Fuel injection valve

Abstract

To provide a fuel injection valve for injecting hydrogen fuel while using a hydrogen shielding film for suppressing the embrittlement of a metal component due to the hydrogen fuel and further improving the durability of the hydrogen shielding film.SOLUTION: The fuel injection valve for injecting hydrogen fuel includes the metal component having a parent material 30 formed of metal, the metal component having a hydrogen shielding film 20 for covering at least another member contact surface on which another member slides or collides, out of the surfaces of the parent material 30, the hydrogen shielding film 20 having a multilayer film 21 where a first nitride containing film 21a formed of a first nitride containing material containing nitride and a second nitride containing film 21b formed of a second nitride containing material having a different composition from the first nitride containing material are stacked, and a surface film 22 covering the multilayer film 21 from the opposite side to the parent material 30 and formed of a chromium nitride containing material containing chrome nitride.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses an electromagnetic fuel injection valve. The electromagnetic fuel injection valve disclosed in Patent Document 1 includes a coil that generates a magnetic force when current is passed through the coil. The electromagnetic fuel injection valve disclosed in Patent Document 1 moves a valve body using the magnetic force generated by passing current through the coil, thereby injecting fuel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6788085 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, attempts have been made to use direct-injection fuel injection valves in internal combustion engines that use hydrogen fuel, which inject and supply hydrogen fuel directly into cylinders. The fuel injection valve disclosed in Patent Document 1 is intended to inject fossil fuels such as gasoline and diesel. The components constituting the fuel injection valve disclosed in Patent Document 1 are mainly made of metal. However, hydrogen fuel is known to embrittle metals. Therefore, when applying a fuel injection valve to inject hydrogen fuel, it is necessary to suppress embrittlement of the metal components.

[0005] To prevent such embrittlement of metal parts, it is conceivable to provide a hydrogen-shielding film that blocks hydrogen on the surface of the base material of the metal part. However, direct-injection fuel injection valves are subject to high fuel pressure and high temperatures. Therefore, it is desirable to further improve the durability of the hydrogen-shielding film, especially in areas where parts slide or collide with each other.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide a fuel injection valve that injects hydrogen fuel, in which a hydrogen-shielding film is used to suppress embrittlement of metal components caused by hydrogen fuel, and to further improve the durability of the hydrogen-shielding film. [Means for solving the problem]

[0007] The present invention employs the following configuration as a means for solving the above problems.

[0008] A first aspect of the present invention is a fuel injection valve for injecting hydrogen fuel, comprising a metal component having a base material formed from a metal, the metal component having a hydrogen-shielding film covering at least a contact surface of the surface of the base material with another member against which the other member slides or collides, the hydrogen-shielding film comprising a multilayer film formed by laminating a first nitride-containing film made of a first nitride-containing material and a second nitride-containing film made of a second nitride-containing material having a composition different from that of the first nitride-containing material, and a surface film covering the multilayer film from the side opposite the base material and made of a chromium nitride-containing material containing chromium nitride. [Effects of the Invention]

[0009] The present invention provides a metal component equipped with a hydrogen-shielding film that covers the surface of its base material. The hydrogen-shielding film has a multilayer structure in which a first nitride-containing film and a second nitride-containing film, each having a different composition, are stacked. This multilayer structure can suppress hydrogen permeation. Therefore, the present invention can prevent hydrogen from coming into contact with the base material of the metal component and prevent the metal component from becoming embrittled. The present invention also provides a surface film that covers the multilayer structure from the side opposite the base material and is made of a chromium nitride-containing material. Because the surface film is made of a chromium nitride-containing material, it can suppress the generation of frictional heat in the hydrogen-shielding film and prevent oxidation of the hydrogen-shielding film due to a temperature rise. According to the present invention, in a fuel injection valve that injects hydrogen fuel, the hydrogen-shielding film can suppress embrittlement of the metal component due to hydrogen fuel, and the durability of the hydrogen-shielding film can be further improved. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing a general configuration of a fuel injection valve according to an embodiment of the present invention. [Figure 2] 2 is a schematic cross-sectional view of a fixed core included in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 3] 2 is a schematic cross-sectional view of a hydrogen-shielding film provided in a fuel injection valve according to an embodiment of the present invention. FIG. [Figure 4] 1 is a conceptual diagram for explaining the principle of hydrogen shielding in a multilayer film of a hydrogen shielding film provided in a fuel injection valve according to an embodiment of the present invention. [Figure 5] 1 is a schematic cross-sectional view including a hard chrome plating layer provided on a fuel injection valve according to an embodiment of the present invention. [Figure 6] 2 is a schematic cross-sectional view of a non-magnetic cylindrical body provided in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 7] 2 is a schematic cross-sectional view of a housing body provided in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 8] 2 is a schematic cross-sectional view of a valve seat member provided in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 9] 1 is a schematic cross-sectional view of a rod, a valve portion, a valve-opening stopper, and a valve-closing stopper provided in a fuel injection valve according to an embodiment of the present invention. [Figure 10] 2 is a schematic cross-sectional view of a movable core included in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 11] 3 is a schematic cross-sectional view of an inner collar included in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 12] 3 is a schematic cross-sectional view of a return spring provided in the fuel injection valve according to the embodiment of the present invention. FIG. [Figure 13] 3 is a schematic cross-sectional view of an auxiliary spring provided in the fuel injection valve according to the embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel injection valve according to the present invention will now be described with reference to the drawings.

[0012] 1 is a schematic cross-sectional view showing the general configuration of a fuel injection valve 1 of this embodiment. The fuel injection valve 1 of this embodiment is an electromagnetic valve device that injects and supplies hydrogen fuel to an internal combustion engine that uses hydrogen fuel. The fuel injection valve of the present invention is particularly suitable as a direct injection type fuel injection valve that injects hydrogen fuel into the cylinder of an internal combustion engine.

