Fuel injection valve and method of manufacturing the same

Abstract

Provided is a fuel injection valve comprising an injection hole-forming member in which a fuel injection hole is formed, the fuel injection valve comprising a protective coating formed on the inner wall surface of the fuel injection hole by vapor deposition.

Description

[Technical Field]

[0001] The present invention relates to a fuel injection valve and a method for manufacturing the fuel injection valve. [Background technology]

[0002] Patent Document 1 discloses a fuel injection valve that directly injects fuel into the combustion chamber of an internal combustion engine. The fuel injection valve disclosed in Patent Document 1 has a coating layer provided around the outlet opening from which fuel is injected. In Patent Document 1, the coating layer prevents coking or film formation at the valve end due to fuel adhesion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japan Special Publication No. 2003-503637 Summary of the Invention [Problem to be solved by the invention]

[0004] The coating layer (protective coating) disclosed in Patent Document 1 is formed, for example, by applying a liquid coating layer-forming material to a nozzle plate or the like and drying the material after application. The coating layer disclosed in Patent Document 1 is also formed by immersing a nozzle plate or the like in the liquid coating layer-forming material and drying the material after immersion. In this way, the coating layer for suppressing the adhesion of deposits is formed using a liquid-phase film-forming method.

[0005] Meanwhile, in recent years, there has been a demand for minute adjustments to the amount of fuel injected from a fuel injection valve (fuel injection valve). Therefore, it is necessary to accurately control the amount of fuel injected from the injection hole. However, it is difficult to uniformize the thickness of a protective coating formed using the liquid-phase film-forming method described above. The liquid forming material tends to become biased due to factors such as surface tension, resulting in an uneven thickness of the protective coating. Therefore, when a protective coating is formed on the inner wall surface of an injection hole using a liquid-phase film-forming method such as that described in Patent Document 1, the thickness of the protective coating becomes uneven, making it impossible to accurately control the injection state of the fuel injected from the injection hole.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to make it possible to control the fuel injection state of a fuel injection valve with higher accuracy. [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 having an injection hole forming member in which a fuel injection hole is formed, and adopts a configuration in which a protective coating is formed on the inner wall surface of the fuel injection hole by a vapor phase film deposition method.

[0009] A second aspect of the present invention is a method for manufacturing a fuel injection valve having an injection hole forming member in which a fuel injection hole is formed, which employs a configuration in which a protective coating is formed on the inner wall surface of the fuel injection hole by a vapor phase film deposition method. [Effects of the Invention]

[0010] According to the present invention, a protective coating formed by a vapor phase deposition method is provided on the inner wall surface of a fuel injection hole. Such a protective coating formed by a vapor phase deposition method has a more uniform film thickness than a protective coating formed by a liquid phase deposition method. This makes it possible to accurately control the injection state of fuel injected from the protective coating. Therefore, according to the present invention, it is possible to more accurately manage the injection state of fuel from a fuel injection valve. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a fuel injection valve according to a first embodiment of the present invention. [Figure 2] 1 is a schematic enlarged cross-sectional view including a valve seat member provided in a fuel injection valve according to a first embodiment of the present invention. [Figure 3] 2 is a schematic diagram of a valve seat member provided in the fuel injection valve according to the first embodiment of the present invention, as viewed from below in FIG. 1. FIG. [Figure 4] 3 is a schematic diagram showing a state in which a protective coating is formed by plasma-induced chemical vapor deposition in the manufacturing method of the fuel injection valve according to the first embodiment of the present invention. FIG. [Figure 5] FIG. 6 is a schematic enlarged cross-sectional view including a valve seat member provided in a fuel injection valve according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a schematic enlarged cross-sectional view including a valve seat member provided in a fuel injection valve according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a schematic view showing a state in which a protective coating is formed by plasma-induced chemical vapor deposition in a manufacturing method of a fuel injection valve according to a fourth embodiment of the present invention. [Figure 8] FIG. 10 is a schematic view showing a state in which a protective coating is formed by plasma-induced chemical vapor deposition in a manufacturing method of a fuel injection valve according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel injection valve and a method for manufacturing a fuel injection valve according to the present invention will now be described with reference to the drawings.

[0013] (First embodiment) 1 is a schematic diagram showing the general configuration of a fuel injection valve 1 according to this embodiment. The fuel injection valve 1 according to this embodiment is driven by an electromagnetic valve drive device (not shown) and injects fuel into an internal combustion engine. The fuel injection valve 1 and the electromagnetic valve drive device are mounted on a vehicle.

[0014] The fuel injection valve 1 is an electromagnetic valve (solenoid valve) that injects fuel into an internal combustion engine such as a gasoline engine or a diesel engine mounted on a vehicle. FIG. 1 is a schematic configuration diagram of the fuel injection valve 1. As shown in FIG. 1, the fuel injection valve 1 includes a fixed core 2, a valve seat member 3 (an injection hole forming member), a solenoid coil 4, a needle 5, a valve body 6, a retainer 7, a lower stopper 8, a valve body biasing spring 9, a movable core 10, and a movable core biasing spring 11. In this embodiment, the fixed core 2, the valve seat member 3, and the solenoid coil 4 are fixed members. The needle 5, the valve body 6, the retainer 7, the lower stopper 8, the valve body biasing spring 9, the movable core 10, and the movable core biasing spring 11 are movable members.

