Diesel engine with dual fuel injection

Abstract

The present application relates to a diesel engine with dual fuel injection. Methods and systems for supplying fuel to a diesel engine during a cycle of a cylinder are described. In one example, fuel is supplied to a cylinder via two fuel injectors having different fuel flow rates. The two fuel injectors may be arranged opposite to each other, or arranged so that the fuel spray from one injector intersects and collides with the fuel spray from the other injector.

Description

Technical Field

[0001] The present invention relates to a diesel engine with dual fuel injection. Background Art

[0002] A diesel engine may include a turbocharger that increases the engine power output performance. A turbocharger may supply pressurized air to the engine so that the cylinder charge mass may be increased to increase the engine output power. However, the engine may also operate at low engine air flow and boost pressure when the vehicle driver does not request torque to propel the vehicle. In addition, a diesel engine may operate within a wide lean air-fuel ratio operating range. Therefore, a diesel fuel injector may have to supply a wide range of fuel amounts to provide a desired air-fuel ratio within a range of operating conditions. Therefore, the size of the diesel fuel injector is set to supply fuel at high engine loads and low engine loads. Nevertheless, due to the kinematics within the fuel injector and due to the fuel injector supplying a wide range of fuel injection amounts, it may be difficult to provide a small and accurate amount of fuel. One or more small fuel injection amounts may be supplied to the cylinder during the cylinder cycle to reduce combustion noise and control the heat release of the fuel being burned. A small fuel injection amount (which may be referred to as a pilot injection) may be injected during the cylinder cycle, and the pilot injection may be before the main fuel injection during the cylinder cycle. If the pilot fuel injection amount is not accurate, engine combustion noise and hydrocarbon emissions may increase. Summary of the invention

[0003] The inventors herein have recognized the above-mentioned shortcomings and have developed an engine system comprising: an engine including at least one cylinder; a first diesel fuel injector supplying fuel to the at least one cylinder; and a second diesel fuel injector supplying fuel to the at least one cylinder, the second diesel fuel injector being a higher fuel flow rate injector compared to the first diesel fuel injector.

[0004] By supplying diesel fuel to a diesel engine via two different diesel fuel injectors having two different diesel fuel flow rates, it is possible to supply an accurate amount of diesel fuel during a pilot fuel injection and to meet the diesel fuel injection amount at a higher engine load. Specifically, the pilot fuel injection may be provided by a lower flow fuel injector, and the main fuel injection amount may be provided by a higher flow fuel injector. Additionally, when the fuel injection time may be short, both the low fuel flow injector and the higher fuel flow injector may supply the main fuel injection pulse to provide a desired engine air-fuel ratio at a higher engine load and a higher engine speed. In this way, the accuracy of injecting small and large fuel amounts during a cylinder cycle may be improved.

[0005] The present description may provide several advantages. In particular, the method may reduce engine emissions by improving the accuracy of the amount of fuel delivered during a cylinder cycle. In addition, the method may reduce engine combustion noise. In addition, the method may provide more consistent engine operation.

[0006] The above and other advantages and features of the present specification will become apparent from the following detailed description taken alone or in conjunction with the accompanying drawings.

[0007] It should be understood that the above summary is provided to introduce selected concepts in a simplified form, which will be further described in the detailed description. This is not meant to identify key or important features of the claimed subject matter, the scope of which is solely defined by the appended claims. In addition, the claimed subject matter is not limited to embodiments that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of an engine is shown;

[0009] Figure 2 shows the fuel injection into Figure 1 A schematic diagram of a cylinder of the engine shown;

[0010] FIG. 3A to FIG. 3C A diagram showing a fuel injection spray pattern for an engine cylinder;

[0011] Figure 4 shows a cross-sectional view of an opposed piston engine;

[0012] Figure 5 shows a cross-sectional view of an opposed piston engine;

[0013] Figure 6 A view showing the pistons of an opposed piston engine;

[0014] 7A to 7H Example fuel injection timing is shown;

[0015] Figure 8 A flow chart illustrating an example method for adjusting fuel injection timing; and

[0016] Fig. 9 An example fuel injection sequence with close coupled pilot fuel injection and post fuel injection is shown.

[0017] Figures 2 to 6 Shown approximately to scale. DETAILED DESCRIPTION

[0018] The present description relates to supplying fuel to a diesel engine. Figure 1 An example of a boosted diesel engine is shown. Figure 2 and Figure 3A Shown are two views of a fuel injector spray pattern that can reduce engine emissions and increase engine oil life. Figure 3B and Figure 3C Two additional fuel spray patterns are shown. Figure 4 An opposed piston two-cycle diesel engine is shown including two fuel injectors per engine cylinder. Figure 5 Shows Figure 4 A cross-sectional view of the engine shown. Figure 6 Shows Figure 4 Detailed view of the engine piston shown. Example fuel injection timing for a diesel engine including two fuel injectors 7A to 7H A flow chart of a method for injecting fuel into a diesel engine via two fuel injectors is shown in Figure 8 Shown in. Figure 8 The method can provide Fig. 9 Close coupled pilot fuel injection and post fuel injection are shown.

[0019] See also Figure 1 , an internal combustion engine 10 (comprising a plurality of cylinders, one cylinder of the internal combustion engine being Figure 1 ) is controlled by an electronic engine controller 12. The controller 12 is controlled by Figure 1 The various sensors receive signals and take actions based on the received signals and the instructions stored in the memory of the controller. Figure 1 A variety of actuators adjust engine operation.

[0020] Engine 10 includes combustion chamber 30 and cylinder walls 32, with piston 36 positioned therein and connected to crankshaft 40. Cylinder head 13 is secured to engine block 14. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54. Each intake valve and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. However, in other examples, the engine may operate the valves via a single camshaft or pushrods. The position of intake cam 51 may be determined by intake cam sensor 55. The position of exhaust cam 53 may be determined by exhaust cam sensor 57.

[0021] Fuel injectors 68 and 69 are shown positioned in cylinder head 13 to inject fuel directly into combustion chamber 30, which is known to those skilled in the art as direct injection. Fuel is delivered to fuel injectors 68 and 69 by a fuel system including fuel tank 95, fuel pump 91, fuel pump control valve 93, and a fuel rail (not shown). The fuel pressure delivered by the fuel system can be adjusted by changing a position valve that regulates flow to the fuel pump (not shown). In addition, a metering valve can be located in or near the fuel rail for closed-loop fuel control. The pump metering valve can also regulate the fuel flow to the fuel pump, thereby reducing the fuel pumped to the high-pressure fuel pump.

[0022] The intake manifold 44 is shown in communication with an optional electronic throttle 62, which adjusts the position of the throttle plate 64 to control the air flow from the intake boost chamber 46. The compressor 162 draws air from the air intake device 42 to supply the boost chamber 46. The exhaust gas rotates the turbine 164, which is coupled to the compressor 162 via the shaft 161. In some examples, a charge air cooler may be provided. The compressor speed may be adjusted by adjusting the position of the variable vane control 72 or the compressor bypass valve 158. In an alternative example, the wastegate 74 may replace the variable vane control 72, or the wastegate 74 may be used in addition to the variable vane control 72. The variable vane control 72 adjusts the position of the variable geometry turbine vane. When the vane is in the open position, the exhaust gas can pass through the turbine 164, thereby supplying very little energy to rotate the turbine 164. When the vane is in the closed position, the exhaust gas can pass through the turbine 164 and apply increased force to the turbine 164. Alternatively, wastegate 74 or a bypass valve allows exhaust gas to flow around turbine 164 to reduce the amount of energy supplied to the turbine. Compressor bypass valve 158 allows compressed air at the outlet of compressor 162 to return to the inlet of compressor 162. In this way, the efficiency of compressor 162 can be reduced to affect the flow of compressor 162 and reduce the possibility of compressor surge.

[0023] Combustion is initiated in combustion chamber 30 when fuel auto-ignites during a compression stroke as piston 36 approaches top dead center. In some examples, universal exhaust gas oxygen (UEGO) sensor 126 may be coupled to exhaust manifold 48 upstream of emissions device 70. In other examples, the UEGO sensor may be located downstream of one or more exhaust aftertreatment devices. Additionally, in some examples, the UEGO sensor may be replaced with a NOx sensor having both a NOx sensing element and an oxygen sensing element.

[0024] At lower engine temperatures, glow plug 66 can convert electrical energy into heat energy to increase the temperature in combustion chamber 30. By increasing the temperature of combustion chamber 30, the cylinder air-fuel mixture can be more easily ignited via compression.

[0025] In one example, the emission device 70 may include an oxidation catalyst and a particulate filter. In another example, multiple emission control devices may be used, each with multiple bricks. In one example, the emission device 70 may include an oxidation catalyst. In other examples, the emission device may include a lean NOx trap or a selective catalytic reducer (SCR) and / or a diesel particulate filter (DPF). Exhaust temperature measurements are provided upstream of temperature sensor 79 and downstream of temperature sensor 81 to determine changes in exhaust temperature across the emission device 70.

[0026] Exhaust gas recirculation (EGR) may be provided to the engine via EGR valve 80. EGR valve 80 is a valve that closes or allows exhaust gas to flow from downstream of exhaust 70 to a location in the engine's air intake system upstream of compressor 162. In an alternate example, EGR may flow from upstream of turbine 164 to intake manifold 44. EGR may bypass EGR cooler 85, or, alternatively, EGR may be cooled by passing through EGR cooler 85. In other examples, a high pressure EGR system and a low pressure EGR system may be provided.

