RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No.

62/592,463, filed on November 30, 2017, titled“ELECTROLESS NICKEL COATING ON A FUEL INJECTOR NEEDLE,” the complete disclosure of which is expressly incorporated by reference herein.

TECHNICAL FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to a coating for a needle valve element of a fuel injector and, more particularly, to an electroless nickel plating or coating for the needle valve element.

BACKGROUND OF THE DISCLOSURE

[0003] Fuel injectors are used to supply fuel to a combustion chamber for combustion therein during operation of an engine. Depending on the quality of the fuel, temperature of combustion, and other parameters, the resultant combustion can affect various operating parameters of the engine and/or contribute to wear or other undesirable effects of combustion.

[0004] Regarding the quality of the fuel, if the fuel contains contaminants, various components of the fuel injector may begin to corrode and/or deposits of such contaminants may interfere with normal operation of the fuel injector. For example, if the fuel contains sulfate- based contaminants, such contaminants may be water-soluble and dissolve within the fuel such that they are carried through the fuel injector with the fuel. However, due to temperature changes within the fuel injector, such sulfate-based contaminants may solidify and an accumulation of sulfate deposits may occur on the needle valve element of a fuel injector and interfere with normal operation thereof.

[0005] It is known that a diamond-like carbon (“DLC”) coating may be used on a portion of a fuel injector to reduce wear on such portions. However, a wear coating, such as a DLC coating, may not have the properties necessary to reduce or minimize deposit formations from contaminants on these various portions of a fuel injector. Additionally, coatings such as a DLC coating may be expensive and too costly to use in various fuel injector applications. [0006] As such, there is a need for a coating or other mechanism to reduce the likelihood of contaminants deposits on portions of the fuel injector and, more particularly, to reduce the likelihood of accumulations of sulfate-based deposits on the needle valve element of the fuel injector.

SUMMARY OF THE DISCLOSURE

[0007] In one embodiment of the present disclosure, a fuel injector comprises an injector body having an injector cavity and a needle valve element positioned within the injector cavity. The needle valve element is configured to move relative to the injector body. At least a portion of the needle valve element includes a hydrophobic coating.

[0008] In another embodiment of the present disclosure, a fuel injector comprises an injector body having an injector cavity and a needle valve element positioned within the injector cavity. The needle valve element is configured to move relative to the injector body. At least a portion of the needle valve element includes a coating configured to form a contact angle of approximately 60-88° with water.

[0009] In a further embodiment of the present disclosure, a method of minimizing a formation of deposits on a portion of a fuel injector comprises providing a needle valve element of the fuel injector and applying a coating to a portion of the needle valve element. The coating is an electroless nickel plated coating. The method further comprises supplying fuel to the fuel injector and forming a contact angle between the coating and water in the fuel.

[0010] Advantages and features of the embodiments of this disclosure will become more apparent from the following detailed description of exemplary embodiments when viewed in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a cross-sectional view of a fuel injector of the present disclosure;

[0012] Fig. 2 is a schematic view of a needle valve element of the fuel injector of Fig. 1 including an electroless nickel coating thereon; and

[0013] Fig. 3 is a flow chart of a method of minimizing deposit formations on the needle valve element of the fuel injector of Fig. 1. DETAILED DESCRIPTION OF THE DRAWINGS

[0014] For the purposes of promoting an understanding of the principals of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. It will be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrative devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates.

[0015] Referring to Fig. 1, a fuel system for an internal combustion engine (not shown) includes one or more fuel injectors 2. The fuel system may also include a fuel pump, a fuel accumulator, valves, and other elements (not shown) which are fluidly coupled to fuel injector 2. Fuel injector 2 is configured to inject metered quantities of fuel (e.g., diesel) into a combustion chamber of the internal combustion engine in timed relation to the reciprocation of an engine piston (not shown).

[0016] As shown in Fig. 1, fuel injector 2 includes an injector body 4 which includes an injection control valve assembly 6, a nozzle module 8, an outer housing 10, and a valve housing 12. Valve housing 12 includes a valve cavity 14 for receiving injection control valve assembly 6 which is actuated by receiving a control signal from a controller (not shown) to cause nozzle module 8 to permit fuel flow into the combustion chamber of the internal combustion engine (not shown). Outer housing 10 secures injection control valve assembly 6, nozzle module 8, and other elements of fuel injector 2 in a fixed relationship. The structural and functional details of fuel injector 2 may be similar to those disclosed in U.S. Patent Nos. 5,676,114 and 7,156,368, the complete disclosures of which are expressly incorporated by reference herein.

