Multi-fuel injector with fuel mixing function

Abstract

A fuel injector (12) capable of injecting a plurality of different fuels in a single fuel injection event, the fuel injector (12) comprising: a nozzle (32) at an end of the fuel injector (12), the nozzle (32) having a tip; an opening (38) in the tip of the nozzle (32), the fuel being configured to be injected through the opening (38); and a check valve (14) member (16, 16A, 16B, 16C) having a tip (26) located within the nozzle (32), the check valve (14) member (16, 16A, 16B, 16C) being movable between an injection position, in which fuel is injected via the opening (38), and a closed position, in which the opening (38) is closed. The fuel injector (12) includes: a main fuel path within the fuel injector (12), the main fuel path configured to supply main fuel to an opening (38) in a tip of a nozzle (32); a pilot fuel path within the fuel injector (12), the pilot fuel path configured to supply pilot fuel to an opening (38) in the tip of the nozzle (32); and a mixing volume (30) located within the nozzle (32) and connecting the main fuel path and the pilot fuel path when the check valve (14) member (16, 16A, 16B, 16C) is in the closed position.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to methods and systems for internal combustion engine components, and more particularly to a fuel injector configured to inject two types of fuel from a single nozzle. BACKGROUND

[0002] While engines that operate entirely through the combustion of conventional fossil fuels are common, there is increasing interest in adapting engines for use with so-called "alternative fuels." Examples of alternative fuels include natural gas and alcohol-containing fuels, such as methanol and ethanol, gasoline, or naphtha. Alternative fuels often have relatively low cetane numbers and are not compatible with conventional compression-ignition (i.e., diesel-cycle) engines. These fuels can offer benefits, for example, due to their environmental qualities, and in some cases, are able to be produced with renewable energy. However, these fuels present challenges due to their differing combustion qualities and other characteristics from conventional fossil fuels.

[0003] To control injection of multiple fuel types with a single fuel injector, some injectors are provided with a "double-check valve" design, which includes either two nozzles with two check valves, or one nozzle with two check valves. These nozzles also contain separate sets of orifices for injecting each type of fuel, for use with a pair of check valve members that open and close these respective sets of orifices. These types of injectors, while generally effective, introduce additional manufacturing complexity and cost. Injectors with double tips and double valve members can also involve more complex wiring and control systems.

[0004] An exemplary fuel injector for injecting more than one type of fuel is described in U.S. Patent Application Publication No. 2014 / 0373806 Al ("the '806 publication") to Hou. The fuel injector described in the '806 publication includes a needle having internal fuel passages, and a variable fuel injection orifice. The fuel passages within the needle terminate at the needle orifice, which operates as a high-pressure fuel passage. When the needle resides in a closed position, these passages are completely sealed, and thus prevent fuel from mixing within the nozzle. While the fuel injector described in the '806 publication can be useful in some circumstances, it can be difficult to inject one or both types of fuel via the needle in the desired amount or timing.

[0005] The systems and methods of the present disclosure can address one or more of the problems described above and / or other issues in the art. However, the scope of the present disclosure is defined by the claims appended hereto, rather than the ability to solve any particular problem. SUMMARY

[0006] In one aspect, a fuel injector capable of injecting multiple different fuels in a single fuel injection event includes a nozzle at an end of the fuel injector, the nozzle having a tip, an opening in the tip of the nozzle through which fuel is configured to be injected, and a check valve member having a tip located within the nozzle, the check valve member being movable between an injection position in which fuel is injected via the opening and a closed position in which the opening is closed. The fuel injector can also include a main fuel path within the fuel injector configured to supply main fuel to the opening in the tip of the nozzle, a pilot fuel path within the fuel injector configured to supply pilot fuel to the opening in the tip of the nozzle, and a mixing volume located within the nozzle and connecting the main fuel path and the pilot fuel path when the check valve member is in the closed position.

[0007] In another aspect, a fuel injection method can include supplying pilot fuel to a nozzle of a fuel injector, supplying main fuel to the nozzle, the pilot fuel being different than the main fuel. The fuel injection method can include at least partially mixing the pilot fuel and the main fuel in the nozzle prior to injecting the main fuel or the pilot fuel with the nozzle, injecting the pilot fuel and the main fuel through a single set of openings in the nozzle.

[0008] In yet another aspect, a fuel injection system can include a first common rail configured to receive pilot fuel, a second common rail configured to receive main fuel, and a fuel injector. The fuel injector can have a nozzle, a check valve member extending within the nozzle, a main fuel path configured to supply main fuel to the nozzle, and a pilot fuel path within the fuel injector configured to supply pilot fuel to an opening in the nozzle, the main fuel path being fluidly connected to the pilot fuel path when the check valve member is in a closed position that prevents injection of the pilot fuel and injection of the main fuel. BRIEF DESCRIPTION OF DRAWINGS

[0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various example embodiments and together with the description, explain the principles of the disclosed embodiments.