[0013] As shown in FIG. 1, the fuel injection valve 1 of this embodiment includes a valve housing 2, a valve element 3, an inner collar 4, a return spring 5 (spring), an auxiliary spring 6 (spring), an orifice member 7, a filter member 8, a covering portion 9, and a coil 10. The valve housing 2, the valve element 3, the inner collar 4, the return spring 5, the auxiliary spring 6, and the orifice member 7 are metal parts made mainly of metal. Such metal parts have a base material made of metal. The base material is made of, for example, stainless steel or brass.

[0014] The valve housing 2 is a component that has a fuel passage R therein that guides the hydrogen fuel X. In this embodiment, the valve housing 2 includes a fixed core 2a, a non-magnetic cylindrical body 2b, a housing body 2c, and a valve seat member 2d. For convenience of explanation, in the following description, the direction in which the hydrogen fuel X is guided in the fuel passage R is referred to as the up-down direction, with the upstream end of the fuel passage R referred to as the upper side and the downstream end of the fuel passage R referred to as the lower side. However, the installation orientation of the fuel injection valve 1 of this embodiment is not limited to the case in which the up-down direction is parallel to the direction of gravity.

[0015] 2 is a schematic cross-sectional view of the fixed core 2a. The fixed core 2a is a cylindrical member located in the upper part of the valve housing 2. The fixed core 2a has a through-hole 2a1 that penetrates in the vertical direction. This through-hole 2a1 forms the upper part of the fuel passage R.

[0016] The lower surface of the fixed core 2a is an abutment surface 2a2 (contact surface with other members) with a movable core 3e (described later) of the valve element 3. The movable core 3e abuts against the abutment surface 2a2 from below, restricting upward movement of the valve element 3. The movable core 3e abuts against the fixed core 2a when the valve element 3 is in the valve open position.

[0017] The through hole 2a1 of the fixed core 2a accommodates the inner collar 4, the return spring 5, and the auxiliary spring 6. The through hole 2a1 of the fixed core 2a accommodates the valve-opening stopper 3c (described later) of the valve body 3 so that the stopper 3c is slidable in the vertical direction. In other words, the inner circumferential surface of the through hole 2a1 is a sliding surface 2a3 (surface that comes into contact with other members) that comes into contact with the valve-opening stopper 3c.

[0018] The fixed core 2a has a hydrogen barrier film 20 that covers at least a portion of the surface of a base material 30. FIG. 3 is a schematic cross-sectional view of the hydrogen barrier film 20. The hydrogen barrier film 20 has a multilayer film 21 and a surface film 22. The multilayer film 21 is formed by alternately stacking first nitride-containing films 21a and second nitride-containing films 21b, and is provided so as to cover the surface of the base material 30. Note that the base material 30 shown in FIG. 3 is not limited to the base material of the fixed core 2a, but may also be the base material of any metal part.

[0019] In FIG. 3, multilayer film 21 includes two first nitride-containing films 21a and two second nitride-containing films 21b. However, the number of first nitride-containing films 21a and second nitride-containing films 21b included in multilayer film 21 is not particularly limited. In FIG. 3, the layer of multilayer film 21 closest to base material 30 is first nitride-containing film 21a, and the layer of multilayer film 21 farthest from base material 30 is second nitride-containing film 21b. However, the layer of multilayer film 21 closest to base material 30 may be second nitride-containing film 21b. Alternatively, the layer of multilayer film 21 farthest from base material 30 may be first nitride-containing film 21a.

[0020] The first nitride-containing film 21a is made of a first nitride-containing material that contains nitride. The first nitride-containing film 21a is made of, for example, chromium aluminum nitride (CrAlN), which is a chromium nitride-containing material that contains aluminum (Al) in addition to chromium nitride (nitride).

[0021] The second nitride-containing film 21b is made of a second nitride-containing material having a different composition from the first nitride-containing material. The second nitride-containing film 21b is made of, for example, titanium silicon niobium nitride (TiSiNbN), which is a titanium nitride-containing material containing silicon (Si) and niobium (Nb) in addition to titanium nitride (nitride). The second nitride-containing film 21b may also be made of titanium molybdenum nitride (TiMoN), which is a titanium nitride-containing material containing molybdenum (Mo) in addition to titanium nitride (nitride).

[0022] 4 is a conceptual diagram illustrating the principle of hydrogen shielding in the multilayer film 21. As shown in FIG. 4, the first nitride-containing film 21a and the second nitride-containing film 21b are made of a nitride-containing material in which an additive is added to nitride, and are composed of an aggregate of finer crystal grains than a film made of nitride alone. The first nitride-containing film 21a and the second nitride-containing film 21b have finer crystal grains, and therefore have a high hydrogen trapping effect within the film.

[0023] Furthermore, the first nitride-containing film 21a and the second nitride-containing film 21b are made of nitride-containing materials with different compositions (i.e., different additives). Such a multilayer film 21 can trap hydrogen at the boundary between the first nitride-containing film 21a and the second nitride-containing film 21b. Therefore, the multilayer film 21 has a higher hydrogen trapping effect than a single-layer hydrogen-shielding film made of only the first nitride-containing film 21a or the second nitride-containing film 21b. Thus, the multilayer film 21 of this embodiment has a high hydrogen trapping effect and can prevent hydrogen from reaching the base material 30.

[0024] The surface film 22 has a lower sliding resistance than the second nitride-containing film 21b of the multilayer film 21. The surface film 22 covers the multilayer film 21 from the side opposite the base material 30 and is made of a chromium nitride-containing material containing chromium nitride (CrN). More specifically, the surface film 22 is made of chromium aluminum nitride (CrAlN), which is a chromium nitride-containing material containing aluminum. That is, in this embodiment, the first nitride-containing film 21a of the multilayer film 21 and the surface film 22 are formed of the same material. The composition ratios of the first nitride-containing film 21a and the surface film 22 of the multilayer film 21 may be different.