[0017] Referring to Fig. 1, nozzle module 8 includes a nozzle housing 18 positioned in outer housing 10 and an injector cavity 16 located within nozzle housing 18. Nozzle housing 18 further includes one or more injector orifices 20 positioned at a distal end of nozzle housing 18. Injector orifice(s) 20 communicate with one end of injector cavity 16 to discharge fuel into the combustion chamber of the engine (not shown). Nozzle module 8 further includes a nozzle or needle valve element 22 positioned in one end of injector cavity 16 adjacent to injector orifice(s) 20. Needle valve element 22 is movable between an open condition which also denotes the beginning of an injection event because fuel may flow through injector orifice(s) 20 into the combustion chamber (not shown) and a closed condition which denotes the end of the injection event because fuel flow through injector orifice(s) 20 is blocked or inhibited.

[0018] Nozzle module 8 includes a needle element guide 24 which includes a proximal cap or end portion 26, a control volume plug 28, and a bias spring 66 positioned between needle valve element 22 and needle element guide 24. A control volume 30 is formed between an end portion 32 of needle valve element 22 and an interior of needle element guide 24 when needle valve element 22, needle element guide 24, and end portion 26 are mounted in injector cavity 16.

[0019] The pressure of fuel in control volume 30 determines whether needle valve element 22 is in an open condition or a closed condition, which is further determined by injection control valve assembly 6, as is further disclosed herein. When needle valve element 22 is positioned in injector cavity 16, needle element guide 24, and more specifically, end portion 26 of needle element guide 24, is positioned longitudinally between needle valve element 22 and injection control valve assembly 6.

[0020] Referring still to Fig. 1, at least one longitudinally-extending fuel delivery passage 34 extends through injection control valve assembly 6 to provide high-pressure fuel to injector cavity 16 and control volume 30. Injection control valve assembly 6 includes valve housing 12, valve cavity 14, and an injection control valve 36 positioned within valve cavity 14. Injection control valve 36 includes a control valve member 38, a flow control member, illustratively a check valve ball 40, a valve seat body 62 which includes a valve seat 64, and an actuator 42 to cause movement of check valve ball 40 between open and closed positions relative to valve seat 64.

[0021] Control valve member 38 is positioned in valve cavity 14 and moves reciprocally between an open position, permitting check valve ball 40 to move longitudinally to permit fuel flow through fuel delivery passage 34, and a closed position, where check valve ball 40 blocks fuel flow through fuel delivery passage 34. Actuator 42 includes a solenoid assembly 44 that includes a stator housing 46 having a first end 48 and a second end 50, a stator core 52, an annular coil assembly 54 positioned circumferentially in and around stator core 52, and an armature 56 operably connected to control valve member 38. Stator housing 46 includes a central aperture or core 58 extending through stator housing 46 from first end 48 to second end 50. Central aperture 58 includes a spring cavity 60 and is positioned to receive control valve member 38. Stator core 52 is positioned on stator housing 46, and in the exemplary

embodiment, stator core 52 is secured to stator housing 46.

[0022] Valve seat body 62 of injection control valve assembly 6 includes valve seat 64 and when control valve member 38 is in the closed position, check valve ball 40 rests against valve seat 64 in a closed position, blocking fuel flow through fuel delivery passage 34. When control valve member 38 is in the open position, check valve ball 40 moves longitudinally away from valve seat 64 into an open position, permitting fuel to flow through fuel delivery passage 34.

[0023] As shown in Fig. 1, when injection control valve assembly 6 is energized by the engine control system (not shown), solenoid assembly 44 is operable to move armature 56 longitudinally toward stator core 52. Movement of armature 56 causes control valve member 38 to move longitudinally away from valve seat 64, which permits control valve member 38 to move from valve seat 64, which causes fuel to flow through fuel delivery passage 34. Fuel then flows between check valve ball 40 and valve seat 64 into valve cavity 14 toward a drain (not shown) to vent pressure in control volume 30. When the pressure in control volume 30 is vented, the pressure imbalance created by the venting pressure causes needle valve element 22 to lift to the open condition, thereby uncovering or exposing injector orifices 20. Fuel is then directed toward injector orifices 20 and into the combustion chamber of the engine (not shown).

