Fuel Injection Valve

Abstract

To provide a fuel injection valve that reduces friction stress on a nozzle body seating face due to fastening of a retaining nut.SOLUTION: In a fuel injection valve 101, a retaining nut 701 fastens an injector body 20 and a nozzle body 30 to each other. In the nozzle body 30, corrosion-resistant coating treatment C is applied to a nozzle body seating face 32 that is an end face of a collar part 31, in addition to a tip of a shaft part 33 and an outer wall. The retaining nut 701 comprises two members that are a large cylindrical member 401 whose inner wall opposes to an outer wall of the injector body 20 and a small cylindrical member 501 through which the shaft part 33 of the nozzle body 30 is inserted and that has a nozzle holding part 58 abutting on the nozzle body seating face 32 to hold the nozzle body 30. The large cylindrical member 401 includes a female screw part (engagement part) 41 engaging with the outer wall of the injector body 20. The small cylindrical member 501 holds the nozzle body 30 by using axial force transmitted from the large cylindrical member 401.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art Fuel injection valves that are subjected to corrosion-resistant treatment to prevent corrosion due to fuel are known.

[0003] For example, the fuel injection nozzle disclosed in Patent Document 1 has a corrosion-resistant amorphous chrome plating applied to the outer circumferential surface of the tip.The fuel injection valve disclosed in Patent Document 2 suppresses the occurrence of cracks in the plating layer due to the pressing stress generated when the retaining nut is pressed against the nozzle body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-209575 [Patent Document 2] JP 2019-163759 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology of Patent Document 2, the deposition rate of the plating is adjusted so that the indentation elastic modulus of the plating layer is an appropriate value based on the relationship between the indentation elastic modulus of the plating layer and the probability of damage to the plating layer due to the pressing stress. This conventional technology requires precise management of manufacturing conditions for the deposition rate of the plating and the pressing stress of the retaining nut. In addition, depending on the size of the fuel injection valve and the equipment capacity, it may not be possible to obtain a realistic appropriate value. Therefore, it is necessary to reduce the friction stress on the nozzle body seating surface during fastening by improving the fastening structure of the retaining nut.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel injection valve which reduces frictional stress on the nozzle body seating surface caused when the retaining nut is tightened. [Means for solving the problem]

[0007] The fuel injection valve of the present invention comprises a needle (39), a nozzle body (30), and an injector body (20 ) and retaining nut (70 3 ) and.

[0008] The needle reciprocates in a valve opening direction and a valve closing direction. The nozzle body is a stepped cylinder with a shaft portion (33) extending from a collar portion (31) at the base end to the tip end, and slidably houses the needle inside. The nozzle body has an injection hole (37) through which fuel is injected when the needle is opened, and a nozzle chamber (36) through which pressure is generated to operate the needle and through which fuel flows in and out so as to supply fuel when the needle is opened.

[0009] The injector body is provided on the opposite side of the collar portion of the nozzle body from the shaft portion, and is cylindrical with a larger diameter than the collar portion. The injector body has a fuel passage (26) through which fuel is supplied to the nozzle chamber. The retaining nut fastens the injector body and the nozzle body together.

[0010] The nozzle body is provided with a corrosion-resistant coating (C) on the tip and outer wall of the shaft portion as well as on the nozzle body seat surface (32) which is the end face of the collar portion.

[0011] The retaining nut is a large cylindrical member (40 3 ), and a small cylindrical member (50) having a nozzle holding portion (58) through which the shaft portion of the nozzle body is inserted and which abuts against the nozzle body seating surface to hold the nozzle body. 3 ), and is composed of two or more members including. The large cylinder member has an engagement portion (41) that engages with the outer wall of the injector body. The small cylinder member holds the nozzle body by axial force transmitted from the large cylinder member.