[0027] Figure 1 The controller 12 shown is a conventional microcomputer that includes: a microprocessor unit (CPU) 102, input / output ports (I / O) 104, read-only memory (ROM) (e.g., non-volatile memory) 106, random access memory (RAM) 108, keep-alive memory (KAM) 110, and a conventional data bus. In addition to those signals previously discussed, the illustrated controller 12 receives various signals from sensors coupled to the engine 10, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling jacket 114; position sensor 134 coupled to accelerator pedal 130 for sensing accelerator pedal position (PP) modulated by a human foot 132; measurement of engine manifold pressure (MAP) from pressure sensor 121 coupled to intake manifold 44; boost pressure from pressure sensor 122; exhaust oxygen concentration from oxygen sensor 126; engine position sensor from Hall effect sensor 118 sensing position of crankshaft 40; measurement of air mass entering the engine from sensor 120 (e.g., a hot wire air flow meter); and measurement of throttle position from sensor 58. Barometric pressure may also be sensed (sensor not shown) for processing by controller 12. In a preferred aspect of the present description, engine position sensor 118 produces a predetermined number of equally spaced pulses per revolution of the crankshaft from which engine speed (RPM) can be determined.

[0028] During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. Typically during the intake stroke, exhaust valve 54 is closed and intake valve 52 is opened. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its largest volume) is typically referred to by those skilled in the art as bottom dead center (BDC). During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its smallest volume) is typically referred to by those skilled in the art as top dead center (TDC). In a process herein referred to as injection, fuel is introduced into the combustion chamber. In some examples, fuel may be injected into a cylinder multiple times during a single cylinder cycle.

[0029] In a process referred to herein as ignition, the injected fuel is ignited by compression ignition to cause combustion. During the expansion stroke, the expanding gases push the piston 36 back to BDC. The crankshaft 40 converts the piston motion into a rotational torque of the rotating shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air-fuel mixture to the exhaust manifold 48, and the piston returns to TDC. Note that the above is only for example, and the intake and exhaust valve opening and / or closing timing may be changed, such as to provide positive or negative valve overlap, delayed intake valve closing, or various other examples. In addition, in some examples, a two-stroke cycle may be used instead of a four-stroke cycle.

[0030] See now Figure 2 , showing the injection of fuel into Figure 1 Detailed schematic diagram of a cylinder of an engine of FIG. In this example, fuel injector 69 and fuel injector 68 are positioned at right angles (e.g., 90 degrees) relative to the longitudinal direction of the two injectors, but the fuel injectors may be positioned at any angle relative to each other that at least partially reduces the spray range of the fuel injectors to reach cylinder wall 32 when both fuel injectors 68 and 69 simultaneously spray fuel. However, in some examples, the fuel injectors may be positioned so that their fuel spray cones do not overlap when the fuel injectors simultaneously spray fuel.

[0031] Air enters combustion chamber 30 via intake valve 52, and exhaust exits combustion chamber 30 via exhaust valve 54. Fuel injector 69 and fuel injector 68 are shown as direct cylinder injectors that inject fuel directly into combustion chamber 30. Fuel injector 69 may be a lower flow fuel injector (e.g., X cc / min@100 bar), and fuel injector 68 may be a higher flow fuel injector (e.g., Y cc / min@100 bar, where Y is greater than X). Alternatively, fuel injector 69 and fuel injector 68 may be fuel injectors having substantially the same fuel injection rate (e.g., injector flow rates within ±2% of each other). Fuel injector 69 may include fewer and / or smaller nozzle holes through which fuel exits than fuel injector 68. Glow plug 66 may be activated during cold engine starting to promote combustion.

[0032] Direct diesel fuel injector 69 delivers diesel fuel that forms a spray cone indicated by dotted line 202. Direct diesel fuel injector 68 delivers diesel fuel that forms a spray cone indicated by dashed line 204. The fuel in the spray cone from fuel injector 69 may intersect and collide with the fuel in the spray cone from fuel injector 68 in the area indicated at 205. In other examples, as shown in FIG. Figure 3B and Figure 3C As shown, the fuel injector can provide multiple fuel spray cones, some of which can intersect and collide when injecting fuel. By intersecting the fuel spray cones, at least some of the fuel range can be reduced or the distance that the fuel travels from each of the fuel injectors 69 and 68 can be reduced. For example, when the fuel from the spray cone 202 collides with the fuel from the spray cone 204, the amount of fuel that leaves the nozzle 212 of the fuel injector 68 and travels through the combustion chamber 30 and directly impacts the combustion chamber wall can be reduced. Similarly, the amount of fuel that leaves the nozzle 210 of the fuel injector 69 and travels through the combustion chamber 30 and directly impacts the combustion chamber wall can be reduced. The dilution of the engine oil can be reduced by reducing the amount of fuel that flows directly from the injector to the cylinder wall. In addition, engine emissions can be reduced by reducing the amount of fuel that flows directly from the fuel injector nozzle to the cylinder wall.

[0033] When the piston 36 is in a lower position, the fuel injector 68 may inject fuel that impacts the cylinder wall 32 with fuel injected only through the fuel injector 68. If the piston 36 is in a higher position, the fuel injected by the fuel injector 68 may impact the first bowl in the top 250 of the piston 36. Likewise, when the piston 36 is in a lower position, the fuel injector 69 may inject fuel that impacts the cylinder wall 32 with fuel injected only through the fuel injector 69. If the piston 36 is in a higher position, the fuel injected by the fuel injector 69 may impact the second bowl in the top 250 of the piston 36.

[0034] See now Figure 3A , showing a view of a fuel injector spray pattern for an engine cylinder. Figure 3A The view shown is from Figure 1 and Figure 2 250 side of the top of the piston 36 shown. The injection direction of the nozzle 210 of the fuel injector 69 is at right angles to the injection direction of the nozzle 212 of the fuel injector 68. The injection direction of each fuel injector is in the longitudinal direction of each fuel injector. In this example, the fuel injector 69 is a lower flow rate fuel injector, and the fuel injector 69 is a higher flow rate fuel injector. In addition, the width of the spray cone 202 emitted by the fuel injection from the fuel injector 69 as indicated at 312 at a predetermined distance 310 from the nozzle 210 is narrower than the width of the spray cone 204 emitted by the fuel injection from the fuel injector 68 as indicated at 314 at a predetermined distance 310 from the nozzle 212. The predetermined distance 310 from the nozzle 210 and the nozzle 212 is the same distance. However, in some examples, the width of the spray cone can be the same.

[0035] If piston 36 is higher in the cylinder (e.g., closer to top dead center) and fuel is injected via fuel injector 69, the fuel injected from injector 69 can flow directly to bowl 308. Bowl 308 includes a land 306 that can be flush with the top of piston 250. Similarly, if piston 36 is higher in the cylinder (e.g., closer to top dead center) and fuel is injected via fuel injector 68, the fuel injected from injector 68 can flow directly to bowl 304. Bowl 304 includes a land 302 that can be flush with the top of piston 250. The diameter of bowl 308 is smaller than the diameter of bowl 304 because each bowl can be sized to reach the range of the corresponding spray cone (e.g., the diameter of the spray cone). By sizing the bowl to the spray cone, the mixing of air and fuel can be improved to reduce emissions. Thus, for a narrower spray cone 202, a smaller diameter bowl 308 may be provided, and for a wider spray cone 204, a larger diameter bowl 304 may be provided. In this manner, the piston geometry may be tailored to the size of the different fuel spray cones provided by different flow rate fuel injectors. The locations and sizes of the bowl 304 and the bowl 308 are for illustrative purposes and should not be construed as limiting. In addition, the bowl 304 and the bowl 308 may be referred to as cavities.

[0036] See now Figure 3B , showing alternative injector positions in the cylinder and spray pattern. In this example, the first fuel injector 330 is shown to be centrally positioned in the cylinder and cylinder head 13. The second fuel injector 331 can be positioned along the cylinder wall 32. The first fuel injector 330 provides a circular spray pattern with multiple spray cones indicated by the dashed line 334. The second fuel injector 331 provides a fan-shaped spray pattern with multiple spray cones indicated by the dotted line 333. When the first fuel injector 330 and the second fuel injector 331 both inject fuel at the same time, the fuel spray cone indicated by the dashed line 334 can intersect and collide with the spray cone indicated by the dotted line 333. Therefore, the fuel range (e.g., the distance the fuel travels in the spray cone) can be at least partially reduced.

[0037] See now Figure 3C, showing alternative injector positions in the cylinder and spray pattern. In this example, the first fuel injector 330 is shown to be centrally located in the cylinder and cylinder head 13. The second fuel injector 331 can be located along the cylinder wall 32, and the third fuel injector 335 can also be located along the cylinder wall 32. The first fuel injector 330 provides a circular spray pattern with multiple spray cones indicated by the dashed line 334. The second fuel injector 331 provides a fan-shaped spray pattern with multiple spray cones indicated by the dotted line 333. The third fuel injector 335 provides a fan-shaped fuel spray pattern with multiple fuel spray cones indicated by the dashed line 336. When the first fuel injector 330 and the second fuel injector 331 both inject fuel simultaneously, the fuel spray cone indicated by the dashed line 334 can intersect and collide with the spray cone indicated by the dotted line 333. Similarly, when both the first fuel injector 330 and the third fuel injector 335 inject fuel simultaneously, the fuel spray cone indicated by the dashed line 334 may intersect and collide with the spray cone indicated by the dashed line 336. Thus, the fuel range (e.g., the distance the fuel travels in the spray cone) may be at least partially reduced.

