 23 can abut against the end face of the intermediate member body 61 on the nozzle hole 23 side, or can be separated from the end face of the intermediate member body 61 on the nozzle hole 23 side. A pressure control chamber 300 is formed between the inner circumferential wall of the cylinder 34, the end face of the needle body 31 opposite to the nozzle hole 23, and the end face of the intermediate member body 61 on the nozzle hole 23 side.

[0035] The end of the high-pressure fuel passage 601 on the injection hole 23 side opens between the inner circumferential wall of the nozzle large diameter portion 213 and the outer circumferential wall of the cylinder 34. As a result, the high-pressure fuel passage 601 is in communication with the nozzle chamber 200. The end of the supply passage 602 and the discharge passage 603 on the injection hole 23 side opens to the radially inner side of the cylinder 34, i.e., to the surface of the intermediate member body 61 on the pressure control chamber 300 side. As a result, the supply passage 602 and the discharge passage 603 are in communication with the pressure control chamber 300.

[0036] The injector body 40 is provided on the opposite side of the intermediate member 60 from the injection hole 23. The injector body 40 has a main body 41, a body thread portion 42, a pipe connection portion 43, and a high-pressure fuel passage 401. The main body 41 is formed into a cylindrical shape from, for example, metal. The end face of the main body 41 on the injection hole 23 side abuts against the end face of the intermediate member main body 61 on the opposite side from the injection hole 23. The body thread portion 42 is formed on the outer peripheral wall of the end of the main body 41 on the injection hole 23 side.

[0037] High-pressure fuel passage 401 is formed between the inner circumferential wall and the outer circumferential wall of main body 41 so as to be approximately parallel to the axis of main body 41. High-pressure fuel passage 401 opens at a position corresponding to the openings of high-pressure fuel passage 601 and supply passage 602 on the end face of main body 41 on the injection hole 23 side. As a result, high-pressure fuel passage 401 communicates with high-pressure fuel passage 601 and supply passage 602.

[0038] The pipe connection portion 43 is formed integrally with the main body 41 so as to extend radially outward from the outer peripheral wall of the main body 41 (see FIG. 1). A passage communicating with the high-pressure fuel passage 401 is formed inside the pipe connection portion 43. A fuel pipe extending from the common rail 2 is connected to the pipe connection portion 43. As a result, high-pressure fuel supplied from the common rail 2 flows into the high-pressure fuel passage 401 via a passage within the pipe connection portion 43. The fuel that flows into the high-pressure fuel passage 401 flows into the nozzle chamber 200 via a high-pressure fuel passage 601 and into the pressure control chamber 300 via a supply passage 602. As a result, the nozzle chamber 200 and the pressure control chamber 300 are filled with high-pressure fuel.

[0039] An opening / closing unit 70 is provided inside the end of the main body 41 on the injection hole 23 side. The opening / closing unit 70 has a drive unit 71 and a movable member 72. The movable member 72 has a shaft portion 73, a magnetic material portion 74, and a tip portion 75. The shaft portion 73 is formed in a rod shape from, for example, a metal. The magnetic material portion 74 is formed in an annular disk shape from, for example, a magnetic material, and is fitted into one end of the shaft portion 73. The tip portion 75 is formed in a substantially spherical shape from, for example, a metal, and is fitted into the other end of the shaft portion 73.

[0040] Movable member 72 is provided inside the end of main body 41 on the injection hole 23 side so as to be able to reciprocate in a direction approximately parallel to the axis of main body 41. Movable member 72 is provided such that a tip end 75 can abut against the opening of discharge passage 603 on the end face of intermediate member main body 61 opposite injection hole 23, or can be moved away from the opening.