[0025] As described above, such a surface film 22 has low sliding resistance and reduces the frictional resistance of the hydrogen shielding film 20. Therefore, by providing the surface film 22, the amount of heat generated when another member slides over it can be reduced. Furthermore, the surface film 22 made of chromium nitride (particularly chromium aluminum nitride) has a higher oxidation start temperature than films made of other nitrides, and is highly durable against high temperatures. Therefore, by providing the surface film 22, it is possible to prevent the adhesion of the hydrogen shielding film 20 from decreasing even in a high-temperature environment. Therefore, by providing the surface film 22, it is possible to prevent the hydrogen shielding film 20 from peeling off even when it collides with another member, and it is possible to improve the impact resistance of the hydrogen shielding film 20.

[0026] As shown in FIG. 5, the metal part may also have a hard chrome plating layer 50 located between the base material 30 and the hydrogen barrier film 20. The hard chrome plating layer 50 is a plating layer containing carbon (C) in addition to chrome, and is formed to a thickness of, for example, 1 μm or more. This hard chrome plating layer 50 is a layer with a higher hardness than the multilayer film 21. By providing such a hard chrome plating layer 50, the impact resistance of the metal part is further improved. The hard chrome plating layer 50 contains, for example, 2 to 4% carbon.

[0027] A hydrogen-shielding film 20 is provided to cover at least the area of ​​the surface of the fixed core 2a that may come into contact with the hydrogen fuel X. The hydrogen-shielding film 20 may be provided on the entire surface of the fixed core 2a.

[0028] The contact surface 2a2 of the fixed core 2a is provided with a laminated multilayer film 21 and a surface film 22 provided to cover the multilayer film 21. By providing the surface film 22 on the contact surface 2a2 in this manner, peeling of the hydrogen shielding film 20 can be prevented even if the movable core 3e collides with the contact surface 2a2.

[0029] Furthermore, sliding surface 2a3 of fixed core 2a is also provided with multilayer film 21 and surface film 22 provided to cover multilayer film 21. By providing surface film 22 on sliding surface 2a3 in this manner, heat generation on sliding surface 2a3 can be suppressed even when valve-opening side stopper 3c rubs against sliding surface 2a3.

[0030] Furthermore, it is preferable that the multilayer film 21 and the surface film 22 are non-magnetic. In other words, it is preferable that the hydrogen shielding film 20 is non-magnetic. By making the hydrogen shielding film 20 a non-magnetic material, it is possible to give the hydrogen shielding film 20 the same function as an air gap in a magnetic circuit, thereby enhancing the non-magnetic effect.

[0031] Furthermore, the contact surface 2a2 of the fixed core 2a and the sliding surface 2a3 of the fixed core 2a may be provided with a hard chrome plating layer 50 located between the base material 30 and the hydrogen shielding film 20. By providing the hard chrome plating layer 50 on the contact surface 2a2 and the sliding surface 2a3 in this manner, the impact resistance of the fixed core 2a can be improved.

[0032] 6 is a schematic cross-sectional view of the non-magnetic cylinder 2b. The non-magnetic cylinder 2b is a cylindrical member connected to the lower part of the fixed core 2a. The non-magnetic cylinder 2b is made of a non-magnetic material and is disposed between the coil 10 and the movable core 3e.

[0033] A hydrogen shielding film 20 is provided on at least an area of ​​the surface of the non-magnetic cylindrical body 2b that may come into contact with the hydrogen fuel X so as to cover the base material 30. The hydrogen shielding film 20 may be provided on the entire surface of the non-magnetic cylindrical body 2b.

[0034] Furthermore, a multilayer film 21 and a surface film 22 provided to cover the multilayer film 21 are laminated on the inner circumferential surface 2b1 of the non-magnetic cylindrical body 2b. A part of the inner circumferential surface 2b1 of the non-magnetic cylindrical body 2b is a sliding surface along which the movable core 3e slides and is a contact surface with other members. By providing the surface film 22 on the inner circumferential surface 2b1 in this manner, heat generation at the inner circumferential surface 2b1 can be suppressed even when the movable core 3e rubs against the inner circumferential surface 2b1.

[0035] It is preferable that both the multilayer film 21 and the surface film 22 provided on the surface of the non-magnetic cylindrical body 2b are made of non-magnetic materials, thereby enhancing the non-magnetic effect as described above.

[0036] 7 is a schematic cross-sectional view of the housing body 2c. The housing body 2c is connected to the lower part of the non-magnetic cylindrical body 2b. The housing body 2c is a substantially cylindrical member with a smaller diameter at the bottom than at the top. The housing body 2c has a through-hole 2c1 that penetrates in the vertical direction. This through-hole 2c1 forms the lower part of the fuel passage R.

[0037] A hydrogen-shielding film 20 is provided on at least an area of ​​the surface of the housing body 2c that may come into contact with the hydrogen fuel X, so as to cover the base material 30. The hydrogen-shielding film 20 may be provided on the entire surface of the housing body 2c.

[0038] A part of the inner wall surface at the top of the through hole 2c1 is a sliding surface 2c2 (surface that comes into contact with another member) along which the movable core 3e slides. A multilayer film 21 and a surface film 22 that is provided so as to cover the multilayer film 21 are laminated on the sliding surface 2c2. By providing the surface film 22 on the sliding surface 2c2 in this manner, heat generation at the sliding surface 2c2 can be suppressed even when the movable core 3e rubs against the sliding surface 2c2.

[0039] It is preferable that both the multilayer film 21 and the surface film 22 provided on the surface of the housing body 2c are made of non-magnetic materials, thereby enhancing the non-magnetic effect as described above.

[0040] 8 is a schematic cross-sectional view of the valve seat member 2d. The valve seat member 2d is formed in a cylindrical shape with a bottom, and is connected to the lower end of the housing body 2c. The internal space of the valve seat member 2d forms the lower end of the fuel passage R. The valve seat member 2d is provided with a fuel injection hole 2d1 for injecting hydrogen fuel X toward the bottom.

[0041] A hydrogen-shielding film 20 is provided on at least an area of ​​the surface of the valve seat member 2d that may come into contact with the hydrogen fuel X, so as to cover the base material 30. The hydrogen-shielding film 20 may be provided on the entire surface of the valve seat member 2d.

