INJETOR DE COMBUSTÍVEL DUPLO PARA INJETAR DOIS COMBUSTÍVEIS SEPARADOS

Abstract

According to the present invention there is provided a dual-fuel injector for injecting two separate fuels into a combustion chamber of an internal combustion engine. The dual-fuel injector comprises a nozzle body housing a dual needle valve arrangement. The dual needle valve arrangement comprises a first fuel needle valve and a second fuel needle valve, and the first fuel needle valve defines a first needle valve axis. The dual-fuel injector further comprises a first fuel control chamber defined at least in part by an upper surface of an upper end of the first fuel needle valve such that varying a first pressure in the first fuel control chamber varies the force on the upper end of the first fuel needle valve. The first fuel needle valve comprises a bore extending through the upper end of the first fuel needle valve from an aperture defined in the upper surface. Further, the second fuel needle valve is slidably received within the bore extending through the upper end of the first fuel needle valve, i.e. within the first fuel needle valve bore. The second fuel needle valve protrudes from the aperture such that an upper end of the second fuel needle valve extends above the upper end of the first fuel needle valve.

Description

1 / 30 Dual fuel injector for injecting two separate fuels. Technical field

[001] The present invention relates generally to fuel injectors and, more specifically, to a dual fuel injector for an internal combustion engine. Fundamentals

[002] Internal combustion (IC) engines are typically powered by the combustion of a fuel, such as gasoline or diesel, in a combustion chamber. New technologies have been developed to increase fuel efficiency and reduce emissions from IC engines. One such development involves the combustion of two distinct fuels within the combustion chamber of a dual-fuel engine. For example, a first fuel, such as methane gas or hydrogen, may be supplied to the combustion chamber due to its advantageous combustion or emission characteristics. A second fuel, such as gasoline or diesel, may be supplied to the combustion chamber to improve the reliability and combustion time of the first fuel.

[003] In a dual-fuel engine, the first and second fuels can be supplied to the combustion chamber in several different ways. Some examples include: mixing the two fuels with air in an intake manifold before supplying the fuel / air mixture to the combustion chamber through an intake valve; supplying air and the first fuel through the intake valve and then injecting the second fuel into the combustion chamber; or injecting each fuel into the combustion chamber using separate fuel injectors. However, each of these methods has disadvantages in terms of efficiency and / or conditioning of engine components. Petition 870250104723, dated 11 / 14 / 2025, page 6 / 44 2 / 30

[004] Dual fuel injectors, that is, single injectors that inject both the first and second fuel into the combustion chamber, were developed in an attempt to overcome these disadvantages. However, significant challenges still exist. For example, dual fuel injectors may require more auxiliary components, such as control valves, housed in a similar or identical housing envelope to that of a comparable single fuel injector. Longer and more complex hydraulic systems may be required to control the needle valves that regulate the distribution of each fuel. This can result in wave activity and delays in the hydraulic control of the needle valves, increasing response times and decreasing the consistency and reliability of fuel distribution. Thus, challenging housing constraints may ultimately result in unfavorable combustion performance.

[005] It is in this context that the present invention was conceived. Summary

[006] According to the present invention, a dual fuel injector is provided for injecting two separate fuels into a combustion chamber of an internal combustion engine. The dual fuel injector comprises a nozzle body housing a dual needle valve arrangement. The dual needle valve arrangement comprises a first fuel needle valve and a second fuel needle valve, and the first fuel needle valve defines a first needle valve shaft. The dual fuel injector further comprises a first fuel control chamber defined, at least in part, by an upper surface of an upper end of the first fuel needle valve, such that varying a first pressure in the first fuel control chamber varies the force at the upper end of the first fuel needle valve. Petition 870250104723, dated 11 / 14 / 2025, page 7 / 44 3 / 30 fuel needle. The first fuel needle valve comprises a bore extending through the upper end of the first fuel needle valve from an opening defined on the upper surface. Furthermore, the second fuel needle valve is received by sliding into the bore extending through the upper end of the first fuel needle valve, i.e., within the first bore of the fuel needle valve. The second fuel needle valve projects from the opening so that an upper end of the second fuel needle valve extends above the upper end of the first fuel needle valve.

[007] The second fuel needle valve is preferably received in a sliding manner within the first fuel needle valve bore, with a corresponding clearance fitting. The corresponding clearance fitting, i.e., the corresponding diameter, between the first fuel needle valve bore and the second fuel needle valve is preferably defined between an inner diameter of the first fuel needle valve bore and an outer diameter of the second fuel needle valve. For example, the first fuel needle valve bore and the second fuel needle valve should preferably have a diametral clearance of 2 µm to 4 µm in the corresponding clearance fitting.

[008] In some examples, the actuation of the first fuel needle valve may be hydraulically controlled by a first fuel control valve. For example, the first fuel control valve may define a first switching volume through which the first fuel control chamber may be selectively fluidly coupled to either a high-pressure fluid source or a low-pressure fluid drain. Thus, the first Petition 870250104723, dated 11 / 14 / 2025, page 8 / 44 A 4 / 30 switching volume can provide a fluid flow path between the first fuel control chamber and the high-pressure fluid source, and can provide a fluid flow path between the first fuel control chamber and the low-pressure fluid drain. Selective and fluid coupling of the first fuel control chamber to the high-pressure fluid source or the low-pressure fluid drain can vary the pressure in the first fuel control chamber and therefore can actuate the first fuel needle valve. The first fuel control chamber can be fluidly coupled to the first fuel control valve, i.e., the first switching volume, via a first control conduit. The first fuel control chamber and the first control conduit can define a first fuel control volume.

[009] In some examples, the second fuel needle valve may extend through the first fuel control chamber. Thus, the upper end of the second fuel needle valve preferably extends through the first fuel control chamber.

[0010] In some examples, the first fuel control chamber can be defined, at least in part, by an external surface of the second fuel needle valve. In this way, the fluid in the first fuel control chamber can come into contact with an external surface of the second fuel needle valve. Thus, the first fuel control chamber can be manufactured as a hollow, open space, and the second fuel needle valve can extend through the open space. Advantageously, such a configuration can facilitate the relatively simple manufacture of the first fuel control chamber.