[0038] See now Figure 4 , shows a schematic cross section of a cylinder 401 of an opposed piston two-stroke engine. A two-stroke opposed piston internal combustion engine 400 (comprising a plurality of cylinders, one of which is Figure 4 ) is controlled by electronic engine controller 12. The opposed piston engine system may include Figure 1 The controller 12 and sensors and actuators associated with the controller 12 are shown for simplicity. Figure 4 Some sensors and actuators are omitted. The two-stroke engine includes a compression stroke and an expansion / exhaust stroke. During the compression stroke, the piston 404 and the piston 406 reciprocate toward the squeeze region 416 and away from the crankshaft 408 and the crankshaft 410, respectively. During the expansion / exhaust stroke, the piston 404 and the piston 406 reciprocate away from the squeeze region 416 and toward the crankshaft 408 and the crankshaft 410, respectively.

[0039] Cylinder 401 includes a squeezing area 416 where air and diesel fuel can be combusted. A first piston 404 is shown mechanically coupled to a first crankshaft 408, and a second piston 406 is shown mechanically coupled to a second crankshaft 410. The first crankshaft 408 can be mechanically coupled to the second crankshaft 410 via a chain or gear set (not shown). Piston 404 and piston 406 reciprocate within the wall 402 of cylinder 410. Piston 404 and piston 406 travel together toward squeezing area 416 during their respective compression strokes, and away from squeezing area 416 after the gases in the cylinder are combusted and expanded. Air enters cylinder 401 via intake passage 412, and exhaust gas leaves cylinder 401 via exhaust passage 420.

[0040] Fuel injector 424 is a relatively low flow rate fuel injector having a Figures 1 to 3A The fuel spray characteristics of fuel injector 69 or other fuel injectors described herein are the same. Fuel injector 414 is a higher flow rate fuel injector having the same Figures 1 to 3A The fuel spray characteristics of fuel injector 68 or other fuel injectors described herein are the same. Fuel injector nozzle 417 and fuel injector nozzle 418 are arranged directly opposite each other so that the spray cones of fuel injected from diesel fuel injector 424 and diesel fuel injector 414 cause the fuel droplets from each spray cone to collide. Section 450 is Figure 5 4 and provides a view of the top of the piston 404 and a view of the fuel injector arrangement. The top 445 of the piston 406 may be the same as the top 490 of the piston 406.

[0041] See now Figure 5 , showing Figure 4 A cross section 450 of cylinder 401 is shown. Fuel injector 424 and fuel injector 414 are shown bisected by vertical centerline 451. Additionally, piston 404 is bisected by vertical centerline 451. Cavity sidewall 457 is a lower sidewall, sidewall 456 is an intermediate sidewall, and sidewall 455 is an upper sidewall of cavity 440. Similarly, cavity sidewall 462 is a lower sidewall, sidewall 461 is an intermediate sidewall, and sidewall 460 is an upper sidewall of cavity 440. Upper sidewall 460 and upper sidewall 455 are closer to top 445 of piston 404 than lower sidewall 462 and lower sidewall 457. Cavity sidewalls 455, 456, 457 are symmetrical about vertical centerline 451 with cavity sidewalls 460, 461, 462. However, cavity sidewalls 455, 456, 457, 460, 461, 462 are asymmetrical about horizontal centerline 452. Thus, cavity 440 resembles a pear shape.

[0042] Cavity 440 is shaped to conform to the spray cones of fuel injector 424 and fuel injector 414. Cavity 440 begins near fuel injector 424 at a first narrow opening 446 at an outer sidewall 491 of piston 404. Cavity 440 includes a second wide opening 444 of fuel injector 414 near outer sidewall 491 of piston 404. Fuel injector 424 provides a narrower fuel spray cone than fuel injector 414, and thus, cavity 440 creates a narrower wall boundary 453 between fuel injector nozzle 417 and horizontal centerline 452 than wall boundary 454 of the fuel spray cone of fuel injector 414 disposed between fuel injector nozzle 418 and horizontal centerline 452. Thus, cavity 440 allows the fuel injector spray cone to increase so that fuel can reach the center of piston 404 to promote fuel mixing. By improving fuel mixing, engine emissions can be improved.

[0043] It should be noted that piston 406 can be formed identically to piston 404. Thus, piston 406 can also accommodate the spray cones of fuel injector 414 and fuel injector 424. Additionally, in some examples, piston 406 can be complementary to piston 404, such that the high portion of piston 406 is opposite the low side of piston 404, and vice versa. In some examples, the top of piston 455 can be higher on one side of cavity 440 than on the other side of cavity 440 (e.g., the left side of piston top 445 can be higher than the right side of piston top 445). Additionally, in some examples, the nozzle of fuel injector 414 can be offset from the nozzle of fuel injector 424.

[0044] Reference now Figure 6 , showing the Figure 4 4. A perspective view of piston 404 is shown. Cavity 440 is shown with upper sidewall 460, middle sidewall 461, and lower sidewall 462 exposed. Cavity opening 444 is shown having a depth 610 and a width 612. Cavity opening 446 is shown having a depth 622 and a width 608. Depth 622 is less than depth 610, and width 608 is less than width 612. The depth and width of cavity 440 are sized to accommodate the spray cones of fuel injector 414 and fuel injector 424 while maintaining the structural strength of piston 404. In an alternative example, the depths of opening 446 and opening 444 may be equal so that cavity 440 has a consistent depth.

[0045] Figures 2 to 6An example configuration with relative positioning of various components is shown. In at least one example, if the elements shown are in direct contact or directly connected to each other, such elements can be referred to as direct contact or direct connection, respectively. Similarly, in at least one example, the elements shown as being adjacent or adjacent to each other can be adjacent or adjacent to each other, respectively. As an example, components placed in coplanar contact with each other can be referred to as coplanar contact. As another example, in at least one example, components that are spaced apart and positioned with only space and no other components between them can be referred to as such. As another example, elements shown as being above / below each other, on opposite sides of each other, or on the left / right side of each other can be referred to as such relative to each other. In addition, as shown in the figure, in at least one example, the highest element or the highest point of an element can be referred to as the "top" of a component, and the lowest element or the lowest point of an element can be referred to as the "bottom" of a component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings and used to describe the positioning of the elements of the accompanying drawings relative to each other. Therefore, in one example, the element shown as being above other elements is vertically positioned above other elements. As yet another example, the shapes of elements depicted within the drawings may be considered to have those shapes (e.g., such as being round, straight, planar, curved, rounded, chamfered, angled, etc.). Additionally, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Furthermore, in one example, elements shown as being within another element or shown as being outside another element may be referred to as such.

[0046] therefore, Figures 1 to 6The system provides an engine system, comprising: an engine including at least one cylinder; a first diesel fuel injector supplying fuel to the at least one cylinder; and a second diesel fuel injector supplying fuel to the at least one cylinder, the second diesel fuel injector being a higher fuel flow rate injector than the first diesel fuel injector. The engine system includes wherein the first diesel fuel injector and the second diesel fuel injector inject diesel fuel directly into the at least one cylinder. The engine system also includes positioning the first diesel fuel injector and the second diesel fuel injector in the engine so that the fuel leaving the first diesel fuel injector collides with the fuel leaving the second diesel fuel injector and the fuel from the first diesel fuel injector and the fuel from the second diesel fuel injector do not collide with the surface of the engine. The engine system also includes a piston in the at least one cylinder, the piston including a first cavity and a second cavity. The engine system includes wherein the first cavity is positioned at the top of the piston to directly receive fuel from the spray cone of the fuel injected via the first diesel fuel injector. The engine system includes wherein the second cavity is positioned in the top of the piston to directly receive fuel from the spray cone of the fuel injected via the second diesel fuel injector, and wherein the second cavity has a larger volume than the first cavity. The engine system includes where a first diesel fuel injector and a second diesel fuel injector are coupled to a cylinder head.

[0047] Figures 1 to 6 The engine system of also provides an engine system, which includes: an opposed piston engine including at least one cylinder and two pistons positioned in the at least one cylinder; a first diesel fuel injector supplying diesel fuel to the at least one cylinder; and a second diesel fuel injector supplying diesel fuel to the at least one cylinder, the second diesel fuel injector being a higher fuel flow rate injector compared to the first diesel fuel injector. The engine system also includes a cavity in the first of the two pistons. The engine system includes wherein the depth of the cavity is non-uniform. The engine system includes wherein the first opening width of the cavity is less than the second opening width of the cavity. The engine system includes wherein the first fuel injector and the second fuel injector are positioned directly opposite each other. The engine system includes wherein the cavity is asymmetric about a horizontal centerline of the first of the two pistons, the horizontal centerline being perpendicular to the longitudinal direction of the first diesel fuel injector and the second diesel fuel injector. The engine system includes wherein the cavity includes three side walls.

[0048] Figures 1 to 6The system also provides an engine system, which includes: an engine including at least one cylinder; a first diesel fuel injector supplying fuel to the at least one cylinder; a second diesel fuel injector supplying fuel to the at least one cylinder, the second diesel fuel injector being a higher fuel flow rate injector compared to the first diesel fuel injector; and a piston positioned within the at least one cylinder and including a first cavity and a second cavity, the first cavity being smaller than the second cavity. The engine system includes wherein the first cavity surrounds the first platform and wherein the second cavity surrounds the second platform. The engine system includes wherein the first cavity is positioned to receive fuel from the first diesel fuel injector. The engine system includes wherein the second cavity is positioned to receive fuel from the second diesel fuel injector. The engine system includes wherein when the first diesel fuel injector and the second diesel fuel injector inject fuel under the same engine operating conditions, the fuel spray cone of the first diesel fuel injector provides a smaller range into the at least one cylinder than the fuel spray cone of the second diesel fuel injector. The engine system includes wherein diesel fuel is supplied to the first diesel fuel injector and the second diesel fuel injector via the same fuel system.