[0041] A low-pressure space 400 is formed radially outward from the end of the shaft portion 73 of the movable member 72 on the injection hole 23 side. The low-pressure space 400 is in communication with a low-pressure fuel passage (not shown). When the tip end portion 75 of the movable member 72 abuts against the opening of the discharge passage 603 on the end face of the intermediate member body 61 opposite the injection hole 23, communication between the pressure control chamber 300 and the low-pressure space 400 via the discharge passage 603 is blocked. On the other hand, when the movable member 72 is separated from the opening of the discharge passage 603 on the end face of the intermediate member body 61 opposite the injection hole 23, communication between the pressure control chamber 300 and the low-pressure space 400 via the discharge passage 603 is permitted. In this way, the opening / closing unit 70 opens and closes the space between the pressure control chamber 300 and the low-pressure space 400 by abutting the movable member 72 against the intermediate member body 61 or separating it from the intermediate member body 61.

[0042] The drive unit 71 is provided on the opposite side of the movable member 72 from the nozzle hole 23, and generates a magnetic attraction force when energized, which can attract the magnetic material portion 74 of the movable member 72 to the opposite side of the nozzle hole 23. An ECU 100 (see FIG. 1) provided in the vehicle can control the energization of the drive unit 71. By controlling the energization of the drive unit 71, the ECU 100 can control the operation of the movable member 72 of the opening / closing unit 70 and control the opening and closing between the pressure control chamber 300 and the low-pressure side space 400.

[0043] The retaining nut 50 has a nut tubular portion 51, a nut thread portion 53, a locked portion 54, and a retaining nut groove portion 55. The nut tubular portion 51 is formed, for example, from metal. The nut tubular portion 51 has a nut small-diameter portion 511, a nut medium-diameter portion 512, and a nut large-diameter portion 513. The nut small-diameter portion 511 is formed in a substantially cylindrical shape. The nut medium-diameter portion 512 is formed integrally with the nut small-diameter portion 511 in a substantially cylindrical shape so as to connect to one end of the nut small-diameter portion 511. The nut medium-diameter portion 512 has an outer diameter larger than the outer diameter of the end of the nut small-diameter portion 511 on the injection hole 23 side. The nut medium-diameter portion 512 has an inner diameter larger than the inner diameter of the nut small-diameter portion 511. The inner peripheral wall of the nut small-diameter portion 511 and the inner peripheral wall of the nut medium-diameter portion 512 are connected by a nut step surface 514 that is flat and annular. The locked portion 54 is formed on a nut stepped surface 514 (see FIGS. 2 and 3).

[0044] The large diameter nut portion 513 is formed integrally with the medium diameter nut portion 512 in a substantially cylindrical shape so as to connect to the end of the medium diameter nut portion 512 opposite to the small diameter nut portion 511. The outer diameter of the large diameter nut portion 513 is larger than the outer diameter of the medium diameter nut portion 512. The inner diameter of the large diameter nut portion 513 is larger than the inner diameter of the medium diameter nut portion 512.

[0045] The nut thread portion 53 is formed on the inner peripheral wall of the end of the nut large diameter portion 513 opposite the nut medium diameter portion 512 so that it can be threaded onto the body thread portion 42 of the injector body 40. The retaining nut 50 is arranged so that the nut step surface 514, i.e., the locked portion 54, abuts against the nozzle step surface 214, i.e., the locking portion 24 of the nozzle body 20, and the nut thread portion 53 threads onto the body thread portion 42. This generates an axial force that moves the nozzle body 20 and the injector body 40 toward each other. Therefore, the intermediate member 60 is sandwiched between the nozzle body 20 and the injector body 40, and a predetermined pressure is applied between the end face of the nozzle large diameter portion 213 on the intermediate member main body 61 side and the end face of the intermediate member main body 61 on the nozzle large diameter portion 213 side, and between the end face of the intermediate member main body 61 on the body main body 41 side and the end face of the body main body 41 on the intermediate member main body 61 side.

[0046] A pin 63 is provided between the injector body 40 and the intermediate member 60. The pin 63 prevents radial misalignment between the injector body 40 and the intermediate member 60. As described above, the guide ring 62 also prevents radial misalignment between the nozzle body 20 and the intermediate member 60. Therefore, there is a risk of axial misalignment occurring between the retaining nut 50 and the nozzle body 20.

