Combustion system for an internal combustion engine
By employing a fuel injector design with a specific geometry of piston dome tip and multiple bridging holes in the combustion system, the problem of reducing ignition fuel consumption in gas-fueled engines has been solved, resulting in lower emissions and better engine performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SETH PERRY CANADA LLP
- Filing Date
- 2024-11-01
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies are insufficient to effectively reduce the consumption of ignition fuel in gas-fueled engines without compromising engine performance, leading to excessive emissions of carbon dioxide, nitrogen oxides, and particulate matter.
An improved combustion system design is adopted, which includes a fuel injector with a specific geometry and multiple bridging holes set at the end of the piston dome. The injector injects ignition fuel and main fuel through a single ignition hole and multiple main holes respectively. The piston dome end design improves the fuel mixture quality and optimizes the combustion process through a segmented injection strategy.
It achieves a significant reduction in ignition fuel consumption without compromising engine performance, thereby reducing emissions of carbon dioxide, nitrogen oxides, and particulate matter and meeting stringent emission regulations.
Smart Images
Figure CN122122378A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a combustion system for an internal combustion engine. Background Technology
[0002] Gaseous fuels such as natural gas, propane, hydrogen, and their blends are cleaner-burning fuels compared to liquid fuels such as diesel. Recent attention has focused on developing engines capable of burning gaseous fuels while matching the power and performance that engine operators are accustomed to expecting from diesel engines. However, because many gaseous fuels have high auto-ignition temperatures, they typically require ignition assistance. In other words, gaseous fuels require an active ignition source, such as a ignition fuel, glow plug, or spark plug, for reliable ignition. In some engine systems, including Diesel-cycle engine systems, ignition injection of a ignition fuel such as diesel (i.e., a fuel with a lower auto-ignition temperature) is used to ignite gaseous fuels that cannot be reliably ignited in the combustion chamber of an internal combustion engine by compression heat alone.
[0003] Because ignition fuels have a relatively high carbon content compared to primary fuels (i.e., gaseous fuels), ignition fuels used to ignite gaseous fuels may still increase emissions of particulate matter, carbon dioxide, and / or nitrogen oxides. In this document, the term "and / or" is used to mean "one or the other or both." To meet increasingly stringent emission regulations, it is desirable to further reduce the consumption of hydrocarbon ignition fuels (i.e., diesel fuels) to further limit emissions of carbon dioxide, nitrogen oxides, and particulate matter.
[0004] One common way to reduce ignition fuel consumption is to reduce the pulse duration of ignition fuel during the ignition injection event. However, due to the risks of inconsistent ignition volume and suboptimal ignition atomization and distribution, the pulse duration of ignition fuel cannot be reduced below a certain limit. Another common way to reduce ignition fuel consumption is to reduce the number of ignition orifices used to discharge ignition fuel. However, the number of ignition orifices is usually selected based on the number of main orifices used to discharge the main fuel (i.e., gaseous fuel). Therefore, reducing the number of ignition orifices means reducing the number of main orifices, which can affect engine performance.
[0005] Therefore, existing technologies lack effective techniques for reducing auto-ignition fuel consumption in gas-fueled engines. This disclosure provides techniques for minimizing auto-ignition fuel consumption in gas-fueled engines without compromising engine performance. Summary of the Invention
[0006] An improved combustion system for an internal combustion engine includes a cylinder extending along a longitudinal axis. The combustion system also includes a cylinder head disposed on the cylinder. The combustion system further includes a piston configured to reciprocate within the cylinder along a longitudinal axis between top dead center and bottom dead center. The piston includes a piston cup comprising a dome extending conically to a dome tip. The dome tip includes a ridge, an annular protrusion, and an annular recessed surface, the annular protrusion being spaced apart from and surrounding the ridge, and the annular recessed surface being disposed between the ridge and the annular protrusion. Each of the ridge and the annular protrusion extends upward from the annular recessed surface such that the ridge, the annular protrusion, and the annular recessed surface define an annular groove therebetween. The combustion system also includes a combustion chamber defined by the cylinder, cylinder head, and piston. The combustion system further includes a fuel injector for introducing pilot fuel and main fuel directly into the combustion chamber. The fuel injector can be mounted in the cylinder head. The fuel injector includes a nozzle that extends at least partially into the combustion chamber. The nozzle includes a nozzle tip that faces a dome tip. A single ignition orifice is located at the nozzle tip and configured to discharge an ignition jet of igniting fuel into the combustion chamber. Multiple main orifices are angularly spaced from each other and configured to discharge corresponding main jets of main fuel into the combustion chamber. Each of the multiple main orifices is spaced apart from the nozzle tip. Attached Figure Description
[0007] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate specific embodiments of the apparatus, system, and method, and together with the general description above and the detailed description of the specific embodiments, serve to explain the principles of the apparatus, system, and method.