[0010] Figure 1 is a schematic illustration of a multi-fuel engine system in accordance with aspects of the present disclosure.

[0011] Figure 2A is a partial schematic cross-sectional view of an example fuel injector in accordance with aspects of the present disclosure.

[0012] Figure 2B is a partial schematic cross-sectional view of an example fuel injector.

[0013] Figure 3AThis is a partial schematic cross-sectional view of an exemplary fuel injector.

[0014] Figure 3B This is a partial schematic cross-sectional view of an exemplary fuel injector.

[0015] Figure 4 This is a partial schematic cross-sectional view of an exemplary fuel injector.

[0016] Figure 5 This is a partial schematic cross-sectional view of an exemplary fuel injector.

[0017] Figure 6 This is a flowchart depicting an exemplary fuel injection method according to various aspects of this disclosure. Detailed Implementation

[0018] The foregoing general description and the following detailed description are merely exemplary and illustrative and do not limit the claimed features. As used herein, the terms “comprises,” “comprising,” “having,” “including,” or other variations thereof are intended to cover non-exclusive inclusion, such that a method or apparatus that includes a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to the method or apparatus. In this disclosure, relative terms such as, for example, “about,” “substantially,” “usually,” and “approximately” are used to indicate possible variations of ±10% in the stated values ​​or characteristics.

[0019] Figure 1 An exemplary multifuel engine system 10 including a plurality of fuel injectors 12 is illustrated according to various aspects of the present disclosure. The multifuel engine system 10 may include an internal combustion engine 100 having a plurality of engine cylinders 102, with the fuel injectors 12 connected to the plurality of engine cylinders 102 for direct fuel injection. The multifuel engine system 10 may also include a fuel supply system for delivering a plurality of different types of fuel to each injector 12.

[0020] The fuel supply system for delivering fuel to injector 12 may include an ignition fuel reservoir 90 (e.g., a fuel tank), an ignition fuel pump 92, and a common rail 94 located downstream of the ignition fuel reservoir 90 and the main fuel pump 92. The fuel supply system may also include a main fuel reservoir 95 for gaseous or liquid main fuels, a fuel pump 96 (e.g., a cryogenic pump compatible with liquefied natural gas or a fuel pump compatible with alcohol-containing liquid fuels) located downstream of the main fuel reservoir 95, and a common rail 98 compatible with either gaseous or liquid fuels. Separate flow paths (e.g., including sleeve shafts) may connect the common rails 94 and 98 to the input ports of each injector 12. The common rails 94 and 98 may be connected to sensors, safety valves, and other structures (not shown) known in the field of common rail fuel injection systems. Furthermore, pumps 92 and 96 may be connected to an electronic control module (not shown) configured to regulate the pressure supplying each type of fuel to the injector 12. The pressure generated by pumps 92 and 96 can be regulated by an electronic control module to adjust the relative amounts of ignition fuel and main fuel injected into cylinder 102.

[0021] Fuel injector 12 can be a multi-fuel injector configured to inject two different types of fuel in a single injection event (e.g., an injection event including ignition injection, main injection, and / or post-injection) via a single nozzle having a shared set of nozzle orifices or openings. In some aspects, the two different fuels can include liquid fuel and gaseous fuel, or two different liquid fuels. As used herein, whether a fuel is “liquid” or “gaseous” is determined based on the state of the fuel when it is delivered to the fuel injector. Fuel delivered to the fuel injector as a gas can be considered a gaseous fuel, even if the gaseous fuel is stored in a liquid state. For example, liquefied natural gas in reservoir 95 can expand such that rail 98 contains fuel in gaseous form, which is delivered to injector 12. In this example, natural gas is considered a gaseous fuel. Diesel fuel can be stored in liquid form and supplied to injector 12 in liquid form as ignition fuel, forming liquid fuel in this example. Other examples of liquid fuels include liquid methanol or ethanol, which can be stored and supplied as a main fuel in liquid form.

