Fuel injector in an engine having an injection hole set configured for offset

Abstract

An engine (12) includes a piston (22) movable in a cylinder (18) and having a combustion bowl (72) and an annular rim (74) forming a scoop (78) extending axially symmetrically about a central axis of the piston. A fuel injector tip (80) extends into the cylinder and includes a first set of bores (82) and a second set of bores (88) offset from each other and from the piston center axis. A plurality of bore-edge distances are defined between bores (90) in the second bore set and the annular edge of the piston. The apertures of the second aperture group have a range of aperture sizes that vary directly in relation to the respective aperture-edge distance. Related methods are also disclosed.

Description

Technical Field

[0001] The present disclosure generally relates to an internal combustion engine having multiple groups of injection holes in a fuel injector, and more particularly to holes in a group of holes in a fuel injector, the holes having a range of hole sizes that vary directly with the distance to the piston edge. Background Art

[0002] Internal combustion engines are widely used worldwide for vehicle propulsion, power generation, liquid and gas processing, and many industrial applications. Fuel and air are burned within the engine cylinders to produce a rapid rise in pressure and temperature that drives a piston coupled to a crankshaft. Spark ignition engines typically employ liquid petroleum distillate fuels (such as gasoline) or gaseous fuels (such as natural gas, methane, propane, various mixtures), and in some applications even gaseous hydrogen. Compression ignition engines utilize fuels such as diesel distillate fuels, biodiesel, etc., which can auto-ignite with air during the compression stroke of the piston. Research investment in recent years has increasingly focused on the flexibility of engines in terms of fuel utilization, especially gaseous fuels.

[0003] Fuel prices tend to be dynamic, and gaseous fuels may have combustion or emission characteristics that are desirable to utilize. Certain engine platforms allow operation with either or both liquid fuel and gaseous fuel. Diesel fuel alone tends to be relatively easy to auto-ignite, but may have certain undesirable emissions. On the other hand, gaseous fuels may have a desirable emission profile, but may exhibit ignition problems such as misfires or knocking, or suffer from combustion stability issues. Such challenges may be particularly severe in so-called lean burn applications where gaseous fuel and air are burned at a lean equivalence ratio of stoichiometry.

[0004] Dual fuel engines can employ a pilot injection of liquid fuel combustion to ignite the main charge of gaseous fuel, and utilize combustion predictability and controllability to address some of these problems. In situations where the use of diesel is undesirable or unavailable, dual fuel engines can also employ a spark plug to ignite the gaseous fuel. Engineers continue to seek improved strategies for combustion phase control and other purposes in dual fuel and other engines, including an extended ability to operate in a so-called diesel-only mode. An exemplary dual fuel engine is described in Coldren's European Patent No. 1275840A2. Summary of the Invention

[0005] In one aspect, an engine includes an engine housing having cylinders formed therein, and pistons movable within the cylinders and including combustion bowls, and annular edges extending circumferentially about the combustion bowls and defining piston center axes. The engine further includes a fuel injector tip having a first set of holes and a second set of holes, the first set of holes including a plurality of holes arranged in a first targeting pattern and distributed about a first tip axis within the cylinder, and the second set of holes including a plurality of holes arranged in a second targeting pattern and distributed about a second tip axis. The second tip axis is offset from the piston center axis such that in a projection plane perpendicular to the piston center axis, a plurality of hole-edge distances are defined between the plurality of holes in the second set of holes and the annular edge. The plurality of holes in the second set of holes have a range of hole sizes that vary directly in relation to the respective hole-edge distances.

[0006] In another aspect, a method of operating an engine includes moving a piston defining a piston center axis toward a top dead center position within a cylinder in the engine, and injecting a first injection of liquid fuel from a sub-set of holes offset from the piston center axis in a fuel injector tip into the cylinder. The method further includes advancing a jet stream of the first injection through the cylinder according to a targeting pattern based on the arrangement of the sub-set of holes in the fuel injector tip and according to a penetration pattern based on varying sizes of the holes in the sub-set of holes. The method further includes injecting a second injection of liquid fuel from a main set of holes in the fuel injector tip into the cylinder, and advancing a jet stream of the second injection through the cylinder. The method further includes compressing and igniting the liquid fuel of the first injection and the second injection within the cylinder.