[0047] 2 and 3, the retaining nut groove 55 is formed in an annular shape so as to be recessed radially outward from the inner circumferential wall of the end of the nut small diameter portion 511 on the injection hole 23 side. As a result, the retaining nut groove 55 has an annular groove surface 551 and a cylindrical groove surface 552 (see FIG. 3). The annular groove surface 551 is formed in a flat annular shape. The cylindrical groove surface 552 is formed in a cylindrical shape.

[0048] The backup ring 80 is made of, for example, metal and formed into an annular shape. The backup ring 80 has a ring plate portion 85, a ring tubular portion 86, an abutting annular surface 801, and an abutting tubular surface 802. The ring plate portion 85 is formed in the shape of an annular plate. The ring tubular portion 86 is formed integrally with the ring plate portion 85 so as to extend in a tubular shape from the outer edge of the ring plate portion 85. The abutting annular surface 801 is formed on the end surface of the ring plate portion 85 on the ring tubular portion 86 side. Therefore, the abutting annular surface 801 is formed in a flat and annular shape. The abutting tubular surface 802 is formed on the inner circumferential wall of the ring tubular portion 86. Therefore, the abutting tubular surface 802 is formed in a tubular shape.

[0049] The backup ring 80 is provided in the retaining nut groove 55 so that the outer edge of the end face of the ring plate portion 85 opposite the ring cylindrical portion 86 abuts against the groove annular surface 551. Here, the nozzle small diameter portion 211 is inserted inside the backup ring 80.

[0050] <3> The inner diameter of the ring plate portion 85, i.e., the inner diameter of the backup ring 80, is the same as the outer diameter of the nozzle small diameter portion 211 of the nozzle body 20. Therefore, the inner peripheral wall of the backup ring 80 contacts the outer peripheral wall of the nozzle body 20 (see FIG. 3). The backup ring 80 is movable axially relative to the nozzle small diameter portion 211.

[0051] The O-ring 91 is formed into an annular shape from an elastic material such as rubber. The O-ring 91 is provided radially outside the nozzle small diameter portion 211 of the nozzle body 20, on the injection hole 23 side of the ring plate portion 85 of the backup ring 80, and radially inside the ring cylindrical portion 86. In other words, the O-ring 91 is provided radially outside the nozzle body 20, on the injection hole 23 side of the backup ring 80 in the axial direction, and radially inside the backup ring 80.

[0052] <5> The inner diameter of the O-ring 91 in a free state before being placed radially outside the nozzle small diameter portion 211 is smaller than the outer diameter of the nozzle small diameter portion 211. Therefore, when the O-ring 91 is placed radially outside the nozzle small diameter portion 211, a radially inner portion of the O-ring 91 contacts the outer peripheral wall of the nozzle small diameter portion 211. The abutment annular surface 801 abuts against a portion of the O-ring 91 on the opposite side from the injection hole 23. The abutment tubular surface 802 abuts against a radially outer portion of the O-ring 91.

[0053] The gasket 92 is formed into an annular plate shape, for example, from metal. The gasket 92 is disposed radially outside the nozzle small-diameter portion 211 of the nozzle body 20, with the outer edge of one axial end face abutting the end face of the nut small-diameter portion 511 of the retaining nut 50 on the injection hole 23 side, and the inner edge abutting the O-ring 91 on the injection hole 23 side. When the backup ring 80 abuts against the groove annular surface 551 and the gasket 92 abuts against the end face of the nut small-diameter portion 511 on the injection hole 23 side, the distance between the abutment annular surface 801 and the end face of the gasket 92 on the O-ring 91 side is smaller than the axial length, i.e., the height, of the O-ring 91 in a free state before being disposed between the backup ring 80 and the gasket 92. Therefore, when the gasket 92 abuts against the end face of the nut small-diameter portion 511 on the injection hole 23 side, the O-ring 91 is compressed by a predetermined amount in the axial direction.

[0054] In this embodiment, the inner diameter of the gasket 92 is the same as the outer diameter of the nozzle small diameter portion 211 of the nozzle body 20. Therefore, the inner peripheral wall of the gasket 92 contacts the outer peripheral wall of the nozzle body 20 (see FIG. 3). The gasket 92 is movable relative to the nozzle small diameter portion 211 in the axial direction.

