Fuel injector

Abstract

A fuel injector for directly introducing a fuel into a combustion chamber of an internal combustion engine is provided. The fuel injector comprises a nozzle body comprising an outer nozzle body surface, an inner nozzle body surface, and a plurality of main discharge orifices. The fuel injector further comprises a valve comprising a valve seat and a valve member. At least a portion of an outer valve member surface of the valve member and a portion of the inner nozzle body surface define a fuel cavity therebetween. The fuel injector has at least one thermal mitigation feature comprising an orifice axis of each main discharge orifice does not intersect with a central longitudinal axis of the valve member and / or a thermal barrier coating disposed on at least the portion of the outer valve member surface and the portion of the inner nozzle body surface defining the fuel cavity.

Description

FUEL INJECTORTechnical Field

[0001] The present application relates to a fuel injector and an internal combustion engine comprising the fuel injector.Background

[0002] Gaseous fuels (e.g., hydrogen) are gaining acceptance as a fuel for internal combustion engines. Such internal combustion engines typically require an ignition source to ignite the gaseous fuel that is directly injected into a combustion chamber of the internal combustion engine through nozzle orifices of a fuel injector that communicate directly with the combustion chamber. The gaseous fuel may be injected through the nozzle orifices upon lifting of a gas needle within the fuel injector. A liquid fuel (e.g., diesel) may be used as the ignition source for the gaseous fuel. In such cases, a small amount of the liquid fuel typically injected into the combustion chamber auto-ignites due to a heat of compression, producing a pressure and a temperature environment in the combustion chamber suitable for igniting the gaseous fuel.

[0003] Fuel injectors of current internal combustion engines utilizing the gaseous fuels have encountered failure during engine operation. Surface erosion was observed in the gas needle of the fuel injectors adjacent to the nozzle orifices. Such surface erosion may be due to a combustion flame of the burnt gaseous fuel travelling back into the fuel injector via the nozzle orifices since flame speeds of gaseous fuels (e.g., hydrogen) are generally greater than liquid fuels. Gaseous fuels also produce higher temperatures when ignited as compared to liquid fuels. The combustion flame may impinge on gas needle surfaces, thereby causing higher surface temperatures on the gas needle surfaces. Excess temperatures may weaken a material of the gas needle, thereby causing surface erosion and making them susceptible to failure, which may be catastrophic for the internal combustion engine.

[0004] The state of the art is therefore lacking in techniques for preventing surface erosion of components of fuel injectors exposed to combustion flames and hot gases. The present disclosure provides techniques for prevention of overheating of components of fuel injectors exposed to combustion flames and hot gases, thereby mitigating surface erosion of such components.Summary

[0005] An improved fuel injector for directly introducing a fuel into a combustion chamber of an internal combustion engine comprises a nozzle body mountable in the internal combustion engine and extending at least partially into the combustion chamber. The nozzle body comprises a nozzle tip disposed in contact with the combustion chamber, an outer nozzle body surface at least partially in contact with the combustion chamber, an inner nozzle body surface opposite to the outer nozzle body surface, and a plurality of main discharge orifices angularly separated from each other. Each main discharge orifice from the plurality of main discharge orifices extends through the nozzle body from the inner nozzle body surface to the outer nozzle body surface along a respective orifice axis. The fuel injector further comprises a valve comprising a valve seat formed on the inner nozzle body surface and a valve member disposed within the nozzle body. The valve member is movable relative to the nozzle body along a central longitudinal axis of the valve member to open or close the valve in cooperation with the valve seat. The valve member comprises an outer valve member surface facing the inner nozzle body surface. At least a portion of the outer valve member surface and a portion of the inner nozzle body surface define a fuel cavity therebetween, such that the fuel cavity is disposed adjacent to and downstream from the valve seat and extends towards the nozzle tip. The fuel cavity is configured to receive the fuel therein. Each main discharge orifice is disposed in fluid communication with the fuel cavity to receive the fuel from the fuel cavity and inject the fuel directly into the combustion chamber. The fuel injector has at least one thermal mitigation feature comprising: the orifice axis of each main discharge orifice does not intersect with the central longitudinal axis of the valve member, and / or a thermal barrier coating disposed on at least the portion of the outer valve member surface and the portion of the inner nozzle body surface defining the fuel cavity.

[0006] An improved internal combustion engine comprises a cylinder, a cylinder head disposed on the cylinder, a piston movable within the cylinder, and a combustion chamber defined by the cylinder, the cylinder head, and the piston. The internal combustion engine further comprises a fuel injector for directly introducing a fuel into the combustion chamber. The fuel injector is mountable in the cylinder head. The fuel injector comprises a nozzle body extending at least partially into the combustion chamber. The nozzle body comprises a nozzle tip disposed in contact with the combustion chamber, an outer nozzle body surface at least partially in contact with the combustion chamber, an inner nozzle body surface opposite to the outer nozzle body surface, and a plurality of main discharge orifices angularly separated fromeach other. Each main discharge orifice from the plurality of main discharge orifices extends through the nozzle body from the inner nozzle body surface to the outer nozzle body surface along a respective orifice axis. The fuel injector further comprises a valve comprising a valve seat formed on the inner nozzle body surface and a valve member disposed within the nozzle body. The valve member is movable relative to the nozzle body along a central longitudinal axis of the valve member to open or close the valve in cooperation with the valve seat. The valve member comprises an outer valve member surface facing the inner nozzle body surface. At least a portion of the outer valve member surface and a portion of the inner nozzle body surface define a fuel cavity therebetween, such that the fuel cavity is disposed adjacent to and downstream from the valve seat and extends towards the nozzle tip. The fuel cavity is configured to receive the fuel therein. Each main discharge orifice is disposed in fluid communication with the fuel cavity to receive the fuel from the fuel cavity and inject the fuel directly into the combustion chamber. The fuel injector has at least one thermal mitigation feature comprising: the orifice axis of each main discharge orifice does not intersect with the central longitudinal axis of the valve member, and / or a thermal barrier coating disposed on at least the portion of the outer valve member surface and the portion of the inner nozzle body surface defining the fuel cavity.Brief Description of the Drawings

[0007] FIG. 1 is a schematic view of a fuel system for an internal combustion engine, according to an embodiment of the present disclosure;