[0042] The valve portion 3b of the valve disc 3, which will be described later, is accommodated within the valve seat member 2d so as to be movable up and down. A portion of the inner wall surface 2d2 of the valve seat member 2d serves as a sliding surface and abutment surface with the valve portion 3b. In other words, a portion of the inner wall surface 2d2 of the valve seat member 2d serves as a contact surface with other members. A multilayer film 21 and a surface film 22 covering the multilayer film 21 are laminated on the inner wall surface 2d2. By providing the surface film 22 on the inner wall surface 2d2 in this manner, heat generation on the inner wall surface 2d2 can be suppressed even if the valve portion 3b rubs against the inner wall surface 2d2. Furthermore, by providing the surface film 22 on the inner wall surface 2d2, peeling of the hydrogen shielding film 20 can be suppressed even if the valve portion 3b collides against the inner wall surface 2d2.

[0043] Furthermore, the valve seat member 2d is disposed, for example, in a cylinder of an internal combustion engine and is exposed to a particularly high-temperature environment. For this reason, the base material 30 is preferably made of martensitic stainless steel. By making the base material 30 out of martensitic stainless steel, the adhesion of the hydrogen barrier film 20 to the base material 30 is improved. Therefore, even when exposed to a high-temperature environment, peeling of the hydrogen barrier film 20 can be prevented.

[0044] The valve element 3 is a member that is moved vertically inside the fuel passage R. The valve element 3 is movable between a valve-closing position where the valve portion 3b closes the fuel nozzle hole 2d1 of the valve seat member 2d and a valve-opening position where the valve portion 3b is moved above the valve-closing position to open the fuel nozzle hole 2d1. The valve element 3 includes a rod 3a, a valve portion 3b, a valve-opening stopper 3c, a valve-closing stopper 3d, and a movable core 3e.

[0045] 9 is a schematic cross-sectional view of rod 3a, valve portion 3b, valve-opening stopper 3c, and valve-closing stopper 3d. Rod 3a is a rod member that is housed in fuel passage R and extends linearly in the vertical direction.

[0046] A hydrogen-shielding film 20 is provided on at least the area of ​​the surface of the rod 3a that may come into contact with the hydrogen fuel X so as to cover the base material 30. The hydrogen-shielding film 20 may be provided on the entire surface of the rod 3a.

[0047] Furthermore, a part of the surface of the rod 3a is a sliding surface 3a1 (surface that comes into contact with another member) on which the movable core 3e slides. A multilayer film 21 and a surface film 22 that is provided so as to cover the multilayer film 21 are laminated on the sliding surface 3a1. By providing the surface film 22 on the sliding surface 3a1 in this manner, heat generation on the sliding surface 3a1 can be suppressed even when the movable core 3e rubs against the sliding surface 3a1.

[0048] The valve portion 3b is a spherical member fixed to the lower end of the rod 3a. The valve portion 3b is welded to the lower end of the rod 3a. A hydrogen-shielding film 20 is provided on at least an area of ​​the surface of the valve portion 3b that may come into contact with the hydrogen fuel X, so as to cover the base material 30. The hydrogen-shielding film 20 may be provided on the entire surface of the valve portion 3b.

[0049] Furthermore, a portion of the surface 3b1 of the valve portion 3b is a contact surface that comes into contact with the valve seat member 2d and abuts against it. In other words, a portion of the surface 3b1 of the valve portion 3b is a contact surface that comes into contact with another member. A multilayer film 21 and a surface film 22 that covers the multilayer film 21 are laminated on the surface 3b1 of the valve portion 3b. By providing the surface film 22 on the surface 3b1 in this manner, heat generation on the surface 3b1 can be suppressed even if the valve seat member 2d rubs against the surface 3b1. Furthermore, peeling of the hydrogen shielding film 20 can be suppressed even if the valve seat member 2d collides against the surface 3b1.

[0050] The valve-opening stopper 3c is a stopper against which the movable core 3e abuts when the valve element 3 is in the valve-open position. The valve-opening stopper 3c is disposed above the movable core 3e and is welded to the rod 3a.

[0051] The valve-opening stopper 3c has a cylindrical portion 3c1 and a flange 3c2 provided at the upper end of the cylindrical portion 3c1. The rod 3a is inserted into the cylindrical portion 3c1 and is welded to the rod 3a. The lower surface of the cylindrical portion 3c1 is an abutment surface 3c3 (contact surface with other members) with the movable core 3e. The upper surface of the flange 3c2 is an abutment surface 3c4 (contact surface with other members) with the return spring 5. The lower surface of the flange 3c2 is an abutment surface 3c5 (contact surface with other members) with the auxiliary spring 6. The peripheral surface of the flange 3c2 is a sliding surface 3c6 (contact surface with other members) with the fixed core 2a (i.e., the valve housing 2).

[0052] A hydrogen-shielding film 20 is provided on at least an area of ​​the surface of the valve-opening stopper 3c that may come into contact with the hydrogen fuel X so as to cover the base material 30. The hydrogen-shielding film 20 may be provided on the entire surface of the valve-opening stopper 3c.

[0053] The contact surfaces 3c3, 3c4, 3c5, and sliding surface 3c6 are provided with a laminated multilayer film 21 and a surface film 22 provided to cover the multilayer film 21. By providing the surface film 22 on the contact surface 3c3 in this manner, peeling of the hydrogen shielding film 20 can be prevented even when the movable core 3e collides with the contact surface 3c3. Furthermore, by providing the surface film 22 on the contact surface 3c4, heat generation at the contact surface 3c4 can be suppressed even when the return spring 5 rubs against the contact surface 3c4. Furthermore, by providing the surface film 22 on the contact surface 3c5, heat generation at the contact surface 3c5 can be suppressed even when the auxiliary spring 6 rubs against the contact surface 3c5. Furthermore, by providing the surface film 22 on the sliding surface 3c6, heat generation at the sliding surface 3c6 can be suppressed even when the valve-opening stopper 3c rubs against the inner wall surface of the fuel passage R.