[0012] The engaging portion of the large cylinder member in the retaining nut is constituted by a female thread portion (41) which is fastened to the male thread portion (21) of the injector body. The large cylinder member has an inner flange (453) which protrudes radially inward at the end on the small cylinder member side. The small cylinder member accommodates a plurality of balls (63) whose spherical surfaces partially protrude from the outer wall of the small cylinder member in a plurality of recesses (53) formed on the outer periphery of the end on the large cylinder member side. The plurality of balls abut against the seat surface (463) of the inner flange of the large cylinder member, and the axial force due to fastening is transmitted from the large cylinder member to the small cylinder member via the plurality of balls.

[0013] In the present invention, since the retaining nut is composed of two or more members including the large cylinder member and the small cylinder member, when the retaining nut is fastened, only the large cylinder member can rotate relative to the injector body while the rotation of the small cylinder member and the nozzle body is restricted. Therefore, it is possible to reduce frictional stress on the nozzle body seating surface caused by fastening the retaining nut. As a result, a corrosion-resistant coating can be applied to the nozzle body seating surface in addition to the tip and outer wall of the shaft portion, improving corrosion resistance. [Brief description of the drawings]

[0014] [Figure 1] 2 is a partial cross-sectional view of a nozzle portion of the fuel injection valve according to the first embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of part II in FIG. [Diagram 3] FIG. 1 is an enlarged cross-sectional view of part III. [Figure 4] FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3 of a fuel injection valve according to a second embodiment. [Diagram 5] FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3 of a fuel injection valve according to a third embodiment. [Figure 6] FIG. 13 is an enlarged cross-sectional view of a modified example of the third embodiment. [Figure 7] FIG. 11 is a partial cross-sectional view of a nozzle portion of a fuel injection valve according to a fourth embodiment. [Figure 8] FIG. 8 is an enlarged cross-sectional view of part VIII in FIG. 7 . [Figure 9] FIG. 4 is a partial cross-sectional view of a nozzle portion of a fuel injection valve of a comparative example. [Figure 10] FIG. 10 is an enlarged cross-sectional view of part X in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A fuel injection valve according to a number of embodiments of the present invention will be described with reference to the drawings. In the number of embodiments, substantially the same configurations are given the same reference numerals, and description thereof will be omitted. The first to fourth embodiments are collectively referred to as "the present embodiment." The fuel injection valve of the present embodiment is provided in each cylinder of, for example, a four-cylinder diesel engine, and is connected to a common rail in which high-pressure fuel is stored. The fuel injection valve injects the high-pressure fuel supplied from the common rail into the combustion chamber of each cylinder. The reference numerals of the fuel injection valve in each of the following embodiments are numbered with the embodiment number as the third digit following "10." The third embodiment corresponds to an embodiment of the invention described in the claims.

[0016] (First embodiment) A fuel injection valve 101 of a first embodiment will be described with reference to Figs. 1 to 3. Fig. 1 shows a partial cross section of the nozzle portion. Figs. 2 and 3 show enlarged views of the indicated portion of Fig. 1. In the following figures, the nozzle tip side where the injection hole 37 is formed is shown on the bottom side. In accordance with this up-down direction, the nozzle tip side will be described as the bottom and the fuel inlet side (not shown) as the top, as appropriate. The configurations of the fuel inlet, filter, connector, etc. provided at the top of the fuel injection valve are in accordance with general well-known techniques and will not be shown in the drawings.

[0017] The fuel injection valve 101 includes, in its nozzle portion, an injector body 20, a nozzle body 30, a needle 39, and a retaining nut 701. All of these members are made of metal and are arranged coaxially about a central axis Z. Hereinafter, the direction of the central axis Z will be referred to as the "axial direction." The injector body 20 is provided in the middle of the axial direction, and the nozzle body 30 is provided at the tip of the axial direction.

[0018] The nozzle body 30 is a stepped cylindrical member with a shaft portion 33 extending from a collar portion 31 at the base end to the tip end. In other words, the shaft portion 33 is formed to be longer and thinner than the collar portion 31. The end face of the collar portion 31, which is the step with the shaft portion 33, forms a nozzle body seat surface 32 that is retained by a retaining nut 701.