[0008] Figure 1 This is a schematic diagram of an internal combustion engine including a combustion system according to an embodiment of the present disclosure; Figure 2 This is a perspective view of a combustion system according to an embodiment of the present disclosure, wherein some components are not shown; Figure 3A According to embodiments of this disclosure Figure 2 A partial side sectional view of the combustion system, in which the piston of the combustion system is at bottom dead center; Figure 3B According to embodiments of this disclosure Figure 2 A partial side sectional view of the combustion system, with the piston at top dead center; Figure 4 According to embodiments of this disclosure Figure 2 A partial cross-sectional view of the fuel injector in the combustion system; Figure 5A According to embodiments of this disclosure Figure 2A grayscale image of a portion of the combustion chamber of the combustion system before the main fuel is ignited; Figure 5B According to embodiments of this disclosure Figure 5A A grayscale image of a portion of the combustion chamber after the main fuel has been ignited; Figure 6A The illustration shows an embodiment according to the present disclosure. Figure 2 A graph showing the cylinder pressure variation with crank angle for the combustion system and a benchmark combustion system used for comparison. Figure 6B The illustration shows an embodiment according to the present disclosure. Figure 2 A graph showing the heat release rate of the combustion system and the reference combustion system used for comparison as a function of crank angle; Figure 6C The illustration shows an embodiment according to the present disclosure. Figure 2 A graph showing the mass flow rate of the main fuel as a function of crankshaft angle for the combustion system and a reference combustion system used for comparison; and Figure 7 The illustration shows embodiments of fuel injection with normal fuel injection and fuel injection with segmented fuel injection according to the present disclosure. Figure 2 A graph showing the change in cylinder pressure of the combustion system with crank angle. Detailed Implementation
[0009] refer to Figure 1 The image shows a combustion system 100 for an internal combustion engine 50 according to an embodiment of the present disclosure. Figure 2 This is a perspective view of a combustion system 100 according to an embodiment of the present disclosure, wherein some components are not shown. Figure 3A and Figure 3B This is a partial side sectional view of a combustion system 100 according to an embodiment of the present disclosure.
[0010] refer to Figures 1 to 3B The internal combustion engine 50 can be used in vehicles, and can also be used in marine applications, locomotive applications, mining transportation applications, power generation applications, or stationary applications. In other words, the internal combustion engine 50 can be a light-duty engine, a medium-duty engine, a heavy-duty engine, or a high-horsepower (HHP) engine.
[0011] The internal combustion engine 50 can be fueled by both liquid and gaseous fuels. In some embodiments, gaseous fuel is used as the primary fuel F1 for the internal combustion engine 50 (e.g., liquid fuel, gaseous ...). Figure 3B As shown), and liquid fuel is used as ignition fuel F2 for the internal combustion engine 50 (as shown). Figure 3B(As shown). In other words, ignition fuel F2 is a liquid fuel, and main fuel F1 is a gaseous fuel. The auto-ignition temperature of main fuel F1 is higher than that of ignition fuel F2. More specifically, for a given pressure condition, the auto-ignition temperature of main fuel F1 is higher than that of ignition fuel F2. As used herein, gaseous fuel is any fuel in a gaseous / gas phase at standard temperature and standard pressure, where, in the context of this application, standard temperature and standard pressure are defined as a temperature of zero (0) degrees Celsius (°C) and an absolute pressure of one hundred (100) kilopascals (kPa). In some embodiments, the gaseous fuel is hydrogen. In some embodiments, the gaseous fuel is selected from the group consisting of natural gas, hydrogen, propane, ethane, butane, methane, ammonia, and mixtures thereof. In some other embodiments, the liquid fuel may be diesel, dimethyl ether (DME), or kerosene.