[0022] As used herein, "primary fuel" refers to the fuel injected at a volume that produces more than 50% of the total energy generated by fuel combustion, under steady-state operating conditions of an internal combustion engine, following an injection event that includes both ignition injection (e.g., diesel fuel, dimethyl ether, biodiesel, vegetable oil, or other ignition fuel) and main injection (e.g., natural gas, methanol, ethanol, or other primary fuel). "Ignition fuel" can refer to the fuel that is injected, mostly or completely, before the primary fuel in an injection event, to initiate combustion. In some respects, fuels with relatively low cetane numbers (e.g., natural gas, methanol, ethanol, etc.) can be used as primary fuels, and fuels with cetane numbers higher than those of the primary fuels (e.g., diesel fuel, dimethyl ether, biodiesel, vegetable oil, etc.) can be used as ignition fuels. Furthermore, while the terms "ignition fuel" and "primary fuel" relate to the general sequence of injection of these different fuels, as understood, ignition fuel injection and primary fuel injection can occur sequentially and can include the injection of a mixture of the two fuels.

[0023] Figure 2A This is a cross-sectional view of an example fuel injector 12. As described below, Figure 2A , Figure 2B , Figure 3A and Figure 3B The injectors shown can be configured for passive metering control. As used herein, “passive” metering does not involve the actuation of an electronically controlled valve (e.g., a solenoid valve) in injector 12 to supply a desired (e.g., calculated) amount of fuel (e.g., ignition fuel) to the tip of injector 12. As used herein, “active” metering does involve the actuation of an electronically controlled valve in injector 12 to supply a desired amount of fuel. Therefore, these injectors can be configured with only one control valve and one solenoid valve, as described below. Figure 4 and Figure 5 The description of active measurement forms a contrast.

[0024] Although Figure 2A The distal portion of the fuel injector 12 is shown, but as understood, the fuel injector 12 may include a body from which... Figure 2A The structure shown extends proximally and includes one or more electromagnetic control valve components (e.g., valve 74 for initiating fuel injection, such as...). Figure 4 and Figure 5 (As shown), electrical connections for communication with the electronic control unit, fuel inlet, and other structures. The fuel injector 12 may include a check valve 14, a main fuel supply passage 36, a mixing volume 30, and a nozzle 32 having one or more orifices or nozzle openings 38. The check valve 14 may include a valve member 16, a spring 18 biasing the valve member 16 to a closed position, an ignition fuel guide space 22, an enlarged clearance 24, and a hydraulic control chamber 42.

[0025] Valve member 16 may include a valve body 15 extending from a proximal end 44 to a distal end 26. Valve body 15 may be entirely solid to accommodate the need to introduce fuel into the exterior of valve member 16, for example... Figure 2A As shown, valve body 15 may include one or more internal passages for supplying fuel, as described below. Proximal end 44 may be closest to hydraulic control passage 40 and positioned within hydraulic control chamber 42. Distal end 26 may be positioned within nozzle 32.

[0026] Valve component 16 is movable between a closed position and an open position. Figure 2A In the closed position, distal end 26 forms a seal with the valve seat within nozzle 32 to close nozzle opening 38. In the open position, valve body 15 is raised to communicate with the enlarged gap 24, nozzle fuel passage 34, and mixing volume 30 through nozzle opening 38, allowing fuel within gap 24, passage 34, and mixing volume 30 to pass through nozzle opening 38.

[0027] In some respects, the fuel injector 12 may define a main fuel path and a pilot fuel path. The main fuel path may be partially isolated from the pilot fuel path and may include a main fuel supply passage 36, a nozzle fuel passage 34, and, if necessary, a one-way valve 35. The one-way valve 35 may allow flow from passage 36 to passage 34 while preventing flow in the direction from passage 34 to the main fuel supply passage 36, thereby isolating the main fuel path upstream of valve 35. The main fuel path may be in fluid communication with the common rail 98 and is located downstream of the common rail 98.

[0028] The ignition fuel path may include an ignition fuel chamber 20, an ignition fuel guide space 22, and an enlarged gap 24. The ignition fuel chamber 20 may be filled with pressurized ignition fuel via one or more supply channels (not shown). The ignition fuel guide space 22 may be formed as an area having a controlled gap (e.g., pitch) between the outer diameter of the valve body 15 and the inner bore of the nozzle 32 surrounding that portion of the valve body 15. In some aspects, this controlled gap may range from about 3 µm to about 8 µm. In some configurations, the ignition fuel path may include a channel within the valve member 16 and / or other channels within the nozzle 32 or other portions of the injector 12, as described below. Figure 3A to Figure 5 ).

[0029] The mixing volume 30 within nozzle 32 represents the location where the main fuel path and the ignition fuel path within nozzle 32 intersect, thereby establishing fluid communication between the two paths. Mixing volume 30 can be the point where fuel from ignition fuel chamber 20 is configured to meet fuel from main fuel supply passage 36 within nozzle 32. Mixing of the ignition fuel and main fuel can be driven or amplified by the pressure difference between the ignition fuel and main fuel. For example, since ignition fuel is typically present at higher pressures, it may tend to mix with the main fuel in volume 30, where increased mixing is associated with an increased pressure difference between the two fuels. Therefore, higher ignition fuel pressure may be associated with increased mixing.