[0055] The fuel injection device 1 is mounted on the engine so that the surface of the gasket 92 opposite the retaining nut 50 abuts against the annular hole step surface 4 formed on the inner wall of the hole that communicates with the engine's combustion chamber 3 (see FIGS. 2 and 3). When the fuel injection device 1 is mounted on the engine, a force acts on the fuel injection device 1 to urge the injector body 40 toward the combustion chamber 3. This causes the backup ring 80 to adhere to the groove annular surface 551, and the gasket 92 to adhere to the end face of the nut small diameter portion 511 on the injection hole 23 side, compressing the O-ring 91 by a predetermined amount in the axial direction.

[0056] The above configuration can prevent the combustion gas in the combustion chamber 3 from entering inside the retaining nut 50. In this embodiment, as a countermeasure against corrosion of the nozzle body 20 by the combustion gas (acid), the outer wall of the nozzle bottom portion 22 and the outer peripheral wall of the nozzle small diameter portion 211 are plated. Note that, when the retaining nut 50 is fastened to the injector body 40, stress may increase at the base of the nozzle body 20, i.e., between the outer peripheral wall of the nozzle medium diameter portion 212 and the nozzle step surface 214, which could cause plating cracks, so the outer peripheral wall of the nozzle medium diameter portion 212 and the nozzle step surface 214 are not plated.

[0057] In this embodiment, the O-ring 91 is provided radially inside the backup ring 80. Therefore, even if axial misalignment occurs between the retaining nut 50 and the nozzle body 20 when the retaining nut 50 is fastened to the injector body 40, the effect of this axial misalignment on the O-ring 91 can be reduced, and the radial compression rate of the O-ring 91 can be expected to be kept constant around the entire circumference.

[0058] <2> The outer diameters of the ring plate portion 85 and the ring cylindrical portion 86, i.e., the outer diameter of the backup ring 80, are smaller than the inner diameter of the groove cylindrical surface 552 of the retaining nut groove 55. Therefore, a radial gap Sr1 is formed between the backup ring 80 and the retaining nut groove 55 (see FIG. 3). The radial gap Sr1 is a cylindrical gap.

[0059] <2> The sum of the plate thickness of the ring plate portion 85 and the axial length of the ring cylindrical portion 86, i.e., the axial length of the backup ring 80, is smaller than the axial length of the groove cylindrical surface 552 of the retaining nut groove portion 55. Therefore, an axial gap Sa1, which is a gap in the direction of the axis Ax1 of the backup ring 80, is formed between the backup ring 80 and the gasket 92 (see FIG. 3).

[0060] Next, the operation of the fuel injection device 1 will be described.

[0061] High-pressure fuel from the common rail 2 is supplied to the nozzle chamber 200 via a high-pressure fuel passage 401 and a high-pressure fuel passage 601 (see FIGS. 1 and 2). A needle spring 33 applies a load to the nozzle needle 30 in the valve closing direction.

[0062] A portion of the fuel in the high-pressure fuel passage 401 is supplied to the pressure control chamber 300 through the supply passage 602. As shown in Fig. 2, when the power supply to the drive unit 71 is turned off, the pressure control chamber 300 is filled with high-pressure fuel. The nozzle needle 30 receives a force in the valve closing direction from the load of the needle spring 33 and the fuel pressure in the pressure control chamber 300.

[0063] When the drive unit 71 is energized, the movable member 72 moves in the valve-opening direction due to the magnetic attraction of the drive unit 71, allowing communication between the pressure control chamber 300 and the low-pressure space 400 via the discharge passage 603. As a result, fuel on the nozzle needle 30 side of the control plate 35 in the pressure control chamber 300 flows through the orifice passage 350 to the intermediate member 60 side of the control plate 35, then flows through the discharge passage 603 to the low-pressure space 400 and is discharged into the low-pressure fuel passage. As a result, the fuel pressure in the pressure control chamber 300 decreases. At this time, the control plate 35 is pressed against the intermediate member 60 by the fuel pressure in the pressure control chamber 300 and the biasing force of the support spring 36.