[0007] In yet another aspect, a fuel injector includes a nozzle having an injector tip with a main tip portion and a sub-tip portion, a main set of holes formed in the main tip portion, and a sub-set of holes formed in the sub-tip portion. The nozzle further has at least one liquid fuel supply passage formed therein, the at least one liquid fuel supply passage extending to the main set of holes and the sub-set of holes. The main tip portion defines a first tip axis, and the sub-tip portion defines a second tip axis offset from the first tip axis. The main set of holes includes a plurality of holes arranged in a first targeting pattern about the first tip axis, and the sub-set of holes includes a plurality of holes arranged in a second targeting pattern about the second tip axis. The plurality of holes in the sub-set of holes have a range of injection angles and a range of hole sizes that vary directly in relation to the respective injection angles. Description of the Drawings

[0008] Figure 1 is a schematic view of an internal combustion engine system according to one embodiment;

[0009] Figure 2 is a schematic cross-sectional side view of a fuel injector nozzle according to an embodiment;

[0010] Figure 3 is a schematic end view of a fuel injector tip according to an embodiment;

[0011] Figure 4 is a schematic view of a fuel injector and a piston in a cylinder according to an embodiment, showing an injection stream of injected fuel; and

[0012] Figure 5 is a graph showing heat release in a combustion cycle according to different fuel injector configurations. DETAILED DESCRIPTION

[0013] Referring to Figure 1 , there is shown an internal combustion engine system 10 according to an embodiment. The engine system 10 includes an internal combustion engine 12 having an engine housing 14, the engine housing including a cylinder block 16 and an engine head 20 attached to the cylinder block 16. The cylinder block 16 has a plurality of combustion cylinders 18 formed therein. In the illustrated embodiment, two cylinders 18 are shown and may be constructed substantially identically to each other, and thus the description and discussion herein of the cylinder 18 or related components in the singular will be understood to refer, by analogy, to any cylinder and related components in the engine 12. The engine 12 may include any number of cylinders in any suitable arrangement, such as an in-line type, a V-type, etc. A plurality of pistons 22 are each movable within one of the cylinders 18 and may be constructed in cooperation with the fuel injectors, as further discussed herein.

[0014] The engine system 10 also includes a fuel system 26 having a liquid fuel supply 28, a low-pressure pump 30, a high-pressure pump 32, and a common rail 34 or other pressurized fuel reservoir that houses pressurized liquid fuel for delivery to a plurality of direct fuel injectors 36. Each fuel injector 36 may be positioned to extend partially into one of the cylinders 16. As further discussed herein, the fuel injectors 36 may be uniquely configured for improved controllability of the heat release rate and combustion phase during combustion. The liquid fuel supply 28 may include any suitable compression ignition liquid fuel, such as liquid diesel distillate fuel, a higher octane fuel with a cetane enhancer, etc. Different from a common rail implementation, the fuel system 26 may include so-called unit pumps, each unit pump constructed with, for example, a hydraulically actuated or cam-actuated fuel pressurization plunger.

[0015] The fuel system 26 also includes a gaseous fuel supply 38. The gaseous fuel supply 38 can accommodate or receive a feed of any suitable gaseous fuel, such as natural gas, methane, ethane, biogas, various mixtures thereof (including hydrogen mixtures), and the like. A delivery pump 40 is fluidly connected to the gaseous fuel supply 38 and conveys the cryogenically stored liquefied form of the gaseous fuel to a vaporization and pressurization device 42. The vaporized and pressurized gaseous fuel can then be conveyed to a gaseous fuel conduit that extends to a plurality of gaseous fuel inlet valves 48. Any means of providing the gaseous fuel can be used, including pressurized gaseous fuel stored or received in gaseous form or cryogenically stored liquefied gaseous fuel such as liquefied natural gas (LNG).

[0016] The engine system 10 also includes a fresh air inlet 50 configured to receive ambient air for conveyance to the engine 12 through a compressor 52 in a turbocharger 54. Compressed air can be fed through an aftercooler 56 to an intake manifold 58 and then to a plurality of intake flow passages 60, each intake flow passage extending to one of the cylinders 18. In the illustrated embodiment, the gaseous fuel inlet valves 48 are fluidly connected to the intake flow passages 60. In other embodiments, the gaseous fuel can be delivered by fumigation into the turbocharger 54, port injection, manifold injection, or direct injection into the cylinders 16. Exhaust from combustion in the cylinders 16 is conveyed through an exhaust conduit 64 to a turbine 62 in the turbocharger 54. A post-treatment device (not shown) can be positioned to receive the exhaust from the turbine 62. A plurality of intake valves 66 and a plurality of exhaust valves 68 can be supported in the engine cover 20 and operated according to any suitable strategy, any suitable strategy including conventional four-cycle operation, or a variable valve timing strategy, such as so-called intake valve late closing. An electronic control module or ECM 70 is in control communication with the fuel injectors 36, with the fuel inlet valves 48, and potentially with other electronically controlled or electronically monitored components in the engine system 10.