[0049] See now 7A to 7D , showing the Figures 1 to 3C Fuel injection timing diagram of a four-stroke engine. Fuel injection timing can be provided via controller 12 and fuel injector 68 and fuel injector 69 or other fuel injectors described herein. Figures 1 to 3C The fuel injection timing shown is provided in the system. Figure 8 Methods and Figures 1 to 3C The systems cooperate to provide fuel injection timing. The vertical lines represent the moments of interest (eg, T1 to T4) during the corresponding sequence curves.

[0050] 7A to 7D The first curve at the top of the diagram represents the cylinder stroke of cylinder number one of the engine. The horizontal axis is divided into a series of segments identifying the cylinder stroke of cylinder number one as time progresses from the left side of the diagram to the right side of the diagram. The exhaust stroke is abbreviated as EXH, while the intake stroke, compression stroke, and expansion stroke are abbreviated as INT, COMP, and EXP, respectively. * indicates the start of combustion for the four-stroke cylinder cycle shown. Therefore, Fig. 7A The development of the cylinder cycle over time is shown.

[0051] 7A to 7D The second curve at the top represents a number one fuel injector (eg, a low flow fuel injector such as Figure 169) during a cylinder cycle of the fuel injection timing, fuel injector number one injects diesel fuel into cylinder number one. The pulse width (e.g., 702, 704, 708) varies in width, and the width is an indication of the amount of fuel injected in the fuel pulse. The wider the pulse, the greater the amount of fuel injected into the cylinder during the pulse.

[0052] 7A to 7D The third curve from the top represents the number two fuel injector (e.g., a high flow fuel injector such as Figure 1 The fuel injection timing during the cylinder cycle of the fuel injector 68 shown in FIG. 1 , fuel injector No. 2 injects diesel fuel into cylinder No. 1. The pulse width (e.g., 706) varies in width, and the width is an indication of the amount of fuel injected in the fuel pulse. The wider the pulse, the greater the amount of fuel injected into the cylinder during the pulse. The shorter the pulse, the smaller the amount of fuel injected into the cylinder during the pulse.

[0053] Fig. 7A An example fuel injection timing is shown for a lower flow fuel injector to supply fuel to an engine cylinder for pilot injection and post injection. A pilot injection is a short duration fuel injection that may be less than 4 mg. The pilot fuel injection starts and ends before the top dead center compression stroke in the cylinder cycle in which it is injected. The pilot fuel injection can reduce engine combustion noise, control peak cylinder pressure, and adjust heat release in the cylinder. The main fuel injection is the injection of the largest amount of fuel during the cylinder cycle. The range of the main fuel injection may be within 3 mg to 100 mg per cylinder cycle. The pilot fuel injection is before the main fuel injection. An early post fuel injection may occur ten crankshaft degrees after the top dead center compression stroke and after the main fuel injection. The range of the early post fuel injection may be within 1 mg to 10 mg. During the cylinder cycle, the late post injection is a fuel injection performed after the combustion of the main fuel injection pulse is completed and before the exhaust valve of the cylinder receiving the fuel is closed. Early post injection and late post injection can be used to regenerate an emission control device in the exhaust system of the engine. Fig. 7A A main fuel injection pulse is provided via a higher flow fuel injector. The main fuel injection pulse can provide significant chemical energy to meet the driver demand torque.

[0054] At time T1, the engine is operated at a medium level engine load (not shown), and the first pilot fuel injection begins via fuel injector No. 1. The first pilot fuel injection 702 is arranged during the compression stroke of cylinder No. 1. Shortly thereafter, the first pilot fuel injection ends. The low flow rate fuel injector can be configured to have a smaller moving mass (e.g., the low flow fuel injector pivot can include a smaller mass), so that the low fuel flow injector can be opened and closed in a shorter time than the high flow fuel injector. Alternatively, the low flow fuel injector can include a nozzle throttle for controlling the flow, and the nozzle throttle can control the pivot opening and closing rate. In addition, the low flow fuel injector can more accurately inject a smaller mass of fuel than the high flow fuel injector. Therefore, the low flow fuel injector can be suitable for providing pilot fuel injection. The second higher flow fuel injector does not inject fuel.

[0055] At time T2, the second pilot fuel injection 704 begins via the first fuel injector. The controller 12 can determine which fuel injector to inject the pilot fuel injection in response to the pilot fuel injection amount and / or the fuel injector minimum pulse width limit. In one example, when the pilot fuel injection amount is less than a threshold amount, the controller selects a low flow fuel injector to inject the pilot fuel injection amount. The second pilot fuel injection 704 is set during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends.

[0056] At time T3, main fuel injection 706 begins via the second fuel injector. Main fuel injection 706 is set during the compression stroke of cylinder number one. The main fuel injection pulse ends before the top dead center compression stroke. The first fuel injector does not inject fuel into cylinder number one.

[0057] At time T4, the first post fuel injection begins. In this example, the post fuel injection is early (e.g., within 30 crankshaft degrees of the end of combustion in cylinder number one). The first post fuel injection is provided via the first fuel injector. The second fuel injector does not inject fuel. Shortly after time T4, the first post fuel injection ends, and fuel delivery to cylinder number one ends for the cylinder cycle shown. In other examples, additional or fewer post fuel injections and pilot fuel injections may be provided.

[0058] In this way, the low flow fuel injector can supply a smaller fuel amount for the pilot fuel injection and the post fuel injection. A larger fuel injection amount can be provided by the higher flow fuel injector. Therefore, the fuel injection can be distributed between the two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount, the post fuel injection amount, and the main fuel injection amount.

[0059] Figure 7BA second example fuel injection timing is shown where a lower flow fuel injector supplies fuel to an engine cylinder for pilot injection, main injection, and post injection. At least one main injection is provided to a cylinder when the cylinder is fueled during a cycle of the cylinder. The lower flow fuel injector may provide a main fuel injection at higher engine speeds and loads when the higher flow fuel injector does not have time to provide a sufficient amount of fuel to meet the cylinder air-fuel requirement. Figure 7B A main fuel injection pulse via a higher flow fuel injector is also provided. Two main fuel injection pulses can provide significant chemical energy to meet the driver demand torque.

[0060] At time T5, the engine is operating at a higher level of engine load (not shown) and the first pilot fuel injection begins via fuel injector number one. The first pilot fuel injector 710 begins during the compression stroke of cylinder number one. Shortly thereafter, the first pilot fuel injection ends. The second higher flow fuel injector does not inject fuel.

[0061] At time T6, a second pilot fuel injection 712 begins via the first fuel injector. The second pilot fuel injection 712 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends. The second fuel injector does not supply fuel to cylinder number one.

[0062] At time T7, main fuel injection 714 begins via the first fuel injector. The main fuel injection is arranged during the compression stroke of cylinder number 1. The first fuel injector may provide the main fuel injection so that a desired engine air-fuel ratio may be provided.

[0063] At time T8, main fuel injection 716 begins via the second fuel injector. Main fuel injection 716 is set during the compression stroke of cylinder number one. Main fuel injection 714 provided via the first fuel injector and main fuel injection 716 provided via the second fuel injector overlap. This overlap can be used to reduce the possibility of injected fuel impacting the cylinder wall.

[0064] It should be noted that in other examples, the second fuel injector may begin injecting its main fuel injection amount in the cylinder cycle before the first fuel injector begins injecting its main fuel injection amount in the cylinder cycle. The specific timing may depend on the fuel injector specifications and engine operating conditions. In addition, if the two fuel injectors have fuel spray patterns that impact each other during simultaneous injection, the two fuel injectors may only inject simultaneously during pilot injection or post-injection. However, if the two fuel injectors have spray patterns (which do not impact each other's fuel spray patterns during simultaneous injection), the two fuel injectors may inject simultaneously during the main fuel injection of each fuel injector.

[0065] At time T9, main fuel pulse 714 provided via the first fuel injector and main fuel pulse 716 provided via the second fuel injector end. The main fuel injection pulses may end simultaneously to reduce exhaust temperature and improve combustion efficiency.

[0066] At time T10, a first post fuel injection is provided. In this example, the post fuel injection is late (e.g., close to exhaust valve closing of cylinder number one). The first post fuel injection is provided via the first fuel injector. Shortly thereafter, the first post fuel injection ends, and fuel delivery to cylinder number one ends for the cylinder cycle shown.

[0067] In this way, the low flow fuel injector can supply a smaller amount of fuel for the pilot fuel injection and the post fuel injection. In addition, the main fuel injection through the second fuel injector can be augmented by the main fuel injection from the first fuel injector. Thus, the fuel injection can be distributed between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount and increases the fuel supplied to meet higher engine loads.

[0068] Figure 7C A third example fuel injection timing is shown in which the first fuel injector and the second fuel injector alternately perform pilot injection and post injection. Main fuel injection is also provided via the first fuel injector and the second fuel injector. When the higher fuel flow injector does not have time to provide a sufficient amount of fuel to meet the cylinder air fuel requirement, the lower fuel flow injector can provide the main fuel injection at a higher engine speed and load. Before the fuel injector is reactivated, the pilot fuel injection can be alternated between the first fuel injector and the second fuel injector to allow the moving mass in the injector to be placed in a desired position (e.g., closed), and allow the electric / magnetic component (e.g., coil) to achieve a desired state (e.g., a magnetic field strength less than a threshold). Therefore, the amount of time between the end of the fuel injector injection and the start of a new injection during the cylinder cycle can be increased to improve fuel delivery accuracy and repeatability. In addition, the amount of time between the end of the first pilot injection in the cylinder cycle and the start of the second pilot fuel injection in the cylinder cycle can be reduced because the fuel injector is less constrained by the closing dwell time of each fuel injector. Two main fuel injection pulses can provide significant chemical energy to meet the driver's demand torque.