[0008] FIG. 2 is a partial schematic sectional view of the internal combustion engine, according to an embodiment of the present disclosure;

[0009] FIG. 3 A is a partial schematic cross-sectional view of a fuel injector of the internal combustion engine, according to an embodiment of the present disclosure;

[0010] FIG. 3B is an enlarged view of a portion of the fuel injector shown in FIG. 3 A, according to an embodiment of the present disclosure;

[0011] FIG. 4A is a schematic sectional view of the fuel injector taken along a section line B-B’ shown in FIG. 3 A, according to an embodiment of the present disclosure;

[0012] FIG. 4B is an enlarged view of a portion of the fuel injector shown in FIG. 4 A, according to an embodiment of the present disclosure;

[0013] FIG. 5 is a partial schematic cross-sectional view of the fuel injector, according to another embodiment of the present disclosure; and

[0014] FIG. 6 is a partial schematic cross-sectional view of the fuel injector, according to yet another embodiment of the present disclosure.Detailed Description

[0015] Referring to FIG. 1, there is shown a fuel system 100 for an internal combustion engine 200, according to an embodiment of the present disclosure. The internal combustion engine 200 may be utilized in a vehicle, and may also be employed in marine, locomotive, mine haul, power generation, or stationary applications. In some embodiments, the internal combustion engine 200 may be a light-duty engine, a medium-duty engine, or a high horsepower (HHP) engine. The term “internal combustion engine,” as used herein, refers to any type of internal combustion engine, such as two- and four-stroke reciprocating piston engines and rotary engines (e.g., Wankel-type engines) having one or more cylinders or combustion chambers.

[0016] The internal combustion engine 200 is capable of being fueled by a gaseous fuel and / or a liquid fuel. The gaseous fuel may serve as a main fuel for the internal combustion engine 200. As used herein, the term "gaseous fuel" may refer to any fuel in a gas state / phase at a standard temperature and pressure. In some embodiments, the gaseous fuel may be selected from the group consisting of natural gas, hydrogen, propane, ethane, butane, methane, and mixtures thereof.

[0017] The liquid fuel is stored in a liquid storage vessel 112. A pumping apparatus 110 pressurizes the liquid fuel stored in the liquid storage vessel 112 and delivers the pressurized liquid fuel to a fuel pressure bias apparatus 120. In some embodiments, the pumping apparatus 110 may include a transfer pump located within the liquid storage vessel 112, an inlet metering valve, and a common rail pump, in addition to other fuel system components known to those skilled in the technology.

[0018] In some embodiments, the gaseous fuel is stored in a cryogenic storage vessel 132. A pumping apparatus 130 pressurizes the gaseous fuel from the cryogenic storage vessel 132 and delivers the gaseous fuel to the fuel pressure bias apparatus 120 through a heat exchange apparatus 134 where an enthalpy of the gaseous fuel is increased. The gaseous fuel is stored in a liquefied phase in the cryogenic storage vessel 132, such that the pumping apparatus 130 is a cryogenic pumping apparatus, and the gaseous fuel changes from the liquified state to either a gaseous state or a supercritical state between the cryogenic storage vessel 132 and downstream of the heat exchange apparatus 134. Although the pumping apparatus 130 and the heat exchange apparatus 134 are illustrated external to the cryogenic storage vessel 132, the pumping apparatus 130 alone or in combination with the heat exchange apparatus 134 may also be located inside the cryogenic storage vessel 132, in whole or in part, as would be known by those familiar with the technology.

[0019] The heat exchange apparatus 134 employs an engine coolant, fluidly communicated from and to the internal combustion engine 200 through conduits 136 and 138, respectively, as a heat exchange medium. A shut-off valve 140 is employed to separate the heat exchange apparatus 134 from the downstream fuel system when the internal combustion engine 200 is shut down. An accumulator 150 stores a predetermined volume of the pressurized and vaporized gaseous fuel as a buffer against fuel demand from the internal combustion engine 200. In some embodiments, the accumulator 150 may be a vessel or an appropriately sized piping.

[0020] In some embodiments, the gaseous fuel may be stored as a compressed gas in a pressure cylinder (not shown) and delivered to the downstream fuel system, particularly to the fuel pressure bias apparatus 120, through a pressure regulator (not shown), and when a pressure of the gaseous fuel in the pressure cylinder drops below a predetermined threshold, a compressor (not shown) may be employed to pressurize the gaseous fuel from the pressure cylinder before delivering the gaseous fuel to the pressure regulator.

[0021] The fuel pressure bias apparatus 120 is employed to keep a pressure of the liquid fuel in a liquid fuel rail 114 within a predetermined range of a pressure of the gaseous fuel in a gaseous fuel rail 116. This is needed for proper operation of a fuel injector 210 fluidly connected with the liquid fuel rail 114 and the gaseous fuel rail 116. Although only one fuel injector 210 is illustrated, there may be a plurality of fuel injectors 210 in other embodiments.An electronic controller 160 is operatively connected with the pumping apparatuses 110 and 130, the shut-off valve 140, and the fuel injector 210 to command their operation.

[0022] In some embodiments, the fuel injector 210 is a dual fuel injector. In such embodiments, the fuel injector 210 is operative to separately and independently inject the liquid fuel and the gaseous fuel into a combustion chamber 208 (shown in FIG. 2) of the internal combustion engine 200. In some embodiments, the fuel injector 210 may employ the liquid fuel as a hydraulic fluid for actuating the fuel injector 210, and accordingly the pressure bias between the liquid fuel and the gaseous fuel is maintained within a predetermined range to operate the fuel injector 210.

[0023] Referring to FIG. 2, there is shown a partial schematic sectional view of the internal combustion engine 200. Some conventional elements of the internal combustion engine 200 are not shown for simplicity and clarity purposes. The fuel injector 210 is shown schematically for the purpose of illustration.

[0024] The internal combustion engine 200 comprises a cylindrical surface 202a in an engine block 202b forming a bore in the shape of a cylinder 202. The internal combustion engine 200 further comprises a cylinder head 204 disposed on the cylinder 202. The cylinder head 204 covers a top end of the cylinder 202. The internal combustion engine 200 further comprises a piston 206 movable within the cylinder 202. Particularly, the piston 206 is arranged to reciprocate within the cylinder 202. The internal combustion engine 200 further comprises the combustion chamber 208 defined by the cylinder 202, the cylinder head 204, and the piston 206.