[0012] Combustion system 100 includes a cylinder 102 extending along a longitudinal axis LA. The cylinder 102 defines a cylindrical surface 104 within an engine block. The cylindrical surface 104 is an inner surface of the cylinder 102 within the engine block. Combustion system 100 also includes a cylinder head 106 disposed on the cylinder 102. The cylinder head 106 covers the top of the cylinder 102. Combustion system 100 also includes a piston 108 configured to reciprocate within the cylinder 102 along the longitudinal axis LA between top dead center (TDC) and bottom dead center (BDC). Figure 3A In the middle, piston 108 is located in BDC. Figure 3B In the combustion system 100, piston 108 is located in the TDC. Combustion system 100 also includes combustion chamber 110, which is defined by cylinder 102, cylinder head 106 and piston 108.
[0013] It should be understood that, for the sake of simplicity and clarity, some conventional components of the internal combustion engine 50 are not shown. Furthermore, only a cross-section of such an internal combustion engine 50 is shown, illustrating the combustion chamber 110 of one cylinder (i.e., cylinder 102); however, those skilled in the art will understand that the internal combustion engine 50 may include other components and multiple cylinders. Figure 2 For illustrative purposes, some components such as cylinder 102 are not shown.
[0014] The combustion system 100 also includes a fuel injector 112 for directly introducing ignition fuel F2 and main fuel F1 into the combustion chamber 110. In an exemplary embodiment, the fuel injector 112 is hydraulically actuated. Figure 4 This is a partial cross-sectional view of a fuel injector 112 according to an embodiment of the present disclosure. Reference Figures 1 to 4Fuel injector 112 can be mounted in cylinder head 106 for directly introducing fuel into combustion chamber 110. Fuel injector 112 extends at least partially through cylinder head 106 into combustion chamber 110. Fuel injector 112 is adapted to deliver pilot fuel F2 and main fuel F1 separately and independently at their respective appropriate times. As will be discussed in more detail below, pilot fuel F2 is introduced toward piston 108, such as... Figure 4 As shown. In some embodiments, the injection start timing of the ignition fuel F2 allows at least 50% of the ignition fuel F2 to evaporate before impacting the piston 108. In other embodiments, the injection start timing of the ignition fuel F2 allows at least 40% of the ignition fuel F2 to evaporate before impacting the piston 108.
[0015] The fuel injector 112 includes a nozzle 114 that extends at least partially into the combustion chamber 110. Figure 4 For illustrative purposes, some components of the fuel injector 112, such as the fuel inlet, electrical connector, and valves, are not shown. (Reference) Figure 4 The nozzle 114 includes a nozzle tip 116. In the nozzle 114, only a single ignition orifice H2 is provided at the nozzle tip 116 and configured to discharge an ignition jet J2 of igniting fuel F2 into the combustion chamber 110. Furthermore, in the nozzle 114, a plurality of main orifices H1 are angularly spaced from each other and configured to discharge corresponding main jets J1 of main fuel F1 into the combustion chamber 110. Each of the plurality of main orifices H1 is spaced apart from the nozzle tip 116. Each main orifice H1 has a main outlet O1 through which the corresponding main jet J1 exits the nozzle 114.
[0016] The fuel injector 112 also includes a main needle valve 118 that controls the discharge of the corresponding main jet J1 through each main orifice H1. The fuel injector 112 also includes an ignition needle valve 120 that controls the discharge of the ignition jet J2 through the ignition orifice H2. Each of the main needle valve 118 and the ignition needle valve 120 extends along the central axis CA1 of the fuel injector 112. However, in other embodiments, the main needle valve 118 and the ignition needle valve 120 may be arranged concentrically and / or adjacent to each other, offset from the central axis CA1 of the fuel injector 112. In some embodiments, the central axis CA1 of the fuel injector 112 is aligned with the longitudinal axis LA of the cylinder 102.