[0011] In addition, in some examples, the first chamber of Petition 870250104723, dated 11 / 14 / 2025, page 9 / 44 5 / 30 fuel control can comprise a first central geometric axis that is coaxial with the first needle valve axis. Locating the first fuel control chamber coaxially with the first needle valve can advantageously minimize the distance between the first fuel control valve and the first fuel control chamber. Thus, the first control volume can be minimized. This reduces the risk of wave activity in the first control volume and decreases delays in the hydraulic control of the first fuel needle valve, thereby speeding up the valve response time, as well as increasing the consistency and reliability of the first fuel delivery to the combustion chamber.

[0012] In some preferred examples, the second fuel needle valve may be coaxial with the first fuel needle valve. For example, the second fuel needle valve may define a second needle valve shaft, and the second needle valve shaft may be coaxial with the first needle valve shaft. It will be recognized that the first and / or second needle valve shafts are preferably longitudinal shafts of the respective needle valve.

[0013] In some preferred examples, the first fuel control chamber may define a substantially circular perimeter. For example, the first fuel control chamber may comprise a rotationally swept volume around the first central axis. Therefore, it will be recognized that the first central axis defines the geometric center of the first fuel control chamber, in some preferred examples. In some examples, the first fuel control chamber may form a ring that extends around a portion of the second fuel needle valve.

[0014] In some preferred examples, the nozzle body may comprise distinct portions configured to perform functions. Petition 870250104723, dated 11 / 14 / 2025, p. 10 / 44 6 / 30 separate. For example, the nozzle body may comprise a lower portion configured to extend into the combustion chamber. Thus, the lower portion of the nozzle body may be formed of a material capable of withstanding the high temperatures and pressures of the combustion chamber. The nozzle body may comprise an upper portion that includes hydraulic conduits to direct fuels and hydraulic control fluids around the injector. In some examples, the upper portion of the nozzle body may also provide attachment points for connecting auxiliary components, such as control valves, to the injector.

[0015] In some examples, the nozzle body may define a needle guide portion. For example, the upper portion of the nozzle body may define the needle guide portion. The upper end of the first fuel needle valve may be received in a sliding manner in the needle guide portion. In some preferred examples, the upper end of the first fuel needle valve may be received in the needle guide portion with a corresponding clearance fitting. The corresponding clearance fitting, i.e., the corresponding diameter, between the upper end of the first fuel needle valve and the needle guide portion is preferably defined between an outer diameter of the upper end of the first fuel needle valve and an inner diameter of the needle guide portion.For example, the needle guide portion and the upper end of the first fuel needle valve should preferably have a diametrical clearance of 2 µm to 3.5 µm.

[0016] In some examples, the first fuel control chamber may be defined, at least in part, by a surface of the roof of the needle guide portion. For example, the first fuel control chamber may be defined between the upper end of the first fuel needle valve and the roof surface of the guide portion. Petition 870250104723, dated 11 / 14 / 2025, p. 11 / 44 7 / 30 needle.

[0017] In some examples, the nozzle body may comprise a bore extending from a defined opening in the roof surface of the needle guide portion. The upper end of the second fuel needle valve may be received within the bore extending from the opening in the roof surface of the needle guide portion. In some preferred examples, the upper end of the second fuel needle valve may be received in the bore with a corresponding clearance fitting. The corresponding clearance fitting, i.e., the corresponding diameter, between the upper end of the second fuel needle valve and the bore in the nozzle body is preferably defined between an outer diameter of the upper end of the second fuel needle valve and an inner diameter of the bore in the nozzle body.For example, the upper end of the second fuel needle valve and the bore should preferably have a diametral clearance of 1.5 pm to 2.5 pm.

[0018] In some examples, the dual fuel injector may additionally include a second fuel control chamber. The second fuel control chamber may be defined, at least in part, by an upper surface of the upper end of the second fuel needle valve, such that varying a second pressure in the second fuel control chamber varies the force at the upper end of the second fuel needle valve. In some examples, the second fuel control chamber may be defined, at least in part, by the nozzle body. For example, the second fuel control chamber may be defined by the hole extending from the opening defined on the roof surface of the needle guide portion of the nozzle body, in some examples.

[0019] In some examples, the actuation of the second fuel needle valve can be hydraulically controlled by a second Petition 870250104723, dated 11 / 14 / 2025, page 12 / 44 8 / 30 Fuel control valve. For example, the second fuel control valve may define a second switching volume through which the second fuel control chamber may be selectively and fluidly coupled to either a high-pressure fluid source or a low-pressure fluid drain. Thus, the second switching volume may provide a fluid flow path between the second fuel control chamber and the high-pressure fluid source, and may provide a fluid flow path between the second fuel control chamber and the low-pressure fluid drain. The selective and fluid coupling of the second fuel control chamber to the high-pressure fluid source or the low-pressure fluid drain may vary the pressure in the second fuel control chamber and therefore may actuate the second fuel needle valve.The second fuel control chamber can be fluidly coupled to the second fuel control valve, i.e., to the second switching volume, by means of a second control conduit. The second fuel control chamber and the second control conduit can define a second fuel control volume.

[0020] As described previously, the second fuel needle valve projects from the opening in the first fuel needle valve so that the upper end of the second fuel needle valve extends above the upper end of the first fuel needle valve. In some examples, particularly where the second fuel control chamber is defined, at least in part, by an upper surface of the upper end of the second fuel needle valve, the configuration of the protruding second fuel needle valve advantageously minimizes the distance between the second fuel control valve and the second fuel control chamber. Consequently, the second control volume is minimized in this Petition 870250104723, dated 11 / 14 / 2025, page 13 / 44 9 / 30 configuration. This reduces the risk of wave activity in the second control volume and decreases delays in the hydraulic control of the second fuel needle valve, thus speeding up the valve response time, as well as increasing the consistency and reliability of the second fuel delivery to the combustion chamber.