[0064] When the fuel pressure in the pressure control chamber 300 decreases, the force that the nozzle needle 30 receives in the valve-opening direction from the fuel pressure in the nozzle chamber 200 becomes greater than the force that the nozzle needle 30 receives in the valve-closing direction from the load of the needle spring 33 and the fuel pressure in the pressure control chamber 300. As a result, the nozzle needle 30 moves in the valve-opening direction and separates from the valve seat 220. As a result, the fuel in the nozzle chamber 200 is injected from the injection hole 23.

[0065] When the power supply to the drive unit 71 is turned off, the movable member 72 moves in the valve closing direction and abuts against the intermediate member 60, thereby blocking communication between the pressure control chamber 300 and the low-pressure space 400 via the discharge passage 603. Therefore, the fuel pressure in the pressure control chamber 300 increases due to the fuel supplied from the supply passage 602. As a result, the force acting on the nozzle needle 30 in the valve closing direction from the load of the needle spring 33 and the fuel pressure in the pressure control chamber 300 becomes greater than the force acting on the nozzle needle 30 in the valve opening direction from the fuel pressure in the nozzle chamber 200. Therefore, the nozzle needle 30 moves in the valve closing direction and abuts against the valve seat 220. This stops injection of fuel from the nozzle hole 23 in the nozzle chamber 200. When high-pressure fuel is supplied from the supply passage 602 to the pressure control chamber 300, the control plate 35 can move toward the nozzle needle 30 against the biasing force of the support spring 36.

[0066] As described above, in this embodiment, the backup ring 80 is provided in the retaining nut groove 55. The O-ring 91 is provided on the radial outside of the nozzle body 20, on the axial side of the backup ring 80 facing the injection hole 23, and radially inward of the backup ring 80. The gasket 92 is provided on the radial outside of the nozzle body 20, on the axial side of the injection hole 23 facing the retaining nut groove 55, the backup ring 80, and the O-ring 91, so as to contact the end face of the retaining nut 50 facing the injection hole 23.

[0067] In this embodiment, the O-ring 91 is provided radially outward of the nozzle body 20, on the axial injection hole 23 side of the backup ring 80, and radially inward of the backup ring 80. Therefore, even if axial misalignment occurs between the retaining nut 50 and the nozzle body 20 when the retaining nut 50 is fastened to the injector body 40, the effect of this axial misalignment on the O-ring 91 can be reduced, and the radial compression rate of the O-ring 91 can be expected to be kept constant all around. This makes it possible to prevent combustion gas from entering the vicinity of the base of the nozzle body 20. As a result, corrosion of the nozzle body 20 can be prevented even if anti-corrosion measures such as plating are not applied to the base of the nozzle body 20.

[0068] Furthermore, in this embodiment, the fuel injection device 1 is provided with a seal structure (sealed portion using the O-ring 91) inside, so there is no effect on the engine dimensions and installation compatibility is ensured.

[0069] Also, <2> In this embodiment, a radial gap Sr1 is formed between the backup ring 80 and the retaining nut groove 55. An axial gap Sa1 is formed between the backup ring 80 and the gasket 92.

[0070] Due to the radial gap Sr1 formed between the backup ring 80 and the retaining nut groove portion 55, even if axial misalignment occurs between the retaining nut 50 and the nozzle body 20, the backup ring 80 is not affected by this axial misalignment, and the radial compression rate of the O-ring 91 can be kept constant around the entire circumference.

[0071] Furthermore, the axial gap Sa1 formed between the backup ring 80 and the gasket 92 allows the gasket 92 to be tightly attached to the end of the retaining nut 50 on the nozzle hole 23 side, and also absorbs the effects of dimensional tolerances of the retaining nut groove 55 and the backup ring 80.

[0072] Also, <3> In this embodiment, the inner peripheral wall of the backup ring 80 contacts the outer peripheral wall of the nozzle body 20. Therefore, the backup ring 80 is positioned by the outer peripheral wall of the nozzle body 20. This allows a stable accommodation space for the O-ring 91 to be provided radially inside the backup ring 80, and the radial compression rate of the O-ring 91 can be kept constant all around more effectively.