[0019] A needle 39 is slidably housed inside the nozzle body 30. The needle 39 reciprocates in the valve opening and closing directions based on commands from the ECU. The nozzle body 30 has a nozzle hole 37 at the tip of the shaft portion 33, and a nozzle chamber 36 inside the collar portion 31. Fuel is injected from the nozzle hole 37 when the needle 39 is open. The nozzle chamber 36 generates pressure to operate the needle 39, and fuel flows in and out of the nozzle chamber 36 to supply fuel when the needle 39 is open. When the retaining nut 701 is fastened, the nozzle body 30 is held in a state where rotation is restricted, since it is necessary to define the angular position of the nozzle hole 37.

[0020] The injector body 20 is provided on the opposite side of the collar portion 31 of the nozzle body 30 from the shaft portion 33, and is cylindrical with a larger diameter than the collar portion 31. Fuel is supplied from a fuel inlet to a nozzle chamber 36 via a fuel passage 26 formed in the injector body 20.

[0021] The retaining nut 701 has a relatively thin cylindrical shape, and is disposed across the radial outside of the injector body 20 and the nozzle body 30. The retaining nut 701 fastens the injector body 20 and the nozzle body 30 together using a structure that will be described later.

[0022] Incidentally, as disclosed in Patent Documents 1 and 2, a technique is known for subjecting the shaft portion 33 of the nozzle body 30 to a corrosion-resistant plating treatment. In particular, when exhaust gas recirculation (EGR) is used frequently due to exhaust regulations, the need for corrosion-resistant treatment to prevent nozzle corrosion caused by fuel increases. It is preferable that corrosion-resistant treatment is applied not only to the tip of the shaft portion 33 exposed to the engine cylinder, but also to the outer wall of the shaft portion 33 that comes into contact with the fuel gas that penetrates inside through the gap with the cylinder head.

[0023] As shown in Fig. 2, the nozzle body 30 of this embodiment is treated with a corrosion-resistant coating C not only on the tip and outer wall of the shaft portion 33 but also on the nozzle body seating surface 32. However, if frictional stress is applied to the nozzle body seating surface 32 when the retaining nut is fastened, there is a risk of cracks occurring in the corrosion-resistant coating. Therefore, in this embodiment, the fastening structure of the retaining nut is improved to reduce the frictional stress on the nozzle body seating surface 32 when fastened.

[0024] The configuration of the retaining nut differs in each embodiment. The retaining nuts in each embodiment are commonly configured with two or more members including a large cylinder member and a small cylinder member. The large cylinder member has an inner wall facing the outer wall of the injector body 20. The shaft portion 33 of the nozzle body 30 is inserted into the small cylinder member. The small cylinder member also has a nozzle holding portion 58 that abuts against the nozzle body seating surface 32 to hold the nozzle body 30.

[0025] The reference numerals of the retaining nuts in each embodiment have the number of the embodiment added as the third digit following "70." Similarly, the reference numerals of the large and small cylinder members have the number of the embodiment added as the third digit following "40" and "50" in principle. However, since the large cylinder member of the second embodiment is common to the first embodiment, the reference numeral "401" of the large cylinder member of the first embodiment is used.

[0026] The retaining nut 701 of the first embodiment is composed of two members, a large cylinder member 401 and a small cylinder member 501. Both the large cylinder member 401 and the small cylinder member 501 are made of metal. Although not shown, a spline groove is formed on the outer wall of the large cylinder member 401 for rotating the large cylinder member 401 with a jig. In addition, a polygonal portion, a restricting groove portion, and the like that can restrict rotation are formed on the outer wall of the small cylinder member 501.