[0025] Although only a cross-section of the internal combustion engine 200 showing the combustion chamber 208 of one cylinder (i.e., the cylinder 202) is shown in FIG. 2, those skilled in the technology will understand that the internal combustion engine 200 may comprise other components and a plurality of cylinders.

[0026] The internal combustion engine 200 further comprises the fuel injector 210 for directly introducing a fuel 212 into the combustion chamber 208. As used herein, the term “fuel injector” refers to any type of fuel injector that directly injects a fuel into a cylinder of an internal combustion engine. Although only one such fuel injector is illustrated, there can be a plurality of fuel injectors in other embodiments.

[0027] The fuel injector 210 is mountable in the cylinder head 204 of the internal combustion engine 200. In other embodiments, the fuel injector 210 may be mounted on a wall of the cylinder 202. In the illustrated embodiment, the fuel injector 210 extends at least partially through the cylinder head 204 into the combustion chamber 208. In some embodiments, the fuel 212 is the gaseous fuel. Further, in some embodiments, the gaseous fuel is hydrogen.

[0028] In some embodiments, the fuel injector 210 is a dual fuel injector that also introduces a pilot fuel 214 into the combustion chamber 208. In some embodiments, the pilot fuel 214 is the liquid fuel. In some embodiments, the pilot fuel 214 is selected from the group consisting of diesel fuel, dimethylether, bio-diesel, and / or kerosene. However, it should be understood that other liquid fuels may also be utilized that are known to those skilled in the technology. The fuel injector 210 may also include known structures for receiving the fuel 212 and the pilot fuel 214 and delivering the same to a nozzle portion of the fuel injector 210, and for housing respective actuator assemblies (not shown) for injecting the fuel 212 and the pilot fuel 214.

[0029] In some embodiments, the pilot fuel 214 may be chosen such that the pilot fuel 214 may auto-ignite in a compression ignition engine more readily than the gaseous fuel. In some embodiments, the pilot fuel 214 may be injected later in a compression stroke of the internal combustion engine 200 into a pressure and temperature environment that causes the pilot fuel 214 to auto-ignite and combust, thereby creating another pressure and temperature environment suitable for igniting the fuel 212. Thus, the pilot fuel 214 may assist with the ignition of the fuel 212. The fuel 212 may be injected before or after the pilot fuel 214. In some other cases, the fuel 212 and the pilot fuel 214 may be injected simultaneously.

[0030] Referring to FIG. 3A, there is shown a partial schematic cross-sectional view of the fuel injector 210. Specifically, FIG. 3A shows a portion of the fuel injector 210 that is disposed in the combustion chamber 208 (shown in FIG. 2) and generally referred to as a nozzle. Referring to FIGS. 2 and 3A, the fuel injector 210 comprises a nozzle body 220 mountable in the internal combustion engine 200 and extending at least partially into the combustion chamber 208. The nozzle body 220 is generally tubular in shape.

[0031] The nozzle body 220 comprises a nozzle tip 222 disposed in contact with the combustion chamber 208, an outer nozzle body surface 224 at least partially in contact with the combustion chamber 208, an inner nozzle body surface 226 opposite to the outer nozzle bodysurface 224, and a plurality of main discharge orifices 230 angularly separated from each other. Although only one main discharge orifice 230 from the plurality of main discharge orifices 230 is illustrated in the cross-sectional view shown in FIG. 3A, it is understood by those familiar with the technology that the nozzle body 220 typically includes a plurality of main discharge orifices 230. The term “plurality of main discharge orifices 230” is interchangeably used herein as “the main discharge orifices 230”.

[0032] A number of the plurality of main discharge orifices 230 may vary based on desired application attributes. Each main discharge orifice 230 from the plurality of main discharge orifices 230 extends through the nozzle body 220 from the inner nozzle body surface 226 to the outer nozzle body surface 224 along a respective orifice axis 231.

[0033] The fuel injector 210 further comprises a valve 227 comprising a valve seat 228 formed on the inner nozzle body surface 226 and a valve member 240 disposed within the nozzle body 220. The valve member 240 is movable relative to the nozzle body 220 along a central longitudinal axis 221 of the valve member 240 to open or close the valve 227 in cooperation with the valve seat 228. In some embodiments, the valve member 240 is in the form of a hollow needle or sleeve, and is actuatable for reciprocating movement within the nozzle body 220. The central longitudinal axis 221 is defined along a length of the valve member 240. The valve member 240 is substantially axisymmetric about the central longitudinal axis 221. The nozzle body 220 further defines a nozzle plane NP perpendicular to the central longitudinal axis 221.

[0034] The valve member 240 comprises an outer valve member surface 242 facing the inner nozzle body surface 226 of the nozzle body 220. At least a portion 243 (shown in FIG. 3B) of the outer valve member surface 242 and a portion 225 (shown in FIG. 3B) of the inner nozzle body surface 226 define a fuel cavity 216 therebetween, such that the fuel cavity 216 is disposed adjacent to and downstream from the valve seat 228 and extends towards the nozzle tip 222. The fuel cavity 216 is configured to receive the fuel 212 therein.

[0035] In some embodiments, the inner nozzle body surface 226 and the outer valve member surface 242 at least partially engage with each other adjacent to the nozzle tip 222 to form a sealing portion 258 extending from the nozzle tip 222 to the fuel cavity 216, such that the fuel cavity 216 is disposed between the valve seat 228 and the sealing portion 258 with respect to the central longitudinal axis 221. Although the sealing portion 258 restricts flow of fluids from thefuel cavity 216 into the combustion chamber 208, the valve member 240 can move axially with respect to the nozzle body 220 along the central longitudinal axis 221 in the vicinity of the sealing portion 258 in an unrestricted manner.

[0036] In some embodiments, the inner nozzle body surface 226 and the outer valve member surface 242 further define a plenum 218 therebetween. The plenum 218 is disposed adjacent to the valve seat 228 opposite to the fuel cavity 216. The plenum 218 fluidly communicates with the fuel cavity 216 when the valve 227 is open and the plenum 218 is fluidly blocked from the fuel cavity 216 when the valve 227 is closed. In some embodiments, the outer valve member surface 242 of valve member 240 further comprises a tapered surface portion 241 configured to at least partially engage with the valve seat 228 to close the valve 227.