[0069] At time T20, the engine is operating at part engine load (not shown) and the first pilot fuel injection 720 begins via fuel injector number one. The first pilot fuel injection 720 begins during the compression stroke of cylinder number one. Shortly thereafter, the first pilot fuel injection ends. The second higher flow fuel injector does not inject fuel.

[0070] At time T21, a second pilot fuel injection 722 begins via the second fuel injector. The second pilot fuel injection 722 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends. The first fuel injector does not supply fuel to cylinder number one.

[0071] At time T22, the third pilot fuel injection 721 begins via fuel injector number one. The third pilot fuel injection 721 begins during the compression stroke of cylinder number one. Shortly thereafter, the third pilot fuel injection ends. The second higher flow fuel injector does not inject fuel.

[0072] At time T23, a fourth pilot fuel injection 723 begins via the second fuel injector. The fourth pilot fuel injection 723 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the fourth pilot fuel injection ends. The first fuel injector does not supply fuel to cylinder number one.

[0073] At time T24, main fuel injection 725 and main fuel injection 726 start via the first fuel injector and the second fuel injector. The main fuel injection is set during the compression stroke of cylinder number 1. The first fuel injector and the second fuel injector can provide the main fuel injection so that a desired engine air-fuel ratio can be provided.

[0074] At time T25, the main fuel pulse 725 provided via the first fuel injector and the main fuel pulse 726 provided via the second fuel injector end. The main fuel injection pulses can end simultaneously to improve engine emissions and regulate heat release during combustion. In addition, by stopping fuel injection via the first fuel injector and the second fuel injector at the same time, the possibility of fuel impacting the cylinder wall can be reduced.

[0075] At time T26, the first post fuel injection begins. In this example, the post fuel injection is late. The first post fuel injection is provided via the first fuel injector. Shortly thereafter, the first post fuel injection ends.

[0076] At time T27, the second post fuel injection begins. The second post fuel injection is provided via the second fuel injector. Shortly thereafter, the second post fuel injection ends.

[0077] At time T28, a third post fuel injection is provided. The third post fuel injection is provided via the first fuel injector. Shortly thereafter, the third post fuel injection ends, and fuel delivery to cylinder number one ends for the cylinder cycle shown. Thus, the post fuel injections may alternate between the first fuel injector and the second fuel injector to allow the operation of the mechanical and electrical / magnetic components of the fuel injector to stabilize, thereby improving fuel delivery accuracy.

[0078] Alternating pilot fuel injection and post fuel injection is also available when the flow rates of the first fuel injector and the second fuel injector are equal or different. In this way, a short recovery time between fuel injections can be provided for each fuel injector of the engine. In addition, the main fuel injection through the second fuel injector can be increased by the main fuel injection from the first fuel injector. Therefore, the fuel injection can be distributed between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount and increases the fuel supplied to meet higher engine loads. In addition, injecting fuel with two fuel injectors allows fuel to be injected via the second fuel injector shortly after the first injector stops injecting fuel, so that the second fuel injector is injected during the closed dwell time of the first fuel injector. This allows for a tighter coupling of the injections, which can improve engine noise reduction and engine emissions.

[0079] Fig.7D A fourth example fuel injection timing is shown in which a lower flow fuel injector (e.g., fuel injector number one) supplies fuel to an engine cylinder for main and post injections. The lower flow fuel injector can provide one or two main fuel injections at higher engine speeds and loads so that the pressure rise in the cylinder can be controlled and limited with early initiation of injection of the main fuel pulses. Fig.7D A pilot fuel injection and a main fuel injection pulse via a higher flow fuel injector (e.g., fuel injector No. 2) are also provided. When the second fuel injector is a higher flow fuel injector, the second fuel injector can supply the pilot fuel injection at higher engine loads. Three main fuel injection pulses can provide significant chemical energy to meet the driver demand torque.

[0080] At time T30, the engine is operating at a higher level of engine load (not shown) and the first pilot fuel injection begins via fuel injector number two. The first pilot fuel injection 742 begins during the compression stroke of cylinder number one and ends shortly thereafter. The first lower flow fuel injector does not inject fuel at time T30.

[0081] At time T31, the second pilot fuel injection 743 begins via the second fuel injector. The second pilot fuel injection 743 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends. The first fuel injector does not supply fuel to cylinder number one.

[0082] At time T32, main fuel injection 740 begins via the first fuel injector. Main fuel injection 740 is provided during the compression stroke of cylinder number one. The first fuel injector may provide the main fuel injection so that a desired engine air-fuel ratio may be provided. Additionally, when the first fuel injector is a lower flow fuel injector, the combustion heat release may be controlled to provide a slower heat release than when the first fuel injector is a higher flow fuel injector.

[0083] At time T33, main fuel injection 744 begins via the second fuel injector. Main fuel injection 744 is set during the compression stroke of cylinder number one. The main fuel injection 740 provided via the first fuel injector and the main fuel injection 744 provided via the second fuel injector do not overlap, but in other examples they may overlap. The second main fuel injection 741 is provided via the first fuel injector shortly after time T33.

[0084] At time T34, a first post fuel injection 745 is provided via the first injector and a second post fuel injection 746 is provided via the second injector. The first injection and the second injection are simultaneous and contemporaneous to reduce the likelihood of fuel impacting the cylinder wall. In this example, the post fuel injection is late (e.g., close to exhaust valve closing of cylinder number one). The first post fuel injection and the second post fuel injection are ended, and fuel delivery to cylinder number one is ended for the cylinder cycle shown.

[0085] In this way, the higher flow fuel injector can supply the pilot fuel injection at higher engine loads when a larger pilot fuel injection amount may be desired. Additionally, the main fuel injection through the second fuel injector can be augmented by the main fuel injection from the first fuel injector. Thus, the fuel injection can be apportioned between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount and increases the fuel supplied to meet higher engine loads.

[0086] See now FIG. 7E to FIG. 7H , showing the Figures 4 to 6 The fuel injection timing of the two-stroke engine is shown in FIG. The fuel injection timing can be provided by the controller 12 and the fuel injectors 414 and 424. The fuel injection timing shown can be Figures 4 to 6 In addition, you can Figure 8 Methods and Figures 4 to 6 The systems cooperate to provide fuel injection timing. The vertical lines represent the moments of interest (eg, T40 to T43) during the corresponding sequence curves.

[0087] FIG. 7E to FIG. 7HThe first curve at the top of represents the cylinder stroke of cylinder number one of the engine. The horizontal axis is divided into a series of segments identifying the cylinder stroke of cylinder number one as time progresses from the left side of the figure to the right side of the figure. The expansion / exhaust stroke is abbreviated as EXP, while the compression stroke is abbreviated as COMP. The * indicates the start of combustion for the two-stroke cylinder cycle shown. Therefore, Fig. 7E The development of a cylinder cycle over time is shown. Thus, the fuel injection of a cycle (eg one operation) of a two-stroke cylinder number one is shown.

[0088] FIG. 7E to FIG. 7H The second curve at the top represents a number one fuel injector (eg, a low flow fuel injector such as Figure 4 The fuel injection timing during the cylinder cycle of 424 shown in FIG. 4, the number one fuel injector injects diesel fuel into the number one cylinder. The pulse width (e.g., 750, 754, 756, and 758) varies in width, and the width is an indication of the amount of fuel injected in the fuel pulse. The wider the pulse, the greater the amount of fuel injected into the cylinder during the pulse.

[0089] FIG. 7E to FIG. 7H The third curve from the top represents the number two fuel injector (eg, a higher flow fuel injector such as Figure 4 The fuel injection timing during the cylinder cycle of the fuel injection device 414 shown in Figure 4, the second fuel injector injects diesel fuel into the first cylinder. The pulse width (e.g., 756) varies in width, and the width is an indication of the amount of fuel injected in the fuel pulse. The wider the pulse, the greater the amount of fuel injected into the cylinder during the pulse. The shorter the pulse, the smaller the amount of fuel injected into the cylinder during the pulse.

[0090] Fig. 7E Example fuel injection timings are shown for a lower flow fuel injector supplying fuel to an engine cylinder for pilot injection and post injection. A pilot injection is a short duration fuel injection of less than a threshold amount of time (e.g., less than 1 millisecond). Pilot fuel injection can reduce engine combustion noise, control peak cylinder pressure, and regulate heat release within the cylinder. Post injection is a fuel injection performed after combustion of the main fuel injection pulse is complete and after the piston passes through the exhaust port during the expansion / exhaust stroke of the cylinder receiving fuel during the cylinder cycle. Post injection can be used to regenerate an emission control device in the exhaust system of the engine. Fig. 7E A main fuel injection pulse 756 is provided via the higher flow fuel injector. The main fuel injection pulse 756 may provide significant chemical energy to meet the driver demand torque.

[0091] At time T40, the engine is operated under a medium level engine load (not shown), and the first pilot fuel injection 750 begins via the No. 1 fuel injector. The first pilot fuel injection 750 is arranged during the compression stroke of the No. 1 cylinder. Shortly thereafter, the first pilot fuel injection ends. The low flow rate fuel injector can be configured to have a smaller moving mass (e.g., the low flow fuel injector pivot can include a smaller mass) so that the low fuel flow injector can be opened and closed in a shorter time than the high flow fuel injector. In addition, the low flow fuel injector can more accurately inject a smaller mass of fuel than the high flow fuel injector. Therefore, the low flow fuel injector can be suitable for providing the pilot fuel injection. The second higher flow fuel injector does not inject fuel.

