Cross-Reference to Related Application:

[0001] The present application claims priority to, and the benefit of the filing date of, U.S. Provisional Application Ser. No. 63/407,446 filed on September 16, 2022, which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present disclosure generally relates to cylinder head assemblies for internal combustion engines and, more particularly, to cylinder head assemblies for cooling fuel injectors and methods for servicing fuel injectors.

BACKGROUND

[0003] Operation of fuel -injected engines can require cooling fuel injectors to prevent overheating. In direct fuel injection engines, fuel injectors experience high local temperatures caused by combustion events near the fuel injector, especially at the tip of the fuel injector. An efficient manner to cool these fuel injectors involves using engine coolant, which is already circulating through various passages of the engine. Known fuel injectors for such engines keep the fuel injector separate (e.g., fluidly isolated) from the engine coolant.

[0004] In those known fuel injectors, a wall of cylinder head or other material surrounds the fuel injector and isolates the fuel injector from contact with coolant. The ability of the coolant to remove heat from the injector is thus a function of the wall thickness of the material around the injector as well as the heat transfer characteristics of the wall material that isolates the fuel injector from the coolant. More effective cooling, therefore, is inhibited by the wall material and any air gaps between the wall material and the injector. Further, when fuel flow is turned off during some operating conditions, (e.g., during cylinder deactivation), the injector tip does not experience internal cooling from the fuel flow. Therefore, further improvements in cooling of fuel injectors is needed. SUMMARY

[0005] An embodiment of the present disclosure includes a cylinder head assembly including a cylinder head and a fuel injector. The cylinder head includes at least one injector mounting bore and a coolant passage for circulation of a coolant in the cylinder head. The coolant passage intersects the injector mounting bore to form a junction at which the coolant passage is in fluid communication with the injector mounting bore. The fuel injector is positioned in the at least one injector mounting bore. The fuel injector is in sealed engagement with the cylinder head on opposite sides of the junction so that an exposed portion of the fuel injector extends through the junction and is directly exposed to contact with coolant in the coolant passage while inhibiting the coolant from flowing past the sealed engagement with the cylinder head on opposite sides of the junction.

[0006] In an embodiment, a cylinder head assembly includes a fuel injector and a cylinder head. The fuel injector has a fuel injector body extending between a first end and an opposite second end. The fuel injector body includes a first-end side adjacent the first end and a second-end side adjacent the second end, the second end of the fuel injector body including a nozzle. A first seal portion is positioned at the first-end side of the fuel injector body and a second seal portion is positioned adjacent the second-end side of the fuel injector body. The cylinder head includes an injector mounting bore and a coolant channel that intersects the injector mounting bore. The fuel injector includes an exposed portion in direct contact with a coolant that is retained in the coolant channel. A sealed engagement is formed between the cylinder head and each of the first seal portion and the second seal portion on opposite sides of the coolant passage to inhibit the coolant from flowing past the sealed engagement at the first seal portion and the second seal portion.

[0007] In an embodiment of the disclosure, a method of servicing a fuel injector of an engine is provided. The engine includes a cylinder head assembly having the fuel injector installed in an injector mounting bore a cylinder head. The cylinder head includes a coolant passage intersecting the injector mounting bore such that an exposed portion of the fuel injector is in direct contact with a coolant that is in the coolant passage. The method includes draining the coolant from the engine until the fuel injector is no longer in direct contact with the coolant in the coolant passage, and uninstalling the fuel injector from the cylinder head assembly by removing the fuel injector from the injector mounting bore after the coolant has drained. [0008] 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

[0009] FIG. l is a schematic of a vehicle system including an engine with a cylinder head assembly according to the present disclosure;

[0010] FIG. 2 is a cross-sectional, cutaway view of a cylinder head assembly with a fuel injector installed therein according to an embodiment of the present disclosure; and

[0011] FIG. 3 is a flowchart of a method for servicing a fuel injector of an engine according to an embodiment the present disclosure.

DETAILED DESCRIPTION

[0012] For the purposes of promoting an understanding of the principles of the present disclosure, reference is now made to the embodiments illustrated in the drawings, which are described below. The exemplary embodiments disclosed herein are not intended to be exhaustive or to limit the disclosure to the precise form disclosed in the following detailed description. Rather, these exemplary embodiments were chosen and described so that others skilled in the art may utilize their teachings. It is not beyond the scope of this disclosure to have a number (e.g., all) the features in a given embodiment to be used across all embodiments.