[0030] The mixing volume 30 can be an annular space surrounding a portion of the valve body 15. For example, in Figure 2A In the configuration shown, the mixing volume 30 may surround a portion of the distal end 26. If desired, the cross-sectional area defined by the mixing volume 30 (e.g., measured as the gap between the inner walls of the defining mixing volume 30 of the valve body 15 and the nozzle 32) may be larger than the corresponding cross-sectional area of ​​the ignition fuel guiding space 22. The cross-sectional area of ​​the mixing volume 30 may also be larger than the cross-sectional area of ​​the tip reservoir 28. The tip reservoir 28 may be defined as a portion extending distally around the ignition fuel guiding space 22.

[0031] Figure 2B Is with Figure 2A The injector 12 shown is a cross-sectional view of an example fuel injector 12 with structural similarity. (By...) Figure 2B and Figure 2A A comparison reveals that the nozzle fuel passage 34 can have a shortened configuration, which results in the mixing volume 30 being located more proximal to the distal end 26. For example, the position of the mixing volume 30 can be related to the distance between the end of the ignition fuel chamber 20 and the mixing volume 30, which represents the distance the ignition fuel travels from the ignition fuel chamber 20 to the mixing volume 30.

[0032] In the configuration of the mixing volume 30 surrounding the distal end 26 at the distal portion of the nozzle 32 ( Figure 2A The distance from L1 can be relatively large. In a configuration where the mixing volume 30 is closer to the ignition fuel guiding space 22 ( Figure 2B The distance L2 can be less than the distance L1. Although in Figure 2A and Figure 2BTwo examples are illustrated, but as understood, the location of the mixing volume 30 can be between the illustrated locations, closer to the distal end 26, or closer to the ignition fuel chamber 20, if desired. In some respects, the distance (e.g., the value of distance L1 or L2) can be set based on the desired mixing amount. For example, using a relatively small distance (such as distance L2) can provide increased mixing compared to a relatively large distance (such as distance L1).

[0033] Figure 3A and Figure 3B This is a cross-sectional view of a fuel injector 12, which is provided with fully hollow or partially hollow valve components, namely valve component 16A and valve component 16B. Valve component 16A ( Figure 3A The valve member 16A may be hollow, such that the proximal end 44 defines an opening 46 configured to receive fuel entering the hollow interior of the valve member 16A. This opening 46 may form a valve member supply device through which the interior of the valve member 16A receives ignition fuel. The opening 46 may define a portion of the hollow interior of the valve member 16A, and particularly a portion of that hollow interior having the largest inner diameter.

[0034] A hole 48 or other flow restrictor may be connected downstream of opening 46 and inside valve member 16A to help regulate the flow of fuel into internal passage 50. For example, the size of hole 48 may be determined in a way that reduces the velocity of fuel traveling distally from opening 46.

[0035] An internal passage 50 connects the opening 46 to one or more fuel outlet ports 52. The ports 52 may have a minimum diameter within the passageway of the valve member 16A and may extend through one or more sidewalls of the distal end 26. In some instances, the fuel outlet ports 52 are sized to perform fuel metering. Specifically, the number, size, and orientation of the fuel outlet ports 52 can be determined to facilitate the positioning of ignited fuel in the distal end 26. Figure 3A and Figure 3BAs shown, a fuel outlet orifice 52 can be formed in the distal end 26 such that the fuel outlet orifice 52 is not blocked when the valve check valve 14 is closed or open. Therefore, the orifice 52 can always communicate with the tip reservoir 28. Although the fuel outlet orifice 52 is shown oriented perpendicular to the longitudinal direction defined by the valve member 16A, other configurations are possible. For example, the fuel outlet orifice 52 can be angled relative to this longitudinal direction (e.g., extending at an upward or downward angle), as long as the fuel outlet orifice 52 is not blocked by the nozzle 32. In some aspects, the fuel outlet orifice 52 can be angled or deviated from the valve member 16A. For example, one or more orifices 52 can extend in a curved or angled direction and thus not align with the radial direction defined by the valve member 16A. Such a curved or angled orientation can cause the fuel exiting the orifice 52 to rotate or circumferentially and can tend to cause the ignition fuel to move in a vortex path around the distal end 26.