[0092] At time T41, a second pilot fuel injection 754 begins via the first fuel injector. The second pilot fuel injection 754 is arranged during the compression stroke of cylinder number 1. Shortly thereafter, the second pilot fuel injection ends.

[0093] At time T42, main fuel injection 756 begins via the second fuel injector. Main fuel injection 756 may be placed during the compression stroke of cylinder number one after the cylinder passes through the exhaust passage. The main fuel injection pulse ends before the top dead center compression stroke. The first fuel injector does not inject fuel into cylinder number one.

[0094] At time T43, the first post fuel injection 758 begins. The first post fuel injection is provided via the first fuel injector. No fuel is injected by the second fuel injector. Shortly after time T43, the first post fuel injection ends, and fuel delivery to cylinder number one ends for the cylinder cycle shown. In other examples, additional or fewer post fuel injections and pilot fuel injections may be provided.

[0095] In this way, the low flow fuel injector can supply a smaller fuel amount for the pilot fuel injection and the post fuel injection. A larger fuel injection amount can be provided by a higher flow fuel injector. Therefore, the fuel injection can be distributed between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount, the post fuel injection amount, and the main fuel injection amount.

[0096] Figure 7F A second example fuel injection timing is shown where a lower flow fuel injector supplies fuel to an engine cylinder for pilot injection, main injection, and post injection. A main fuel injection is a longer duration fuel injection greater than a threshold amount of time (e.g., greater than 1 millisecond). A lower flow fuel injector may provide a main fuel injection at higher engine speeds and loads when a higher flow fuel injector does not have time to provide a sufficient amount of fuel to meet the cylinder air-fuel requirement. Figure 7FA main fuel injection via a higher flow fuel injector is also provided. Two main fuel injection pulses can provide significant chemical energy to meet the driver demand torque.

[0097] At time T44, the engine is operating at a higher level of engine load (not shown) and the first pilot fuel injection begins via fuel injector number one. The first pilot fuel injection 760 begins during the compression stroke of cylinder number one. Shortly thereafter, the first pilot fuel injection ends. The second higher flow fuel injector does not inject fuel.

[0098] At time T45, a second pilot fuel injection 762 begins via the first fuel injector. The second pilot fuel injection 762 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends. The second fuel injector does not supply fuel to cylinder number one.

[0099] At time T46, main fuel injection 764 begins via the first fuel injector. The main fuel injection is arranged during the compression stroke of cylinder number 1. The first fuel injector can provide the main fuel injection so that the desired engine air-fuel ratio can be provided.

[0100] At time T47, main fuel injection 766 begins via the second fuel injector. Main fuel injection 766 is set during the compression stroke of cylinder No. 1. Main fuel injection 746 provided via the first fuel injector and main fuel injection 766 provided via the second fuel injector overlap. This overlap can be used to reduce the possibility of injected fuel impacting the cylinder wall.

[0101] At time T48, the main fuel pulse 764 provided via the first fuel injector and the main fuel pulse 766 provided via the second fuel injector end. The main fuel injection pulses can end simultaneously to improve engine emissions and regulate heat release during combustion. In addition, by stopping fuel injection via the first fuel injector and the second fuel injector at the same time, the possibility of fuel impacting the cylinder wall can be reduced.

[0102] At time T49, a first post fuel injection is provided. The first post fuel injection is provided via the first fuel injector. Shortly thereafter, the first post fuel injection ends, and fuel delivery to cylinder number one ends for the illustrated cylinder cycle.

[0103] In this way, the low flow fuel injector can supply a smaller amount of fuel for the pilot fuel injection and the post fuel injection. In addition, the main fuel injection through the second fuel injector can be augmented by the main fuel injection from the first fuel injector. Thus, the fuel injection can be allocated between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount and increases the fuel supplied to meet higher engine loads. In other examples, additional or fewer post fuel injections and pilot fuel injections can be provided.

[0104] Figure 7G A third example fuel injection timing is shown in which the first fuel injector and the second fuel injector alternately perform pilot injection and post injection. The main fuel injection is also provided via the first fuel injector and the second fuel injector. When the higher flow fuel injector does not have time to provide a sufficient amount of fuel to meet the cylinder air fuel requirement, the lower flow fuel injector can provide the main fuel injection at a higher engine speed and load. Before the fuel injector is reactivated, the pilot fuel injection can be alternated between the first fuel injector and the second fuel injector to allow the moving mass in the injector to be placed in the desired position (e.g., closed) and allow the electric / magnetic component (e.g., coil) to achieve the desired state (e.g., less than the magnetic field strength of the threshold). Therefore, the amount of time between the end of the fuel injector injection and the start of a new injection during the cylinder cycle can be increased to improve the accuracy and repeatability of fuel delivery. In addition, the amount of time between the end of the first pilot injection in the cylinder cycle and the start of the second pilot fuel injection in the cylinder cycle can be reduced because the fuel injector is less constrained by the closing residence time of each fuel injector. Two main fuel injection pulses can provide significant chemical energy to meet the driver's demand torque.

[0105] At time T50, the engine is operating at part engine load (not shown) and the first fuel injection 770 begins via fuel injector number one. The first pilot fuel injection 770 begins during the compression stroke of cylinder number one. Shortly thereafter, the first pilot fuel injection ends. The second higher flow fuel injector does not inject fuel.

[0106] At time T51, a second pilot fuel injection 772 begins via the second fuel injector. The second pilot fuel injection 772 is provided during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends. The first fuel injector does not supply fuel to cylinder number one.

[0107] At time T52, the third pilot fuel injection 771 begins via fuel injector number one. The third pilot fuel injection 771 begins during the compression stroke of cylinder number one. Shortly thereafter, the third pilot fuel injection ends. The second higher flow fuel injector does not inject fuel.

[0108] At time T53, the fourth pilot fuel injection 773 begins via the second fuel injector. The fourth pilot fuel injection 773 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the fourth pilot fuel injection ends. The first fuel injector does not supply fuel to cylinder number one.

[0109] At time T54, main fuel injection 775 and main fuel injection 776 begin via the first fuel injector and the second fuel injector. The main fuel injection is arranged during the compression stroke of cylinder number 1. The first fuel injector and the second fuel injector may provide the main fuel injection so that a desired engine air-fuel ratio may be provided.

[0110] At time T55, the main fuel pulse 775 provided via the first fuel injector and the main fuel pulse 776 provided via the second fuel injector end. The main fuel injection pulses can end simultaneously to improve engine emissions and regulate heat release during combustion. In addition, by stopping fuel injection via the first fuel injector and the second fuel injector at the same time, the possibility of fuel impacting the cylinder wall can be reduced.

[0111] At time T56, the first post fuel injection begins. In this example, the post fuel injection is late. The first post fuel injection is provided via the first fuel injector. Shortly thereafter, the first post fuel injection ends.

[0112] At time T57, the second post fuel injection begins. The second post fuel injection is provided via the second fuel injector. Shortly thereafter, the second post fuel injection ends.

[0113] At time T58, a third post fuel injection is provided. The third post fuel injection is provided via the first fuel injector. Shortly thereafter, the third post fuel injection ends, and fuel delivery to cylinder number one ends for the cylinder cycle shown. Thus, the post fuel injections may alternate between the first fuel injector and the second fuel injector to allow the operation of the mechanical and electrical / magnetic components of the fuel injector to stabilize, thereby improving fuel delivery accuracy.

[0114] Alternating pilot fuel injection and post fuel injection is also available when the flow rates of the first fuel injector and the second fuel injector are equal or different. In this way, a short recovery time between fuel injections can be provided for each fuel injector of the engine. In addition, the main fuel injection through the second fuel injector can be increased by the main fuel injection from the first fuel injector. Therefore, the fuel injection can be distributed between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount and increases the fuel supplied to meet higher engine loads. In addition, injecting fuel with two fuel injectors allows fuel to be injected via the second fuel injector shortly after the first injector stops injecting fuel, so that the second fuel injector is injected during the closed dwell time of the first fuel injector. This allows the injection to be more closely coupled, which can improve engine noise reduction and engine emissions.

[0115] Figure 7H A fourth example fuel injection timing is shown in which a lower flow fuel injector (e.g., fuel injector number one) supplies fuel to an engine cylinder for main and post injections. The lower flow fuel injector can provide one or two main fuel injections at higher engine speeds and loads so that the pressure rise in the cylinder can be controlled and limited with early initiation of injection of the main fuel pulses. Figure 7H A pilot fuel injection and a main fuel injection pulse via a higher flow fuel injector (e.g., fuel injector No. 2) are also provided. When the second fuel injector is a higher flow fuel injector, the second fuel injector can supply the pilot fuel injection at higher engine loads. Three main fuel injection pulses can provide significant chemical energy to meet the driver demand torque.

[0116] At time T60, the engine is operating at a higher level of engine load (not shown) and the first pilot fuel injection begins via fuel injector number two. The first pilot fuel injection 792 begins during the compression stroke of cylinder number one. Shortly thereafter, the first pilot fuel injection ends. At time T60, the first lower flow fuel injector does not inject fuel.

[0117] At time T61, the second pilot fuel injection 793 begins via the second fuel injector. The second pilot fuel injection 793 is arranged during the compression stroke of cylinder number one. Shortly thereafter, the second pilot fuel injection ends. At time T61, the first fuel injector does not supply fuel to cylinder number one.