[0015] The fixed core 2 is a cylindrical member, and is fixed to a housing (not shown) of the fuel injection valve 1. The fixed core 2 is made of a magnetic material. The valve seat member 3 is fixed to the housing of the fuel injection valve 1. The valve seat member 3 has a plurality of fuel injection holes 12. The fuel injection holes 12 are holes through which fuel is injected, and are closed when the valve body 6 is seated on the valve seat member 3, and are opened when the valve body 6 is separated from the valve seat member 3.

[0016] The solenoid coil 4 is formed by winding an electric wire in a circular shape. The solenoid coil 4 is arranged concentrically with the fixed core 2. The solenoid coil 4 is electrically connected to the electromagnetic valve drive device. When current is applied from the electromagnetic valve drive device, the solenoid coil 4 forms a magnetic path including the fixed core 2 and the movable core 10.

[0017] The needle 5 is a long rod member extending along the central axis of the fixed core 2. The needle 5 is moved in the axial direction of the central axis of the fixed core 2 (extension direction of the needle 5) by an attractive force generated by a magnetic path including the fixed core 2 and the movable core 10.

[0018] There is no particular limitation on the installation posture of the fuel injection valve 1. However, in the following description, the direction in which the movable core 10 moves due to the above-mentioned attractive force in the axial direction of the central axis of the fixed core 2 will be referred to as "upward," and the direction opposite to the direction in which the movable core 10 moves due to the above-mentioned attractive force will be referred to as "downward."

[0019] The valve element 6 is formed at the lower tip of the needle 5. The valve element 6 closes the fuel injection hole 12 by seating on the valve seat member 3, and opens the fuel injection hole 12 by moving away from the valve seat member 3. The retainer 7 includes a guide member 7a and a flange 7b. The guide member 7a is a cylindrical member fixed to the upper tip of the needle 5. The flange 7b is formed at the end of the upper guide member 7a so as to protrude in the radial direction of the needle 5. The lower end face of the flange 7b is the abutment surface with the movable core biasing spring 11. The upper end face of the flange 7b is the abutment surface with the valve element biasing spring 9.

[0020] The lower stopper 8 is a cylindrical member fixed to the needle 5 between the valve seat member 3 and the guide member 7a. The upper end face of the lower stopper 8 is the contact surface with the movable core 10.

[0021] The valve element biasing spring 9 is a compression coil spring housed inside the fixed core 2, and is interposed between the inner wall surface of the housing and the flange 7b. The valve element biasing spring 9 biases the valve element 6 downward. That is, when the solenoid coil 4 is not energized, the biasing force of the valve element biasing spring 9 causes the valve element 6 to abut against the valve seat member 3.

[0022] The movable core 10 is disposed between the guide member 7a and the lower stopper 8. The movable core 10 is a cylindrical member and is provided coaxially with the needle 5. A through-hole through which the needle 5 is inserted is formed in the center of the movable core 10, and the movable core 10 is movable in the direction in which the needle 5 extends. The upper end face of the movable core 10 is an abutment surface with the fixed core 2 and the movable core biasing spring 11. On the other hand, the lower end face of the movable core 10 is an abutment surface with the lower stopper 8. The movable core 10 is formed from a magnetic material.

[0023] The movable core biasing spring 11 is a compression coil spring interposed between the flange 7b and the movable core 10. The movable core biasing spring 11 biases the movable core 10 downward. That is, when the solenoid coil 4 is not supplied with power, the movable core 10 is brought into contact with the lower stopper 8 by the biasing force of the movable core biasing spring 11.

[0024] FIG. 2 is a schematic enlarged cross-sectional view including the valve seat member 3. FIG. 3 is a schematic view of the valve seat member 3 as seen from below in FIG. 1. As shown in these figures, the valve seat member 3 is a substantially cylindrical member. A valve element 6 is movably housed inside the valve seat member 3. The surface of the valve seat member 3 exposed to the outside is referred to as the outer surface 3a. The surface of the valve seat member 3 facing the space in which the valve element 6 is housed is referred to as the inner surface 3b.

[0025] 2, the fuel injection valve 1 of this embodiment has a plurality of fuel injection holes 12 for injecting fuel formed in the valve seat member 3. Each fuel injection hole 12 is formed penetrating from the inner surface 3b to the outer surface 3a of the valve seat member 3. Furthermore, fuel passes through each fuel injection hole 12 from the inner surface 3b side toward the outer surface 3a side of the valve seat member 3, and is injected to the outside of the fuel injection valve 1.