[0073] <5> In this embodiment, the backup ring 80 has an annular contact surface 801 that contacts the O-ring 91 at a location opposite the injection hole 23, and a cylindrical contact surface 802 that contacts the O-ring 91 at a radially outer location.

[0074] This makes it easy to design the accommodation rate of the O-ring 91 on the radially inner side of the backup ring 80. Furthermore, the components of forces acting on the O-ring 91 from the annular contact surface 801 and the cylindrical contact surface 802 can be designed individually, thereby improving design freedom.

[0075] (Second embodiment) A portion of a fuel injection device according to the second embodiment is shown in Figure 4. The second embodiment differs from the first embodiment in the configuration of the backup ring 80.

[0076] <4> In this embodiment, the inner diameter of the backup ring 80 is larger than the outer diameter of the nozzle body 20 .

[0077] More specifically, the inner diameter of the ring plate portion 85 is larger than the outer diameter of the nozzle small diameter portion 211. Therefore, a radial gap Sr2 is formed between the inner peripheral wall of the ring plate portion 85 of the backup ring 80 and the outer peripheral wall of the nozzle small diameter portion 211 (see FIG. 4).

[0078] In this embodiment, the radial gap Sr2 can prevent the backup ring 80 from damaging the plating on the outer peripheral wall of the nozzle small diameter portion 211.

[0079] (Third embodiment) A portion of a fuel injection device according to the third embodiment is shown in Figure 5. The third embodiment differs from the first embodiment in the configuration of the backup ring 80.

[0080] <3> In this embodiment, the inner peripheral wall of the backup ring 80 contacts the outer peripheral wall of the nozzle body 20 .

[0081] Also, <6> In this embodiment, the backup ring 80 has a contact tapered surface 803 that contacts the O-ring 91 at a portion opposite to the injection hole 23 and at a radially outer portion of the O-ring 91.

[0082] Also, <7> In this embodiment, the backup ring 80 has an opposing cylindrical surface 804 that faces the outer peripheral wall of the nozzle body 20 radially inward of the abutting tapered surface 803, and a flat opposing annular surface 805 that faces the gasket 92 on the injection hole 23 side of the abutting tapered surface 803.

[0083] More specifically, the abutting tapered surface 803 is tapered so as to approach the axis Ax1 of the backup ring 80 as it moves from the injection hole 23 side toward the opposite side from the injection hole 23 (see FIG. 5). The opposing cylindrical surface 804 is formed in a cylindrical shape. The inner diameter of the opposing cylindrical surface 804 is the same as the outer diameter of the nozzle small diameter portion 211. Therefore, the opposing cylindrical surface 804 faces the outer peripheral wall of the nozzle small diameter portion 211 and is in contact with the outer peripheral wall of the nozzle small diameter portion 211. The opposing annular surface 805 is formed in a flat and annular shape. An axial gap Sa1 is formed between the opposing annular surface 805 and the gasket 92.

[0084] <6> In this embodiment, the backup ring 80 has one surface that abuts against the O-ring 91 (abutting tapered surface 803), and therefore has superior machining accuracy compared to the first embodiment, in which the backup ring 80 has two surfaces that abut against the O-ring 91 (abutting annular surface 801 and abutting cylindrical surface 802).

[0085] <7> In the cross section of the backup ring 80 taken along a plane including the axis Ax1, the opposing cylindrical surface 804 and the opposing annular surface 805 have linear shapes, which allows the size of the backup ring 80 to be reduced in the radial and axial directions.

[0086] (Fourth embodiment) A part of a fuel injection device according to the fourth embodiment is shown in Fig. 6. The fourth embodiment differs from the third embodiment in the configuration of the backup ring 80.

[0087] <4> In this embodiment, the inner diameter of the backup ring 80 is larger than the outer diameter of the nozzle body 20 .

[0088] More specifically, the inner diameter of the opposing cylindrical surface 804 is larger than the outer diameter of the nozzle small diameter portion 211. Therefore, a radial gap Sr2 is formed between the inner peripheral wall of the backup ring 80 (opposing cylindrical surface 804) and the outer peripheral wall of the nozzle small diameter portion 211 (see FIG. 6).