[0054] The valve-closing side stopper 3d is a stopper against which the movable core 3e abuts when the valve element 3 is in the valve-closed position. The valve-closing side stopper 3d is disposed below the movable core 3e and is welded to the rod 3a. The valve-opening side stopper 3c and the valve-closing side stopper 3d are disposed at a distance that allows the movable core 3e to slide up and down relative to the rod 3a.

[0055] At least an area of ​​the surface of the closing-side stopper 3d that may come into contact with the hydrogen fuel X is provided with a hydrogen-shielding film 20 so as to cover the base material 30. Note that the hydrogen-shielding film 20 may be provided on the entire surface of the closing-side stopper 3d.

[0056] The upper surface of the closing-side stopper 3d is a contact surface 3d1 (contact surface with other members) of the movable core 3e. A multilayer film 21 and a surface film 22 provided to cover the multilayer film 21 are laminated on the contact surface 3d1. By providing the surface film 22 on the contact surface 3d1 in this manner, peeling of the hydrogen shielding film 20 can be prevented even if the movable core 3e collides with the contact surface 3d1.

[0057] In this embodiment, the hydrogen shielding film 20 is provided so as to cover a joint portion P1 between the valve portion 3b and the rod 3a, a joint portion P2 between the valve-opening stopper 3c and the rod 3a, and a joint portion P3 between the valve-closing stopper 3d and the rod 3a, as shown in Fig. 10. Such a hydrogen shielding film 20 is formed, for example, by welding the rod 3a, the valve portion 3b, the valve-opening stopper 3c, and the valve-closing stopper 3d together to form an integrated member, and then forming a film on the integrated member. Such a hydrogen shielding film 20 is formed, for example, by physical vapor deposition.

[0058] FIG. 10 is a schematic cross-sectional view of the movable core 3e. The movable core 3e is a member that is moved within the fuel passage when current is applied to the coil 10, and is formed in a disk shape with a certain thickness. The movable core 3e is moved upward by the magnetic force generated when current is applied to the coil 10. The movable core 3e is disposed so as to straddle the interior of the non-magnetic cylindrical body 2b and the interior of the upper part of the housing body 2c. The rod 3a passes through the center of the movable core 3e in the vertical direction. The movable core 3e is movable in the vertical direction so as to slide relative to the rod 3a.

[0059] The movable core 3e has a plurality of through holes 3e1 that penetrate in the vertical direction. Hydrogen fuel X flows from top to bottom through these through holes 3e1 through the movable core 3e. The upper surface of the movable core 3e is an abutment surface 3e2 (contact surface with other members) with the valve-opening stopper 3c and the auxiliary spring 6. The lower surface of the movable core 3e is an abutment surface 3e3 with the valve-closing stopper 3d. The outer peripheral surface of the movable core 3e is a sliding surface 3e4 (contact surface with other members) with the valve housing 2 (non-magnetic cylindrical body 2b and housing body 2c). The inner peripheral surface of the movable core 3e is a sliding surface 3e5 (contact surface with other members) with the rod 3a.

[0060] The entire surface of the movable core 3e may come into contact with the hydrogen fuel X. For this reason, the hydrogen-shielding film 20 is provided so as to cover the entire surface of the base material 30 of the movable core 3e. That is, the multilayer film 21 and the surface film 22 provided so as to cover the multilayer film 21 are laminated on the contact surface 3e2, the contact surface 3e3, the sliding surface 3e4, and the sliding surface 3e5. By providing the surface film 22 on the contact surface 3e2 in this manner, peeling of the hydrogen-shielding film 20 can be prevented even if the valve-opening side stopper 3c collides with the contact surface 3e2. Furthermore, by providing the surface film 22 on the contact surface 3e2, heat generation at the contact surface 3e2 can be suppressed even if the auxiliary spring 6 rubs against the contact surface 3e2. Furthermore, by providing the surface film 22 on the contact surface 3e3, peeling of the hydrogen-shielding film 20 can be prevented even if the valve-closing side stopper 3d collides with the contact surface 3e3. Furthermore, by providing the surface film 22 on the sliding surface 3e4, even if the movable core 3e rubs against the inner wall surface of the fuel passage R, heat generation on the sliding surface 3e4 can be suppressed.

[0061] Furthermore, the contact surfaces 3e2, 3e3, and sliding surface 3e4 may be provided with a hard chrome plating layer 50 located between the base material 30 and the hydrogen shielding film 20. By providing the hard chrome plating layer 50 on the contact surfaces 3e2, 3e3, and sliding surface 3e4 in this manner, the impact resistance of the movable core 3e can be improved.

[0062] 11 is a schematic cross-sectional view of the inner collar 4. The inner collar 4 is a cylindrical member disposed inside the fuel passage R. The inner collar 4 is disposed above the return spring 5. The lower surface of the inner collar 4 is a contact surface 4a (contact surface with other members) with the return spring 5.

[0063] The inner collar 4 is press-fitted into the through-hole 2a1 of the fixed core 2a. The peripheral surface of the inner collar 4 forms a pressure-contact surface 4b with the valve housing 2 (fixed core 2a). The inner collar 4 is a member for adjusting the compression amount of the return spring 5 and regulating the pressure of the return spring 5.

[0064] A hydrogen-shielding film 20 is provided on at least the area of ​​the surface of the inner collar 4 that may come into contact with the hydrogen fuel X, so as to cover the base material 30. In this embodiment, the hydrogen-shielding film 20 is provided on the entire surface of the inner collar 4.

[0065] That is, the contact surface 4a and the pressure contact surface 4b are provided with a laminated multilayer film 21 and a surface film 22 provided to cover the multilayer film 21. By providing the surface film 22 on the contact surface 4a in this manner, heat generation at the contact surface 4a can be suppressed even if the return spring 5 rubs against the contact surface 4a.