[0026] Such a fuel injection hole 12 has an outlet opening 12a that opens to the outer surface 3a of the valve seat member 3 and an inlet opening 12b that opens to the inner surface 3b of the valve seat member 3. In other words, fuel flows into the fuel injection hole 12 from the inlet opening 12b and is injected out of the fuel injection hole 12 from the outlet opening 12a.

[0027] 2, each fuel injection hole 12 has a large diameter portion 13 and a small diameter portion 14. The large diameter portion 13 and the small diameter portion 14 are both formed in a cylindrical shape with a circular cross section, and are arranged so that their axes are connected in a straight line.

[0028] The large diameter portion 13 has a larger diameter than the small diameter portion 14, and is located closer to the outer surface 3a of the valve seat member 3 than the small diameter portion 14. The end face of the large diameter portion 13 opposite to the end face connected to the small diameter portion 14 opens to the outer surface 3a of the valve seat member 3, and forms the above-mentioned outlet opening 12a.

[0029] The small diameter portion 14 has a smaller diameter than the large diameter portion 13, and is located closer to the inner surface 3b of the valve seat member 3 than the large diameter portion 13. The end face of the small diameter portion 14 opposite to the end face connected to the large diameter portion 13 opens to the inner surface 3b of the valve seat member 3, and forms the inlet opening 12b described above.

[0030] That is, in this embodiment, each fuel injection hole 12 has a large diameter portion 13 having a circular cross section and provided with an outlet opening 12a that opens to the outer surface 3a of the valve seat member 3, and a small diameter portion 14 having a circular cross section and provided with an inlet opening 12b that opens to the inner surface 3b of the valve seat member 3.

[0031] An inner wall surface 15 of each fuel injection hole 12 is formed by the inner wall surface of the large diameter portion 13 and the inner wall surface of the small diameter portion 14. Furthermore, inside each fuel injection hole 12, a corner portion 16 is formed where the inner wall surface of the large diameter portion 13 and the inner wall surface of the small diameter portion 14 are connected.

[0032] The fuel injection valve 1 of this embodiment is also provided with a protective coating 20. As shown in Fig. 2, this protective coating 20 is provided so as to cover the inner wall surface 15 of the fuel injection hole 12 and the outer surface 3a of the valve seat member 3. In other words, the fuel injection valve 1 of this embodiment is provided with the protective coating 20 formed on the inner wall surface 15 of the fuel injection hole 12.

[0033] In this embodiment, the protective coating 20 is not formed on the inner surface 3b of the valve seat member 3. That is, in this embodiment, the protective coating 20 is formed so as to avoid the inner surface 3b of the valve seat member 3.

[0034] This protective coating 20 contains fluorine, carbon, and silicon and is a coating designed to suppress the adhesion of deposits, which are fuel residues. In this embodiment, the protective coating 20 is formed by plasma-enhanced chemical vapor deposition (PCVD), a type of vapor deposition method. Plasma-enhanced chemical vapor deposition converts raw materials into plasma to form a carbon coating in which fluorine is also bonded to silicon. In such a coating, silicon and fluorine form strong covalent bonds, preventing the bonding of fuel components and suppressing deposit adhesion, while also preventing fluorine from being desorbed from the coating. Preventing fluorine from being desorbed from the coating inhibits the fluorine on the coating surface from substituting fuel components. As a result, fuel components can be prevented from bonding to the coating surface, which would increase the affinity between the coating and the fuel components. Furthermore, preventing the affinity between the coating and the fuel components from increasing reduces the deterioration of the oil repellency of the coating, thereby reducing the amount of fuel residue that causes deposit adhesion. This suppresses deposit adhesion.

[0035] The protective coating 20 formed by plasma-induced chemical vapor deposition can have a thickness controllable on the order of μm. In this embodiment, the protective coating 20 is formed to a thickness of 10 μm or less with an in-plane variation in thickness of 1 μm or less. In the method of spraying a liquid material or the method of immersing the valve seat member 3 in a liquid material, the liquid material tends to be unevenly distributed on the inner wall surface 15 of the fuel injection hole 12 due to the influence of surface tension, etc., making it impossible to form a coating with a uniform thickness.

[0036] For example, with the spray injection method or immersion method, the film thickness at the corners 16 formed inside the fuel injection hole 12 is likely to be greater than the film thickness at other locations. Furthermore, with the spray injection method or immersion method, the film thickness at the corners formed at the boundary between the outer surface 3a of the valve seat member 3 and the inner wall surface 15 of the fuel injection hole 12 is likely to be greater than the film thickness at other locations. In contrast, the protective coating 20 of this embodiment is formed by a vapor-phase film deposition method in which a vapor-phase material is deposited, and therefore the film thickness is more uniform than when formed by a liquid-phase film deposition method.