[0037] FIG. 3A shows the fuel injector 210 when the valve 227 is closed. The valve 227 is open when the valve member 240 moves along the central longitudinal axis 221 away from the nozzle tip 222 and the tapered surface portion 241 of the outer valve member surface 242 disengages from the valve seat 228 of the valve 227. The fuel cavity 216 is configured to receive the fuel 212 from the plenum 218 when the valve 227 is open.

[0038] Each main discharge orifice 230 is disposed in fluid communication with the fuel cavity 216 to receive the fuel 212 from the fuel cavity 216 and inject the fuel 212 directly into the combustion chamber 208. Thus, when the valve 227 is open, the fuel 212 flows from the plenum 218, through an annular opening between the valve seat 228 and the valve member 240, and exits the nozzle body 220 through the plurality of main discharge orifices 230 into the combustion chamber 208. In some embodiments, the valve member 240 may be directly actuated by electromagnetic forces or a piezoelectric element and made to move within the nozzle body 220 along the central longitudinal axis 221. In some other embodiments, the valve member 240 may be hydraulically actuated using apparatus known by people skilled in fuel injector technology.

[0039] The fuel 212 is injected into the combustion chamber 208 via the plurality of main discharge orifices 230. The plurality of main discharge orifices 230 are angularly separated from each other about the central longitudinal axis 221. In some embodiments, the plurality of main discharge orifices 230 may be equiangularly spaced apart from each other with respect to the central longitudinal axis 221. However, in some other embodiments, the plurality of maindischarge orifices 230 may not be equally spaced apart from each other with respect to the central longitudinal axis 221.

[0040] In some embodiments, the valve member 240 of the dual fuel injector (i.e., the fuel injector 210) further comprises a valve tip 246 disposed in contact with the combustion chamber 208, an inner valve member surface 244 opposite to the outer valve member surface 242 of the valve member 240, and a plurality of pilot orifices 250 angularly separated from each other. Although only one pilot orifice 250 is representatively illustrated in the cross-sectional view shown in FIG. 3A, it is understood by those familiar with the technology that the valve member 240 typically includes a plurality of pilot orifices 250. The term “plurality of pilot orifices 250” is interchangeably used herein as “the pilot orifices 250”.

[0041] In some embodiments, a number of the plurality of pilot orifices 250 is substantially equal to the number of the plurality of main discharge orifices 230. Each pilot orifice 250 from the plurality of pilot orifices 250 extends through the valve member 240 from the inner valve member surface 244 of the valve member 240 to the outer valve member surface 242 of the valve member 240 and is configured to inject the pilot fuel 214 into the combustion chamber 208.

[0042] The dual fuel injector (i.e., the fuel injector 210) further comprises a pilot valve 247 comprising a pilot valve seat 248 formed on the inner valve member surface 244 of the valve member 240 and a pilot valve member 252 disposed within the valve member 240. In some embodiments, the pilot valve member 252 is in the form of a needle, and is actuatable for reciprocating movement within the valve member 240.

[0043] The plurality of pilot orifices 250 are angularly separated from each other about a pilot central longitudinal axis 253 of the pilot valve member 252. The pilot central longitudinal axis 253 is disposed along a length of the pilot valve member 252. The pilot valve member 252 is substantially axisymmetric about the pilot central longitudinal axis 253. In some embodiments, the pilot central longitudinal axis 253 of the pilot valve member 252 coincides with the central longitudinal axis 221 of the valve member 240. Therefore, the valve member 240 and the pilot valve member 252 are coaxial with each other.

[0044] The pilot valve member 252 is movable relative to the valve member 240 to open or close the pilot valve 247 in cooperation with the pilot valve seat 248. In some embodiments, the inner valve member surface 244 of the valve member 240 and a pilot outer surface 256 of the pilot valve member 252 define a pilot plenum 254 therebetween. The pilot plenum 254 is disposed adjacent to the pilot valve seat 248 opposite to the valve tip 246.

[0045] FIG. 3A shows the fuel injector 210 when the pilot valve 247 is closed. When the pilot valve 247 is closed, the pilot fuel 214 is blocked from the plurality of pilot orifices 250. The pilot valve 247 is open when the pilot valve member 252 moves along the pilot central longitudinal axis 253 away from the nozzle tip 222, thereby disengaging from the pilot valve seat 248 of pilot valve 247. When the pilot valve 247 is open, the pilot fuel 214 flows from the pilot plenum 254, through the pilot valve seat 248, and exits the valve member 240 through the plurality of pilot orifices 250 into the combustion chamber 208.

[0046] In some embodiments, the pilot valve member 252 may be directly actuated by electromagnetic forces or a piezoelectric element and made to move within the valve member 240 along the pilot central longitudinal axis 253. In some other embodiments, the pilot valve member 252 may be hydraulically actuated using apparatus known by people skilled in fuel injector technology. In some embodiments, the plurality of pilot orifices 250 and the plurality of main discharge orifices 230 directly introduce the pilot fuel 214 and the fuel 212, respectively, into the combustion chamber 208.

[0047] Referring to FIG. 3B, there is shown an enlarged view of a portion A (shown in FIG. 3A) of the fuel injector 210. In some embodiments, each pilot orifice 250 from the plurality of pilot orifices 250 extends through the valve member 240 along a respective pilot axis 251. In some embodiments, the pilot axis 251 of each pilot orifice 250 aligns with the orifice axis 231 of a corresponding main discharge orifice 230. In some embodiments, the pilot axis 251 of each pilot orifice 250 forms a pilot inclination angle PA relative to the central longitudinal axis 221 that is substantially equal to a main inclination angle MA formed by the orifice axis 231 of the corresponding main discharge orifice 230 relative to the central longitudinal axis 221.

[0048] In some embodiments, a combustion of the fuel 212 in the combustion chamber 208 (shown in FIG. 2) is configured to generate a flame 238 that travels back through each maindischarge orifice 230 to the fuel cavity 216 as indicated by an arrow 211. The flame 238 is shown schematically in FIG. 3B for the purpose of illustration.