[0089] In this embodiment, similarly to the second embodiment, the radial gap Sr2 can prevent the backup ring 80 from damaging the plating on the outer peripheral wall of the nozzle small diameter portion 211.

[0090] (Fifth embodiment) A portion of a fuel injection device according to a fifth embodiment is shown in Fig. 7. The fifth embodiment differs from the first embodiment in the configuration of a backup ring 80.

[0091] <8> In this embodiment, the backup ring 80 has a first ring 81 that abuts against a portion of the O-ring 91 opposite the injection hole 23, and a second ring 82 that is formed separately from the first ring 81 and abuts against a radially outer portion of the O-ring 91.

[0092] <2> More specifically, the first ring 81 is formed in the shape of an annular plate. The outer diameter of the first ring 81 is smaller than the inner diameter of the cylindrical groove surface 552 of the retaining nut groove 55. Therefore, a radial gap Sr1 is formed between the first ring 81 and the retaining nut groove 55. The inner diameter of the first ring 81 is larger than the outer diameter of the nozzle small diameter portion 211. Therefore, a radial gap Sr2 is formed between the first ring 81 and the outer peripheral wall of the nozzle small diameter portion 211. An annular contact surface 801 is formed on the end face of the first ring 81 on the injection hole 23 side. The annular contact surface 801 comes into contact with a portion of the O-ring 91 on the opposite side from the injection hole 23.

[0093] The second ring 82 is formed in a cylindrical shape. The outer diameter of the second ring 82 is smaller than the inner diameter of the cylindrical groove surface 552 of the retaining nut groove 55. Therefore, a radial gap Sr3 is formed between the second ring 82 and the retaining nut groove 55. The axial length of the second ring 82 is smaller than the distance between the first ring 81 and the gasket 92 when the first ring 81 abuts against the annular groove surface 551 and the gasket 92 abuts against the end face of the nozzle small diameter portion 211 on the injection hole 23 side. Therefore, an axial gap Sa1 is formed between the second ring 82 and the gasket 92, which is a gap in the axial direction Ax1 of the backup ring 80. Furthermore, an axial gap Sa2 is formed between the second ring 82 and the first ring 81, which is a gap in the axial direction Ax1 of the backup ring 80.

[0094] In this embodiment, by configuring the backup ring 80 with the first ring 81 and the second ring 82, it is possible to select a backup ring 80 (second ring 82) that matches the wire diameter of the O-ring 91, and to absorb the dimensional tolerance of the O-ring 91. In addition, processing of the backup ring 80 (first ring 81, second ring 82) is simplified, improving processability.

[0095] (Other embodiments) In another embodiment, it is desirable to form a radial gap between the backup ring and the retaining nut groove. If a radial gap is formed, even if axial misalignment occurs between the retaining nut and the nozzle body, the backup ring is not affected by this axial misalignment, and the radial compression rate of the O-ring can be kept constant around the entire circumference.

[0096] In another embodiment, it is desirable to form an axial gap between the backup ring and the gasket. If an axial gap is formed, the gasket can be tightly attached to the end of the retaining nut on the nozzle hole side, and the intrusion of combustion gas into the area around the base of the nozzle body can be more effectively suppressed.

[0097] In addition, in the above-described first and third embodiments, the inner diameter of the backup ring is the same as the outer diameter of the nozzle body. However, in other embodiments, the inner diameter of the backup ring may be smaller than the outer diameter of the nozzle body, and the backup ring may be press-fitted into the nozzle body.

[0098] In addition, in the above-described fifth embodiment, an example was shown in which the inner diameter of the first ring of the backup ring was larger than the outer diameter of the nozzle body. In contrast to this, in other embodiments, the inner diameter of the first ring may be the same as the outer diameter of the nozzle body, or the inner diameter of the first ring may be smaller than the outer diameter of the nozzle body, and the first ring may be press-fitted into the nozzle body.