[0037] If the thickness of the protective coating 20 is non-uniform, it is not possible to control the shape of the opening of the fuel injection hole 12 after the film is formed, and it is not possible to accurately control the flow rate and spray shape of the fuel injected from the fuel injection hole 12 (the shape of the injected fuel when it spreads). On the other hand, if the thickness of the protective coating 20 is uniform, it is possible to accurately control the shape of the opening of the fuel injection hole 12 after the film is formed. This makes it possible to accurately control the flow rate and spray shape of the fuel injected from the fuel injection hole 12. Because the protective coating 20 of this embodiment has a uniform thickness, it is possible to accurately control the flow rate and spray shape of the fuel injected from the fuel injection hole 12.

[0038] Furthermore, as described above, the protective coating 20 formed by plasma-enhanced chemical vapor deposition prevents fluorine from being desorbed, which makes it possible to prevent the flow rate and spray pattern of the fuel injected from the fuel injection holes 12 from changing over the long term.

[0039] The fuel injection valve 1 as described above injects fuel when an electromagnetic valve driving device (not shown) supplies electricity to the solenoid coil 4. For example, the fuel injection valve 1 performs full-lift injection or half-lift injection.

[0040] Full lift injection is a fuel injection in which, for each fuel injection, the movable core 10 of the fuel injection valve 1 is moved until it abuts against the fixed core 2. That is, in full lift injection, the movable core 10 is moved to the maximum position within its movable range.

[0041] Half-lift injection is a type of fuel injection in which the movable core 10 of the fuel injection valve 1 is not moved until it abuts against the fixed core 2 during one fuel injection. In other words, in half-lift injection, the movable core 10 is not moved to the maximum position within its movable range. In this type of half-lift injection, the position of the movable core 10 changes over time in a parabolic curve, so it is also called ballistic injection. Note that in half-lift injection, the maximum displacement position of the movable core 10 is not limited to half the maximum position of the movable core 10 in full-lift injection.

[0042] When the solenoid coil 4 is not energized, the biasing force of the valve body biasing spring 9 causes the valve body 6 to close the flow path leading to the fuel injection hole 12. Therefore, when the solenoid coil 4 is not energized, fuel is not injected from the fuel injection hole 12.

[0043] On the other hand, when the solenoid coil 4 is energized and the movable core 10 moves toward the fixed core 2, the flow path that was blocked by the valve body 6 is opened and fuel is supplied to the fuel injection hole 12. As a result, fuel is injected from the fuel injection hole 12. The fuel is injected from the fuel injection hole 12 while the flow path leading to the fuel injection hole 12 is open.

[0044] The manufacturing method of such a fuel injection valve 1 includes a step of forming a protective coating 20 on the outer surface 3a of the valve seat member 3 and the inner wall surface 15 of the fuel injection hole 12. The protective coating 20 is formed by plasma-induced chemical vapor deposition as described above. That is, in this embodiment, the protective coating 20 is formed by a vapor deposition method.

[0045] 4 is a schematic diagram showing the formation of a protective coating 20 by plasma-induced chemical vapor deposition. As shown in this figure, the valve seat member 3 is housed inside a reaction vessel 100 where plasma is generated. At this time, the valve seat member 3 is arranged so that the outer surface 3a faces the plasma generation region R. The valve seat member 3 is placed on a pedestal 120, for example, as shown in FIG. 4.

[0046] The inside of the reaction vessel 100 is evacuated, and a raw material gas is supplied and then energized to generate plasma inside the reaction vessel 100. This decomposes and activates the raw material gas, causing a chemical reaction between the outer surface 3a of the valve seat member 3 and the inner wall surface 15 of the fuel injection hole 12, thereby forming the protective coating 20.

[0047] In this embodiment, the method of forming the protective coating 20 by plasma-induced chemical vapor deposition has been described. However, the method of forming the protective coating is not limited to this. For example, the protective coating can also be formed by physical vapor deposition (vacuum deposition or sputtering). The protective coating 20 can also be formed by chemical vapor deposition methods other than plasma-induced chemical vapor deposition. For example, chemical vapor deposition methods other than plasma-induced chemical vapor deposition include thermal chemical vapor deposition, photochemical vapor deposition, atmospheric pressure chemical vapor deposition, and reduced pressure chemical vapor deposition.

[0048] The fuel injection valve 1 of this embodiment as described above includes the valve seat member 3 in which the fuel injection hole 12 is formed. The fuel injection valve 1 of this embodiment also includes a protective coating 20 formed on the inner wall surface 15 of the fuel injection hole 12 by a vapor phase film deposition method.

[0049] In the fuel injection valve 1 of this embodiment, a protective coating 20 formed by a vapor phase film deposition method is provided on the inner wall surface 15 of the fuel injection hole 12. The protective coating 20 formed by such a vapor phase film deposition method has a more uniform film thickness than a protective coating 20 formed by a liquid phase film deposition method. This makes it possible to accurately control the injection state of the fuel injected from the protective coating 20. Therefore, the fuel injection valve 1 of this embodiment makes it possible to more accurately manage the injection state of the fuel in the fuel injection valve 1.