[0049] The fuel injector 210 has at least one thermal mitigation feature 260 comprising a thermal barrier coating 262 (indicated by the shaded area in FIG. 3B) disposed on at least the portion 243 of the outer valve member surface 242 and the portion 225 of the inner nozzle body surface 226 defining the fuel cavity 216. Thus, the fuel cavity 216 is at least partially surrounded by the thermal barrier coating 262. In some embodiments, the thermal barrier coating 262 may protect at least the outer valve member surface 242 of the valve member 240 against erosion by the flame 238. Since a thickness required by the thermal barrier coating 262 is small, there would be negligible impact on a volume of the fuel cavity 216 due to presence of the thermal barrier coating 262.

[0050] As used herein, the term “thermal barrier coating” refers to those coatings that are capable of reducing heat flow to an underlying substrate. In general, thermal barrier coatings are relatively easy and inexpensive to implement. In some embodiments, the thermal barrier coating 262 may be made of any suitable material capable of preventing overheating of the components exposed to the flame 238 and hot gases. Suitable materials for the thermal barrier coating 262 may comprise metal alloys, including nickel alloys, nickel-aluminum alloys, iron-chromium- aluminum alloys, aluminum alloys with high silicon content, aluminum and bronze alloys, stainless steel, and carbon steel; and a variety of ceramic materials, including aluminum oxide, i.e., those compounds and compositions comprising AI2O3, including unhydrated and hydrated forms, various zirconias, in particular chemically phase-stabilized zirconias.

[0051] In some embodiments, coating materials may be provided as feedstock (e.g., in the form of wires or powders) and may be sprayed using any suitable coating process to form the thermal barrier coating 262. Known spray coating processes may include depositing the coatings by a thermal spray technique, e.g., plasma spraying (air (APS), vacuum (VPS), and low pressure (LPPS)), high velocity air-fuel thermal spray processes, or high velocity oxy -fuel (HVOF) thermal spray processes. However, the thermal barrier coating 262 may also be formed using other deposition processes, examples of which may include low and high pressure cold spray processes, chemical vapor deposition processes, physical vapor deposition processes, solutionplasma spray processes, suspension plasma processes, flame spray processes, and electric arc spray processes.

[0052] In some embodiments, the thermal barrier coating 262 may also form a hydrophobic and oleophobic coating that provides a non-stick type of protection. Such coatings may also inhibit an ability of deposits to stick to the fuel cavity 216 and other components of the fuel injector 210. A particularly effective category of this type of coating is fluorosilane-based coatings, since they have excellent hydrophobic and oleophobic qualities, in addition to a relatively high resistance to solvents, acids and bases, which is advantageous in gaseous and liquid fuel applications.

[0053] Each main discharge orifice 230 extends from an orifice inlet 232 disposed in fluid communication with the fuel cavity 216 and an orifice outlet 234 disposed in fluid communication with the combustion chamber 208 (shown in FIG. 2) along the orifice axis 231. When the valve 227 is open, the fuel 212 enters the main discharge orifice 230 through the orifice inlet 232 and exits the main discharge orifice 230 through the orifice outlet 234 into the combustion chamber 208. The orifice axis 231 of each main discharge orifice 230 intersects the outer valve member surface 242 of the valve member 240 at an orifice intersection point 236.

[0054] Referring to FIG. 4A, there is shown a schematic sectional view of the fuel injector 210 taken along a section line B-B’ shown in FIG. 3A. The section line B-B’ is in the nozzle plane NP (shown in FIG. 3A), and therefore the schematic sectional view of FIG. 4A is in the nozzle plane NP. The main discharge orifices 230 and the pilot orifices 250 are schematically shown by dashed lines in FIG. 4A for the purpose of illustration. In some embodiments, the pilot axis 251 of each pilot orifice 250 aligns with the orifice axis 231 of the corresponding main discharge orifice 230. Therefore, each pilot orifice 250 is substantially parallel to the corresponding main discharge orifice 230. In some embodiments, each pilot orifice 250 is configured to inject the pilot fuel 214 (shown in FIGS. 2 and 3A) between two corresponding adjacent main discharge orifices 230.

[0055] In some embodiments, the nozzle body 220 further defines a radial axis RA perpendicular to the central longitudinal axis 221 and extending radially with respect to the central longitudinal axis 221 in the nozzle plane NP. The at least one thermal mitigation feature 260 of the fuel injector 210 alternatively or additionally further comprises that the orifice axis231 of each main discharge orifice 230 does not intersect with the central longitudinal axis 221 of the valve member 240. Specifically, in the nozzle plane NP, the orifice axis 231 of each main discharge orifice 230 projected onto the nozzle plane NP is inclined to the radial axis RA extending from the orifice intersection point 236 of the corresponding main discharge orifice 230 by an inclination angle IA. The inclination angle IA may vary based on application requirements.

[0056] Referring to FIG. 4B, there is shown an enlarged view of a portion B (shown in FIG. 4A) of the fuel injector 210. Referring to FIGS. 4A and 4B, in the nozzle plane NP, a first distance DI is defined between the orifice intersection point 236 and the orifice inlet 232 along the orifice axis 231 of each main discharge orifice 230 projected onto the nozzle plane NP. Further, in the nozzle plane NP, a second distance D2 is defined between the orifice intersection point 236 of the corresponding main discharge orifice 230 and the inner nozzle body surface 226 of the nozzle body 220 along the radial axis RA. Due to the inclination angle IA, the first distance DI is greater than the second distance D2.

[0057] In some embodiments, the first distance DI is configured to increase a distance that is travelled by the flame 238 through the fuel cavity 216 as compared to the second distance D2, thereby at least partially reducing the erosion of at least the outer valve member surface 242 of the valve member 240 by the flame 238.

[0058] Referring to FIGS. 3B, 4A and 4B, it should be noted that the at least one thermal mitigation feature 260 of the fuel injector 210 comprises the orifice axis 231 of each main discharge orifice 230 does not intersect with the central longitudinal axis 221 of the valve member 240 and / or the thermal barrier coating 262 disposed on at least the portion 243 of the outer valve member surface 242 and the portion 225 of the inner nozzle body surface 226 defining the fuel cavity 216. The fuel injector 210 may selectively utilize any one of these features or both these features together. The at least one thermal mitigation feature 260 of the fuel injector 210 may prevent or mitigate the erosion of at least the outer valve member surface 242 of the valve member by the flame 238.