[0017] Each piston 22, referred to hereinafter in the singular, is movable within a respective cylinder 18 and includes a combustion bowl 72 and an annular edge 74 that extends circumferentially around the combustion bowl 72 and defines a piston central axis 76. Now also referring to Figure 2 , each fuel injector 36 (in Figure 2shown and also referred to herein in the singular) includes a nozzle 37 having a fuel injector tip 80 extending into the cylinder 18. The fuel injector tip 80, sometimes referred to interchangeably herein with the nozzle 37, includes a first orifice group 82 having a plurality of orifices 84 arranged in a first targeting pattern and distributed about a first tip axis 86 within the cylinder 18. The fuel injector tip 80 further includes a second orifice group 88 having a plurality of orifices 90 arranged in a second targeting pattern different from the first targeting pattern and distributed about a second tip axis 92. The first orifice group 82 may include a main orifice group, such as a second or main injection that may be used to inject liquid fuel during an engine cycle. The second orifice group 88 may include a pilot orifice group configured to inject a first or pilot injection of liquid fuel at an earlier time during the engine cycle. The terms "first," "second," "main," "pilot," and like terms are used herein for descriptive convenience and do not require or imply any particular structure, size, or order of operation. Generally, the "main" orifice group 82 will be larger in size than the "pilot" orifice group 88 and provide a larger sized fuel injection, but the present disclosure is not limited thereto.

[0018] In one embodiment, the first or pilot injection is smaller and may be injected approximately 60° before the top dead center position of the piston 18, and the second or main injection is larger and may be injected only a few degrees at or before the top dead center position of the piston 22 during the engine cycle. In some embodiments, both the first orifice group 82 and the second orifice group 88 may be used to inject the first and second injections simultaneously, such as at the top dead center position of the piston 22 in a diesel-only mode. However, in a typical case, the diesel-only mode includes a first injection of each engine cycle using the second orifice group 88 and a subsequent larger injection using the first orifice group 82. In a dual fuel mode, generally the second orifice group 88 will be used to inject an early ignition injection and also for a subsequent larger main injection at approximately top dead center. Combustion of the liquid fuel injected in the dual fuel mode triggers ignition of a larger main charge of gaseous fuel.

[0019] As discussed herein, the targeting pattern refers to the pattern through the space defined by the orifices in the respective first orifice group 82 and second orifice group 88. The first targeting pattern may differ from the second targeting pattern based on at least one of a varying injection angle, a difference between the respective orifice groups, or a varying orifice-to-orifice spacing within the respective orifice groups. As further discussed herein, the first targeting pattern may include a wider injection angle 102, and the second targeting pattern may include at least one narrower injection angle 104 and 106. The number of orifices in the first orifice group 82 may be from 5 to 7, typically a total of 6, and the number of orifices in the second orifice group 88 may include from 3 to 5, typically a total of 4.

[0020] The fuel injector tip 80 may also include a first or primary tip portion 94 having a first set of holes 82 formed therein, and a second or secondary tip portion 96 having a second set of holes 88 formed therein. The fuel injector 36 may also include a first check member 98 and a second check member 100 movable within the fuel injector tip 80 and configured to open and close the first set of holes 82 and the second set of holes 88. The check members 98 and 100 may be electrically actuated, such as by a solenoid-operated pilot valve. The common rail 34 may feed liquid fuel to each respective fuel injector 36 through a plurality of liquid fuel supply pipes (not numbered) such that liquid fuel at the same pressure may be supplied simultaneously to each of the first tip portion 94 and the second tip portion 96. The fuel injector 36 includes at least one liquid fuel supply passage 39 extending to the first set of holes 82 and the second set of holes 88.