[0050] Furthermore, in the fuel injection valve 1 of this embodiment, the protective coating 20 is a deposit-preventing coating that contains fluorine, carbon, and silicon and suppresses the adhesion of deposits. Therefore, the fuel injection valve 1 of this embodiment can suppress the adhesion of deposits to the inner wall surface 15 of the fuel injection hole 12.

[0051] Furthermore, in the fuel injection valve 1 of this embodiment, the protective coating 20 is formed by plasma-induced chemical vapor deposition, and has a film thickness of 10 μm or less with an in-plane variation of the film thickness of 1 μm or less. With the fuel injection valve 1 of this embodiment, since the film thickness of the protective coating 20 is 10 μm or less, it is possible to suppress a reduction in the opening area of ​​the fuel injection hole 12 due to the formation of the protective coating 20. Furthermore, since the in-plane variation of the protective coating 20 is within 1 μm, the film thickness of the protective coating 20 is made uniform. This makes it possible to accurately control the injection amount and spray shape of the fuel injected from the fuel injection hole 12.

[0052] Furthermore, in the fuel injection valve 1 of this embodiment, the protective coating 20 is formed up to the outer surface 3a of the valve seat member 3 where the outlet opening 12a of the fuel injection hole 12 is opened. Therefore, according to the fuel injection valve 1 of this embodiment, the protective coating 20 can also provide a function to the outer surface 3a of the valve seat member 3. The protective coating 20 of this embodiment suppresses the adhesion of deposits as described above. Therefore, according to the fuel injection valve 1 of this embodiment, the protective coating 20 provided up to the outer surface 3a of the valve seat member 3 can suppress the adhesion of deposits to the outer surface 3a of the valve seat member 3.

[0053] In the fuel injection valve 1 of this embodiment, the fuel injection hole 12 has a large diameter portion 13 and a small diameter portion 14. The large diameter portion 13 is a portion having a circular cross section and provided with an outlet opening 12a that opens to the outer surface of the valve seat member 3. The small diameter portion 14 is a portion having a circular cross section with a smaller diameter than the large diameter portion 13 and provided with an inlet opening 12b that opens to the inner surface of the valve seat member 3.

[0054] With such a fuel injection hole 12, it is possible to appropriately adjust the fuel spray shape and fuel injection amount compared to a fuel injection hole with a constant cross-sectional shape. In the fuel injection valve 1 of this embodiment, the protective coating 20 is formed by a vapor-phase film deposition method, and therefore the protective coating 20 is formed with a uniform film thickness at the corners 16 located inside the fuel injection hole 12, as described above. In other words, with the fuel injection valve 1 of this embodiment, even if the corners 16 are provided inside the fuel injection hole 12 by forming the large diameter portion 13 and the small diameter portion 14, it is possible to prevent the protective coating 20 from becoming thicker at the corners 16. Therefore, with the fuel injection valve 1 of this embodiment, it is possible to inject fuel from the fuel injection hole 12 with a predetermined injection amount and spray shape, even if the shape of the fuel injection hole 12 is complex.

[0055] Furthermore, in the fuel injection valve 1 of this embodiment, the protective coating 20 is formed so as to avoid the inner surface 3b of the valve seat member 3. According to the fuel injection valve 1 of this embodiment, it is not necessary to form the protective coating 20 on the inner surface 3b of the valve seat member 3. Therefore, when forming the protective coating 20, it is not necessary to change the position of the valve seat member 3, and the protective coating 20 can be easily formed.

[0056] The manufacturing method of the fuel injection valve 1 of this embodiment is a manufacturing method of the fuel injection valve 1 including the valve seat member 3 having the fuel injection hole 12 formed therein. In the manufacturing method of the fuel injection valve 1 of this embodiment, the protective coating 20 is formed on the inner wall surface 15 of the fuel injection hole 12 by a vapor phase film deposition method.

[0057] According to the manufacturing method of the fuel injection valve 1 of this embodiment, the protective coating 20 is formed by a vapor phase film deposition method on the inner wall surface 15 of the fuel injection hole 12. The protective coating 20 formed by such a vapor phase film deposition method has a more uniform film thickness than the protective coating 20 formed by a liquid phase film deposition method. This makes it possible to accurately control the injection state of the fuel injected from the protective coating 20. Therefore, according to the manufacturing method of the fuel injection valve 1 of this embodiment, it becomes possible to more accurately control the injection state of the fuel in the fuel injection valve 1.

[0058] Furthermore, in the manufacturing method of the fuel injection valve 1 of this embodiment, the vapor deposition method is a plasma-induced chemical vapor deposition method. According to the fuel injection valve 1 of this embodiment, the film thickness of the protective coating 20 can be set to 10 μm or less, and the in-plane variation of the protective coating 20 can be set to 1 μm or less. By setting the film thickness of the protective coating 20 to 10 μm or less, it is possible to suppress a decrease in the opening area of ​​the fuel injection hole 12 caused by forming the protective coating 20. Furthermore, by setting the in-plane variation of the protective coating 20 to 1 μm or less, the film thickness of the protective coating 20 can be made more uniform. This makes it possible to accurately control the injection amount and spray shape of the fuel injected from the fuel injection hole 12.