[0066] 12 is a schematic cross-sectional view of the return spring 5. The return spring 5 is interposed between the inner collar 4 and the valve-opening stopper 3c, and biases the valve element 3 toward the valve-closed position. The return spring 5 holds the valve element 3 in the valve-closed position when the coil 10 is not energized.

[0067] The entire surface of the return spring 5 comes into contact with the hydrogen fuel X. For this reason, the return spring 5 is provided with a hydrogen-shielding film 20 so as to cover the entire surface of the base material 30. The upper end surface of the return spring 5 is an abutment surface 5a (contact surface with other members) with the inner collar 4. The lower end surface of the return spring 5 is an abutment surface 5b (contact surface with other members) with the valve-opening stopper 3c.

[0068] A multilayer film 21 and a surface film 22 provided to cover the multilayer film 21 are laminated on the contact surfaces 5a and 5b. By providing the surface film 22 on the contact surface 5a in this manner, heat generation at the contact surface 5a can be suppressed even when the inner collar 4 rubs against the contact surface 5a. Furthermore, by providing the surface film 22 on the contact surface 5b, heat generation at the contact surface 5b can be suppressed even when the valve-opening stopper 3c rubs against the contact surface 5b.

[0069] 13 is a schematic cross-sectional view of auxiliary spring 6. Auxiliary spring 6 is inserted between flange 3c2 of valve-opening stopper 3c and movable core 3e, and urges movable core 3e downward. Auxiliary spring 6 holds movable core 3e in the valve-closing position (position in contact with valve-closing stopper 3d) when coil 10 is not energized.

[0070] The entire surface of such auxiliary spring 6 comes into contact with hydrogen fuel X. For this reason, the auxiliary spring 6 is provided with a hydrogen shielding film 20 so as to cover the entire surface of the base material 30. The upper end surface of such auxiliary spring 6 is an abutment surface 6a (contact surface with other members) with the valve-opening stopper 3c. The lower end surface of auxiliary spring 6 is an abutment surface 6b (contact surface with other members) with the movable core 3e.

[0071] A multilayer film 21 and a surface film 22 provided to cover the multilayer film 21 are laminated on the contact surfaces 6a and 6b. By providing the surface film 22 on the contact surface 6a in this manner, heat generation at the contact surface 6a can be suppressed even when the valve-opening stopper 3c rubs against the contact surface 6a. Furthermore, by providing the surface film 22 on the contact surface 6b, heat generation at the contact surface 6b can be suppressed even when the movable core 3e rubs against the contact surface 6b.

[0072] Returning to FIG. 1, the orifice member 7 is attached to the upper end opening of the fixed core 2a. In other words, the orifice member 7 is installed at the entrance of the fuel passage R. Such an orifice member 7 adjusts the flow rate of the hydrogen fuel X supplied to the fuel passage R.

[0073] A hydrogen-shielding film 20 is provided to cover at least the area of ​​the surface of the orifice member 7 that may come into contact with the hydrogen fuel X. The hydrogen-shielding film 20 may be provided on the entire surface of the orifice member 7.

[0074] The filter member 8 is disposed below the orifice member 7 and is housed inside the fuel passage R. This filter member 8 is a member for removing foreign matter contained in the hydrogen fuel X. The filter member 8 is press-fitted into the fixed core 2a via a filter collar 11. In other words, the filter collar 11 is interposed between the filter member 8 and the inner wall surface of the fuel passage R.

[0075] The filter collar 11 is a metal part whose base material 30 is made of metal. A hydrogen-shielding film 20 may be provided on the surface of such a filter collar 11. By providing the hydrogen-shielding film 20 on the surface of the filter collar 11, it is possible to prevent the filter collar 11 from becoming embrittled by hydrogen.

[0076] The covering portion 9 is provided for machining the fixed core 2a from the radial outside. The covering portion 9 is formed of an insulator and holds the wiring connected to the coil 10. The covering portion 9 also has a connector 9a for connecting the end of the wiring connected to the coil 10 to an external terminal. The coil 10 is molded with an insulator and is fixed to the valve housing 2 for machining the movable core 3e. When current is applied from the outside, the coil 10 generates a magnetic force, which moves the movable core 3e upward.

[0077] In the fuel injection valve 1 of this embodiment, when the coil 10 is energized, the movable core 3e moves upward and abuts against the valve-opening stopper 3c. The movable core 3e further rises until it abuts against the fixed core 2a. As the movable core 3e rises toward the fixed core 2a, the valve-opening stopper 3c moves upward, and the valve element 3 moves to the valve-open position. When the valve element 3 moves to the valve-open position in this manner, the fuel nozzle hole 2d1 in the valve seat member 2d is opened, and hydrogen fuel X from the fuel passage R is injected.

[0078] On the other hand, when the coil 10 is de-energized, the movable core 3e is moved downward by the biasing force of the auxiliary spring 6 and abuts against the valve-closing stopper 3d. Furthermore, the valve element 3 is moved to the valve-closing position by the biasing force of the return spring 5. This closes the fuel injection hole 2d1 of the valve seat member 2d, and the injection of hydrogen fuel X is stopped.

[0079] The fuel injection valve 1 of this embodiment as described above injects hydrogen fuel X. The fuel injection valve 1 of this embodiment also includes metal components (the valve housing 2, the valve element 3, the inner collar 4, the return spring 5, and the auxiliary spring 6) having a base material 30 formed from metal. The metal components have a hydrogen-shielding film 20 that covers at least the contact surface of the base material 30 with other components that slide against or collide with other components.

[0080] The hydrogen barrier film 20 also includes a multilayer film 21 and a surface film 22. The multilayer film 21 is formed by laminating a first nitride-containing film 21a made of a first nitride-containing material containing nitride and a second nitride-containing film 21b made of a second nitride-containing material having a different composition from the first nitride-containing material. The surface film 22 covers the multilayer film 21 from the side opposite the base material 30, and is made of a chromium nitride-containing material containing chromium nitride.