[0059] Referring to FIG. 5, there is shown a partial schematic cross-sectional view of a fuel injector 310, according to another embodiment of the present disclosure, wherein same components in this embodiment are referred to by same reference numerals and differencesbetween the embodiments are discussed. The fuel injector 310 is substantially similar and functionally equivalent to the fuel injector 210 shown in FIGS. 2, 3A, 3B, 4A, and 4B. However, in the embodiment shown in FIG. 5, the thermal barrier coating 262 is also disposed on other parts / portions of the fuel injector 310.

[0060] In the illustrated embodiment, each main discharge orifice 230 is defined by a nozzle wall 372 of the nozzle body 220. The nozzle wall 372 extends from the inner nozzle body surface 226 to the outer nozzle body surface 224. The thermal barrier coating 262 is further disposed on the nozzle wall 372 of each main discharge orifice 230. The outer nozzle body surface 224 comprises an upper surface portion 374 extending from each main discharge orifice 230 away from the nozzle tip 222. The thermal barrier coating 262 is further disposed on the upper surface portion 374 of the outer nozzle body surface 224. The thermal barrier coating 262 may prevent or mitigate erosion of the nozzle wall 372 and the upper surface portion 374 of the outer nozzle body surface 224 due to the flame 238 (shown in FIGS. 3B and 4 A).

[0061] Referring to FIG. 6, there is shown a partial schematic cross-sectional view of a fuel injector 410, according to yet another embodiment of the present disclosure, wherein same components in this embodiment are referred to by same reference numerals and differences between the embodiments are discussed. The fuel injector 410 is substantially similar and functionally equivalent to the fuel injector 310 shown in FIG. 5. However, in the embodiment shown in FIG. 6, the thermal barrier coating 262 may be further disposed on other parts / portions of the fuel injector 410.

[0062] In the illustrated embodiment, the outer nozzle body surface 224 comprises a lower surface portion 476 extending from each main discharge orifice 230 to the nozzle tip 222. The thermal barrier coating 262 is further disposed on the nozzle tip 222 and the lower surface portion 476 of the outer nozzle body surface 224. Moreover, the thermal barrier coating 262 is further disposed on the valve tip 246 adjacent to the nozzle tip 222. The thermal barrier coating 262 may prevent or mitigate erosion of the nozzle tip 222, the lower surface portion 476 of the outer nozzle body surface 224, and the valve tip 246 due to the flame 238 (shown in FIGS. 3B and 4 A).

[0063] Referring to FIGS. 2, 3A, 3B, 4A, 4B, 5 and 6, the at least one thermal mitigation feature 260 may reduce an impact of the flame 238 on at least the outer valve member surface242 of the valve member 240 by increasing a distance between the main discharge orifice 230 and the outer valve member surface 242 of the valve member 240. For example, the first distance DI is configured to increase the distance travelled by the flame 238 through the fuel cavity 216 as compared to the second distance D2, thereby at least partially reducing the erosion of at least the outer valve member surface 242 of the valve member 240 by the flame 238.

[0064] Alternatively, or additionally, the at least one thermal mitigation feature 260 includes the thermal barrier coating 262 that may prevent excessive heating of at least the outer valve member surface 242 of the valve member 240 that is exposed to the flame 238, thereby preventing erosion of at least the outer valve member surface 242.

[0065] In some embodiments, a pilot cavity 264 (shown in FIGS. 3A, 5 and 6) is defined by a tip of the pilot valve member 252 and a portion of the inner valve member surface 244 of the valve member 240. In some embodiments, a thermal barrier coating may also be disposed on walls of the plurality of pilot orifices 250, the tip of the pilot valve member 252, and / or the portion of the inner valve member surface 244 to protect these surfaces from other flames traveling from the combustion chamber 208 through one or more of the plurality of pilot orifices 250.

[0066] While particular elements, embodiments, and applications of the present invention have been shown and described, it will be understood, that the invention is not limited thereto since modifications can be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.

Claims

What is claimed is:

1. A fuel injector for directly introducing a fuel into a combustion chamber of an internal combustion engine, the fuel injector comprising: a nozzle body mountable in the internal combustion engine and extending at least partially into the combustion chamber, the nozzle body comprising a nozzle tip disposed in contact with the combustion chamber, an outer nozzle body surface at least partially in contact with the combustion chamber, an inner nozzle body surface opposite to the outer nozzle body surface, and a plurality of main discharge orifices angularly separated from each other, each main discharge orifice from the plurality of main discharge orifices extending through the nozzle body from the inner nozzle body surface to the outer nozzle body surface along a respective orifice axis; and a valve comprising a valve seat formed on the inner nozzle body surface and a valve member disposed within the nozzle body, wherein the valve member is movable relative to the nozzle body along a central longitudinal axis of the valve member to open or close the valve in cooperation with the valve seat, the valve member comprising an outer valve member surface facing the inner nozzle body surface, wherein at least a portion of the outer valve member surface and a portion of the inner nozzle body surface define a fuel cavity therebetween, such that the fuel cavity is disposed adjacent to and downstream from the valve seat and extends towards the nozzle tip, wherein the fuel cavity is configured to receive the fuel therein, and wherein each main discharge orifice is disposed in fluid communication with the fuel cavity to receive the fuel from the fuel cavity and inject the fuel directly into the combustion chamber; the fuel injector having at least one thermal mitigation feature comprising: the orifice axis of each main discharge orifice does not intersect with the central longitudinal axis of the valve member; and / or a thermal barrier coating disposed on at least the portion of the outer valve member surface and the portion of the inner nozzle body surface defining the fuel cavity.

2. The fuel injector of claim 1, wherein the nozzle body further defines a nozzle plane perpendicular to the central longitudinal axis of the valve member and a radial axis perpendicular to the central longitudinal axis and extending radially with respect to the central longitudinal axis in the nozzle plane, wherein the orifice axis of each main discharge orifice intersects the outer valve member surface of the valve member at an orifice intersection point, and wherein, in thenozzle plane, the orifice axis of each main discharge orifice projected onto the nozzle plane is inclined to the radial axis extending from the orifice intersection point of the corresponding main discharge orifice by an inclination angle.