[0059] In this embodiment, the protective coating 20 is described as a deposit-preventing coating that can suppress the adhesion of deposits. However, the present invention is not limited to this. For example, a protective coating having other functions may be formed. For example, it is also possible to form a heat-resistant protective coating or a scratch-resistant protective coating. Even when forming a protective coating with such functions, forming it by a vapor deposition method makes it possible to make the thickness of the protective coating uniform.

[0060] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to Fig. 5. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0061] 5 is a schematic enlarged cross-sectional view including the valve seat member 3 of the fuel injection valve 1A of this embodiment. As shown in this figure, in the fuel injection valve 1A of this embodiment, the protective coating 20 is provided only on the inner wall surface 15 of the fuel injection hole 12. In other words, in the fuel injection valve 1A of this embodiment, the protective coating 20 is not provided on the outer surface 3a of the valve seat member 3 on which the protective coating 20 is provided in the fuel injection valve 1 of the first embodiment.

[0062] When manufacturing such a fuel injection valve 1A, for example, the protective coating 20 is formed by plasma-induced chemical vapor deposition with a mask on the outer surface 3a of the valve seat member 3. Thereafter, the mask is removed, so that the protective coating 20 can be formed only on the inner wall surface 15 of the fuel injection hole 12.

[0063] Like the fuel injection valve 1 of the first embodiment, the fuel injection valve 1A of this embodiment has a protective coating 20 formed on the inner wall surface 15 of the fuel injection hole 12 by a vapor phase film deposition method. The protective coating 20 formed by such a vapor phase film deposition method has a more uniform film thickness than the protective coating 20 formed by a liquid phase film deposition method. This makes it possible to accurately control the injection state of the fuel injected from the protective coating 20. Therefore, the fuel injection valve 1A of this embodiment makes it possible to more accurately manage the injection state of the fuel in the fuel injection valve 1.

[0064] Furthermore, in the manufacturing method of the fuel injection valve 1A of this embodiment, similar to the manufacturing method of the fuel injection valve 1 of the first embodiment, a protective coating 20 formed by a vapor phase film deposition method is provided on the inner wall surface 15 of the fuel injection hole 12. The protective coating 20 formed by such a vapor phase film deposition method has a more uniform film thickness than the protective coating 20 formed by a liquid phase film deposition method. This makes it possible to accurately control the injection state of the fuel injected from the protective coating 20. Therefore, according to the manufacturing method of the fuel injection valve 1A of this embodiment, it becomes possible to more accurately control the injection state of the fuel in the fuel injection valve 1.

[0065] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Fig. 6. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0066] 6 is a schematic enlarged cross-sectional view including a valve seat member 31 and a nozzle plate 32 provided in a fuel injection valve 1B of this embodiment. As shown in this drawing, the fuel injection valve 1B of this embodiment includes a valve seat member 31 and a nozzle plate 32 (injection hole forming member) instead of the valve seat member 3 of the first embodiment.

[0067] The valve seat member 31 is fixed to the housing of the fuel injection valve 1B. The valve seat member 31 accommodates a valve element 6 (not shown in FIG. 6) therein. An internal flow path 31a that is opened and closed by the valve element 6 is formed inside the valve seat member 31. The internal flow path 31a is open to the nozzle plate 32, and the open end is closed by the nozzle plate 32.

[0068] The nozzle plate 32 is a plate-shaped member provided with the fuel injection holes 12. The surface of the nozzle plate 32 exposed to the outside is referred to as the outer surface 32a. The surface of the nozzle plate 32 facing the space in which the valve body 6 is housed is referred to as the inner surface 32b.

[0069] 6, the fuel injection valve 1B of this embodiment has a plurality of fuel injection holes 12 formed in a nozzle plate 32. In this embodiment, each fuel injection hole 12 is formed penetrating from the inner surface 32b to the outer surface 32a of the nozzle plate 32. Furthermore, fuel passes through each fuel injection hole 12 from the inner surface 32b side toward the outer surface 32a side of the valve seat member 3, and is injected to the outside of the fuel injection valve 1.

[0070] Each of the fuel injection holes 12 has an outlet opening 12 a that opens in the outer surface 32 a of the nozzle plate 32 and an inlet opening 12 b that opens in the inner surface 32 b of the nozzle plate 32 .

[0071] 6, the protective coating 20 is provided so as to cover the inner wall surface 15 of the fuel injection hole 12 and the outer surface 32a of the nozzle plate 32. In other words, the fuel injection valve 1B of this embodiment has the protective coating 20 formed on the inner wall surface 15 of the fuel injection hole 12.