[0036] exist Figure 3A and Figure 3B In the configuration shown, by forming a minimum gap between the nozzle 32 and the valve body 15, such as about 3 µm or less than about 3 µm, the gap between the valve body 15 and the nozzle 32 (e.g., corresponding to...) can be made... Figure 2A and Figure 2B The influence of the region (the area of ​​the ignition fuel guiding space 22) can be minimized. Additionally, the distance of this guiding space can be extended (e.g., similar to or equal to...). Figure 2A L1 in the middle, thus providing a larger length-to-diameter ratio for the space between valve body 15 and nozzle 32.

[0037] like Figure 3B As shown, valve member 16B may have a sealed proximal end 44 that prevents fuel from flowing from internal passage 50 to proximal end 44. The sealed proximal end 44 may be formed by a seal or plug 56 extending inside valve member 16B. Plug 56 may fill a portion of valve member 16B that has been removed to facilitate the formation of internal passage 50 (e.g., by gun drilling, precision electrical discharge machining, or additive manufacturing).

[0038] Valve member 16B may include one or more fuel inlet holes 54 that form a valve member supply device through which ignition fuel is delivered to the internal passage 50. The fuel inlet holes 54 may be positioned within and in fluid communication with the ignition fuel chamber 20, such that fuel is supplied from the ignition fuel chamber 20 to the internal passage 50.

[0039] Figure 4A configuration of a fuel injector 12 is shown, which includes a valve member 16C, a metering inlet valve 60, a metering control valve 70, and an injection control valve 74. The valve member 16C may include a plug 56 or other seal at the proximal end 44, an internal passage 50, a fuel inlet orifice 54, and a fuel outlet orifice 52. The fuel inlet orifice 54 may be located within the nozzle 32, between the ignition fuel chamber 20 and the distal end 26. This configuration may also place the mixing volume 30 adjacent to the orifice 52 in the distal end 26. In some aspects, this configuration may omit the one-way valve 35 between the nozzle fuel passage 34 and the main fuel supply passage 36. However, if desired, the one-way valve 35 may be included in this configuration.

[0040] Control valve 74 may be an electronically controlled normally closed valve that selectively connects a control fluid (e.g., ignition fuel) discharge port 76 to a hydraulic control chamber 42 via a hydraulic discharge passage 80 and a flow rate regulating orifice 78. When closed, control valve 74 facilitates the discharge of pressurized fluid from a fluid source ( Figure 4 (Not shown) is supplied to hydraulic chamber 42, and this pressurized fluid applies hydraulic pressure to proximal end 44 as described above. When actuated (e.g., energized) and opened, control valve 74 can release the pressure acting on valve member 16C by connecting fluid discharge port 76 to hydraulic control chamber 42 via hydraulic discharge passage 80. For example, control valve 74 can be connected to discharge port 76, such as... Figure 4 As schematically shown, this is to facilitate the release of pressure from the hydraulic control chamber 42.

[0041] Metering valve 70 may be an electronically controlled normally closed valve that selectively connects a control fluid (e.g., ignition fuel) discharge port 72 to metering inlet valve 60 via a hydraulic discharge passage 66 and a port 68. When closed, metering valve 70 allows pressurized ignition fuel or another control fluid to act on the valve members of metering inlet valve 60. When actuated (e.g., energized) and opened, metering valve 70 may connect a hydraulic discharge passage 66 to control fluid discharge port 72. Control valve 70 may be connected to discharge port 72 to release pressure from the surface of valve 60, thereby allowing actuation of valve 60.

[0042] Valve 60 may include a spring-biased closed position (e.g.) Figure 4 The valve component (shown) is shown. Valve 60 may have an open position in which the valve component is lifted away from channel 64. Connection channel 62 may always be in communication with valve component 60.

[0043] The valve component of the metering inlet valve 60 may have an upper hydraulic surface (e.g., in...). Figure 4In the configuration shown (facing the spring), the upper hydraulic surface causes the metering inlet valve 60 to close when a high-pressure fluid is present. Valve 60 can be configured to open when the pressure of the fluid acting on the upper hydraulic surface decreases (e.g., by releasing pressure via passage 66 and outlet 72) and fluid from passage 62 lifts a component of valve 60 by acting on the lower hydraulic surface of valve 60.

[0044] When open, valve 60 facilitates communication between the ignition fuel chamber 20 and the internal passage 50. For example, when valve 60 is open, fluid can flow into the internal passage 50 through a path including a connecting passage 62, a supply passage 64, and one or more fuel inlet holes 54.

[0045] Figure 5 This is a partial schematic cross-sectional view of a fuel injector 12 used in conjunction with a solid valve member 16 and a metering inlet valve 60. In addition to the valve member 16, this configuration may also include the above-mentioned... Figure 4 The structure may also include a one-way valve 35 to prevent ignition fuel from flowing into the channel 36.