[0081] The fuel injection valve 1 of this embodiment includes a metal component provided with a hydrogen-shielding film 20 that covers the surface of a base material 30. In addition, in the fuel injection valve 1 of this embodiment, the hydrogen-shielding film 20 has a multilayer film 21 in which a first nitride-containing film 21a and a second nitride-containing film 21b, which have different compositions, are stacked. Such a multilayer film 21 can suppress hydrogen permeation. Therefore, the fuel injection valve 1 of this embodiment can suppress hydrogen from coming into contact with the base material 30 of the metal component, thereby suppressing embrittlement of the metal component.

[0082] Furthermore, the fuel injector 1 of this embodiment has a surface film 22 that covers the multilayer film 21 from the side opposite the base material 30 and is made of a chromium nitride-containing material. Because the surface film 22 is made of a chromium nitride-containing material, it suppresses the generation of frictional heat in the hydrogen shielding film 20. By suppressing the generation of frictional heat, it is possible to suppress a temperature rise in the hydrogen shielding film 20 and prevent oxidation of the hydrogen shielding film 20. If the hydrogen shielding film 20 oxidizes, the adhesion of the hydrogen shielding film 20 to the base material 30 will decrease. Therefore, the fuel injector 1 of this embodiment can improve the durability of the hydrogen shielding film 20 by preventing oxidation of the hydrogen shielding film 20.

[0083] According to the fuel injection valve 1 of this embodiment, in the fuel injection valve 1 that injects hydrogen fuel X, the hydrogen shielding film 20 can suppress embrittlement of metal components due to hydrogen fuel, and the durability of the hydrogen shielding film 20 can be further improved.

[0084] Furthermore, in the fuel injection valve 1 of this embodiment, the surface film 22 is made of, for example, chromium aluminum nitride, which is a chromium nitride-containing material that also contains aluminum. By forming the surface film 22 from chromium aluminum nitride in this manner, it is possible to reliably suppress the generation of frictional heat in the hydrogen shielding film 20. Furthermore, chromium aluminum nitride has a high oxidation onset temperature and is highly durable against high temperatures. Therefore, by forming the surface film 22 from chromium aluminum nitride, it is possible to further suppress oxidation of the hydrogen shielding film 20 and further increase the durability of the hydrogen shielding film 20.

[0085] In the fuel injection valve 1 of this embodiment, the first nitride-containing film 21a is made of, for example, chromium aluminum nitride, which is a first nitride-containing material containing aluminum in addition to the nitride chromium nitride. The second nitride-containing film 21b is made of, for example, titanium silicon niobium nitride, which is a second nitride-containing material containing silicon and niobium in addition to the nitride titanium nitride, or titanium molybdenum nitride, which is a titanium nitride-containing material containing molybdenum in addition to the nitride titanium nitride. Chromium aluminum nitride has a high oxidation onset temperature and is highly durable against high temperatures. Therefore, the multilayer film 21 including such a first nitride-containing film 21a is inhibited from oxidation and is highly durable. Even if the surface film 22 wears and the first nitride-containing film 21a wears further due to long-term use, the second nitride-containing film 21b is exposed on the surface of the hydrogen shielding film 20, allowing the friction coefficient of the hydrogen shielding film 20 to be maintained.

[0086] Furthermore, in the fuel injection valve 1 of this embodiment, the metal component has, for example, a hard chromium plating layer 50 containing chromium and carbon located between the surface of the base material 30 and the hydrogen shielding film 20. The hardness of the carbon-containing hard chromium plating layer 50 increases when heated to a temperature range of up to approximately 700°C. The first nitride-containing film 21a and the second nitride-containing film 21b are formed by, for example, an arc ion plating method, in which the temperature increases to approximately 450°C. Therefore, the hardness of the carbon-containing hard chromium plating layer 50 increases during the process of forming the first nitride-containing film 21a and the second nitride-containing film 21b. The provision of such a carbon-containing hard chromium plating layer 50 improves the impact resistance of the fuel injection valve 1 of this embodiment.

[0087] Furthermore, in the fuel injection valve 1 of this embodiment, the base material 30 is made of, for example, martensitic stainless steel. Martensitic stainless steel is prevented from losing its hardness even when heated to, for example, about 450°C. Therefore, by using martensitic stainless steel as the base material 30, it is possible to prevent a decrease in the hardness of the base material 30 when the first nitride-containing film 21a and the second nitride-containing film 21b are formed by the above-mentioned arc ion plating method. Furthermore, it is possible to prevent a decrease in the hardness of the base material 30 even when metal parts are placed inside the cylinders of an internal combustion engine.

[0088] The fuel injection valve 1 of this embodiment includes a valve housing 2, a valve element 3, and springs (a return spring 5 and an auxiliary spring 6). The valve housing 2 has a fuel passage R therein. The valve element 3 moves within the fuel passage R. The spring biases the valve element 3 toward a closed position. In the fuel injection valve 1 of this embodiment, the valve housing 2, the valve element 3, and the spring are metal components having a hydrogen-shielding film 20. Therefore, the hydrogen-shielding film 20 can suppress embrittlement of the valve housing 2, the valve element 3, and the spring due to hydrogen fuel X, and the durability of the hydrogen-shielding film 20 can be further improved.

[0089] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0090] For example, in the above embodiment, the valve housing 2, valve element 3, inner collar 4, return spring 5, and auxiliary spring 6 are metal parts, and a configuration has been described in which these metal parts are provided with the hydrogen shielding film 20. However, the present invention is not limited to this. For example, it is also possible to adopt a configuration in which only some of the multiple metal parts are provided with the hydrogen shielding film 20.

[0091] Furthermore, in the above embodiment, a configuration in which the hydrogen-shielding film 20 is formed on the entire surface of the metal component exposed to hydrogen fuel X has been described as an example. However, it is also possible to form the hydrogen-shielding film 20 having the surface film 22 only on the contact surface with other components that slides or collides with other components, and to provide a hydrogen-shielding film without the surface film 22 on the surface of the metal component that is not provided with the hydrogen-shielding film 20 and comes into contact with the hydrogen fuel X. Such a hydrogen-shielding film without the surface film 22 can be, for example, a multilayer film in which titanium silicon niobium nitride and titanium molybdenum nitride are laminated. In other words, in the fuel injection valve of the present invention, the hydrogen-shielding film 20 having the surface film 22 can be formed by patterning on part of the surface of the metal component.