[0072] In this embodiment, the protective coating 20 is not formed on the inner surface 32b of the nozzle plate 32. That is, in this embodiment, the protective coating 20 is formed so as to avoid the inner surface 32b of the nozzle plate 32. Furthermore, in this embodiment, in addition to the inner surface 32b of the nozzle plate 32, the protective coating 20 is not provided on the inner wall surface (tapered surface shown in FIG. 6 ) of the valve seat member 31 either. The inner wall surface of the valve seat member 31 serves as the abutting surface for the valve disc 6. By not forming the protective coating 20 on such a abutting surface of the valve disc 6, it is possible to prevent the protective coating 20 from reducing the sealing performance between the valve disc 6 and the valve seat member 31.

[0073] The manufacturing method of such a fuel injection valve 1B includes a step of forming a protective coating 20 on the outer surface 32a of the nozzle plate 32 and the inner wall surface 15 of the fuel injection hole 12. When forming the protective coating 20, the nozzle plate 32 is placed inside the reaction vessel 100 where plasma is generated. At this time, the nozzle plate 32 is positioned so that the outer surface 32a of the nozzle plate 32 faces the plasma generation region R.

[0074] The fuel injection valve 1B of this embodiment as described above includes a nozzle plate 32 in which the fuel injection holes 12 are formed. Similarly to the fuel injection valve 1 of the first embodiment, the fuel injection valve 1B of this embodiment also includes a protective coating 20 formed on the inner wall surface 15 of the fuel injection hole 12 by a vapor phase film deposition method.

[0075] In the fuel injection valve 1B of this embodiment, a protective coating 20 formed by a vapor phase film deposition method is provided on the inner wall surface 15 of the fuel injection hole 12. The protective coating 20 formed by such a vapor phase film deposition method has a more uniform film thickness than the protective coating 20 formed by a liquid phase film deposition method. This makes it possible to accurately control the injection state of the fuel injected from the protective coating 20. Therefore, the fuel injection valve 1B of this embodiment makes it possible to more accurately manage the injection state of the fuel in the fuel injection valve 1.

[0076] Furthermore, according to the manufacturing method of the fuel injection valve 1B of this embodiment, the protective coating 20 is formed by a vapor phase film deposition method on the inner wall surface 15 of the fuel injection hole 12. The protective coating 20 formed by such a vapor phase film deposition method has a more uniform film thickness than the protective coating 20 formed by a liquid phase film deposition method. This makes it possible to accurately control the injection state of the fuel injected from the protective coating 20. Therefore, according to the manufacturing method of the fuel injection valve 1B of this embodiment, it becomes possible to more accurately control the injection state of the fuel in the fuel injection valve 1.

[0077] In this embodiment, the configuration has been described in which the protective coating 20 is provided not only on the inner wall surface 15 of the fuel injection hole 12 but also on the outer surface 32a of the nozzle plate 32. However, the present invention is not limited to this. It is also possible to adopt a configuration in which the protective coating 20 is provided only on the inner wall surface 15 of the fuel injection hole 12, and the protective coating 20 is not provided on the outer surface 32a of the nozzle plate 32.

[0078] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to Fig. 7. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0079] 7 is a schematic diagram illustrating a manufacturing method of a fuel injection valve according to this embodiment. As shown in this figure, in this embodiment, the valve seat member 3 is housed inside a reaction vessel 100 in which plasma is generated. At this time, the valve seat member 3 is arranged so that the outer surface 3a faces the plasma generation region R. Furthermore, an insulator 110 is arranged on the inner surface 3b side of the valve seat member 3. Thereafter, the inside of the reaction vessel 100 is evacuated, a raw material gas is supplied, and electricity is applied to generate plasma inside the reaction vessel 100. In this way, by arranging the insulator 110 on the inner surface 3b side of the valve seat member 3, it is possible to make the thickness of the protective coating 20 10 μm or less.

[0080] As shown in FIG. 8, the thickness of the protective coating 20 can be reduced to 10 μm or less by not placing the insulator 110 but by providing an opening 121 in the base 120 that supports the valve seat member 3 so that the inside of the valve seat member 3 is not sealed.

[0081] 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.

[0082] The above embodiment can also be described as follows, for example:

[0083] (Appendix 1) A fuel injection valve including an injection hole forming member in which a fuel injection hole is formed, The fuel injection valve has a protective coating formed on the inner wall surface of the fuel injection hole by a vapor phase film deposition method.

[0084] (Appendix 2) The protective coating is It is a deposit-preventing coating that contains fluorine, carbon, and silicon to prevent deposits from adhering. 10. A fuel injection valve as described in appended claim 1.

[0085] (Appendix 3) The protective coating is Formed by plasma-induced chemical vapor deposition, the film thickness is 10 μm or less, and the in-plane variation of the film thickness is within 1 μm. 3. A fuel injection valve according to claim 1 or 2.

[0086] (Appendix 4) The protective coating is The outlet opening of the fuel injection hole is formed on the outer surface of the injection hole forming member. 4. A fuel injection valve according to any one of claims 1 to 3.