[0027] The large cylinder member 401 has an "engagement portion" that engages alone with the outer wall of the injector body 20. The locking portion of the large cylinder member 401 in the first embodiment is formed by the female thread portion 41 that is fastened to the male thread portion 21 of the injector body 20. The large cylinder member 401 also has an inner flange 451 that protrudes radially inward at the end on the small cylinder member 501 side. As shown in Fig. 3, the inner flange 451 is formed with a substantially flat seat surface 461.

[0028] An insertion hole 59 is formed at the end of the small cylinder member 501 on the nozzle tip side, through which the shaft portion 33 of the nozzle body 30 is inserted. A nozzle holding portion 58 that protrudes radially inward is formed around the insertion hole 59. The nozzle holding portion 58 abuts against the nozzle body seating surface 32 to hold the collar portion 31 of the nozzle body 30. The small cylinder member 501 also has an outer flange 51 that protrudes radially outward at the end on the large cylinder member 401 side. The outer flange 51 of the small cylinder member 501 is engaged with the inner flange 451 of the large cylinder member 401.

[0029] When fastened by the retaining nut 701, the large cylinder member 401 rotates relative to the injector body 20 while the rotation of the small cylinder member 501 and the nozzle body 30 is restricted. When the female thread portion 41 of the large cylinder member 401 is screwed into the male thread portion 21 of the injector body 20, the seating surface 461 of the inner flange 451 of the large cylinder member 401 comes into contact with the seating surface 516 of the outer flange 51 of the small cylinder member 501. As the large cylinder member 401 rotates, the seating surface 461 of the inner flange 451 and the seating surface 516 of the outer flange 51 slide against each other.

[0030] In this way, the axial force pulling the large cylinder member 401 up by fastening it to the injector body 20 is transmitted from the large cylinder member 401 to the small cylinder member 501. The small cylinder member 501 holds the nozzle body 30 at the nozzle holding portion 58 by the axial force transmitted from the large cylinder member 401.

[0031] At least one of the seat surface 461 of the inner flange 451 of the large cylinder member 401 and the seat surface 516 of the outer flange 51 of the small cylinder member 501 is subjected to a friction coefficient reducing treatment F. For example, DLC coating treatment, hard chrome plating treatment, or the like is used as the friction coefficient reducing treatment F (see JP 2008-69678 A and JP 2008-232180 A).

[0032] Furthermore, the hardness of the corrosion-resistant film applied to the nozzle body seating surface 32 is higher than the hardness of the material of the small cylinder member 501. This also applies to the following second to fourth embodiments.

[0033] (effect) The effects of the first embodiment will be described in comparison with a comparative example shown in Figures 9 and 10. In the comparative example reflecting the conventional techniques of Patent Documents 1, 2, etc., the retaining nut 709 is configured as a single member. In this configuration, when the retaining nut 709 is rotated and screwed into the injector body 20 while the rotation of the nozzle body 30 is restricted, slippage occurs between the nozzle holding portion 58 and the nozzle body seating surface 32, and friction stress is generated in the nozzle body seating surface 32.

[0034] 10, the tip and outer wall of the shaft portion 33 can be coated with a corrosion-resistant coating C, but the nozzle body seating surface 32 cannot be coated with the corrosion-resistant coating C, resulting in a problem of reduced corrosion resistance against fuel penetrating through gaps. When the nozzle body 30 corrodes, its strength decreases.

[0035] In contrast to this, in the first embodiment, the retaining nut 701 is composed of two members, the large cylinder member 401 and the small cylinder member 501, so that when fastened, only the large cylinder member 401 can rotate relative to the injector body 20 while the rotation of the small cylinder member 501 and the nozzle body 30 is restrained. This makes it possible to reduce friction stress on the nozzle body seating surface 32 caused by fastening the retaining nut 701. This allows the corrosion-resistant coating treatment C to be applied to the nozzle body seating surface 32 in addition to the tip and outer wall of the shaft portion 33, improving corrosion resistance.