[0046] like Figure 5 As shown, the metering inlet valve 60 is in fluid communication with the supply channel 64, such that when the metering inlet valve 60 is open, ignition fuel from the ignition fuel chamber 20 flows into the supply channel 64. This fuel can be delivered to locations adjacent to the periphery of the solid valve member 16, such as distal end 26, as... Figure 5 As shown, or transported to... Figure 2B The position corresponding to the mixing volume 30 in the middle (e.g., when it is necessary to increase the mixing of the main fuel and the ignition fuel).

[0047] In the above embodiments (for example, corresponding to...) Figure 2A to Figure 5 In each of these embodiments, the ignition fuel can be supplied at a pressure higher than the main fuel pressure. This may be true in embodiments where the pressure of these fuels varies over time. In some aspects, the ignition fuel pressure can be about 1 MPa or 50 MPa. In at least some embodiments, ignition fuel pressures exceeding 50 MPa are also expected.

[0048] In some respects, the configuration of the metering inlet valve 60 enables operation in a single-fuel ignition mode (e.g., operation only with diesel fuel). This mode can be achieved by increasing the ignition fuel pressure from a dual-fuel operating level (e.g., about 35 MPa to about 60 MPa) to a single-fuel operating level (e.g., about 220 MPa). This can be achieved by controlling the ignition fuel pump 92 ( Figure 1 This is achieved by omitting the metering inlet valve 60 (e.g., Figure 2A to Figure 3BThe multi-fuel engine system 10 can be configured to operate in a restricted mode in which the internal combustion engine 100 operates at low power to provide motion or other restricted operation. The restricted mode can be a "limp" mode, in which the engine operates only by igniting the spark fuel but not at full power. Industrial applicability

[0049] The multi-fuel engine system 10 and fuel injector 12 can be used with any suitable internal combustion engine. In particular, the fuel injector 12 can be used with an engine 100 capable of operating with multiple fuels simultaneously. These fuels can be liquid and gaseous fuels, or different liquid fuels such as diesel and methanol. Examples of suitable internal combustion engines include engines for stationary machinery (e.g., generators or other power generation devices), mobile machinery (e.g., earthmoving equipment, tractor trucks, drilling rigs, etc.), or other applications. Internal combustion engines can generate electricity, propulsion power, and / or power to operate one or more implement systems (e.g., via hydraulics).

[0050] During one or more injection events, injector 12 can inject ignition fuel and main fuel into the combustion chamber of engine cylinder 102. Ignition fuel is supplied to fuel injector 12 via ignition fuel reservoir 90, ignition fuel pump 92, and common rail 94, while main fuel is supplied to injector 12 via main fuel reservoir 95, fuel pump 96, and common rail 98. After being at least partially mixed within injector 12, the fuel can be injected through a single set of nozzle orifices 38 in nozzle 32.

[0051] Figure 6 The flowchart includes an exemplary method 600 that can be performed during operation of system 10, which includes an internal combustion engine 100 and a fuel injector 12. During method 600, pressurized fuel can be received through two separate paths within the fuel injector 12. These two paths may include an ignition fuel path and a main fuel path, which are connected by a mixing volume located within the injector 12. The pressurized ignition fuel may replace at least some of the main fuel within the nozzle tip, such that the nozzle 32 includes a relatively high concentration of diesel fuel around the distal end 26. This may promote the injection of an amount of ignition fuel to initiate ignition (e.g., compression ignition via diesel fuel) and promote complete combustion of the main fuel at the desired engine timing.

[0052] Step 602 of method 600 may include supplying ignition fuel (e.g., liquid diesel fuel) to fuel injector 12. Figure 1As shown, ignition fuel can be pumped from ignition fuel reservoir 90 and supplied to common rail 94 via ignition fuel pump 92. Ignition fuel pump 92 can pressurize ignition fuel in the range of about 35 MPa to about 60 MPa, as measured within fuel rail 94 or within injector 12.

[0053] During step 602, ignition fuel can be supplied to the ignition fuel chamber 20 and the hydraulic control chamber 42. The ignition fuel can be supplied via the ignition fuel guide space 22 ( Figure 2A , 2B ), opening 46, internal channel 50, fuel outlet port 52 ( Figure 3A ), ignition fuel chamber 20, fuel inlet port 54, internal passage 50 and fuel outlet port 52 ( Figure 3B ), ignition fuel chamber 20, connecting channel 62, supply channel 64, one or more fuel inlet holes 54, internal channel 50 and fuel outlet hole 52 ( Figure 4 ), or ignite the fuel chamber 20, the connecting channel 62 and the supply channel 64 ( Figure 5 ) Supply to a mixed volume of 30.