[0087] (Appendix 5) The fuel injection hole is a large diameter portion having a circular cross section and provided with an outlet opening that opens to an outer surface of the injection hole forming member; an inlet end that opens onto the inner surface of the injection hole forming member and a small diameter portion that is circular in cross section and has a diameter smaller than that of the large diameter portion; have 5. A fuel injection valve according to any one of claims 1 to 4.

[0088] (Appendix 6) The protective coating is The injection hole forming member is formed so as to avoid the inner surface thereof. 6. A fuel injection valve according to any one of appendices 1 to 5.

[0089] (Appendix 7) A method of manufacturing a fuel injection valve including an injection hole forming member having a fuel injection hole formed therein, comprising: A method for manufacturing a fuel injection valve, in which a protective coating is formed on the inner wall surface of the fuel injection hole by a vapor phase film deposition method.

[0090] (Appendix 8) 8. The method for manufacturing a fuel injection valve according to claim 7, wherein the vapor deposition method is a plasma-induced chemical vapor deposition method.

[0091] (Appendix 9) The plasma-induced chemical vapor deposition method includes: an outer surface of the injection hole forming member, on which the outlet opening of the fuel injection hole is opened, facing a plasma formation region; An insulator is disposed on the inner surface side of the injection hole forming member where the inlet end of the fuel injection hole is opened. 9. A method for manufacturing a fuel injection valve according to claim 8.

[0092] (Appendix 10) The plasma-induced chemical vapor deposition method includes: an outer surface of the injection hole forming member, on which the outlet opening of the fuel injection hole is opened, facing a plasma formation region; The injection hole forming member is placed on a base provided with an opening. 9. A method for manufacturing a fuel injection valve according to claim 8. [Explanation of symbols]

[0093] 1 fuel injection valve 1A fuel injection valve 1B fuel injection valve 2 fixed core 3 Valve seat material 3a outer surface 3b Inner surface 4 solenoid coils 5 needles 6 Valve body 7 Retainer 7a Guide member 7b flange 8 Lower stopper 9 Valve body biasing spring 10 moving core 11 Movable core bias spring 12 Fuel injection hole 12a Exit opening 12b Inlet opening 13 Large diameter section 14 Small diameter section 15 Inner wall surface 16 Corner 20 Protective coating 31 Valve seat member 31a Internal flow path 32 Nozzle plate 32a outer surface 32b Inner surface 100 reaction vessels 110 Insulator 120 pedestal 121 Aperture R Plasma formation region

Claims

1. A fuel injection hole forming member is provided with a plurality of fuel injection holes formed through from an inner surface that abuts against a valve body to an outer surface, The solenoid coil is energized by the electromagnetic valve drive unit to perform full-lift or half-lift injection. A fuel injection valve that injects fuel into an internal combustion engine, A protective coating formed by a vapor deposition method is provided, the protective coating is provided on the outer surface between openings of the plurality of fuel injection holes and on inner wall surfaces of the fuel injection holes, avoiding the inner surface; The protective coating has a thickness of 10 μm or less and is formed with an in-plane variation in thickness of 1 μm or less. Fuel injection valve.

2. The protective coating is It is a deposit-preventing coating that contains fluorine, carbon, and silicon to prevent deposits from adhering.

2. The fuel injection valve according to claim 1.

3. The protective coating is The outlet opening of the fuel injection hole is formed on the outer surface of the injection hole forming member.

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

4. The fuel injection hole is a large diameter portion having a circular cross section and provided with an outlet opening that opens to an outer surface of the injection hole forming member; an inlet end that opens onto the inner surface of the injection hole forming member and a small diameter portion that has a circular cross section and a diameter smaller than that of the large diameter portion; have 3. A fuel injection valve according to claim 1 or 2.

5. The protective coating is The injection hole forming member is formed so as to avoid the inner surface thereof.

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

6. A fuel injection hole forming member is provided with a plurality of fuel injection holes formed through from an inner surface that abuts against the valve body to an outer surface, The solenoid coil is energized by the electromagnetic valve drive unit to perform full-lift or half-lift injection. A method for manufacturing a fuel injection valve that injects fuel into an internal combustion engine, comprising: A protective coating is formed by a vapor deposition method with an insulator disposed on the inner surface side of the injection hole forming member where the inlet end of the fuel injection hole is opened, so that the protective coating is formed between the openings of the plurality of fuel injection holes on the outer surface and on the inner wall surface of each of the fuel injection holes, with a film thickness of 10 μm or less and an in-plane variation of the film thickness within 1 μm. A method for manufacturing a fuel injection valve.

7. 7. The method for manufacturing a fuel injection valve according to claim 6, wherein the vapor deposition method is a plasma-induced chemical vapor deposition method.

8. The plasma-induced chemical vapor deposition method includes: an outer surface of the injection hole forming member, on which the outlet opening of the fuel injection hole is opened, facing a plasma formation region; The injection hole forming member is placed on a base provided with an opening. The method for manufacturing a fuel injection valve according to claim 7.

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