[0021] Turning now also to Figure 3 , a fuel injector 36 including a nozzle 37 is shown in relation to a schematic illustration of the scoop portion 78. The fuel injector 36 and the fuel injector tip 80 may be understood to define a fuel injector center axis which, when the fuel injector 36 is installed in the engine cover 20 for service, will generally be collinear with the piston center axis 76. Thus, the fuel injector center axis is shown in Figure 3 with the reference numeral 76. The primary tip portion 94 defines a first tip axis 86, and the secondary tip portion 96 defines a second tip axis 92. The second tip axis 92 is offset from the first tip axis 86 and offset from the piston center axis and the fuel injector center axis 76 such that in a projection plane perpendicular to the axis 76, a plurality of different hole-edge distances 110 and 112 are defined between the holes 90 in the second set of holes 88 and the annular edge 74. The second set of holes 88 may include smaller holes 114 at a radially outward position relative to the axis 76 and larger holes 116 at a radially inward position relative to the axis 76.

[0022] As can be understood from the drawings and the accompanying description, the offset sub-tip portion 96 and the holes 90 in the second hole group 88 position the holes 90 at different distances from the annular piston edge 74, particularly at different distances from the scoop portion 78. Based on the different distances separating the holes 90 from the scoop portion 78 when fuel is injected, individual fuel injection streams have different travel distances to reach the scoop portion 78, depending on the angular orientation about the second tip axis 92. In the absence of the present disclosure, and with holes of uniform size and arrangement, it would be expected that the individual injection streams of fuel injected at a given injection pressure would reach or approach the scoop portion 78 at different times during the engine cycle, such that some of the injection streams would fail to enter the scoop portion 78, enter the scoop portion 78 too soon, or enter the scoop portion 78 too late. It is generally desirable for earlier injected combustion or pre-combustion to occur relatively uniformly within the scoop portion 78. According to the present disclosure, it is expected that the injection streams from the second hole group 88 will reach the scoop portion 78 approximately simultaneously.

[0023] To this end, the plurality of holes 90 in the second hole group 88 have a range of hole sizes that vary directly in relation to the respective hole-edge distances 110 and 112. Thus, the larger holes 116 are associated with the larger hole-edge distance 110. The smaller holes 114 are associated with the smaller hole-edge distance 112. The larger size of the larger holes 116, compared to the smaller holes 114, can contribute to a greater momentum of the injection stream and thus a faster and greater penetration into the cylinder 18, which compensates for the larger hole-edge distance 110. In the illustrated embodiment, the injection holes 84 in the primary hole group 82 have a uniform size and a uniform injection angle. The holes 90 can have a total of two different sizes and a total of two different injection angles, such as the injection angles 104 and 106 depicted in Figure 2 Considering the shorter hole-edge distance 112 and the smaller jet penetration from the smaller holes 114, the relatively narrower injection angle 106, compared to the injection angle 104, can help to target the respective injection stream to the scoop portion 78. The injection angle 102 can be greater than the injection angles 104 and 106. The plurality of holes 90 in the second injection hole group 88 can have a range of injection angles (at least one relatively narrow injection angle) that vary directly in relation to the respective hole-edge distances. In various extensions, more than two different injection angles can be used in the sub-hole group. Similarly, more than two different sizes can be used in the sub-hole group. Thus each individual hole can be adjusted to an injection angle, size, hole-to-hole spacing, and potentially even an exit orientation based on its respective hole-edge distance. Generally, the plurality of holes 90 in the second hole group 88 have a range of hole sizes that vary directly in relation to the respective injection angles.

[0024] Now also referring to Figure 4 it can be seen that the piston 22 includes an outer edge surface 77 and an inner edge surface 79 that forms the scoop portion 78. In Figure 4 the illustration in Figure 3The illustration is flipped left - right. The outer edge surface 77, the inner edge surface 79, and the spoon portion 78 can each extend axially symmetrically about the piston central axis 76 and about the combustion bowl 72. At Figure 4 the piston 22 is shown at approximately 60° before top dead center position as it may appear in the engine cycle. The injection streams 118 and 120 of the first injection have advanced from the larger hole 116 and the smaller hole 114 respectively. The injection stream 120 can be injected at a more narrow injection angle 106 than the injection angle 104 of the injection stream 118. Both the injection streams 118 and 120 can be targeted at the spoon portion 78, so the second targeting pattern discussed herein can include a spoon - targeting pattern that enters the spoon portion 78 when the piston 22 is between the bottom dead center position and the top dead center position. When the piston 22 is at the top dead center position, the second targeting pattern can include a bowl - targeting pattern that enters the combustion bowl 72.