[0017] Each of the main needle valve 118 and the ignition needle valve 120 is movably received within the nozzle 114. The ignition needle valve 120 is concentrically guided in an orifice disposed within the main needle valve 118. The main needle valve 118 is a hollow needle adapted to open or close a plurality of main orifices H1 disposed at the nozzle tip 116. The ignition needle valve 120 is a conventional needle valve or an internal needle valve adapted to open or close a single ignition orifice H2 disposed at the nozzle tip 116. In some embodiments, during each injection cycle of the fuel injector 112, the main needle valve 118 is configured to have an open duration of 0.5 milliseconds to 3 milliseconds to allow the discharge of the corresponding main jet J1 through each main orifice H1. The fuel injector 112 also includes valves (not shown) and fluid chambers (not shown) for controlling the opening and closing movements of the main needle valve 118 and the ignition needle valve 120.
[0018] Ignition hole H2 has an ignition hole diameter D2 (e.g. Figure 4 (as shown) and ignition cross-sectional area A2. Each main hole H1 has a main cross-sectional area A1. In some embodiments, the ignition cross-sectional area A2 is less than 2% of the main cross-sectional area A1. In other embodiments, the ignition cross-sectional area A2 is less than 5% of the main cross-sectional area A1. In other embodiments, the ignition cross-sectional area A2 is less than 10% of the main cross-sectional area A1.
[0019] Ignition holes H2 extend along the ignition axis PA. Each main hole H1 extends along the main axis MA, which is inclined at a main tilt angle b1 relative to the ignition axis PA. In some embodiments, the main tilt angle b1 is between 40 degrees and 80 degrees. In some embodiments, the ignition axis PA is aligned with the central axis CA1 of the fuel injector 112. In some embodiments, the ignition axis PA is aligned with the longitudinal axis LA of the cylinder 102. In some embodiments, the ignition axis PA is aligned with the central axis CA2 of the piston 108 (e.g., ...). Figure 3A (As shown) Alignment. In some embodiments, the central axis CA2 of the piston 108 is aligned with the longitudinal axis LA of the cylinder 102.
[0020] In some embodiments, the nozzle 114 further includes a plurality of bridging orifices H3, which are angularly spaced from each other and angularly disposed between the ignition orifice H2 and the plurality of main orifices H1 relative to the central axis CA1 of the fuel injector 112. The plurality of bridging orifices H3 are configured to discharge corresponding bridging jets J3 of the main fuel F1. In some embodiments, the number of the plurality of bridging orifices H3 is equal to the number of the plurality of main orifices H1. In other embodiments, the number of the plurality of bridging orifices H3 is different from the number of the plurality of main orifices H1.
[0021] Each of the plurality of bridging holes H3 extends along the bridging axis BA. The bridging axis BA is inclined relative to the ignition axis PA by a bridging tilt angle b2, which is smaller than the principal tilt angle b1. In some embodiments, the bridging tilt angle b2 is between 20% and 90% of the principal tilt angle b1. In some embodiments, the bridging tilt angle b2 is approximately 50% of the principal tilt angle b1.
[0022] Each bridging orifice has a bridging cross-sectional area A3. In some embodiments, the bridging cross-sectional area A3 is between 5% and 100% of the main cross-sectional area A1. In some embodiments, the bridging cross-sectional area A3 is between 40% and 60% of the main cross-sectional area A1. Each of the plurality of bridging orifices H3 has a bridging outlet O3 through which the corresponding bridging jet J3 exits the nozzle 114. The bridging outlet O3 of each bridging orifice H3 is positioned relative to the central axis CA1 of the fuel injector 112 between the nozzle tip 116 and the main outlet O1 of each main orifice H1.