[0021] In some preferred embodiments, the second fuel control chamber may comprise a second central axis that is coaxial with the first needle valve axis. Furthermore, in some preferred embodiments, the second fuel control chamber may define a substantially circular perimeter. For example, the second fuel control chamber may comprise a volume rotationally swept around the second central axis. Thus, it will be recognized that the second central axis defines the geometric center of the second fuel control chamber in the preferred embodiments. This configuration and arrangement are further advantageous for the manufacture of the dual fuel injector and for minimizing the second control volume.

[0022] In some preferred examples, the first central shaft and / or the second central shaft may be coaxial with the second needle valve shaft. Consequently, in some preferred examples, the first and second needle valve shafts and the first and second central shafts may all be coaxial with each other. Such an arrangement may be advantageous for manufacturing and assembly, as well as for loading and wear of components in use. Furthermore, such an arrangement may further facilitate a reduction in the respective control volumes by decreasing the distance between the control valves and the control chambers.

[0023] In some preferred examples, the second fuel needle valve and the associated second fuel control chamber may hydraulically dampen the opening rate of the first fuel needle valve. For example, the second pressure in the second chamber of Petition 870250104723, dated 11 / 14 / 2025, p. 14 / 44 The 10 / 30 fuel control system can apply a closing force to the second fuel needle valve, so that the valve is held in a closed position against a second fuel valve seat portion of the first fuel needle valve, as will be described in more detail later. Thus, the second pressure can apply a force on the first fuel needle valve, via the second fuel needle valve and the second fuel valve seat portion. When opening, i.e., lifting, the first fuel needle valve, for example, by reducing the first pressure in the first fuel control chamber, if the second pressure in the second fuel control chamber is maintained, this can provide an opposing force (i.e., the closing force mentioned above) that acts against the opening of the first fuel needle valve.Consequently, this can delay the opening rate of the first fuel needle valve.

[0024] Furthermore, the opposing force provided by the second pressure and the second fuel needle valve can act in the same direction as a force from the first pressure in the first fuel control chamber, which acts to close the first fuel needle valve. This configuration can therefore accelerate the closing of the first fuel needle valve. Both the damped opening of the first fuel needle valve and the accelerated closing of the first fuel needle valve are advantageous for combustion in the engine's combustion chamber.These advantages are facilitated primarily by the arrangement of the second fuel needle valve, which projects from the first fuel needle valve so that the upper end of the second fuel needle valve extends above the upper end of the first fuel needle valve, allowing the first and second fuel needle valves to meet. Petition 870250104723, dated 11 / 14 / 2025, page 15 / 44 11 / 30 move in a substantially independent manner.

[0025] In some instances, the nozzle body may define a first fuel valve seat portion. For example, the lower portion of the nozzle body, which is configured to extend into the combustion chamber, may define the first fuel valve seat portion. The dual fuel injector may additionally comprise a first bias means configured to bias the first fuel needle valve into engagement with the first fuel valve seat portion.

[0026] In some examples, the nozzle body may define, at least in part, a first fuel accumulator volume and one or more first fuel injection outlets in fluid communication with the first fuel accumulator volume to inject the first fuel from the first fuel accumulator volume into the combustion chamber. For example, the first fuel accumulator volume may be defined, at least in part, between the first fuel needle valve and an inner surface of the nozzle body. Furthermore, the first fuel valve seat portion may define one or each first fuel injection outlet. Thus, the first bias means may bias the first fuel needle valve to close one or each first fuel injection outlet in order to interrupt fluid communication between the first fuel accumulator volume and the combustion chamber.Similarly, increased pressure in the first fuel control chamber can push the first fuel needle valve to engage with the first portion of the fuel valve seat, thus closing the first or each first fuel injection outlet. The first bias medium can advantageously accelerate the closing of the first fuel needle valve at the end of the first fuel injection. This can be beneficial for... Petition 870250104723, dated 11 / 14 / 2025, page 16 / 44 12 / 30 combustion and fuel efficiency.

[0027] In some examples, the first polarization means may be disposed around the first fuel needle valve. In some preferred examples, the first polarization means may comprise a helical spring extending around an outer surface of the first fuel needle valve. Furthermore, in some examples, the first polarization means may be situated within the first fuel accumulator volume. For example, the first polarization means may be located between the first fuel needle valve and an inner bore of the nozzle body. Thus, the first polarization means may be situated in a completely separate portion of the injector compared to the first fuel control chamber.This means that there is no need to size the first fuel control chamber to accommodate the first polarization medium, which means that the first fuel control chamber, and by extension the first fuel control volume, can be minimized, thus improving fuel distribution and combustion performance as described earlier.

[0028] In some examples, the first fuel needle valve may comprise a lobe portion, and the first bias means may abut or engage the lobe portion of the first fuel needle valve. Advantageously, the first bias means may be configured to bias the first fuel needle valve along the first needle valve axis without necessarily abutting the upper end of the first fuel needle valve. In this way, the volume of the first fuel control chamber may be minimized, which is advantageous for the reasons described above.

[0029] Petition 870250104723, dated 11 / 14 / 2025, page 17 / 44 13 / 30

[0030] In some examples, the dual fuel injector may additionally include a collar coupled to the first fuel needle valve. For example, the collar may define the protrusion portion. The first bias means may engage the collar and a portion of the nozzle body to bias the first fuel needle valve into engagement with the first fuel valve seat portion. For example, the nozzle body may comprise a seat configured to engage the first bias means. The first bias means is preferably held under compression between the collar and the nozzle body seat to bias the first fuel needle valve. In some examples, the collar may be press-fitted onto the first fuel needle valve, i.e., onto the outer surface of the first fuel needle valve.Including a collar to attach the first polarization medium can be advantageous for easier manufacturing and assembly.

[0031] As described previously, in some examples, the first fuel needle valve may define a second fuel valve seat portion. The dual fuel injector may additionally comprise a second bias means configured to bias the second fuel needle valve in engagement with the second fuel valve seat portion. Furthermore, in some examples, the second bias means may be disposed in a second fuel accumulator volume within the first fuel needle valve.