[0036] Furthermore, by applying the friction coefficient reduction treatment F to the axial force transmission section from the large cylinder member 401 to the small cylinder member 501, friction loss caused by the axial force transmission is reduced, and the axial force transmission efficiency is improved. Also, wear of the large cylinder member 401 and the small cylinder member 501 can be suppressed.

[0037] Next, fuel injection valves 102, 103 of second and third embodiments will be described with reference to an enlarged cross-sectional view corresponding to Fig. 3 of the first embodiment. The configurations of the injector body 20 and the nozzle body 30 of the first embodiment shown in Fig. 1 and the basic structure of the large cylinder member are common to the second and third embodiments. Also, the second and third embodiments are similar to the first embodiment in that the large cylinder member rotates relative to the injector body 20 while the rotation of the small cylinder member and the nozzle body 30 is restricted when the retaining nut is fastened.

[0038] In the second and third embodiments, the configuration in which the axial force is transmitted from the large cylinder member to the small cylinder member differs from that in the first embodiment, and the axial force is transmitted via a third member added between the large cylinder member and the small cylinder member. As the third member, a snap ring is used in the second embodiment, and a ball is used in the third embodiment.

[0039] Second embodiment 4 shows a fuel injection valve 102 of the second embodiment. A retaining nut 702 is composed of three members, a large cylinder member 401, a small cylinder member 502, and a snap ring 62. In the second embodiment, the large cylinder member 401 is used in common with the first embodiment. The locking portion of the large cylinder member 401 is composed of a female thread portion 41 that is fastened to the male thread portion 21 of the injector body 20. The large cylinder member 401 has an inner flange 451 that protrudes radially inward at the end on the small cylinder member 502 side. A substantially flat seat surface 461 is formed on the inner flange 451.

[0040] A snap ring 62 is inserted into a ring groove 52 formed on the outer periphery of the end of the small cylinder member 502 on the large cylinder member 401 side. The snap ring 62 is made of spring steel and formed into a C-shape with part of the circumference cut off, and is inserted into the ring groove 52 by elastically deforming so as to expand its diameter. When inserted into the ring groove 52, the outer edge of the snap ring 62 protrudes from the outer wall of the small cylinder member 502.

[0041] 4, the line cross-sectional shape of snap ring 62 is substantially rectangular. However, in other examples, the line cross-sectional shape of snap ring 62 may be polygonal or elliptical, and the seat surface of the inner flange of the large tubular member may be formed into a tapered or concave curved shape depending on the line cross-sectional shape.

[0042] When the female thread portion 41 of the large cylinder member 401 is screwed into the male thread portion 21 of the injector body 20 during fastening with the retaining nut 702, the seating surface 461 of the inner flange 451 of the large cylinder member 401 comes into contact with the snap ring 62. As the large cylinder member 401 rotates, the outer circumferential side of the snap ring 62 slides against the seating surface 461 of the inner flange 451, and the inner circumferential side slides against the wall surface of the ring groove 52. In this way, the axial force generated by fastening is transmitted from the large cylinder member 401 to the small cylinder member 502 via the snap ring 62.

[0043] Furthermore, at least one of the seat surface 461 of the inner flange 451 of the large cylinder member 401 and the ring groove 52 of the small cylinder member 502 is subjected to a friction coefficient reducing treatment F.

[0044] In the second embodiment, by using the snap ring 62 as the axial force transmission member, the slipperiness is improved due to the surface roughness of the snap ring 62 itself. Furthermore, by applying the friction coefficient reduction treatment F, the friction loss accompanying the axial force transmission is reduced.

[0045] Third embodiment 5 shows a fuel injection valve 103 of the third embodiment. A retaining nut 703 is composed of three components: a large cylinder member 403, a small cylinder member 503, and a plurality of balls 63. As in the first and second embodiments, the locking portion of the large cylinder member 403 is composed of a female thread portion 41 that is fastened to the male thread portion 21 of the injector body 20. The large cylinder member 403 has an inner flange 453 that protrudes radially inward at the end on the small cylinder member 503 side. The inner flange 453 is formed with a tapered seating surface 463 that is inclined relative to the axis in an axial cross section, or has an arc-shaped cross section.