[0023] Refer again Figures 2 to 4 The piston 108 includes a piston bowl 122, which includes a dome 124 extending in a conical shape to a dome tip 126. In some embodiments, the piston bowl 122 also includes a toroidal surface 128 surrounding the dome 124. The dome tip 126 includes a ridge 130 (e.g., Figure 3A As shown, an annular protrusion 132 and an annular recessed surface 134 are provided between the protrusion 130 and the annular protrusion 132. The annular protrusion 132 is spaced apart from and surrounds the ridge 130, and the annular recessed surface 134 is provided between the ridge 130 and the annular protrusion 132. Each of the ridge 130 and the annular protrusion 132 extends upward from the annular recessed surface 134, such that the ridge 130, the annular protrusion 132 and the annular recessed surface 134 define an annular groove 136 therebetween.
[0024] In some embodiments, the raised portion 130 is centrally disposed on the dome end 126 and aligned with the central axis CA2 of the piston 108. In other embodiments, the raised portion 130 may not be aligned with the central axis CA2 of the piston 108. In some embodiments, the dome end 126 is symmetrical with respect to the central axis CA2 of the piston 108. In other embodiments, the dome end 126 may not be symmetrical with respect to the central axis CA2 of the piston 108. In some embodiments, the raised portion 130 is convex relative to the annular recessed surface 134. In some embodiments, the annular protrusion 132 is disposed along the periphery P1 of the dome end 126.
[0025] In some embodiments, the annular recessed surface 134 is planar. In other embodiments, the annular recessed surface 134 may be curved. In some embodiments, the dome 124 has a conical side surface 138 extending at an angle from the dome tip 126. In some embodiments, when the piston 108 is at top dead center (e.g. Figure 3B As shown, the distance D1 between the nozzle tip 116 and the raised portion 130 along the longitudinal axis LA of the cylinder 102 is greater than 30 times the ignition hole diameter D2. In other embodiments, when the piston 108 is at top dead center, the distance D1 can be greater than 20 times the ignition hole diameter D2.
[0026] In some embodiments, the annular protrusion 132 includes an angled surface 140 extending from the annular recessed surface 134. The angled surface 140 forms an inclination angle b3 with a horizontal plane HP orthogonal to the central axis CA2 of the piston 108. In some embodiments, the inclination angle b3 is between -30 degrees and 45 degrees. In some embodiments, the inclination angle b3 is approximately 35 degrees.
[0027] Furthermore, in some embodiments, the dome tip 126 is configured to receive the ignition jet J2 from the nozzle tip 116 and deflect the ignition jet J2 into a conical spray surface 142. The conical spray surface 142 delineates the direction of the deflected spray, which can be continuous in a circumferential direction along the longitudinal axis LA around the cylinder 102. The dome tip 126 is configured to receive the ignition jet J2 from the nozzle tip 116 and guide the ignition jet J2 toward multiple main jets J1 discharged from multiple main orifices H1.
[0028] The raised portion 130, the annular protrusion 132, and the annular recessed surface 134 together provide the desired geometry for the dome tip 126 to guide the ignition jet J2 toward the multiple main jets J1 emitted from the multiple main orifices H1. This geometry of the dome tip 126 can bring the ignition jet J2 closer to the multiple main jets J1 emitted from the multiple main orifices H1. In other words, the design of the dome tip 126 guides or deflects the ignition jet J2 of the ignition fuel F2 toward the multiple main jets J1 of the main fuel F1 in order to improve the mixing quality of the main fuel F1 (gaseous fuel) and the ignition fuel F2 (liquid fuel) in the combustion chamber 110.
[0029] In some embodiments, including a plurality of bridging orifices H3 in the nozzle 114 between the ignition orifice H2 and the plurality of main orifices H1 can improve the ignition of the main fuel F1 in the combustion chamber 110. In other words, the plurality of bridging jets J3 of the main fuel F1 located between the ignition jet J2 and the plurality of main jets J1 can provide robust ignition of the main fuel F1 in the combustion chamber 110. Therefore, the geometry of the dome tip 126 of the disclosed piston 108 and the inclusion of the plurality of bridging orifices J3 can improve the mixing quality of the main fuel F1 and the ignition fuel F2, and enable robust ignition of the main fuel F1 in the combustion chamber 110.