[0054] Some configurations of the injector 12 can facilitate active metering control of the supply of pilot fuel within the injector 12 to the nozzle 32. As described above, active metering involves the actuation of electronically controlled valves of the injector 12. Therefore, active control can include generating commands (e.g., as electronic signals) to induce actuation of valve components included in the injector 12. These commands can be generated based on current or predicted engine conditions, such as boost pressure, intake manifold temperature, coolant temperature, etc. For example, active control can include the use of solenoid valves, such as electronically controlled metering valves 70.

[0055] Active control of ignition fuel metering can be achieved through the electronic control module of the multi-fuel engine system 10. When ignition fuel needs to be supplied to the nozzle 32, the control module can generate a signal to actuate the control valve 70, preventing pressurized fuel from being delivered to the valve control passage 66 and releasing pressure from the hydraulic surface of the metering inlet valve 60. This allows fuel from the ignition fuel chamber 20 to pass through the connecting passage 62 and lift the valve member of the metering inlet valve 60, thereby delivering fuel to the location adjacent to the distal end 26. During active control, the amount of ignition fuel supplied to the nozzle 32 is controlled based on the amount of time the metering valve 70 is actuated. The pressure difference between the ignition fuel and the main fuel when the metering inlet valve 60 is open can also affect the rate at which fuel flows from the connecting passage 62 to the supply passage 64. In some aspects, the electronic control module can take this pressure into account when generating the signal for actuating the metering valve 70. For example, when the ignition fuel pressure increases, the metering valve 70 can be actuated for a shorter period of time to inject a given amount of fuel.

[0056] Passive metering can include controlling the amount of ignition fuel supplied without generating commands to the valves of injector 12 that are only associated with metering the ignition fuel. Passive metering of the ignition fuel can be achieved using ignition fuel pump 92 and fuel pump 96 without including a solenoid valve for ignition fuel within the fuel injector 12. Figure 2A to Figure 3B During indirect control, the electronic control unit can generate commands for pumps 92 and 96 to set the corresponding pressures of the ignition fuel and main fuel. While these pressures can be adjusted to control the ratio of ignition fuel to main fuel, it is generally desirable to maintain the pressure of the ignition fuel above that of the main fuel. The pressure difference between the ignition fuel and the main fuel can be increased, for example, to inject a larger amount of ignition fuel.

[0057] Step 604 may include supplying main fuel to injector 12. Main fuel may be supplied to injector 12 from fuel reservoir 95 via fuel pump 96 and common rail 98, as described above. This may include supplying main fuel supply passage 36, check valve 35 (if present), and nozzle fuel passage 34 (…). Figure 2A to Figure 5 The main fuel is supplied to the mixing volume 30. As described above, the fuel pump 96 can pressurize the main fuel to a pressure ranging from about 1 MPa to about 50 MPa, or from about 35 MPa to about 60 MPa. Higher pressures are also possible. In at least some configurations, even if one or both of these pressures vary over time, the pressure of the main fuel can be maintained below the pressure of the ignition fuel.

[0058] Step 606 may include at least partially mixing the ignition fuel and the diesel fuel. As mentioned above, the pressure of the ignition fuel may be maintained at a pressure greater than that of the main fuel. Mixing may occur when the valve member is in the closed position and no fuel is injected. Therefore, when the ignition fuel encounters the main fuel, the ignition fuel may tend to replace the main fuel. Although the mixing location (e.g., mixing volume 30) may include the location where the ignition fuel and the main fuel meet when the ignition fuel is first introduced, the mixing location may extend further upstream along the main fuel path. For example, mixing may occur as far upstream of the one-way valve 35 ( Figure 2A to Figure 3B and Figure 5 Mixing does not require a uniform distribution of ignition fuel and main fuel. As used herein, the presence of a direct interface between the ignition fuel and the main fuel is considered as partial mixing of these fuels.

[0059] In some configurations ( Figure 4 and Figure 5 Fuel mixing can occur in step 606 due to the activation of the electronically controlled valve. For example, mixing can occur simultaneously with the discharge of fluid through the actuated valve 70, thereby allowing valve 60 to meter the ignition fuel. In other configurations ( Figure 2A to Figure 3B), mixing can occur when the ignition fuel passes through the ignition fuel guide space 22 ( Figure 2A and Figure 2B ) or exit from fuel outlet port 52 ( Figure 3A and Figure 3B This occurs when ( ).