[0024] As disclosed herein, during such operation of fuel injector 2, fuel is supplied to fuel injector 2 from the fuel accumulator (not shown) and the fuel contacts various components. When the fuel is free of any contaminants, the fuel may generally pass through the various components of fuel injector 2 without causing any increased corrosion or wear to fuel injector 2. However, at times, the fuel may include various contaminants such as sulfur, which may cause corrosion of the various components of fuel injector 2 in contact with the fuel, thereby increasing the likelihood of wear and/or corrosion of various components of fuel injector 2 which may interfere with normal operation of fuel injector 2.

[0025] Referring to Figs. 2 and 3, to reduce wear and avoid contaminant deposits, a coating 80 is applied to at least a portion of needle valve element 22 of fuel injector 2. Coating 80 is generally configured to form a contact angle of approximately 60-88° with any water present in the fuel, which allows any contaminants dissolved within the water to slide over or roll off of the surface of needle valve element 22 such that deposits do not accumulate on the surface of needle valve element 22. In one embodiment, the contact angle may be approximately 62-84° with water. The thickness of coating 80 on the surface of needle valve element 22 is generally approximately 1-5 pm. In this way, coating 80 allows for a large contact angle to form between the surface of needle valve element 22 and any water within the fuel such that the water, which may contain dissolved contaminants (e.g., sulfur contaminants), easily rolls off of the surface of needle valve element 22 rather than allowing the water with contaminants to remain thereon and accumulate.

[0026] As shown in Fig. 3, an illustrative method of reducing contaminant deposits on a portion of fuel injector 2 includes applying coating 80 to a portion of needle valve element 22 in Step 100. When, in Step 102, fuel is supplied to fuel injector 2, for example diesel fuel, any water within the fuel (which may include dissolved contaminants) forms a contact angle at the surface of needle valve element 22, as shown in Step 104. As disclosed herein, the contact angle may be large (e.g., 60-88°), thereby allowing the water (with the dissolved contaminants therein) to easily roll or slide off of needle valve element 22, thereby reducing the likelihood that any water and/or contaminants within the fuel will remain and accumulate on the surface of needle valve element 22.

[0027] In various embodiments, coating 80 may be an electroless nickel plated coating in that it may be chemically or catalytically applied to the surface of needle valve element 22. For example, the electroless nickel plating process may be a non-galvanic plating process occurring within an aqueous solution without the use of any external electrical power.

[0028] The electroless nickel plated coating 80 may include an amount of phosphorous that may be as little as approximately 3 weight %, 4 weight % or 5 weight %, as high as approximately 9 weight %, 10 weight %, or 11 weight %, or within any range therebetween such as approximately 3-11 weight %, for example. The use of phosphorous in coating 80 in this weight percentage range increases the wear resistance of coating 80 such that needle valve element 22 may experience decreased wear when coating 80 is applied thereon. Additionally, the electroless plating process also increases the wear resistance of coating 80.

[0029] In some embodiments, electroless nickel plated coating 80 may also include an amount of polytetrafluoroethylene (PTFE) that may be as little as approximately 1 weight %, 2 weight % or 3 weight %, as high as approximately 10 weight %, 11 weight %, or 12 weight %, or within any range therebetween such as approximately 1-12 weight %, for example. The use of PTFE within coating 80 allows for coating to have hydrophobic properties, thereby repelling any water within the fuel and contributing to the large contact angle formed between the surface of needle valve element 22 and any water in the fuel. Therefore, the use of PTFE within coating 80 reduces the likelihood of contaminant deposits on portions of needle valve element 22. In this way, coating 80 both increases the wear resistance and the resistance to contaminant deposit formation on needle valve element 22 through the use of disclosed weight percentage of phosphorous, the electroless plating process, and the disclosed weight percentage of PTFE.

[0030] The balance of the weight percentage of coating 80 may be comprised of nickel, for example, in one embodiment, coating 80 may include approximately 78-87 weight % nickel. As such, the composition of coating 80 may be generally comprised of nickel, PTFE, and phosphorous.

[0031] It may be appreciated that coating 80 is configured to be applied to a movable component of fuel injector 2, such as needle valve element 22, and is configured to reduce corrosion and wear thereon when in contact with diesel fuel. Because coating 80 is applied to a movable component, such as needle valve element 22, coating 80 is configured to prevent sticking or other restrictions to the movement of the movable component due to wear, corrosion, and/or deposit formations which may restrict the movement of the component. In this way, coating 80 allows for normal operation of the movable components of fuel injector 2.

[0032] While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.