[0118] At time 62, main fuel injection 790 begins via the first fuel injector. Main fuel injection 790 is provided during the compression stroke of cylinder number one. The first fuel injector can provide the main fuel injection so that a desired air-fuel ratio can be provided. In addition, when the first fuel injector is a lower flow fuel injector, the combustion heat release can be controlled to provide a slower heat release than when the first fuel injector is a higher flow fuel injector.

[0119] At time T63, main fuel injection 794 begins via the second fuel injector. Main fuel injection 794 is provided during the compression stroke of cylinder number one. The main fuel injection 790 provided via the first fuel injector and the main fuel injection 794 provided via the second fuel injector overlap. This overlap can be used to reduce the likelihood of the injected fuel impacting the cylinder wall and can also increase heat release within the cylinder. The main fuel injection pulse ends early in the expansion stroke.

[0120] At time T64, a first post fuel injection is provided. The first post fuel injection is provided via the first fuel injector because only a small fuel injection amount is desired. Shortly thereafter, the first post fuel injection ends, and fuel delivery to cylinder number one ends for the cylinder cycle shown.

[0121] In this way, the higher flow fuel injector can supply the pilot fuel injection at higher engine loads when a larger pilot fuel injection amount may be desired. Additionally, the main fuel injection through the second fuel injector may be augmented by the main fuel injection from the first fuel injector. Thus, the fuel injection may be apportioned between two different fuel injectors in a manner that improves the accuracy of the pilot fuel injection amount and increases the fuel supplied to meet the higher engine loads. In other examples, additional or fewer post fuel injections and pilot fuel injections may be provided.

[0122] Reference now Figure 8 , a method for adjusting fuel injection timing is shown. Figure 8 Methods can be stored as executable instructions in a program such as Figures 1 to 6 A flow chart of a method for adjusting fuel injection timing of an internal combustion engine is shown. Figure 8 The method can be combined with Figures 1 to 6 in the system and can be Figures 1 to 6 In addition, Figure 8 At least a portion of the method may be incorporated as executable instructions stored in a non-transitory memory, while other portions of the method may be executed via a controller that transforms the operating conditions of devices and actuators in the physical world. According to the method described below, the controller may use an engine actuator of an engine system to adjust engine operation.

[0123] At 802, method 800 determines engine operating conditions. Engine operating conditions may include, but are not limited to, engine temperature, accelerator pedal position, and engine speed. Engine operating conditions may be determined via engine sensors and an engine controller. Method 800 proceeds to 804.

[0124] At 804, method 800 determines the driver demand torque. In one example, method 800 determines the driver torque demand via retrieving or referencing a table or function that stores empirically determined values ​​of the driver demand torque. The table or function may be retrieved or referenced via engine speed and accelerator pedal position. The table outputs the driver demand torque. Method 800 proceeds to 806.

[0125] At 806, method 800 determines the amount of fuel injected into the cylinder during the cycle of the cylinder. In one example, the amount of fuel injected into the cylinder during the cylinder cycle can be determined via retrieval or reference to a table of empirically determined fuel amounts. The table can be referenced via driver demand torque and engine speed. The table outputs the empirically determined amount of fuel injected during the cycle of the cylinder. Method 800 proceeds to 808.

[0126] At 808, method 800 determines the pilot fuel injection amount and the main fuel injection amount. In one example, the amount of fuel injected during the cycle of the cylinder determined at 806 is divided into the pilot fuel injection amount and the main fuel injection amount. Specifically, a portion of the amount of fuel injected into the cylinder during the cylinder cycle is output from a table or function of the pilot fuel injection portion determined empirically. The table or function can be referenced via engine speed and driver demand torque. The main fuel injection amount is the amount of fuel determined at 806 minus the predetermined amount of fuel allocated to the pilot fuel injection during the cylinder cycle. For example, if X grams of fuel are to be injected into the cylinder during the cycle of the cylinder, 10% of the X grams of fuel are to be pilot injected, and the main fuel injection amount is X-(X·0.1) or 90% of X.

[0127] Alternatively, a predetermined amount of fuel may be allocated to the pilot fuel injection during a cylinder cycle. The predetermined amount may be determined empirically and may be stored in a table or function. The table or function may be referenced via engine speed and driver demand torque. The table outputs a predetermined amount of fuel to be injected for pilot combustion. The main fuel injection amount is the amount of fuel determined at 806 minus the predetermined amount of fuel allocated to the pilot fuel injection during a cylinder cycle. Method 800 proceeds to 810.

[0128] At 810, method 800 determines the actual total number of pilot fuel injections during the cycle of the cylinder. In one example, a table or function holds a value for the total number of pilot fuel injections provided to the cylinder during the cycle of the cylinder. The value can be determined empirically. The table or function can be retrieved or referenced via engine speed and driver demand torque. The amount of pilot fuel to be injected can be divided by the actual total number of pilot fuel injections to determine the amount of fuel in each pilot fuel injection. Alternatively, the amount of fuel in each pilot injection can be a portion / fraction of the amount of pilot injected fuel determined at 808. Method 800 proceeds to 812.

[0129] At 812, method 800 determines the actual total number of main fuel injections during a cycle of the cylinder. In one example, a table or function holds a value for the total number of main fuel injections provided to a cylinder during a cycle of the cylinder. The value can be determined empirically. The table or function can be retrieved or referenced via engine speed and driver demand torque. When the cylinder is fueled during a cylinder cycle, the actual total number of main fuel injections can be a value of one or two. The amount of main injection fuel to be injected can be divided by the actual total number of main fuel injections to determine the amount of fuel in each main fuel injection. Alternatively, the amount of fuel in each main injection can be a portion of the amount of main injection fuel determined at 808. Method 800 proceeds to 814.

[0130] At 814, method 800 determines the amount of post-combustion fuel injected into the cylinder during the cycle of the cylinder. In one example, the amount of post-combustion fuel injected into the cylinder during the cycle of the cylinder can be determined by retrieving or referencing a table of empirically determined post-combustion fuel injection amounts. The table can be referenced via catalyst temperature and engine air flow. The table outputs the amount of post-combustion fuel injected into the cylinder during the cycle of the cylinder. In addition, method 800 can determine the actual total number of post-combustion fuel injections from a table or function that stores the number of post-combustion injections determined empirically. The table or function can be referenced via engine speed and driver demand torque. The amount of fuel injected in each post-combustion fuel injection can be the post-combustion fuel injection amount of the cylinder cycle divided by the actual total number of post-combustion injections during the cylinder cycle. Method 800 proceeds to 816.

[0131] At 816, method 800 determines the timing of pilot fuel injection, main fuel injection, and post-fuel injection. In one example, the starting point of the injection timing of the pilot injection is determined empirically and stored in a table or function. The table or function is referenced by the engine speed and the driver's demand torque. The table or function outputs the starting point of the pilot injection time in units of engine crankshaft angle. The pilot fuel injection starts at the starting point of the pilot fuel injection time. Similarly, the starting point of the injection timing of the main combustion injection and the post-combustion injection is determined empirically and stored in a table or function. The table or function is referenced by the engine speed and the driver's demand torque. The table or function outputs the starting point of the main injection time and the starting point of the post-combustion injection time in units of engine crankshaft angle. The main combustion fuel injection and the post-combustion fuel injection start at the corresponding starting points of the injection time. Alternatively, method 800 can determine the end point of the injection time of the pilot combustion injection, the main combustion injection, and the post-combustion injection. Then determine the starting point of the injection time from the injector flow rate, the engine of the injection time, and the amount of fuel injected.

[0132] Method 800 also assigns injections to each of the fuel injectors. In one example, which fuel injectors are assigned pilot injections, main injections, and post injections can be empirically determined and stored in a table or function. The fuel injector assignments are output from the table or function, and can be retrieved or referenced via engine speed and driver demand torque. For example, at lower engine speeds and loads, the table may assign lower flow rate fuel injectors to output pilot fuel injections and main fuel injections. At medium engine speeds and loads, the table or function may assign lower flow rate fuel injectors to output pilot fuel injections, and assign higher flow rate fuel injectors to output main pulse injections. The table may also assign post fuel injections to lower flow rate fuel injectors. At higher engine speeds and loads, the table or function may assign higher flow rate fuel injectors to output pilot fuel injections and main pulse injections. The table or function may also be used in a manner such as 7A to 7H The pilot injection and main injection are distributed alternately between the lower flow rate injectors and the higher flow rate injectors as shown. The table or function can provide 7A to 7H All fuel injector assignments and combinations described in.

[0133] Alternatively, which fuel injectors are allocated to inject fuel can be based on the amount of fuel injected in the pilot injection, main injection, and post injection. For example, if the amount of fuel to be delivered as pilot injection fuel is less than or equal to a threshold, a lower flow rate fuel injector can be allocated to inject pilot fuel. If the amount of fuel to be delivered as pilot injection fuel is greater than a threshold, a higher flow rate fuel injector can be allocated to inject pilot fuel. Similarly, if the amount of fuel to be delivered as main injection fuel is less than or equal to a threshold, a lower flow rate fuel injector can be allocated to inject main pulse fuel. If the amount of fuel to be delivered as main injection fuel is greater than a threshold, a higher flow rate fuel injector can be allocated to inject main pulse fuel. Similarly, if the amount of fuel to be delivered as post-combustion injection fuel is less than or equal to a threshold, a lower flow rate fuel injector can be allocated to inject post-combustion fuel. If the amount of fuel to be delivered as post-combustion injection fuel is greater than a threshold, a higher flow rate fuel injector can be allocated to inject post-combustion fuel. Method 800 advances to 818.