[0025] From the state depicted in Figure 4 the piston 22 can move upward toward its top dead center position, at which time a main injection of liquid fuel can be injected through the first orifice group 82. At or closer to top dead center, the liquid fuel of the early injection and the main injection is compression - ignited. Now also turning to Figure 5 , a graph 200 is shown, depicting the heat release rate for different scenarios, where "EP" represents the early ignition or first injection of liquid fuel, and the main injection of liquid fuel is injected at or near "TDC". The trace 210 shows the heat release that might be expected using a dual - outlet check valve as discussed herein but with secondary holes of uniform size and injection angle. Thus, the trace 210 shows the result that might be expected if the first injection of liquid fuel is injected using a fuel injector with a group of secondary holes offset from the piston central axis and having uniform size and uniform injection angle. Another trace 220 shows the target or optimal heat release at the highest amplitude at approximately TDC. The third heat release trace 230 shows the result that might be expected according to the present disclosure. Thus, from Figure 5 it can be seen that the present disclosure is close to the optimal heat release rate, and it can be expected that a method such as in the trace 210 is delayed in heat release beyond the TDC position.

[0026] Industrial applicability

[0027] Generally referring to the drawings, operating the engine system 10 can include moving the piston 22 toward the top dead center position in the cylinder 18. After passing through the bottom dead center position, but before reaching the top dead center position, the fuel injector 36 can be operated to inject a first injection of liquid fuel from the sub-orifice group 88 into the cylinder 18. The injection stream of the first injection can advance through the cylinder 18 according to a targeting pattern based on the arrangement of the sub-orifice group 88 in the fuel injector tip 80. The advancement of the injection stream of the first injection can also occur according to a penetration pattern based on the varying sizes of the orifices in the sub-orifice group 88. Thus, according to the present disclosure, the injection stream from the larger orifices can penetrate relatively faster than the injection stream from the relatively smaller orifices.

[0028] At or near the time point when the piston 22 reaches the top dead center position, a second injection of liquid fuel can be injected from the main orifice group 82 into the cylinder 18. The injection stream of the second injection can advance through the cylinder 18 and generally begins to burn when leaving the fuel injector tip 80 or shortly thereafter. The liquid fuel of the first injection and the second injection is compressed and ignited in the cylinder 18.

[0029] This specification is for illustrative purposes only and should not be construed as limiting the scope of the present disclosure in any way. Thus, those skilled in the art will understand that various modifications can be made to the presently disclosed embodiments without departing from the full and reasonable scope and spirit of the present disclosure. Other aspects, features, and advantages will become apparent by viewing the drawings and the appended claims. As used herein, the articles "a" and "an" are intended to include one or more items and can be used interchangeably with "one or more". When intending to indicate only one item, the term "one" or similar language is used. Additionally, as used herein, the terms "has", "have", "having", etc. are intended to be open-ended terms. Further, the phrase "based on" is intended to mean "at least partially based on" unless otherwise expressly stated.

Claims

1. An engine (12), comprising: An engine housing (14) having cylinders (18) formed therein; A piston (22) movable within the cylinders and including a combustion bowl (72), and an annular edge (74) extending circumferentially around the combustion bowl and defining a piston central axis; A fuel injector tip (80) including a first orifice group (82) and a second orifice group (88), the first orifice group having a plurality of orifices (84) arranged in a first targeting pattern within the cylinder and distributed around a first tip axis, the second orifice group having a plurality of orifices (90) arranged in a second targeting pattern and distributed around a second tip axis; The second tip axis is offset from the piston central axis such that in a projection plane perpendicular to the piston central axis, a plurality of orifice-edge distances are defined between the plurality of orifices in the second orifice group and the annular edge; and The plurality of orifices in the second orifice group have an orifice size range that varies directly in relation to the respective orifice-edge distances.

2. The engine according to claim 1, wherein: The annular edge includes an outer edge surface (77) and an inner edge surface (79), the inner edge surface forming a scoop portion (78) extending axially symmetrically around the piston central axis; The piston is movable between a bottom dead center position and a top dead center position within the cylinder; The first targeting pattern includes a bowl targeting pattern that enters the combustion bowl when the piston is at the top dead center position; and The second targeting pattern includes a scoop portion targeting pattern that enters the scoop portion when the piston is between the bottom dead center position and the top dead center position.

3. The engine according to claim 1 or 2, wherein the first targeting pattern includes a wider injection angle, and the second targeting pattern includes at least one narrower injection angle; and The at least one narrower injection angle includes an injection angle range that varies directly in relation to the respective orifice-edge distances.