[0013] Disclosed herein are devices, systems, assemblies, and methods related to fuel injectors that improve fuel injector life and allow use of fuel injectors over a wider range of engine operations due to providing a cooler operating environment than known fuel injectors. Cooling the fuel injector involves direct contact of the engine coolant with the fuel injector and convection cooling the fuel injector (e.g., the fuel injector tip, the nozzle, or another downstream portion of the fuel injector) using coolant (e.g., engine coolant) and some additional cooling is provided by the internal flow of fuel through the fuel injector.

[0014] Referring to FIGs. 1-2, an embodiment of the present disclosure includes a cylinder head assembly 100 including a cylinder head 102 and a fuel injector 110. The cylinder head 102 includes at least one injector mounting bore 126 and a coolant passage 130 for circulation of a coolant in the cylinder head 102. Coolant passage 130 intersects injector mounting bore 126 to form a junction 134 at which coolant passage 130 is in fluid communication with injector mounting bore 126. Fuel injector 110 is positioned in injector mounting bore 126. Fuel injector 110 is in a sealed engagement with cylinder head 102 on opposite sides of junction 134 so that an exposed portion 118 of fuel injector 110 extends through junction 134 and is directly exposed to contact with coolant in coolant passage 130 while inhibiting the coolant from flowing past the sealed engagement with cylinder head 102 on opposite sides of junction 134

[0015] In an embodiment, cylinder head assembly 100 includes fuel injector 110 and cylinder head 102. Fuel injector 110 includes a fuel injector body 112 that has a first end 115 and an opposite second end 116. Fuel injector body 112 includes a first-end side 117 adjacent the first end 115 and a second-end side 119 adjacent the second end 116, the second end 116 of the fuel injector 112 including a nozzle 111. A first seal portion 141 is positioned at first-end side 117 of fuel injector body 112 and a second seal portion 143 is positioned adjacent second-end side 119 of fuel injector body 112. Cylinder head 102 includes injector mounting bore 126 and coolant channel 130 that intersecting injector mounting bore 126. Fuel injector 110 includes exposed portion 118 in direct contact with coolant that is retained in coolant channel 130. A sealed engagement is formed between cylinder head 120 and each of first seal portion 141 and second seal portion 143 on opposite sides of the coolant passage 130 to inhibit the coolant from flowing past the sealed engagement at first seal portion 141 and second seal portion 143.

[0016] In an embodiment of the disclosure, a method 300 of servicing fuel injector 110 of an engine 10 is provided. Engine 10 includes cylinder head assembly 100 having fuel injector 110 installed in an injector mounting bore 126 of cylinder head 102. Cylinder head 102 includes coolant passage 130 intersecting the injector mounting bore 126 such that exposed portion 118 of fuel injector 110 is in direct contact with a coolant that is in coolant passage 100. The method 300 includes draining the coolant from engine 10 until fuel injector 110 is no longer in direct contact with the coolant in coolant passage 130, and uninstalling fuel injector 110 from cylinder head assembly 100 by removing fuel injector 110 from injector mounting bore 126 after the coolant has drained.

[0017] As described in more detail below with reference to FIGs. 1-2, examples of the present disclosure provide direct cooling of the fuel injector 110. For instance, some such examples involve removing the cylinder head wall or other material in the cylinder head 102 that isolates the fuel injector 110 from the coolant in coolant passage 130. The allows the coolant to come into direct contact with the fuel injector body (e.g., an exposed portion 118 thereof as discussed further below) itself, and thus cools fuel injector 110 more effectively than is possible without direct contact between the fuel injector 110 and the coolant. Under these circumstances, convective heat transfer is improved because the colder coolant (relative to the fuel injector) is in direct contact with the fuel injector 110 rather than in contact with material that isolated the fuel injector from the coolant, which only indirectly cools the injector. Further, because there is more efficient cooling, the number of engine operations in which the fuel injector 110 can be employed e can be increased, e.g., to include operations where there is only pilot injections or main injection that provide a cooling fuel flow through the fuel injector 110.