[0030] Due to the disclosed geometry of the dome tip 126 of the piston 108 and the inclusion of multiple bridging orifices J3, a single ignition orifice H2 is sufficient to achieve robust ignition of the main fuel F1 in the combustion chamber 110. Therefore, multiple ignition jets (as in conventional injectors) are not required in the fuel injector 112 to meet the ignition requirements of the main fuel F1. Thus, compared to conventional combustion systems, the combustion system 100 consumes less ignition fuel F2 due to the single ignition orifice H2, the geometry of the dome tip 126 of the piston 108, and the multiple bridging orifices H3. This reduction in ignition fuel F2 consumption results in lower emissions of carbon dioxide, nitrogen oxides, and particulate matter, thereby meeting stringent emission regulations without compromising the performance of the internal combustion engine 50.
[0031] Furthermore, due to the geometry of the dome tip 126 of the disclosed piston 108, including multiple bridging holes J3 and a single ignition hole H2, the ignition rate of the combustion system 100 can be reduced by at least 5 times compared to a conventional combustion system. In some embodiments, the ignition rate of the combustion system 100 can be reduced from 5% to 1% of total fuel consumption (including ignition fuel and main fuel).
[0032] Figure 5A This is a grayscale image of a portion of the combustion chamber 110 of a combustion system 100 according to an embodiment of the present disclosure before the main fuel F1 is ignited. Figure 5A As shown in the grayscale image, the ignition fuel F2 is guided towards the main fuel F1 by the main jet J1 after impacting the dome tip 126 of the piston 108. The bridging jet J3 discharged through the bridging orifice H3 improves the ignition of the main fuel F1.
[0033] Figure 5B This is a grayscale image of a portion of the combustion chamber 110 according to an embodiment of the present disclosure after the main fuel F1 has been ignited. Figure 5B As shown in the grayscale image, the ignition of the main fuel F1 is represented by the shaded area 144. The shaded area 144 indicates robust and desirable ignition of the main fuel F1 in the combustion chamber 110.
[0034] Figure 6A The illustration shows an embodiment according to the present disclosure. Figure 2 Figure 146 shows the cylinder pressure variation with crank angle for the combustion system 100 and the reference combustion system (not shown) used for comparison. The combustion system 100 and the reference combustion system used for comparison have the same construction, except that in the reference combustion system used for comparison, the fuel injector 100 ( Figures 1 to 4 The dome tip 126 (as shown) does not include any bridging holes (i.e., bridging hole H3). Furthermore, in the reference combustion system used for comparison, the dome tip 126 does not include annular protrusions and annular recessed surfaces. In other words, in the reference combustion system used for comparison, the piston has a conventional design. Cylinder pressure is the combustion chamber 110 inside cylinder 102 (as shown). Figure 1 The pressure is shown in Figure 146. Furthermore, to plot Figure 146, natural gas was used as the primary fuel F1, and diesel fuel was used as the ignition fuel F2.
[0035] In Figure 146, crank angle is shown in arbitrary units on the horizontal axis, and cylinder pressure is shown in arbitrary units on the vertical axis. Figure 146 includes curves 148, 150, and 152. Curve 148 depicts the cylinder pressure of a benchmark combustion system used for comparison as a function of crank angle. Curve 150 depicts the cylinder pressure of combustion system 100 as a function of crank angle, wherein, during each injection cycle of fuel injector 112, the main needle valve 118 (e.g., Figure 4 (As shown) The main needle valve 118 opens to allow the corresponding main jet J1 to be discharged through each main orifice H1. Curve 152 depicts the cylinder pressure of the combustion system 100 as a function of crank angle, wherein, during each injection cycle of the fuel injector 112, the main needle valve 118 transitions from the closed position to the fully open position over a duration (the opening time of the fuel injector 112), which is twice the duration in the case of curve 150, to allow the corresponding main jet J1 to be discharged more slowly through each main orifice H1. In other words, the fuel injector 112 in curve 152 opens more slowly than the fuel injector 112 in curve 150.