[0032] In some examples, the first fuel needle valve may set one or more secondary fuel injection outlets in fluid communication with the second fuel accumulator volume to inject the second fuel from the second fuel accumulator volume into the combustion chamber. In some examples, the second fuel valve seat portion may set one or more secondary fuel injection outlets in fluid communication with the second fuel accumulator volume to inject the second fuel from the second fuel accumulator volume into the combustion chamber. Petition 870250104723, dated 11 / 14 / 2025, page 18 / 44 14 / 30 second fuel injection outlet. Thus, the second bias means can bias the second fuel needle valve to close the second fuel injection outlet, in order to interrupt the fluid communication between the second fuel accumulator volume and the combustion chamber. Similarly, the increased pressure in the second fuel control chamber can push the second fuel needle valve to engage the second fuel valve seat portion, thus closing the second fuel injection outlet.

[0033] In some preferred embodiments, the second bias means may be disposed around the second fuel needle valve within the second fuel accumulator volume. For example, the second bias means may comprise a helical spring extending around the outer surface of the second fuel needle valve. In some embodiments, the second fuel needle valve may comprise a protrusion portion, or a collar may be coupled to the second fuel needle valve. The second bias means may engage the protrusion or collar portion and a roof surface of the second fuel accumulator volume to bias the second fuel needle valve into engagement with the second fuel valve seat portion.For example, the second polarization medium can be held under compression between the protrusion or collar portion of the second fuel needle valve and the roof surface of the second fuel accumulator volume.

[0034] Notably, in preferred examples, the second polarization means may be disposed within the second fuel accumulator volume, within the first fuel needle valve, while the second fuel control chamber may be defined, at least in part, by an upper surface of the upper end of the second valve. Petition 870250104723, dated 11 / 14 / 2025, page 19 / 44 15 / 30 of the fuel needle extending above the upper end of the first fuel needle valve. Thus, in preferred embodiments, the second bias medium may be situated in a location completely separate from the second fuel control chamber. The second fuel control chamber therefore need not be sized to accommodate the second bias medium, and the volume of the second fuel control chamber may therefore be minimized.

[0035] In some preferred examples, the first fuel may be a gaseous fuel. For example, the first fuel may be methane gas or hydrogen. Additionally or alternatively, the second fuel may be a liquid fuel. For example, the second fuel may be gasoline or diesel.

[0036] In some examples, the dual fuel injector may additionally comprise an annular hydraulic seal gallery extending around the outer surface of the first fuel needle valve. The annular hydraulic seal gallery may be fluidly coupled to a high-pressure fluid source. In some examples, the annular hydraulic seal gallery may be fluidly coupled to at least one of the first switching volume and / or the second switching volume, such that the respective switching volume is fluidly coupled to the high-pressure fluid source via the seal gallery. Thus, the control chamber or chambers may be fed via the seal gallery in some examples.

[0037] In some examples, the first fuel control valve may be a three-way valve. The first switching volume may have a diameter of less than 5 mm, preferably less than 3 mm, and most preferably less than 1.5 mm. Additionally or alternatively, in some examples, the second fuel control valve may be a three-way valve. The second volume of Petition 870250104723, dated 11 / 14 / 2025, p. 20 / 44 16 / 30 switching can have a diameter of less than 5 mm, preferably less than 3 mm and, more preferably, less than 1.5 mm.

[0038] In some examples, the first fuel control valve may comprise a first piston configured to move along a first control valve axis to selectively and fluidly couple the first fuel control chamber to the high-pressure fluid source or the low-pressure fluid drain. Thus, the first piston may be situated in the first switching volume. The first fuel control valve is preferably configured so that the first piston can be moved selectively along the first control valve axis between a first position and a second position.The first fuel control valve is preferably configured so that, in the first position, the first piston is configured to facilitate one of two actions: a) fluidly coupling the first fuel control chamber to the high-pressure fluid source and fluidly disconnecting (i.e., blocking fluid communication between) the first fuel control chamber and the low-pressure fluid drain, or b) fluidly coupling the first fuel control chamber to the low-pressure fluid drain and fluidly disconnecting the first fuel control chamber and the high-pressure fluid source.The first fuel control valve is preferably configured so that, in the second position, the first piston is configured to facilitate one of two: a) smooth coupling of the first fuel control chamber to the high-pressure fluid source and smooth disconnection of the first fuel control chamber and the low-pressure fluid drain, or b) smooth coupling of the first fuel control chamber to the low-pressure fluid drain and smooth disconnection of the first fuel control chamber and the high-pressure fluid source. Petition 870250104723, dated 11 / 14 / 2025, page 21 / 44 17 / 30

[0039] The second fuel control valve may comprise a second piston configured to move along a second control valve axis to selectively and fluidly couple the second fuel control chamber to the high-pressure fluid source or to a low-pressure fluid drain. Thus, the second piston may be situated in the second switching volume. The second fuel control valve is preferably configured so that the second piston can be moved selectively along the second control valve axis between a first position and a second position.The second fuel control valve is preferably configured so that, in the first position, the second plunger is configured to facilitate one of two actions: a) fluidly coupling the second fuel control chamber to the high-pressure fluid source and fluidly disconnecting (i.e., blocking fluid communication between) the second fuel control chamber and the low-pressure fluid drain, or b) fluidly coupling the second fuel control chamber to the low-pressure fluid drain and fluidly disconnecting the second fuel control chamber and the high-pressure fluid source.The second fuel control valve is preferably configured so that, in the second position, the second piston is configured to facilitate either a) smooth coupling of the second fuel control chamber to the high-pressure fluid source and smooth disconnection of the second fuel control chamber and the low-pressure fluid drain, or b) smooth coupling of the second fuel control chamber to the low-pressure fluid drain and smooth disconnection of the second fuel control chamber and the high-pressure fluid source.