[0018] FIG. 1 shows a schematic of a vehicle system 1. In an example embodiment, vehicle system 1 is operated by an operator (e.g., a driver) and is supported on a vehicle chassis (not shown), such as for a car or truck as shown. However, it shall be appreciated that a variety of different types of vehicles and non-vehicles are also contemplated by this disclosure. Non-limiting examples of vehicles include on-highway vehicles, off-highway vehicles, construction equipment, mining trucks, buses, and passenger vehicles, among others. Non-limiting examples of nonvehicles include generator sets, marine engines, mining engines, and construction engines, among others. As depicted, the vehicle system 1 includes a vehicle 3 that has a plurality of systems, such as a powertrain 5 with an integrated internal combustion engine 10 (also referred to herein as an “engine”), a transmission system 12, and a drive system 14.

[0019] Depending on desired application, the engine 10 may be provided in a variety of forms. In the illustrated embodiment, the engine 10 includes a cylinder block 16 (also referred to as an engine block) with one or more cylinders 18 that each include a combustion chamber 103 (FIG. 2) for receiving the charge flow from intake system (not shown) and a fuel flow. For example, in the depicted embodiment, the engine 10 includes four cylinders 18 in an in-line arrangement. However, the engine 10 may have any different number of cylinders 18, as well as cylinders 18 in a variety of different arrangements. In an exemplary embodiment, vehicle system 1 includes a turbocharged air intake system and an exhaust aftertreatment system 19 connected to engine 10. However, non-turbocharged systems are also contemplated.

[0020] Operatively connected to the cylinder block 16 is a cylinder head assembly 100. The cylinder head assembly 100 includes a cylinder head 102 that operatively accommodates fuel injectors, such as fuel injector 110 in FIG. 2, and spark plugs, such as spark plug 120 in FIG. 2, or other ignition devices that are used in the production of combustion events during operation of the engine 10. Although shown in a direct fuel injection arrangement, other arrangements of the fuel injector 110 (e.g., for “indirect” fuel injection) are also contemplated and within the scope of this disclosure.

[0021] During operation of the illustrated embodiment, sparks produced by the spark plugs 120 ignite fuel spray that is injected into combustion chamber 103 of the engine 10. The fuel injector(s) 110 for cylinder 18 are configured to inject metered quantities of fuel into cylinder 18 in timed relation to the reciprocation of pistons (not shown), while intake port(s) (not shown) are configured to provide the necessary fresh air to cylinder 18 for a combustion event to occur. Exhaust port(s) (not shown) are configured to allow exhaust created by the combustion event to leave cylinder 18 once exhaust piston has passed exhaust port(s) after the combustion event has occurred. Intake port(s) and exhaust port(s) are each positioned along a wall of the cylinder 18 at positions spaced apart from each other.

[0022] In example embodiments, each cylinder 18 is sized to accommodate slidable reciprocating displacement of a piston (not shown) along at least a portion of the cylinder 18 such that the piston may reciprocate between a top-dead-center position and a bottom-dead-center position. Each of the cylinders 18, its respective piston, and cylinder head 102 form a combustion chamber. Further, at least a portion of the forces generated by the slidable displacement of the piston along at least a portion of the cylinder 18 during combustion events in the combustion chamber are transmitted to a mechanical drive system. For example, the pistons are typically operably coupled to a crank shaft (not shown) of the engine 10 that converts the reciprocal movement of the pistons of the engine 10 into rotational movement.

[0023] Fuel for the engine 10 can be provided from a fuel source (not shown) and used during operation of the engine 10. For example, the engine 10 can operate using traditional fuels, such as gasoline or diesel fuel, or alternative fuels, such as hydrogen, biodiesel, natural gas, and propane. It is contemplated fuel for the engine 10 can include any fuels under development or already developed and available for production. In examples of the present disclosure, fuel injector 110 is a hydrogen fuel injector is used to spray fuel into combustion chamber 103 of a cylinder that is then ignited with spark plug 120. In some such examples employing direct fuel injection, the tip of the injector 110 protrudes into the combustion chamber 103 and is in direct contact with the combustion flame. This arrangement results in high temperatures at the tip of the fuel injector 110. The present disclosure provides efficient and effective cooling the fuel injector 110 to thereby improve its durability and expand its range of operation, even in direct injection applications.