[0046] The small cylinder member 503 has a plurality of balls (e.g., steel balls) 63 housed in a plurality of recesses 53 formed on the outer periphery of the end portion on the large cylinder member 403 side. The recesses 53 and balls 63 are provided evenly in the circumferential direction, for example, at about 6 to 24 locations. In the example of FIG. 5, the recesses 53 are cylindrical holes with a bottom, and the balls 63 are press-fitted and fixed. When housed in the recesses 53, a part of the spherical surface of each ball 63 protrudes from the outer wall of the small cylinder member 503.

[0047] When the female thread portion 41 of the large cylinder member 403 is screwed into the male thread portion 21 of the injector body 20 during fastening with the retaining nut 703, the seating surface 463 of the inner flange 453 of the large cylinder member 403 comes into contact with the multiple balls 63. If the seating surface 463 is a tapered surface, point contact occurs. If the cross section of the seating surface 463 is formed with the same radius as the balls 63, line contact occurs. As the large cylinder member 403 rotates, the contact point or tangent of the ball 63 slides against the seating surface 463 of the inner flange 453. In this way, the axial force generated by fastening is transmitted from the large cylinder member 403 to the small cylinder member 503 via the multiple balls 63.

[0048] In the third embodiment, the contact area is reduced and the slipperiness is improved by using a plurality of balls 63 as the axial force transmission members, and therefore the friction coefficient reduction process F is not required.

[0049] 6 shows a fuel injection valve 103R according to a modified example of the third embodiment. A recess 53R in a small cylinder member 503 is a semispherical hole whose inner diameter is slightly larger than the outer diameter of a ball 63. A plurality of balls 63 are housed in the recess 53R so as to be rotatable about their own axis, and a retainer ring 66 prevents the balls 63 from falling out.

[0050] In the modified example of the third embodiment, the slipperiness is further improved by the rotation of the multiple balls 63. Therefore, the friction coefficient reduction process F is not necessary.

[0051] (Fourth embodiment) 7 and 8, a fuel injection valve 104 according to the fourth embodiment will be described. A retaining nut 704 is composed of three members: a large cylinder member 404, a snap ring 64, and a small cylinder member 504. The snap ring 64 is made of spring steel and formed into a C-shape with a portion of the circumference cut off, similar to the snap ring used in the second embodiment, but the manner of use is different from that of the second embodiment.

[0052] Unlike the first to third embodiments, in the fourth embodiment, a body-side ring groove 24 is formed on the outer wall of the injector body 204 instead of a male thread portion. Also, a nut-side ring groove 44 is formed on the inner wall of the large cylinder member 404 instead of a female thread portion, and a snap ring 64 is inserted across the body-side ring groove 24 and the nut-side ring groove 44. During assembly, the large cylinder member 404 slides together with the holding jig to be assembled to the injector body 204 in a state where the snap ring 64 is elastically deformed and pressed into the body-side ring groove 24 by the holding jig. The snap ring 64 is released from elastic deformation at the position of the nut-side ring groove 44, and is positioned across the inner and outer ring grooves 24, 44.

[0053] Thus, in the large cylinder member 404 of the fourth embodiment, the nut-side ring groove 44 serving as the “engagement portion” engages with the outer wall of the injector body 204 in cooperation with the snap ring 64 serving as the “other member”.

[0054] A female thread portion 47 is formed on the inner periphery of the end of the large cylinder member 404 facing the small cylinder member 504, and a male thread portion 57 is formed on the outer periphery of the end of the small cylinder member 504 facing the large cylinder member 404. When fastening with the retaining nut 704, the female thread portion 47 of the large cylinder member 404 is screwed into the male thread portion 57 of the small cylinder member 504 while restraining the rotation of the small cylinder member 504 and the nozzle body 30, thereby applying an axial force that pulls the nozzle body 30 towards the injector body 204.