[0040] The first and second fuel control valves may be arranged side by side, so that the first control valve shaft extends parallel to the second control valve shaft. Petition 870250104723, dated 11 / 14 / 2025, page 22 / 44 18 / 30 In some preferred examples, both the first and second control valve shafts may extend parallel to the first needle valve shaft, and both the first and second control valve shafts may be offset from the first needle valve shaft, so that neither control valve shaft is coaxial with the first needle valve shaft. In some examples, the first control valve shaft and the second control valve shaft may each be offset from the first needle valve shaft by the same distance. Thus, in advantageous examples, neither control valve has priority over the other control valve, and instead, both control conduits are optimized in terms of reducing the distance to the respective control chamber and, consequently, reducing the respective control volume.

[0041] The side-by-side arrangement of the first and second fuel control valves can facilitate a reduction in the overall size of the dual fuel injector, as well as allowing better control of valve movement to improve combustion in the combustion chamber in use. For example, arranging the first and second fuel control valves side-by-side, with their respective axes parallel but not concentric to the axis of the first needle valve, can mean that both control valves can be provided close to their respective control chambers. Reducing the distance between the control valves, i.e., the switching volumes of the control valves, and their respective control chambers reduces the length of the control ducts and, consequently, also reduces each control volume.This, in turn, means that switching losses or control volume losses are minimized, needle valve responses (i.e., opening and closing rates) are faster, and hydraulic wave activity in each control volume is reduced, thus providing more precise distribution. Petition 870250104723, dated 11 / 14 / 2025, page 23 / 44 19 / 30 and consistent fuel to the combustion chamber.

[0042] In some examples, the dual fuel injector may comprise a first control orifice through which the first fuel control chamber is in fluid communication with the first control conduit. The flow area of ​​the first control orifice, or the diameter of the first control orifice, may therefore influence the flow rate into and out of the first fuel control chamber. Thus, the flow area or diameter of the first control orifice may influence the opening and closing rates of the first fuel needle valve.For example, the first control orifice can be configured to dampen, that is, to decrease the opening rate of the first fuel needle valve when the first control valve is operated, in order to smoothly connect the first fuel control chamber with the low-pressure fluid drain, so that the fluid in the first fuel control chamber is evacuated to the low-pressure fluid drain through the first control orifice. Thus, the flow area of ​​the first control orifice, or the diameter of the first control orifice, can be smaller than the flow area, or diameter, of the first control conduit.

[0043] In some examples, the dual fuel injector may comprise a second control orifice through which the second fuel control chamber is in fluid communication with the second fuel control conduit. The flow area of ​​the second control orifice, or the diameter of the second control orifice, may therefore influence the flow rate into and out of the second fuel control chamber. Thus, the flow area or diameter of the second control orifice may influence the opening and closing rates of the second fuel needle valve. For example, the second control orifice may be configured to dampen, i.e., Petition 870250104723, dated 11 / 14 / 2025, page 24 / 44 20 / 30 decrease the opening rate of the second fuel needle valve when the second control valve is operated to smoothly connect the second fuel control chamber with the low-pressure fluid drain, so that the fluid in the second fuel control chamber is evacuated to the low-pressure fluid drain through the second control orifice. Thus, the flow area of ​​the second control orifice, or the diameter of the second control orifice, may be smaller than the flow area, or diameter, of the second fuel control conduit.

[0044] In some instances, the nozzle body may comprise an assembly of a plurality of nozzle body sections. For example, the nozzle body may comprise separate nozzle body sections that define, at least partially, the previously described portions of the nozzle body. For example, the nozzle body may comprise a tip section that defines at least part of the lower portion of the nozzle body and thus extends into the combustion chamber. The tip section of the nozzle body may comprise a material of or from each of the other nozzle body sections in order to withstand the high temperatures and pressures in the combustion chamber. For example, the tip section of the nozzle body may define the first fuel valve seat and, consequently, the tip section may also define the first or each first fuel injection outlet.Additionally or alternatively, in some examples, the tip section of the nozzle body may define at least part of the first fuel accumulator volume.

[0045] To inject a dose of the first fuel into the combustion chamber, the dual fuel injector can be operated to smoothly connect the first fuel control chamber to the low-pressure fluid drain, using the first fuel control valve, so that the first pressure in the first fuel control chamber decreases, thus decreasing the force at the upper end of the first Petition 870250104723, dated 11 / 14 / 2025, page 25 / 44 21 / 30 fuel needle valve. The pressure of the first fuel in the first volume of fuel accumulator can therefore overcome the remaining closing force that holds the first fuel needle valve against the first fuel valve seat, so that the first fuel needle valve lifts and allows the first fuel to exit from the first volume of fuel accumulator into the combustion chamber.

[0046] Under normal operating conditions, a dose of the second fuel may be injected into the combustion chamber during or after the injection of the first fuel. Thus, the second pressure in the second fuel control chamber can be maintained by keeping the second fuel needle valve in a closed position against the second fuel valve seat of the first fuel needle valve during the opening, i.e., lifting, of the first fuel needle valve. When held closed, the second fuel needle valve can therefore apply a force on the first fuel needle valve, because the second fuel needle valve can operate substantially independently of the first fuel needle valve. Thus, in some instances, the second fuel needle valve can dampen, i.e., decrease the opening rate of the first fuel needle valve.Furthermore, the additional force provided by the second fuel needle valve can accelerate the closing rate of the first fuel needle valve. Both effects are beneficial for combustion.

[0047] In some examples, the first fuel may be a gaseous fuel. For example, the first fuel may be a gas such as methane gas or hydrogen gas. Additionally or alternatively, the second fuel may be a liquid fuel. For example, the second fuel may be a liquid, such as liquid diesel or gasoline. Petition 870250104723, dated 11 / 14 / 2025, page 26 / 44 22 / 30 liquid, in some examples. In some other examples, the first and second fuels may be of the same fuel type. For example, the first and second fuels may both be liquid fuels in some examples or, alternatively, the first and second fuels may both be gaseous fuels in other examples.