[0024] FIG. 2 shows fuel injector 110 and spark plug 120 arranged for direct fuel injection in combustion chamber 103 of the cylinder head assembly 100. The cylinder head 100 has formed therein an injector mounting bore 126 that includes an injector mounting seat 124. The injector mounting bore 126 is arranged within the cylinder head 102 such that fuel injector 110 is installable in and engaged to cylinder head 102 so that a fuel injector body 112 of fuel injector 122 contacts the injector mounting seat 124 along an upper portion of the injector mounting bore 126.

[0025] The injector mounting bore 126 has a lower portion (e.g., below a level of the coolant in coolant passage 130) which may be referred to herein as the “lower injector bore” or “injector tip bore” or “injector sealing bore” or the like. In this regard, the fuel injector 110 can extend through the injector mounting bore 126, e.g., such that central longitudinal axes of the fuel injector 110 and the injector mounting bore 126 are coaxial. In an embodiment, portions (e.g., some or all) of fuel injector body 112 can complementarily mate with portions (e.g., some or all) of the injector mounting seat 124.

[0026] In an embodiment, the injector mounting seat 124 includes a shoulder 125 that serves as a stop for axial movement of the fuel injector 110 relative to the injector mounting seat 124 and can mate with, be sealingly engaged to, or otherwise correspond to a shoulder 113 of fuel injector body 112 of the fuel injector 110. In an embodiment, a flange seal 122 is provided between shoulder 113 and shoulder 125 to sealing engage fuel injector body 112 to cylinder head 102 in injector mounting bore 126.

[0027] Cylinder head 102 includes a coolant passage wall 132 that defines coolant passage 130. Coolant is able to be retained and circulated in coolant passage 130 to cool the cylinder head

102 and connected components. A junction 134 is formed where the coolant passage wall 132 intersects the injector mounting bore 126 such that the coolant passage 130 is in fluid communication with the injector mounting bore 126. The fuel injector 110 can be removably installed into the cylinder head 102 such that an exposed portion 118 of the fuel injector 110 extends into and is exposed to coolant that is present at the junction 134.

[0028] In the illustrated embodiment, fuel injector 110 includes fuel injector body 112 that extends between first and second ends 115, 116. First and second ends 115, 116 are located at opposing ends of the fuel injector 110. The exposed portion 118 of fuel injector 110 is positioned between first and second ends 115, 116 to form a first-end side 117 of the exposed portion 118 and a second-end side 119 of the exposed portion 118. In an example embodiment, flange seal 122 threadedly engages a barrel 123 of fuel injector body 112 and/or injector mounting seat 124 to secure barrel 123 in a compressive or abutting relationship against cylinder head 102.

[0029] A nozzle 111 of the fuel injector 110 is positioned at the second end 116 of the fuel injector body 112 and sprays fuel flowing through fuel injector 110 into the combustion chamber

103 where spark plug 120 ignites the inflowing fuel spray during a combustion event of the engine 10. The nozzle 111 can be engaged to fuel injector body 112 with a retainer sleeve, cap, fastener, integral structure, or other suitable connection arrangement. In example embodiments, nozzle 111 is a valved nozzle with for opening and closing injector orifices (not shown) thereby controlling the flow of injection fuel into the combustion chamber 103. For instance, when the nozzle 111 is in an open position, fuel may flow through injector orifices into the combustion chamber 103. When nozzle 111 is in a closed position, it blocks fuel flow through injector orifices. Nozzle 111 and the second end 116 of fuel injector body 112 will experience high temperatures, particularly in a direct injector arrangement, that benefit from cooling of these components.

[0030] As noted above, improved cooling is provided via coolant in the cylinder head 102 directly contacting exposed portion 118 of fuel injector 110. Proper sealing around the fuel injector 110 protects media (e.g., combustion gases, coolant, etc.) from entering undesired locations in the cylinder head 102. To that end, a sealed engagement is formed when fuel injector 110 is installed in cylinder head 102 (e.g., at the injector mounting seat 124). For instance, one or more seals of various types can be arranged at locations along mating surfaces of fuel injector 110 and injector mounting seat 124. Due to seals between injector mounting seat 124 and fuel injector 110, coolant may run through coolant passage 130 and come in direct contact with exposed portion 118 of fuel injector 110 without leaking into the combustion chamber 103 or other parts of the cylinder head 102

[0031] The seals 150, 152 can be the product of mechanical seals and/or fit between fuel injector 110 and the injector mounting seat 124 in the cylinder head 102. Multiple seals can be used to seal (e.g., fluidly and/or hermetically) at different locations along fuel injector body 112 to thereby inhibit media from flowing past the seals and into undesired locations in the cylinder head assembly 100. As shown, there are seals 150, 152 at each side of junction 134. Specifically, there is shown a first seal portion 141 positioned along fuel injector body 112 at first-end side 117 of exposed portion 118, and a second seal portion 143 positioned along fuel injector body 112 at second-end side 119 of exposed portion 118.