3. The fuel injector of claim 2, wherein each main discharge orifice extends from an orifice inlet disposed in fluid communication with the fuel cavity and an orifice outlet disposed in fluid communication with the combustion chamber along the orifice axis, wherein, in the nozzle plane, a first distance is defined between the orifice intersection point and the orifice inlet along the orifice axis of each main discharge orifice projected onto the nozzle plane, wherein, in the nozzle plane, a second distance is defined between the orifice intersection point of the corresponding main discharge orifice and the inner nozzle body surface of the nozzle body along the radial axis, and wherein, due to the inclination angle, the first distance is greater than the second distance.

4. The fuel injector of claim 3, wherein a combustion of the fuel in the combustion chamber is configured to generate a flame that travels back through each main discharge orifice to the fuel cavity, and wherein the first distance is configured to increase a distance that is travelled by the flame through the fuel cavity as compared to the second distance, thereby at least partially reducing an erosion of at least the outer valve member surface of the valve member by the flame.

5. The fuel injector of claim 1, wherein a combustion of the fuel in the combustion chamber is configured to generate a flame that travels back through each main discharge orifice to the fuel cavity, and wherein the thermal barrier coating is configured to protect at least the outer valve member surface of the valve member against erosion by the flame.

6. The fuel injector of claim 1, wherein each main discharge orifice is defined by a nozzle wall of the nozzle body, the nozzle wall extending from the inner nozzle body surface to the outer nozzle body surface, and wherein the thermal barrier coating is further disposed on the nozzle wall of each main discharge orifice.

7. The fuel injector of claim 1, wherein the outer nozzle body surface comprises an upper surface portion extending from each main discharge orifice away from the nozzle tip, andwherein the thermal barrier coating is further disposed on the upper surface portion of the outer nozzle body surface.

8. The fuel injector of claim 1, wherein the outer nozzle body surface comprises a lower surface portion extending from each main discharge orifice to the nozzle tip, and wherein the thermal barrier coating is further disposed on the nozzle tip and the lower surface portion of the outer nozzle body surface.

9. The fuel injector of claim 1, wherein the inner nozzle body surface and the outer valve member surface at least partially engage with each other adjacent to the nozzle tip to form a sealing portion extending from the nozzle tip to the fuel cavity, such that the fuel cavity is disposed between the valve seat and the sealing portion with respect to the central longitudinal axis of the valve member.

10. The fuel injector of claim 1, wherein the inner nozzle body surface and the outer valve member surface further define a plenum therebetween, wherein the plenum is disposed adjacent to the valve seat opposite to the fuel cavity, wherein the plenum fluidly communicates with the fuel cavity when the valve is open and the plenum is fluidly blocked from the fuel cavity when the valve is closed, and wherein the fuel cavity is configured to receive the fuel from the plenum when the valve is open.

11. The fuel injector of claim 1, wherein the fuel injector is a dual fuel injector that also introduces a pilot fuel into the combustion chamber, the valve member of the dual fuel injector further comprising a valve tip disposed in contact with the combustion chamber, an inner valve member surface opposite to the outer valve member surface of the valve member, and a plurality of pilot orifices angularly separated from each other, wherein each pilot orifice from the plurality of pilot orifices extends through the valve member from the inner valve member surface of the valve member to the outer valve member surface of the valve member and is configured to inject the pilot fuel into the combustion chamber, wherein the dual fuel injector further comprises a pilot valve comprising a pilot valve seat formed on the inner valve member surface of the valve member and a pilot valve member disposed within the valve member, wherein the pilot valve member is movable relative to the valve member to open or close the pilot valve in cooperationwith the pilot valve seat, and wherein the plurality of pilot orifices are angularly separated from each other about a pilot central longitudinal axis of the pilot valve member.

12. The fuel injector of claim 11, wherein a number of the plurality of pilot orifices is substantially equal to a number of the plurality of main discharge orifices.

13. The fuel injector of claim 11, wherein the pilot central longitudinal axis of the pilot valve member coincides with the central longitudinal axis of the valve member, wherein each pilot orifice from the plurality of pilot orifices extends through the valve member along a respective pilot axis, and wherein the pilot axis of each pilot orifice forms a pilot inclination angle relative to the central longitudinal axis that is substantially equal to a main inclination angle formed by the orifice axis of a corresponding main discharge orifice relative to the central longitudinal axis.

14. The fuel injector of claim 13, wherein the pilot axis of each pilot orifice aligns with the orifice axis of the corresponding main discharge orifice.

15. The fuel injector of claim 14, wherein each pilot orifice is configured to inject the pilot fuel between two corresponding adjacent main discharge orifices.

16. The fuel injector of claim 11, wherein the thermal barrier coating is further disposed on the valve tip adjacent to the nozzle tip.

17. The fuel injector of claim 11, wherein the pilot fuel is a liquid fuel.

18. The fuel injector of any one of claims 11-17, wherein the thermal barrier coating is further disposed on at least one of a pilot cavity, a pilot valve member, and / or a portion of the inner valve member surface.

19. The fuel injector of any one of claims 1-18, wherein the fuel is a gaseous fuel.

20. The fuel injector of claim 19, wherein the gaseous fuel is hydrogen.

21. An internal combustion engine comprising:a cylinder; a cylinder head disposed on the cylinder; a piston movable within the cylinder; a combustion chamber defined by the cylinder, the cylinder head, and the piston; and a fuel injector for directly introducing a fuel into the combustion chamber, the fuel injector mountable in the cylinder head, the fuel injector comprising: a nozzle body extending at least partially into the combustion chamber, the nozzle body comprising a nozzle tip disposed in contact with the combustion chamber, an outer nozzle body surface at least partially in contact with the combustion chamber, an inner nozzle body surface opposite to the outer nozzle body surface, and a plurality of main discharge orifices angularly separated from each other, each main discharge orifice from the plurality of main discharge orifices extending through the nozzle body from the inner nozzle body surface to the outer nozzle body surface along a respective orifice axis; and a valve comprising a valve seat formed on the inner nozzle body surface and a valve member disposed within the nozzle body, wherein the valve member is movable relative to the nozzle body along a central longitudinal axis of the valve member to open or close the valve in cooperation with the valve seat, the valve member comprising an outer valve member surface facing the inner nozzle body surface of the nozzle body, wherein at least a portion of the outer valve member surface and a portion of the inner nozzle body surface define a fuel cavity therebetween, such that the fuel cavity is disposed adjacent to and downstream from the valve seat and extends towards the nozzle tip, wherein the fuel cavity is configured to receive the fuel therein, and wherein each main discharge orifice is disposed in fluid communication with the fuel cavity to receive the fuel from the fuel cavity and inject the fuel into the combustion chamber; the fuel injector having at least one thermal mitigation feature comprising: the orifice axis of each main discharge orifice does not intersect with the central longitudinal axis of the valve member; and / or a thermal barrier coating disposed on at least the portion of the outer valve member surface and the portion of the inner nozzle body surface defining the fuel cavity.