[0048] In some preferred examples, each of the corresponding diameters mentioned in this document is preferably concentric within 0.5 pm of the first fuel needle valve axis. Brief description of the drawings

[0049] Examples of the present invention will now be described by way of non-limiting example only, with reference to the accompanying Figures, in which: Figure 1 is a schematic cross-sectional view of a dual fuel injector; Figure 2 is an enlarged view of the cross-section shown in Figure 1; and Figure 3 is a schematic perspective view of the internal volumes defined by the first and second control chambers of the dual fuel injector. Detailed description

[0050] Figure 1 shows a schematic cross-sectional view of a dual fuel injector 10 for injecting two separate fuels into a combustion chamber 12 of an internal combustion engine. For example, the injector 10 can be configured to inject a first fuel in gaseous form, such as methane or hydrogen, for example, and a second fuel in liquid form, such as gasoline or diesel, for example. As explained earlier for context, the first fuel can be selected for its advantageous combustion or emission characteristics, and the second fuel supplied to the combustion chamber 12 can help improve reliability and time. Petition 870250104723, dated 11 / 14 / 2025, page 27 / 44 23I30 of the combustion of the first fuel.

[0051] The dual fuel injector 10 comprises a nozzle body 14 housing a dual needle valve arrangement 16 for regulating the supply of the first and second fuels to the combustion chamber 12. Thus, the dual needle valve arrangement 16 comprises a first fuel needle valve 18 and a second fuel needle valve 20. The injector 10 also includes a first fuel control chamber 22. The first fuel control chamber 22 is preferably configured to hydraulically control the movement of the first fuel needle valve 18. For example, the first fuel control chamber 22 is defined, at least in part, by an upper surface 24 of an upper end 26 of the first fuel needle valve 18.Thus, varying the initial pressure in the first fuel control chamber 22 varies the force at the upper end 26 of the first fuel needle valve 18. The movement of the first fuel needle valve 18 can therefore be controlled by controlling the pressure in the first fuel control chamber 22.

[0052] Referring further to Figure 2, which shows an enlarged view of the cross-sectional view of Figure 1 for ease of reference, in some preferred examples, the upper end 26 of the first fuel needle valve 18 may be received in a sliding manner in a needle guide portion 28 defined by the nozzle body 14. Thus, the first fuel control chamber 22 may be defined, at least in part, by a roof surface 30 of the needle guide portion 28, as shown in the example of Figure 2. The first fuel needle valve 18 may be received in the needle guide portion 28 with a corresponding clearance fitting to facilitate the movement of the first fuel needle valve 18 relative to the nozzle body 14. It will be recognized that the Petition 870250104723, dated 11 / 14 / 2025, p. 28 / 44 24 / 30 first fuel needle valve 18 defines a first needle valve shaft 32 and the needle guide portion 28 is preferably configured to restrict the first fuel needle valve 18 to move linearly along the first needle valve shaft 32.

[0053] With further reference to Figures 1 and 2, as previously noted, the double needle valve arrangement 16 comprises a second fuel needle valve 20 for regulating the supply of the second fuel to the combustion chamber 12. The second fuel needle valve 20 is sliding relative to the first fuel needle valve 18 and, as will be described in more detail later, can advantageously move substantially independently of the first fuel needle valve 18. As shown more clearly in Figure 2, the first fuel needle valve 18 comprises a bore 34 extending through its upper end 26 from an opening 36 defined on the upper surface 24. The second fuel needle valve 20 is received slidingly within this first bore of the fuel needle valve 34.

[0054] Notably, an upper end 38 of the second fuel needle valve 20 extends above the upper end 26 of the first fuel needle valve 18 because the second fuel needle valve 20 projects from the opening 36 on the upper surface 24 of the upper end 26 of the first fuel needle valve 18. It will be recognized that this configuration facilitates the separate control and movement of the second fuel needle valve 20, independently of the first fuel needle valve 18. For example, as shown more clearly in Figure 2, the movement of the second fuel needle valve 20 can be controlled by varying a second pressure in a second fuel control chamber 40 defined, at least in part, by a surface Petition 870250104723, dated 11 / 14 / 2025, page 29 / 44 25 / 30 upper 42 of the upper end 38 of the second fuel needle valve 20.

[0055] Furthermore, independent control of the second fuel needle valve 20 is facilitated, at least in part, because the second fuel control chamber 40 can be provided in a portion of the injector 10 that is completely separate from the first fuel needle valve 18. For example, still with reference to Figure 2, the nozzle body 14 may comprise an opening 44 in the roof surface 30 of the needle guide portion 28. The upper end 38 of the second fuel needle valve 20 may be received in a hole 46 extending from the opening 44. Thus, the second fuel control chamber 40 can be defined, at least in part, by the upper end 38 of the second fuel needle valve 20 and, at least in part, by the nozzle body 14.

[0056] As illustrated in Figures 1 and 2, in some preferred examples, the second fuel needle valve 20 may extend through the first fuel control chamber 22. The first fuel control chamber 22 may therefore be defined, at least in part, by an external surface 48 of the second fuel needle valve 20. Referring again to Figure 3, which shows the internal volumes defined by the first and second fuel control chambers 22 and 40 separately, in some examples, the first fuel control chamber 22 may form a ring extending around a portion of the second fuel needle valve 20. For advantageous load balancing and conditioning in use, the dual fuel injector 10 may be configured so that a central axis 50 of the first fuel control chamber 22 is coaxial with the first needle valve axis 32.For the same reason, a central shaft 52 of the second fuel control chamber 40 can be coaxial with a shaft. Petition 870250104723, dated 11 / 14 / 2025, pp. 30 / 44 26 / 30 defined by the second needle valve 20. The first and second fuel needle valves 18, 20 may be coaxial and, in some examples, each of the needle valves 18, 20 and control chambers 22, 40 may therefore be coaxial with each other for advantageous load distribution in use.