[0032] First seal portion 141 is positioned between first end 115 of fuel injector 110 and exposed portion 118. Second seal portion 143 is positioned between second end 116 of fuel injector 110 and exposed portion 118 such that the exposed portion 118 is flanked by the first and second seal portions 141, 143). Further, each of the first and second seal portions 141, 143 can include one or more seals that are sandwiched between complementary surface of the fuel injector body 112 and the injector mounting seat 124. For instance, an outer surface of fuel injector 110 can complementarily mate with or be received in an inner surface of injector mounting seat 124 along injector mounting bore 126. The fuel injector 110 is arranged within cylinder head 102 such that exposed portion 118 of fuel injector 110 comes in direct contact with the coolant in the coolant passage 130, and injector mounting bore 126 is sealed such that coolant is inhibited from flowing past the first and second seals 150, 152.

[0033] Fuel injector 110 can form a sealed engagement with cylinder head 102 at either or both sides of exposed portion 118 when fuel injector 110 is installed in cylinder head 102. First seal 150 can form a sealed engagement at the first-end side 117 (e.g., at an upper seal portion or upstream relative to injector fuel flow) of exposed portion 118 of fuel injector 110. In an embodiment, the first seal 150 is arranged in injector mounting bore 126 between the first (e.g., upper or upstream) seal portion 141 and the injector mounting seat 124. In an example embodiment, first seal 150 is a radial seal that surrounds the upper seal portion 141. A radial seal effectively seals the coolant and/or combustion gases from flowing past the seal 150 without introducing clamp load driven stress into either the cylinder head 102 or the fuel injector 110.

[0034] In addition, or in alternative, flange seal 122 is arranged between shoulder 125 of injector mounting seat 124 and a corresponding shoulder 113 of fuel injector body 112. In an embodiment, first seal 150 can be integrated into or can replace the flange seal 122, thereby serving as a self-sufficient or redundant seal for another seal placed closer to the first-end side 117 of the exposed portion 118.

[0035] In an embodiment, second seal 152 is provided to create a seal engagement at second-end side 119 (e.g., at a lower seal portion or downstream relative to injector fuel flow) of exposed portion 118 of fuel injector 110. In an embodiment, second seal 152 can be arranged in injector mounting bore 126 between second (e.g., lower or downstream) seal portion 143 and injector mounting seat 124. Because second end 116 is adjacent to combustion chamber 103, second seal 152 can be configured to both seal the coolant from coolant passage 130 and combustion gases from combustion chamber 103 from escaping along injector mounting bore 126. In an embodiment, second seal 152 can be a radial seal that does not require a mechanical press fit and reduces clamp load driven stresses in cylinder head 100 and fuel injector 110.

[0036] In an embodiment, coolant can flow from coolant passage 130 and into injector bore 126 until coolant contacts seals 150, 152 in injector mounting bore 126. In an embodiment, the exposed portion 118 is the part of fuel injector 110 that is directly connected to nozzle 111. In an embodiment, the exposed portion 118 is the only wall structure that separates an interior cavity of fuel injector 110 from coolant. In an embodiment, the plunger for fuel injector 110 resides in the cavity formed by the wall of injector 110 that forms the exposed portion 118. [0037] To create both the fluid-tight and gas-tight seal of second seal, any of the seals 150, 152 can comprise elastomer or other pliable material. Further adjustments to these seals 150, 152 can be made by suitable material selection, including based on the permeability of the fluid and its resistance to the installation site (e.g., types of coolant and fuel or gas). The portion of second seal 152 exposed to coolant can comprise a material that is resistant to degradation by the coolant, and the portion of seal 152 exposed to combustion chamber 103 can comprise a material resistant to the combustion gases.

[0038] Referring to FIG. 3, a method 300 is illustrated for servicing the fuel injector 110 of engine 10. The selected engine 10 may have cylinder head assembly 100 as described above in reference to FIG. 2. The engine 10 may comprise cylinder head 102 that includes coolant passage 130 configured to allow coolant to flow through the coolant passage 130. The fuel injector 110 may be installed such that exposed portion 118 of fuel injector 110 is in direct contact with the coolant in the coolant passage 130 of the cylinder head 102.