[0099] In the above-described embodiment, the inner diameter of the gasket is the same as the outer diameter of the nozzle body. However, in other embodiments, the inner diameter of the gasket may be smaller than the outer diameter of the nozzle body and the gasket may be press-fitted into the nozzle body. In this case, the backup ring and the O-ring can be held in the retaining nut groove by the gasket before the fuel injection device is installed in the engine.

[0100] In the above-described embodiment, the backup ring has an annular contact surface, a cylindrical contact surface, or a tapered contact surface as the wall surface that contacts the portion of the O-ring opposite the injection hole and the radially outer portion of the O-ring. However, in other embodiments, the backup ring may have any shape of wall surface that contacts the portion of the O-ring opposite the injection hole and the radially outer portion of the O-ring, such as a shape that corresponds to the shape of the outer wall of the O-ring.

[0101] As such, the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit of the present disclosure. [Explanation of symbols]

[0102] 1 fuel injection device, 20 nozzle body, 23 injection hole, 24 locking portion, 30 nozzle needle, 40 injector body, 42 body thread portion, 50 retaining nut, 53 nut thread portion, 54 locked portion, 55 retaining nut groove portion, 80 backup ring, 91 O-ring, 92 gasket, 200 nozzle chamber, 401 fuel passage

Claims

1. a nozzle body (20) having a nozzle chamber (200) into which fuel flows, a nozzle hole (23) communicating with the nozzle chamber and for injecting fuel, and a locking portion (24) formed on an outer peripheral wall; a nozzle needle (30) provided reciprocally movable within the nozzle chamber, opening and closing the space between the nozzle chamber and the injection hole to intermittently inject fuel from the injection hole; an injector body (40) provided on the opposite side of the nozzle body from the injection hole, the injector body having a fuel passage (401) through which fuel flows into the nozzle chamber, and a body thread portion (42) formed on an outer peripheral wall; a cylindrical retaining nut (50) provided radially outward of the nozzle body and the injector body, the retaining nut having a nut thread portion (53) that threads onto the body thread portion, a locked portion (54) that locks onto the locking portion, and an annular retaining nut groove portion (55) that is recessed radially outward from an inner circumferential wall of an end portion on the injection hole side, the retaining nut being capable of generating an axial force between the nozzle body and the injector body in a direction that brings them closer to each other; an annular backup ring (80) provided in the retaining nut groove; an annular O-ring (91) provided on the radially outer side of the nozzle body, on the injection hole side in the axial direction with respect to the backup ring and on the radially inner side with respect to the backup ring; an annular gasket (92) provided on the radially outer side of the nozzle body on the nozzle hole side relative to the retaining nut groove portion, the backup ring, and the O-ring so as to contact the nozzle hole side end face of the retaining nut; A fuel injection device comprising:

2. A radial gap (Sr1, Sr2) is formed between the backup ring and the retaining nut groove, The fuel injection device according to claim 1, wherein axial gaps (Sa1, Sa2) are formed between the backup ring and the gasket.

3. 3. The fuel injection device according to claim 2, wherein an inner peripheral wall of the backup ring is in contact with an outer peripheral wall of the nozzle body.

4. 3. The fuel injection device according to claim 2, wherein the inner diameter of the backup ring is larger than the outer diameter of the nozzle body.

5. 5. The fuel injection device according to claim 1, wherein the backup ring has an annular abutment surface (801) that abuts against a portion of the O-ring opposite to the injection hole, and a cylindrical abutment surface (802) that abuts against a radially outer portion of the O-ring.

6. 5. The fuel injection device according to claim 1, wherein the backup ring has a contact tapered surface that contacts a portion of the O-ring opposite the injection hole and a portion of the O-ring on a radially outer side.

7. 7. The fuel injection device according to claim 6, wherein the backup ring has an opposing cylindrical surface (804) facing the outer peripheral wall of the nozzle body on the radially inner side of the contact tapered surface, and an opposing flat annular surface (805) facing the gasket on the injection hole side of the contact tapered surface.

8. 5. The fuel injection device according to claim 1, wherein the backup ring includes a first ring (81) that abuts against a portion of the O-ring on the opposite side from the injection hole, and a second ring (82) that is formed separately from the first ring and abuts against a portion of the O-ring on the radially outer side.

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