[0057] Referring again to Figures 1 and 2, in some examples, the nozzle body 14 may define one or more first fuel injection outlets 56. One or more first fuel injection outlets 56 may be defined by a first fuel valve seat portion 58 of the nozzle body 14. One or more first fuel injection outlets 56 may be configured to facilitate fluid communication between a first fuel accumulator volume 60 and the combustion chamber 12. Consequently, the first fuel needle valve 18 is preferably configured to selectively block or allow fluid communication between the first fuel accumulator volume 60 and the combustion chamber 12 via the first fuel injection outlets 56.For example, a high pressure in the first fuel control chamber 22 can provide a closing force that acts on the upper end 26 of the first fuel needle valve 18, causing the needle valve 18 to engage with the first seat portion of the fuel valve 58, thus blocking the first fuel injection outlets 56. To inject the first fuel into the combustion chamber 12, the first pressure in the first fuel control chamber 22 can be reduced so that a pressure in the first fuel accumulator volume 60 is greater than the first pressure in the first fuel control chamber 22, thus moving the first fuel needle valve 18 away from the first seat portion of the fuel valve 58 to facilitate fluid communication between the first fuel accumulator volume. Petition 870250104723, dated 11 / 14 / 2025, pp. 31 / 44 27 / 30 and the combustion chamber 12 via the first fuel injection outlets 56.

[0058] The dual fuel injector 10 may also include a first bias means 62 configured to bias the first fuel needle valve 18 for engagement with the first fuel valve seat portion 58. This additional bias force may help to accelerate the closing rate of the first fuel needle valve 18. As shown in Figures 1 and 2, the first bias means 62 may be disposed around the first fuel needle valve 18 in some examples. For example, the first bias means 62 may be located in the first fuel accumulator volume 60. In particular, it should be noted that in advantageous examples, the first bias means 62 may therefore be situated in a completely separate region of the injector 10 compared to the first fuel control chamber 22.Consequently, the first fuel control chamber 22 does not need to be sized to accommodate the first bias medium 62 and, instead, can be minimized to improve the responsiveness of the first fuel needle valve 18 to pressure variations in the first fuel control chamber 22 when actuating the needle valve 18 in use.

[0059] The first polarization means 62 preferably engages a portion of the nozzle body 14 to polarize the first fuel needle valve 18 in engagement with the first fuel valve seat portion 58. For ease of manufacture, the injector 10 may include a collar 64 coupled to the first fuel needle valve 18, and the first polarization means 62 may engage the collar 64 and a portion of the nozzle body 14.

[0060] Referring again to Figures 1 and 2, and as described earlier, the movement of the second fuel needle valve 20 Petition 870250104723, dated 11 / 14 / 2025, pp. 32-44 28 / 30 can be controlled by varying a second pressure in the second fuel control chamber 40. This varies the force at the upper end 38 of the second fuel needle valve 20, resulting in the actuation of the second fuel needle valve 20. It should be recognized that, similarly to the description provided with reference to the first fuel needle valve 18, the actuation of the second fuel needle valve 20 blocks or opens one or more second fuel injection outlets 66. Each second fuel injection outlet 66 can be defined by a second fuel valve seat portion 68 of the first fuel needle valve 18. Each second fuel injection outlet 66 can facilitate fluid communication between a second fuel accumulator volume 70 and the combustion chamber 12.Thus, when the second fuel needle valve 20 is held against the second fuel valve seat portion 68 in use, for example, when the second pressure in the second fuel control chamber 40 is greater than a pressure in the second fuel accumulator volume 70, the fluid communication between the second fuel accumulator volume 70 and the combustion chamber 12 is blocked.

[0061] The dual fuel injector 10 may also include a second bias means 72 configured to bias the second fuel needle valve 20 for engagement with the second fuel valve seat portion 68. The additional bias force provided by the second bias means 72 may help to accelerate the closing rate of the second fuel needle valve 20. As illustrated in Figures 1 and 2, the second bias means 72 may be disposed in the second fuel accumulator volume 70 in some preferred embodiments. Similar to what was previously described in relation to the first fuel control chamber 22 and the first bias means 62, locating the second bias means 72 in a region Petition 870250104723, dated 11 / 14 / 2025, pp. 33 / 44 29 / 30 being completely separate from injector 10 compared to the second fuel control chamber 40 means that the second fuel control chamber 40 does not need to be sized to accommodate the second bias medium 72. Consequently, the volume of the second fuel control chamber 40 can be minimized to improve the responsiveness of the second fuel needle valve 20 to pressure variations in the second fuel control chamber 40 in use.

[0062] Finally, as shown in Figure 1 and more clearly in Figure 2, in some examples, the injector 10 may additionally include an annular sealing gallery 74 extending around an outer surface 76 of the first fuel needle valve 18. As described earlier, the first fuel needle valve 18 is preferably received in a sliding manner in a needle guide portion 28 of the nozzle body 14. Thus, there may be a small gap between the needle guide portion 28 and the first fuel needle valve 18 for a clearance fit that allows the sliding relationship. The inclusion of a sealing gallery 74 may therefore be advantageous for the seal between the first fuel needle valve 18 and the needle guide portion 28 of the nozzle body 14.

[0063] For example, the sealing gallery 74 may be arranged between the first fuel control chamber 22 and the first fuel accumulator volume 60. The sealing gallery 74 may be in fluid communication with a high-pressure fluid source and, in preferred embodiments, the sealing gallery 74 may therefore be maintained at a higher pressure than the first fuel in the first fuel accumulator volume 60. Consequently, there may be a pressure differential between the sealing gallery 74 and the first fuel accumulator volume 60 that inhibits any movement of the first fuel from the first fuel accumulator volume 60 towards the gallery. Petition 870250104723, dated 11 / 14 / 2025, pp. 34 / 44 30 / 30 seal 74 and / or to the first fuel control chamber 22.

[0064] Although not represented in the cross-sectional views of the accompanying figures, in some preferred examples, the sealing gallery 74 may have another function besides the main sealing function. For example, a multi-functional sealing gallery 74 may perform the sealing between the first fuel needle valve 18 and the needle guide portion 28, as well as provide a control fluid to one or both control chambers 22, 40. In such an example, the control fluid is preferably supplied to one or both control chambers 22, 40 by means of respective control valves 78, 80 configured to vary the pressures in the control chambers 22, 40, thereby actuating the first and second fuel needle valves 18, 20. Thus, the sealing gallery 74 may be in fluid communication with at least one of the first fuel control chamber 22 and / or the second fuel control chamber 40.It will be recognized that this fluid communication is preferably made by means of the respective control valve 78, 80 to regulate the fluid supply to the respective control chamber 22, 40 to control the first and / or second fuel needle valves 18, 20.