[0060] Step 608 may include injecting the primary fuel and ignition fuel supplied and mixed in steps 602 through 606. Fuel injection can be performed by releasing pressure from the hydraulic control chamber 42, thereby allowing valve member 16 to lift and compress spring 18. This can be achieved using an electronically controlled valve (such as control valve 74) within the injector 12. Figure 4 and Figure 5 To execute. As mentioned above, although not in Figure 2A to Figure 3B As shown, however, control valve 74 may be present within injector 12 to allow the control module to generate a command that causes actuation of check valve assembly 16. When control valve 74 is actuated, the release of pressure from hydraulic control chamber 42 allows ignition of fuel lift valve assembly 16 within fuel chamber 20 and the initiation of fuel injection from nozzle opening 38.

[0061] During fuel injection, ignition fuel may be injected first, although a certain amount of main fuel may be mixed with this initial ignition fuel. The ignition fuel may initially be concentrated at the distal end 26 and the mixing volume 30, and may exit the nozzle 32 through one or more nozzle openings 38. After most or all of the ignition fuel has been injected, the main fuel may be injected through the nozzle openings 38. Combustion of the ignition fuel, for example by compression ignition, may produce a flame that burns the main fuel injected through the same set of openings 38.

[0062] The disclosed systems and methods enable the injection of two different types of fuel, including ignition fuel and main fuel, using a single fuel injector. The main fuel and ignition fuel can be pressurized and delivered to the injector via a corresponding common rail. Specifically, the disclosed systems and methods can provide a common rail dual-fuel injector with a single tip for injecting two different fuels from a single set of orifices. Furthermore, the injection of the two fuels can be achieved via a single check valve member at the distal end of the injector. Passive metering of the ignition fuel (e.g., diesel fuel) can be performed via the nozzle mating clearance or via a hollow check valve at the bottom of the tip. Active metering of the ignition fuel can be achieved using a solenoid valve if desired. Each configuration can facilitate fuel mixing prior to injection, while the fuel injected at the start of the injection event provides a sufficient amount of ignition fuel to initiate full ignition of the main fuel.

[0063] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed systems and methods without departing from the scope of this disclosure. Other embodiments of the system and methods disclosed herein will be apparent to those skilled in the art in light of the specification and the systems and methods described herein. This specification and embodiments are to be considered exemplary only, and the true scope of this disclosure is indicated by the appended claims and their equivalents.

Claims

1. A fuel injector (12) capable of injecting multiple different fuels in a single fuel injection event, said fuel injector (12) comprising: The nozzle (32) at the end of the fuel injector (12) has a tip; In the opening (38) at the tip of the nozzle (32), fuel is configured to be injected through the opening (38); Check valve (14) components (16, 16A, 16B, 16C) having a tip (26) located within the nozzle (32) and being movable between an injection position and a closed position, in which fuel is injected through the opening (38) and in the closed position, the opening (38) is closed. The main fuel path within the fuel injector (12) is configured to supply main fuel to the opening (38) in the tip of the nozzle (32). The ignition fuel path within the fuel injector (12) is configured to supply ignition fuel to the opening (38) in the tip of the nozzle (32). as well as A mixing volume (30) is located within the nozzle (32) and connects the main fuel path and the ignition fuel path when the check valve (14) components (16, 16A, 16B, 16C) are in the closed position.

2. The fuel injector (12) according to claim 1 further includes a one-way valve (35) configured to allow the main fuel to flow toward the mixing volume (30) and prevent the ignition fuel from flowing away from the mixing volume (30).

3. The fuel injector (12) according to any of the preceding claims, wherein the check valve (14) component (16) is completely solid.

4. The fuel injector (12) according to claim 3 further includes an ignition fuel inlet valve connected upstream of the mixing volume (30).

5. The fuel injector (12) according to claim 1 or claim 2, wherein the check valve member (16A, 16B, 16C) includes an internal passage (50) forming part of the ignition fuel path.

6. The fuel injector (12) according to claim 5, wherein the check valve member (16A) includes an open proximal end (44).

7. The fuel injector (12) according to claim 5, wherein the check valve member (16B, 16C) includes at least one fuel inlet hole (54) extending through the sidewall of the check valve (14) member (16B, 16C).

8. The fuel injector (12) according to claim 5 further includes an ignition fuel inlet valve (60) connected upstream of the internal passage (50).

9. A fuel injection method (600), comprising: Ignition fuel is supplied to the nozzle (32) of the fuel injector (12); The main fuel is supplied to the nozzle (32), and the ignition fuel is different from the main fuel; Before injecting the main fuel or the ignition fuel through the nozzle (32), the ignition fuel and the main fuel are at least partially mixed in the nozzle (32); and The ignition fuel and the main fuel are injected through a single set of openings (38) in the nozzle (32).

10. The fuel injection method (600) according to claim 9, wherein the ignition fuel is supplied to the fuel injector (12) via a common rail (94) and the main fuel is supplied to the fuel injector (12) via a common rail (98).

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