[0055] At this time, as shown in Fig. 8, the large cylinder member 404 moves down relative to the injector body 204. During this process, sliding friction occurs between the upper and lower end faces of the snap ring 64 and the inner wall surfaces of the body-side ring groove 24 and the nut-side ring groove 44. When the snap ring 64 is finally sandwiched between the lower inner wall surface 24L of the body-side ring groove 24 and the upper inner wall surface 44U of the nut-side ring groove 44, the injector body 204 and the large cylinder member 404 are integrated via the snap ring 64. In this manner, the nozzle body 30 and the injector body 204 are fastened together.

[0056] In the fourth embodiment, similarly to the first to third embodiments, the friction stress on the nozzle body seating surface 32 can be reduced.

[0057] (Other embodiments) The configurations of the components of the fuel injection valve other than the retaining nut are not limited to those shown in the above embodiment, and any known configuration may be appropriately adopted.

[0058] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention. [Explanation of symbols]

[0059] 101-104...Fuel injection valve, 20, 204... injector body, 26... fuel passage, 30... nozzle body, 31... collar portion, 32... nozzle body seat surface, 33 ... shaft portion, 36 ... nozzle chamber, 37 ... nozzle hole, 39... needle, 401, 403, 404... Large cylinder members, 41: Female thread portion (engagement portion), 44: Ring groove (engagement portion), 501-504: Small cylinder member; 58: Nozzle holding portion; 701-704 Retaining nut, C: Corrosion-resistant coating treatment, F: Friction coefficient reduction treatment.

Claims

1. A needle (39) that reciprocates in a valve opening direction and a valve closing direction; a nozzle body (30) having a stepped cylindrical shape with a shaft portion (33) extending from a collar portion (31) at a base end toward a tip end, slidably housing the needle therein, the nozzle body having an injection hole (37) through which fuel is injected when the needle is opened, and a nozzle chamber (36) through which pressure for operating the needle is generated and through which fuel flows in and out so as to supply fuel when the needle is opened; an injector body (20) provided on the opposite side of the shaft portion with respect to the collar portion of the nozzle body, the fuel passage (26) being tubular and having a larger diameter than the collar portion, and through which fuel is supplied to the nozzle chamber; a retaining nut (703) for fastening the injector body and the nozzle body; Equipped with The nozzle body is provided with a corrosion-resistant coating (C) on the tip and outer wall of the shaft portion as well as on a nozzle body seat surface (32) which is an end face of the collar portion, The retaining nut is the nozzle body is supported by a nozzle seat and supported by a nozzle support member. The nozzle body is supported by a nozzle support member. The nozzle support member is configured of two or more members including a large cylinder member (403) whose inner wall faces the outer wall of the injector body, and a small cylinder member (503) having a nozzle holding portion (58) through which the shaft portion of the nozzle body is inserted and which abuts against the nozzle body seating surface to hold the nozzle body, the large cylinder member has an engagement portion (41) which engages with the outer wall of the injector body, and the small cylinder member holds the nozzle body by an axial force transmitted from the large cylinder member, the engaging portion of the large cylinder member in the retaining nut is constituted by a female thread portion (41) which is fastened to a male thread portion (21) of the injector body, The large cylinder member has an inner flange (453) protruding radially inward at an end portion on the small cylinder member side, The small cylinder member has a plurality of recesses (53) formed on the outer periphery of the end portion of the large cylinder member, and a plurality of balls (63) each having a spherical surface partially protruding from the outer wall of the small cylinder member are accommodated in the recesses (53), A fuel injection valve in which the seat surface (463) of the inner flange of the large cylinder member and the multiple balls abut against each other, and axial force due to fastening is transmitted from the large cylinder member to the small cylinder member via the multiple balls.

2. 2. The fuel injection valve according to claim 1, wherein the hardness of the corrosion-resistant film applied to the nozzle body seating surface is higher than the hardness of the material of the small cylinder member.

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