[0039] In order to service the fuel injector 110, in step 301 of method 300 the coolant is drained from the engine 10 until the coolant is no longer in direct contact with the fuel injector 110 in the coolant passage 130 of the cylinder head 102. Draining the coolant may also include draining the coolant until the coolant is below the cylinder head 102 of the engine 10.

[0040] After the coolant is drained from the coolant passage 130, fuel injector 110 may be uninstalled from the cylinder head 102 in step 302. To uninstall the fuel injector 110, a first seal 150 may be removed. The first seal 150 may be arranged upstream of the exposed portion 118 of the fuel injector 110 between the fuel injector 110 and the cylinder head 102. Further, a second seal 152 may be removed to uninstall the fuel injector 110. The second seal 152 may be arranged downstream of the exposed portion 118 of the fuel injector 110 between the fuel injector 110 and the cylinder head 102.

[0041] In step 303, method 300 includes reinstalling the fuel injector 110 into the cylinder head 102 to form a sealed engagement between the fuel injector 110 and the cylinder head 102. The sealed engagement refrains from imparting clamp load driven stress into the cylinder head 102 and the fuel injector 110.

[0042] It is well understood that methods that include one or more steps, the order listed is not a limitation of the claim unless there are explicit or implicit statements to the contrary in the specification or claim itself. It is also well settled that the illustrated methods are just some examples of many examples disclosed, and certain steps can be added or omitted without departing from the scope of this disclosure. Such steps can include incorporating devices, systems, or methods or components thereof as well as what is well understood, routine, and conventional in the art.

[0043] Various aspects of the present disclosure are contemplated. According to one aspect, a cylinder head assembly for an internal combustion engine is provided. The cylinder head assembly includes a cylinder head and a fuel injector. The cylinder head includes at least one injector mounting bore. The cylinder head further includes a coolant passage for circulation of a coolant in the cylinder head. The coolant passage intersects the injector mounting bore to form a junction at which the coolant passage is in fluid communication with the injector mounting bore. The fuel injector is positioned in the at least one injector mounting bore. The fuel injector is in a sealed engagement with the cylinder head on opposite sides of the junction so that an exposed portion of the fuel injector extends through the junction and is directly exposed to contact with coolant in the coolant passage while inhibiting the coolant from flowing past the sealed engagement with the cylinder head on opposite sides of the junction.

[0044] In an embodiment, the fuel injector includes a fuel injector body having a first end and an opposite second end. The exposed portion of the fuel injector is positioned between the first and second ends to form a first-end side of the fuel injector body and a second-end side of the fuel injector body on opposite sides of the exposed portion. The fuel injector includes a nozzle positioned at the second end of the fuel injector, and a first seal portion at the first-end side of the fuel injector body and a second seal portion at the second-end side of the fuel injector body. The sealed engagement is formed between the fuel injector body and the cylinder head at each of the first seal portion and the second seal portion to thereby inhibit the coolant from flowing past the sealed engagement.

[0045] In a further embodiment, the cylinder head assembly includes a first seal that is arranged to form the sealed engagement at the first-end side of the exposed portion of the fuel injector body.

[0046] In a further embodiment, the first seal is positioned in the injector mounting bore between the first seal portion and the cylinder head.

[0047] In yet a further embodiment, the first seal is a radial seal that extends around the first seal portion of the injector body. [0048] In yet a further embodiment, the first seal is a flange seal that is arranged between a shoulder of the injector mounting bore and a corresponding shoulder in the fuel injector body.

[0049] In yet a further embodiment, the cylinder head assembly includes a second seal that is arranged to form the sealed engagement at the second-end side of the exposed portion. A portion of a combustion chamber is formed by the cylinder head downstream of the injector mounting bore, and the second seal is configured to both seal the coolant from the coolant passage from entering the combustion chamber and seal combustion gases from the combustion chamber from entering the coolant passage.

[0050] In still a further embodiment, the second seal is a radial seal that extends around the second-end portion of the injector body and sealingly engages the second-end portion of the injector body and the cylinder head without clamp load driven stresses being imparted to the cylinder head and the fuel injector.