[0065] It will be acknowledged that the description provided above serves to demonstrate possible examples of the present invention. The features described in relation to any of the examples above can be easily combined with any other features described with reference to different examples, without departing from the scope of the invention, as defined in the appended claims. Petition 870250104723, dated 11 / 14 / 2025, pages 35 / 44

Claims

1 / 5 CLAIMS 1. A dual fuel injector (10) for injecting two separate fuels into a combustion chamber (12) of an internal combustion engine, characterized in that the dual fuel injector (10) comprises: a nozzle body (14) housing a dual needle valve arrangement (16), the dual needle valve arrangement (16) comprising a first fuel needle valve (18) and a second fuel needle valve (20), and the first fuel needle valve (18) defining a first needle valve shaft (32); and a first fuel control chamber (22) defined at least in part by an upper surface (24) of an upper end (26) of the first fuel needle valve (18) such that varying a first pressure in the first fuel control chamber (22) varies the force at the upper end (26) of the first fuel needle valve (18);wherein the first fuel needle valve (18) comprises a bore (34) extending through the upper end (26) of the first fuel needle valve (18) from an opening (36) defined on the upper surface (24); wherein the second fuel needle valve (20) is received in a sliding manner within the first bore of the fuel needle valve (34); and wherein the second fuel needle valve (20) projects from the opening (36) such that an upper end (38) of the second fuel needle valve (20) extends above the upper end (26) of the first fuel needle valve (18).

2. Dual fuel injector (10) according to claim 1, characterized in that the second fuel needle valve (20) extends through the first fuel control chamber (22).

3. Dual fuel injector (10) according to claim 1 or 2, characterized in that the first fuel control chamber (22) is defined at least in part by an outer surface (48) of the second fuel needle valve (20).

4. Dual fuel injector (10) according to any of the preceding claims, characterized in that the first fuel control chamber (22) comprises a first central shaft (50) that is coaxial with the first needle valve shaft (32).

5. Dual fuel injector (10) according to any of the preceding claims, characterized in that the first fuel control chamber (22) forms a ring that extends around a portion of the second fuel needle valve (20).

6. Dual fuel injector (10) according to any of the preceding claims, characterized in that the nozzle body (14) defines a needle guide portion (28), and in that the upper end (26) of the first fuel needle valve (18) is received in a sliding manner in the needle guide portion (28).

7. Dual fuel injector (10) according to claim 6, characterized in that the first fuel control chamber (22) is defined at least in part by a roof surface (30) of the needle guide portion (28).

8. Dual fuel injector (10) according to claim 7, characterized in that the nozzle body (14) comprises a bore (46) extending from an opening (44) defined on the roof surface (30) of the needle guide portion (28), and wherein the upper end (38) of the second fuel needle valve (20) is received within the bore (46). Petition 870250104723, dated 11 / 14 / 2025, page 37 / 44 3 / 5 9. Dual fuel injector (10) according to any of the preceding claims, characterized in that it further comprises a second fuel control chamber (40) defined at least in part by an upper surface (42) of the upper end (38) of the second fuel needle valve (20) such that varying a second pressure in the second fuel control chamber (40) varies the force at the upper end (38) of the second fuel needle valve (20).

10. Dual fuel injector (10) according to claim 9, characterized in that the second fuel control chamber (40) is defined at least in part by the nozzle body (14).

11. Dual fuel injector (10) according to claim 9 or 10, characterized in that the first fuel control valve comprises a first piston configured to move along a first control valve shaft to selectively and fluidly couple the first fuel control chamber (22) to a high-pressure fluid source or a low-pressure fluid drain; the dual fuel injector further comprises a second fuel control valve comprising a second piston (46) configured to move along a second control valve shaft (48) to selectively and fluidly couple the second fuel control chamber (40) to a high-pressure fluid source or a low-pressure fluid drain;wherein the first and second fuel control valves are arranged side by side so that the first control valve shaft extends parallel to the second control valve shaft, wherein both the first and second control valve shafts extend parallel to the first needle valve shaft, and wherein both the first and second control valve shafts are offset from the first needle valve shaft so that neither of the control valve shafts is coaxial with the first needle valve shaft.

12. Dual fuel injector (10) according to any of the preceding claims, characterized in that the nozzle body (14) defines a first fuel valve seat portion (58), and wherein the dual fuel injector (10) further comprises a first biasing means (62) configured to bias the first fuel needle valve (18) for engagement with the first fuel valve seat portion (58).

13. Dual fuel injector (10) according to claim 12, characterized in that the first polarization means (62) is arranged around the first fuel needle valve (18).

14. Dual fuel injector (10) according to claim 12 or 13, characterized in that it further comprises a collar (64) coupled to the first fuel needle valve (18), wherein the first polarizing means (62) engages the collar (64) and a portion of the nozzle body (14) to polarize the first fuel needle valve (18) for engagement with the first fuel valve seat portion (58).

15. Dual fuel injector (10) according to any of the preceding claims, characterized in that the first fuel needle valve (18) defines a second fuel valve seat portion (68), and wherein the dual fuel injector (10) further comprises a second biasing means (72) configured to bias the second fuel needle valve (20) for engagement with the second fuel valve seat portion (68).

16. Dual fuel injector (10) according to claim 15, characterized in that the second polarization means (72) is arranged in a second fuel accumulator volume (70) within the first fuel needle valve (18).

17. Dual fuel injector (10) according to any of the preceding claims, characterized in that it further comprises an annular sealing gallery (74) extending around an outer surface (76) of the first fuel needle valve (18), wherein the sealing gallery (74) is in fluid communication with a high-pressure fluid source. Petition 870250104723, dated 11 / 14 / 2025, pp. 40 / 44

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