22. The internal combustion engine of claim 21, wherein the nozzle body further defines a nozzle plane perpendicular to the central longitudinal axis of the valve member and a radial axis perpendicular to the central longitudinal axis and extending radially with respect to the centrallongitudinal axis in the nozzle plane, wherein the orifice axis of each main discharge orifice intersects the outer valve member surface of the valve member at an orifice intersection point, and wherein, in the nozzle plane, the orifice axis of each main discharge orifice projected onto the nozzle plane is inclined to the radial axis extending from the orifice intersection point of the corresponding main discharge orifice by an inclination angle.

23. The internal combustion engine of claim 22, wherein each main discharge orifice extends from an orifice inlet disposed in fluid communication with the fuel cavity and an orifice outlet disposed in fluid communication with the combustion chamber along the orifice axis, wherein, in the nozzle plane, a first distance is defined between the orifice intersection point and the orifice inlet along the orifice axis of each main discharge orifice projected onto the nozzle plane, wherein, in the nozzle plane, a second distance is defined between the orifice intersection point of the corresponding main discharge orifice and the inner nozzle body surface of the nozzle body along the radial axis, and wherein, due to the inclination angle, the first distance is greater than the second distance.

24. The internal combustion engine of claim 23, wherein a combustion of the fuel in the combustion chamber is configured to generate a flame that travels back through each main discharge orifice to the fuel cavity, and wherein the first distance is configured to increase a distance that is travelled by the flame through the fuel cavity as compared to the second distance, thereby at least partially reducing an erosion of at least the outer valve member surface of the valve member by the flame.

25. The internal combustion engine of claim 21, wherein a combustion of the fuel in the combustion chamber is configured to generate a flame that travels back through each main discharge orifice to the fuel cavity, and wherein the thermal barrier coating is configured to protect at least the outer valve member surface of the valve member against erosion by the flame.

26. The internal combustion engine of claim 21, wherein each main discharge orifice is defined by a nozzle wall of the nozzle body, the nozzle wall extending from the inner nozzle body surface to the outer nozzle body surface, and wherein the thermal barrier coating is further disposed on the nozzle wall of each main discharge orifice.

27. The internal combustion engine of claim 21, wherein the outer nozzle body surface comprises an upper surface portion extending from each main discharge orifice away from the nozzle tip, and wherein the thermal barrier coating is further disposed on the upper surface portion of the outer nozzle body surface.

28. The internal combustion engine of claim 21, wherein the outer nozzle body surface comprises a lower surface portion extending from each main discharge orifice to the nozzle tip, and wherein the thermal barrier coating is further disposed on the nozzle tip and the lower surface portion of the outer nozzle body surface.

29. The internal combustion engine of claim 21, wherein the inner nozzle body surface and the outer valve member surface at least partially engage with each other adjacent to the nozzle tip to form a sealing portion extending from the nozzle tip to the fuel cavity, such that the fuel cavity is disposed between the valve seat and the sealing portion with respect to the central longitudinal axis of the valve member.

30. The internal combustion engine of claim 21, wherein the inner nozzle body surface and the outer valve member surface further define a plenum therebetween, wherein the plenum is disposed adjacent to the valve seat opposite to the fuel cavity, wherein the plenum fluidly communicates with the fuel cavity when the valve is open and the plenum is fluidly blocked from the fuel cavity when the valve is closed, and wherein the fuel cavity is configured to receive the fuel from the plenum when the valve is open.

31. The internal combustion engine of claim 21, wherein the fuel injector is a dual fuel injector that also introduces a pilot fuel into the combustion chamber, the valve member of the dual fuel injector further comprising a valve tip disposed in contact with the combustion chamber, an inner valve member surface opposite to the outer valve member surface of the valve member, and a plurality of pilot orifices angularly separated from each other, wherein each pilot orifice from the plurality of pilot orifices extends through the valve member from the inner valve member surface to the outer valve member surface and is configured to inject the pilot fuel into the combustion chamber, wherein the dual fuel injector further comprises a pilot valve comprising a pilot valve seat formed on the inner valve member surface of the valve member and a pilot valve member disposed within the valve member, wherein the pilot valve member ismovable relative to the valve member to open or close the pilot valve in cooperation with the pilot valve seat, and wherein the plurality of pilot orifices are angularly separated from each other about a pilot central longitudinal axis of the pilot valve member.

32. The internal combustion engine of claim 31, wherein a number of the plurality of pilot orifices is substantially equal to a number of the plurality of main discharge orifices.

33. The internal combustion engine of claim 31, wherein the pilot central longitudinal axis of the pilot valve member coincides with the central longitudinal axis of the valve member, wherein each pilot orifice from the plurality of pilot orifices extends through the valve member along a respective pilot axis, and wherein the pilot axis of each pilot orifice forms a pilot inclination angle relative to the central longitudinal axis that is substantially equal to a main inclination angle formed by the orifice axis of a corresponding main discharge orifice relative to the central longitudinal axis.

34. The internal combustion engine of claim 33, wherein the pilot axis of each pilot orifice aligns with the orifice axis of the corresponding main discharge orifice.

35. The internal combustion engine of claim 34, wherein each pilot orifice is configured to inject the pilot fuel between two corresponding adjacent main discharge orifices.

36. The internal combustion engine of claim 31, wherein the thermal barrier coating is further disposed on the valve tip adjacent to the nozzle tip.

37. The internal combustion engine of claim 31, wherein the pilot fuel is a liquid fuel.

38. The internal combustion engine of any one of claims 31-37, wherein the thermal barrier coating is further disposed on at least one of a pilot cavity, a pilot valve member, and / or a portion of the inner valve member surface.

39. The internal combustion engine of any one of claims 21-38, wherein the fuel is a gaseous fuel.

40. The internal combustion engine of claim 39, wherein the gaseous fuel is hydrogen.

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