4. The engine according to claim 1, wherein: The plurality of orifices in the second orifice group include smaller orifices (114) at a radially outward position relative to the piston central axis, and larger orifices (116) at a radially inward position relative to the piston central axis; and The number of orifices in the second orifice group is from 3 to 5.

5. The engine according to any one of claims 1-4, wherein the second tip axis is offset from the first tip axis, and further includes a first check member (98) and a second check member (100) movable within the fuel injector tip and configured to open and close the first orifice group and the second orifice group, respectively.

6. The engine according to claim 5, further comprising a pressurized liquid fuel supply (28), a liquid fuel supply pipe fluidly connecting the pressurized liquid fuel supply to the fuel injector tip, a gaseous fuel supply (38), and a gaseous fuel inlet valve (48) fluidly positioned between the gaseous fuel supply and the cylinder.

7. A method of operating an engine (12), comprising: Moving a piston (22) defining a piston central axis towards a top dead center position in a cylinder (18) in the engine (12); Injecting a first injection of liquid fuel from a sub - hole group (38) offset from the piston central axis in a fuel injector tip (80) into the cylinder; Advancing an injection stream of the first injection through the cylinder according to a targeting pattern based on the arrangement of the sub - hole group in the fuel injector tip and according to a penetration pattern based on varying sizes of holes in the sub - hole group; Injecting a second injection of liquid fuel from a main - hole group (82) in the fuel injector tip into the cylinder; Advancing an injection stream of the second injection through the cylinder; and Compressing and igniting the liquid fuel of the first injection and the second injection in the cylinder.

8. The method according to claim 7, wherein advancing the injection stream of the first injection includes advancing the injection stream towards a scoop portion (78) formed in an edge (74) of the piston, and advancing the injection stream of the second injection includes advancing the injection stream into a combustion bowl (72) in the piston; and The targeting pattern includes at least one of a varying injection angle or a varying spacing of a plurality of holes in the sub - hole group.

9. The method according to claim 8, wherein the sub - hole group includes smaller holes (114) at a radially outward position relative to the piston central axis and larger holes (116) at a radially inward position relative to the piston central axis; and The plurality of holes in the sub - hole group are arranged in an injection - angle range that varies directly in relation to a hole - edge distance defined between each respective hole in the plurality of holes and the scoop portion.

10. The method according to any one of claims 7 - 9, wherein: Injecting the first injection includes injecting the first injection through the sub - hole group in a sub - tip portion (96) of a fuel injector (36), and injecting the second injection includes injecting the second injection through the main - hole group in a main - tip portion (82) of the fuel injector, the main - tip portion being offset from the sub - tip portion; And Injecting the first injection includes injecting a smaller amount of the liquid fuel, and injecting the second injection includes injecting a larger amount of the liquid fuel.

11. A fuel injector (36), comprising: A nozzle (37), the nozzle including an injector tip (80) having a main - tip portion (94) and a sub - tip portion (96), a main - hole group (82) formed in the main - tip portion (94), and a sub - hole group (88) formed in the sub - tip portion; The nozzle further has at least one liquid - fuel supply passage (39) formed therein, the at least one liquid - fuel supply passage extending to the main - hole group and the sub - hole group; The main - tip portion defines a first tip axis, and the sub - tip portion defines a second tip axis offset from the first tip axis; The main hole group includes a plurality of holes (84) arranged in a first targeting pattern around the first tip axis, and the secondary hole group includes a plurality of holes (90) arranged in a second targeting pattern around the second tip axis; The plurality of holes in the secondary hole group have a range of injection angles and a range of hole sizes that vary directly with the respective injection angles.

12. The fuel injector according to claim 11, wherein the first targeting pattern includes a wider injection angle and the second targeting pattern includes at least one narrower injection angle.

13. The fuel injector according to claim 11 or 12, wherein a fuel injector central axis is defined between the first tip axis and the second tip axis, and the plurality of injection holes in the secondary hole group include smaller holes (114) at a radially inward position relative to the fuel injector central axis and larger holes (116) at a radially outward position relative to the fuel injector central axis.

14. The fuel injector according to any one of claims 11-13, wherein the plurality of injection holes in the main hole group are 5 to 7 in number and have a uniform size and a uniform injection angle, and the plurality of injection holes in the secondary hole group are 3 to 5 in number and have a total of two different sizes and a total of two different injection angles.

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