[0051] In an embodiment, the cylinder head assembly includes a radial seal that is arranged to form the sealed engagement at the second-end side of the exposed portion of the fuel injector body. In a further embodiment, a portion of a combustion chamber is formed by the cylinder head downstream of the injector mounting bore. The radial seal at the second-end side of the exposed portion of the injector body is configured to both seal the coolant from the coolant passage from entering the combustion chamber and seal combustion gases from the combustion chamber from entering the coolant passage.

[0052] In an embodiment, the fuel injector is operable to inject hydrogen fuel. In an embodiment, the cylinder head assembly includes a spark plug that is installed on the cylinder head.

[0053] According to one aspect of the disclosure, a method of servicing a fuel injector of an engine is provided. The engine includes cylinder head assembly having the fuel injector installed in an injector mounting bore a cylinder head. The cylinder head includes a coolant passage intersecting the injector mounting bore such that an exposed portion of the fuel injector is in direct contact with a coolant that is in the coolant passage. The method includes draining the coolant from the engine until the fuel injector is no longer in direct contact with the coolant in the coolant passage; and uninstalling the fuel injector from the cylinder head assembly by removing the fuel injector from the injector mounting bore after the coolant has drained. [0054] In an embodiment, draining the coolant from the engine until the coolant is no longer in direct contact with the coolant in the coolant passage of the cylinder head assembly includes draining the coolant until the coolant is below the cylinder head.

[0055] In an embodiment, the fuel injector includes a fuel injector body having a first end and an opposite second end. The first and second ends define opposing ends of the fuel injector. The exposed portion of the fuel injector is positioned between the first and second ends to form a first-end side of the fuel injector and a second-end side of the fuel injector on a side of the coolant passage opposite the first-end side. Uninstalling the fuel injector from the cylinder head assembly by removing the fuel injector from the injector mounting seat includes at least one of: removing a first seal that is arranged at the first-end side of the fuel injector body; and removing a second seal that is arranged at the second-end side of the fuel injector body.

[0056] In an embodiment, the method includes reinstalling the fuel injector into the injector mounting bore of the cylinder head in sealed engagement with the cylinder head body on opposite sides of the coolant passage without imparting clamp load driven stresses into the cylinder head body and the fuel injector.

[0057] According to another aspect, a cylinder head assembly is provided. The cylinder head assembly includes a fuel injector and a cylinder head. The fuel injector includes a fuel injector body having a first end and an opposite second end. The fuel injector body includes a first-end side adjacent the first end and a second-end side adjacent the second end, and the second end of the fuel injector includes a nozzle. A first seal portion is positioned at the first-end side of the fuel injector body and a second seal portion is positioned adjacent the second-end side of the fuel injector body. The cylinder head includes an injector mounting bore and a coolant channel that intersects the injector mounting bore. The fuel injector includes an exposed portion in direct contact with a coolant that is retained in the coolant channel. A sealed engagement is formed between the cylinder head and each of the first seal portion and the second seal portion on opposite sides of the coolant passage to inhibit the coolant from flowing past the sealed engagement at the first seal portion and the second seal portion.

[0058] In an embodiment, the cylinder head assembly includes a first seal that is arranged to form the sealed engagement at the first-end side of the fuel injector body, and a second seal that is arranged to form the sealed engagement at the second-end side of the fuel injector body. [0059] In a further embodiment, the first seal is formed as either a radial seal that surrounds the fuel injector body at the first-end side of the fuel injector body, or a flange seal between a shoulder of the fuel injector body and a corresponding shoulder of in the injector mounting bore in the cylinder head.

[0060] In a further embodiment, the second seal is a gas-tight seal between the fuel inj ector body and the cylinder head.

[0061] Throughout this disclosure, the words “distal,” “lower,” and words of similar effect correspond to portions of the fuel injector 110 that are downstream relative to other portions in terms of the flow of fuel from the fuel injector 110 to the combustion chamber 103 of engine 100, such as the injector openings or spray holes. Similarly, the words “proximal,” “upper,” and words of similar effect correspond to portions of the fuel injector 110 that are upstream of the downstream portions. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

[0062] The connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections could be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that can cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements. The scope is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone can be present in an embodiment, B alone can be present in an embodiment, C alone can be present in an embodiment, or that any combination of the elements A, B or C can be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. [0063] In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.

[0064] Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0065] 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.