[0134] At 818, method 800 injects the pilot fuel injection amount, the main fuel injection amount, and the post fuel injection amount. Fuel may be injected via a lower flow rate fuel injector and a higher flow rate fuel injector. Alternatively, in some examples, the fuel injectors may have substantially the same flow rate (e.g., flow rates within 2% of each other). Method 800 proceeds to exit.

[0135] Figure 8 The method can be performed for each engine cylinder, so that multiple engine cylinders can be supplied with fuel via dual diesel fuel injectors. In addition, if necessary, each engine cylinder can be assigned a unique fuel injection timing.

[0136] See now Fig. 9 , shows a curve of cylinder cycle, which shows the Figure 8 A method for closely coupling pilot fuel injection and post fuel injection during a cylinder cycle. Figures 1 to 6 The system shown provides Fig. 9 sequence. Fig. 9 A fuel injection timing diagram for a four-stroke engine or a two-stroke engine is shown. The fuel injection timing may be provided via a controller and a fuel injector as described herein. The vertical lines represent the moments of interest (e.g., T70 to T86) during the corresponding sequence curves.

[0137] Fig. 9 The first curve at the top of the diagram represents the cylinder stroke of cylinder number one of the engine. The horizontal axis is divided into a series of segments identifying the cylinder stroke of cylinder number one as time progresses from the left side of the diagram to the right side of the diagram. The compression stroke is abbreviated as COMP and the expansion stroke is abbreviated as EXP. * indicates the start of combustion of the cylinder cycle shown.

[0138] Fig. 9 The second curve at the top represents a number one fuel injector (eg, a low flow fuel injector such as Figure 1 69) during a cylinder cycle of fuel injector number 1, which injects diesel fuel into cylinder number 1. The pulse width (e.g., 901 and 903) varies in width, and the width is an indication of the amount of fuel injected in the fuel pulse. The wider the pulse, the greater the amount of fuel injected into the cylinder during the pulse. Wide line 998 represents the injector closed dwell time, during which fuel injector number 1 cannot open to inject fuel after being most recently closed. The fuel injector closed dwell time can be related to the physical properties of fuel injector number 1 and / or the driver circuit.

[0139] Fig. 9 The third curve from the top represents the number two fuel injector (e.g., a high flow fuel injector such as Figure 1 68) shown, the number two fuel injector injecting diesel fuel into the number one cylinder. The pulse width (e.g., 906 and 908) varies in width, and the width is an indication of the amount of fuel injected in the fuel pulse. The wider the pulse, the greater the amount of fuel injected into the cylinder during the pulse. The shorter the pulse, the less the amount of fuel injected into the cylinder during the pulse. The wide line 999 represents the injector closed dwell time, during which the number two fuel injector cannot open to inject fuel after being most recently closed. The fuel injector closed dwell time can be related to the physical properties of the number two fuel injector and / or the driver circuit.

[0140] At time T70, the fuel injector starts to inject the first pilot fuel injection 901 during the cylinder cycle. Fuel injector number two does not inject fuel. Fuel injector number one stops injecting fuel at time T71, and the injector closing dwell time 998 of fuel injector number one begins. At time T72, fuel injector number two starts to inject the second pilot fuel injection 906 during the fuel injection closing dwell time of fuel injector number one. Fuel injector number two stops injecting fuel at time T73, and the closing dwell time 999 of fuel injector number two begins. While the closing dwell time of fuel injector number two is in progress, fuel injector number one provides the third pilot fuel injection 902 at time T74. The third pilot fuel injection provided by fuel injector number one stops at time T75. When the closing dwell time of fuel injector number one is activated, fuel injector number two starts the fourth pilot injection 907 at time T76. Thus, by staggering the fuel injection times of the two fuel injectors, tighter pilot fuel injections may be provided than could be provided by using a single fuel injector.

[0141] Between time T76 and time T80, fuel injector number one and fuel injector number two each provide a main fuel injection with their respective closed dwell times following the main fuel injection. The closed dwell times end well before the post fuel injection begins at time T80.

[0142] At time T80, the fuel injector starts to inject the first post fuel injection 904 during the cylinder cycle. No. 2 fuel injector does not inject fuel. No. 1 fuel injector stops injecting fuel at time T81, and the injector closing dwell time 998 of fuel injector No. 1 begins. At time T82, fuel injector No. 2 starts injecting the second post fuel injection 909 during the fuel injection closing dwell time of fuel injector No. 1. Fuel injector No. 2 stops injecting fuel at time T83, and the closing dwell time 999 of fuel injector No. 2 begins. While the closing dwell time of fuel injector No. 2 is in progress, fuel injector No. 1 provides the third post fuel injection 905 at time T84. The third pilot fuel injection provided by fuel injector No. 1 stops at time T85. When the closing dwell time of fuel injector No. 1 is activated, fuel injector No. 2 starts the fourth post injection 910 at time T86. Thus, by staggering the fuel injection times of the two fuel injectors, tighter post fuel injections may be provided than would be possible by using a single fuel injector.

[0143] In addition, a main injection through another injector can be initiated during the closed dwell time of one injector after the injector has completed the pilot fuel injection, so that the main fuel injection can be closely coupled to the pilot fuel injection. For example, during the closed dwell time of the No. 1 fuel injector after the No. 1 fuel injector completes the pilot fuel injection, the main injection from the No. 2 fuel injector can be initiated. Similarly, a post-fuel injection through another injector can be initiated during the closed dwell time of the injector after the injector has completed the main fuel injection, so that the post-fuel injection can be closely coupled to the main fuel injection. For example, during the closed dwell time of the No. 2 fuel injector after the No. 2 fuel injector completes the main fuel injection, the post-fuel injection from the No. 1 fuel injector can be initiated.

[0144] Note that the example control and estimation procedures included herein can be used with various engine and / or vehicle system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be implemented by a control system including a controller in combination with various sensors, actuators, and other engine hardware. In addition, part of the method can be an actual action taken in the real world to change the state of the device. The specific program described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Therefore, the various actions, operations, and / or functions shown can be executed in the sequence shown, executed in parallel, or omitted in some cases. Similarly, the order of processing is not necessary to achieve the features and advantages of the examples described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown can be repeatedly performed according to the specific strategy used. In addition, the described actions, operations, and / or functions can be represented in a pattern to be programmed into the code in the non-transitory memory of a computer-readable storage medium in the engine control system, wherein the described actions are implemented by combining the electronic controller execution instructions in a system including various engine hardware components. If necessary, one or more of the method steps described herein can be omitted.

[0145] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, as many variations are possible, and these specific examples should not be considered limiting. For example, the above techniques may be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, and other features, functions, and / or properties.

[0146] The appended claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal to, or different in scope from the original claims, are also deemed to be included in the subject matter of the present disclosure.

Claims

1. An engine system, comprising: an engine comprising at least one cylinder and two pistons positioned within the at least one cylinder; a first diesel fuel injector supplying fuel to the at least one cylinder; a second diesel fuel injector supplying fuel to the at least one cylinder, the second diesel fuel injector being a higher fuel flow rate injector than the first diesel fuel injector; as well as A cavity in a first of the two pistons, and wherein the cavity is asymmetric about a horizontal centerline of the first of the two pistons, the horizontal centerline being perpendicular to a longitudinal direction of the first diesel fuel injector and the second diesel fuel injector. 2 . The engine system of claim 1 , wherein the first diesel fuel injector and the second diesel fuel injector inject diesel fuel directly into the at least one cylinder. 3 . The engine system of claim 2 , further comprising positioning the first and second diesel fuel injectors in the engine such that fuel exiting the first diesel fuel injector collides with fuel exiting the second diesel fuel injector.

4. The engine system of claim 1, wherein the engine is an opposed piston engine.

5. The engine system according to claim 1, wherein: The first diesel fuel injector has a narrower fuel spray cone than the second diesel fuel injector. The engine system of claim 1 , wherein a depth of the cavity is non-uniform. 7 . The engine system of claim 5 , wherein a first opening width of the cavity is smaller than a second opening width of the cavity. 8 . The engine system of claim 4 , wherein the first diesel fuel injector and the second diesel fuel injector are positioned directly opposite one another.

9. The engine system of claim 1, wherein the cavity includes three side walls.

10. An engine system comprising: an engine comprising at least one cylinder; a first diesel fuel injector supplying fuel to the at least one cylinder; a second diesel fuel injector supplying fuel to the at least one cylinder, the second diesel fuel injector being a higher fuel flow rate injector than the first diesel fuel injector; as well as a piston in the at least one cylinder, the piston comprising a first chamber and a second chamber, wherein the first chamber is positioned in the top of the piston to receive fuel directly from a spray cone of fuel injected via the first diesel fuel injector, Wherein the second chamber is positioned in the top of the piston to directly receive fuel from a spray cone of fuel injected via the second diesel fuel injector, and wherein the second chamber has a larger volume than the first chamber. 11 . The engine system of claim 10 , wherein the first diesel fuel injector and the second diesel fuel injector are coupled to a cylinder head. 12 . The engine system of claim 10 , wherein the first diesel fuel injector and the second diesel fuel injector inject diesel fuel directly into the at least one cylinder.

13. The engine system of claim 10 further comprising positioning the first diesel fuel injector and the second diesel fuel injector in the engine such that fuel exiting the first diesel fuel injector collides with fuel exiting the second diesel fuel injector and such that fuel from the first diesel fuel injector and fuel from the second diesel fuel injector do not collide with surfaces of the engine.

Images