[0092] The above embodiment can also be described as follows, for example:

[0093] (Appendix 1) A fuel injection valve that injects hydrogen fuel, a metal part having a base material formed of metal; the metal component has a hydrogen barrier film that covers at least a contact surface of the base material with another member, the contact surface being a surface that slides against or collides with another member; The hydrogen barrier film is a multilayer film formed by laminating a first nitride-containing film made of a first nitride-containing material containing nitride and a second nitride-containing film made of a second nitride-containing material having a different composition from the first nitride-containing material; a surface film covering the multilayer film from the side opposite to the base material and made of a chromium nitride-containing material; have A fuel injection valve characterized by:

[0094] (Appendix 2) 2. The fuel injection valve according to claim 1, wherein the surface film is made of chromium nitride aluminum, which is the chromium nitride-containing material that also contains aluminum.

[0095] (Appendix 3) the first nitride-containing film is made of chromium aluminum nitride, which is the first nitride-containing material containing aluminum in addition to chromium nitride, which is the nitride; The second nitride-containing film is made of titanium silicon niobium nitride, which is the second nitride-containing material containing silicon and niobium in addition to titanium nitride, or titanium molybdenum nitride, which is the second nitride-containing material containing molybdenum in addition to titanium nitride. 3. The fuel injection valve according to claim 1 or 2.

[0096] (Appendix 4) 4. The fuel injection valve according to any one of claims 1 to 3, wherein the metal component has a plating layer containing chromium and carbon located between the surface of the base material and the hydrogen-shielding film.

[0097] (Appendix 5) 5. The fuel injection valve according to any one of claims 1 to 4, wherein the base material is made of martensitic stainless steel.

[0098] (Appendix 6) a valve housing having a fuel passage therein; a valve body that moves within the fuel passage; a spring that biases the valve body toward a closed position; Equipped with At least one of the valve housing, the valve body, and the spring is a metal part having the hydrogen barrier film. 6. The fuel injection valve according to any one of claims 1 to 5. [Explanation of symbols]

[0099] 1... fuel injection valve, 2... valve housing (metal part), 2a... fixed core, 2a1... through hole, 2a2... abutment surface (contact surface with other parts), 2a3... sliding surface (contact surface with other parts), 2b... non-magnetic cylindrical body, 2b1... inner circumferential surface (contact surface with other parts), 2c... housing body, 2c1... through hole, 2c2... sliding surface (contact surface with other parts), 2d... valve seat member, 2d1... fuel nozzle, 2d2... inner wall surface (contact surface with other parts), 3... valve body (metal part) product), 3a... rod, 3a1... sliding surface (contact surface with other parts), 3b... valve part, 3b1... surface (contact surface with other parts), 3c... valve opening side stopper, 3c1... cylindrical part, 3c2... flange, 3c3... contact surface (contact surface with other parts), 3c4... contact surface (contact surface with other parts), 3c5... contact surface (contact surface with other parts), 3c6... sliding surface (contact surface with other parts), 3d... valve closing side stopper, 3d1... contact surface (contact surface with other parts), 3e... moving core, 3e1... ...Through hole, 3e2...Abutment surface (contact surface with other parts), 3e3...Abutment surface (contact surface with other parts), 3e4...Sliding surface (contact surface with other parts), 3e5...Sliding surface (contact surface with other parts), 4...Inner collar (metal part), 4a...Abutment surface (contact surface with other parts), 4b...Pressure contact surface, 5...Return spring (metal part, spring), 5a...Abutment surface (contact surface with other parts), 5b...Abutment surface (contact surface with other parts), 6...Auxiliary spring (metal part, spring) spring), 6a...contact surface (contact surface with other members), 6b...contact surface (contact surface with other members), 7...orifice member (metal part), 8...filter member, 9...covering portion, 9a...connector, 10...coil, 11...filter collar, 20...hydrogen shielding film, 21...multilayer film, 21a...first nitride-containing film, 21b...second nitride-containing film, 22...surface film, 30...base material, 50...hard chrome plating layer, R...fuel passage, X...hydrogen fuel

Claims

1. A fuel injection valve that injects hydrogen fuel, a metal part having a base material formed of metal; the metal component has a hydrogen barrier film that covers at least a contact surface of the base material with another member, the contact surface being a surface that slides against or collides with another member; The hydrogen barrier film is a multilayer film formed by laminating a first nitride-containing film made of a first nitride-containing material containing nitride and a second nitride-containing film made of a second nitride-containing material having a different composition from the first nitride-containing material; a surface film covering the multilayer film from the side opposite to the base material and made of a chromium nitride-containing material; have A fuel injection valve characterized by:

2. 2. The fuel injection valve according to claim 1, wherein the surface film is made of chromium nitride aluminum, which is the chromium nitride-containing material containing aluminum.

3. the first nitride-containing film is made of chromium aluminum nitride, which is the first nitride-containing material containing aluminum in addition to chromium nitride, which is the nitride; The second nitride-containing film is made of titanium silicon niobium nitride, which is the second nitride-containing material containing silicon and niobium in addition to titanium nitride, or titanium molybdenum nitride, which is the second nitride-containing material containing molybdenum in addition to titanium nitride.

3. The fuel injection valve according to claim 1 or 2.

4. 3. The fuel injection valve according to claim 1, wherein the metal component has a plating layer containing chromium and carbon located between the surface of the base material and the hydrogen barrier film.

5. 3. The fuel injection valve according to claim 1, wherein the base material is made of martensitic stainless steel.

6. a valve housing having a fuel passage therein; a valve body that moves within the fuel passage; a spring that biases the valve body toward a closed position; Equipped with At least one of the valve housing, the valve body, and the spring is a metal part having the hydrogen barrier film.

3. The fuel injection valve according to claim 1 or 2.

Images