[0036] Referring to curves 148, 150, and 152, it is evident that in combustion system 100, when the opening duration of the main needle valve 118 is twice that of curve 150, the peak cylinder pressure is relatively low. Therefore, such a slow opening of the main needle valve 118 helps reduce peak cylinder pressure, resulting in better performance of the internal combustion engine 50.
[0037] Figure 6B The illustration shows an embodiment according to the present disclosure. Figure 2The graph 154 shows the heat release rate of the combustion system 100 and the reference combustion system used for comparison as a function of crank angle. To plot the graph 154, natural gas was used as the main fuel F1 and diesel was used as the ignition fuel F2.
[0038] In Figure 154, crank angle is shown in arbitrary units on the horizontal axis, and heat release rate is shown in arbitrary units on the vertical axis. Figure 154 includes curves 156, 158, and 160. Curve 156 depicts the heat release rate of a benchmark combustion system used for comparison as a function of crank angle. Curve 158 depicts the heat release rate of combustion system 100 as a function of crank angle, wherein, during each injection cycle of fuel injector 112, the main needle valve 118 (e.g., Figure 4 (As shown) it opens to allow the corresponding main jet J1 to be discharged through each main orifice H1. Curve 160 depicts the heat release rate of the combustion system 100 as a function of crank angle, wherein, during each injection cycle of the fuel injector 112, the main needle valve 118 changes from the closed position to the fully open position for a duration that is twice the duration in the case of curve 158, to allow the corresponding main jet J1 to be discharged more slowly through each main orifice H1.
[0039] Referring to curves 158 and 160, for combustion system 100, it is evident that when the opening duration of the main needle valve 118 is twice that of curve 158, the peak heat release rate is relatively low. Therefore, such a slow opening of the main needle valve 118 can help reduce the peak heat release rate, thereby reducing combustion abrasiveness and improving the durability of the internal combustion engine 50.
[0040] Figure 6C The illustration shows an embodiment according to the present disclosure. Figure 2 Graph 162 shows the mass flow rate of the main fuel F1 in the combustion system 100 and the reference combustion system used for comparison as a function of crank angle. To plot Graph 162, natural gas was used as the main fuel F1, and diesel fuel was used as the ignition fuel F2. The mass flow rate of the main fuel F1 is the rate at which the main fuel F1 flows out of nozzle 114.
[0041] In Figure 162, crank angle is shown in arbitrary units on the horizontal axis, and mass flow rate is shown in arbitrary units on the vertical axis. Figure 162 includes curves 164, 166, and 168. Curve 164 depicts the mass flow rate of a reference combustion system used for comparison as a function of crank angle. Curve 166 depicts the mass flow rate of combustion system 100 as a function of crank angle, wherein, during each injection cycle of fuel injector 112, the main needle valve 118 (e.g., Figure 4(As shown) Opens to allow the corresponding main jet J1 to be discharged through each main orifice H1. Curve 168 depicts the mass flow rate of the combustion system 100 as a function of crank angle, wherein, during each injection cycle of the fuel injector 112, the main needle valve 118 is open for a duration twice that of curve 150, to allow the corresponding main jet J1 to be discharged more slowly through each main orifice H1.
[0042] Referring to curves 164, 166, and 168, it is clear that the peak mass flow rate of the main fuel F1 is relatively high in the case of combustion engine 100 (described as curves 166 and 168) compared to the baseline combustion engine used for comparison (curve 164). This can improve the combustion process and reduce greenhouse gas emissions.
[0043] Figure 7 The illustration shows embodiments of the present disclosure with normal fuel injection and with split fuel injection. Figure 2 The graph 170 shows the cylinder pressure of the combustion system 100 as a function of crankshaft angle. To plot graph 170, hydrogen is used as the main fuel F1, and diesel fuel is used as the ignition fuel F2. Staged injection is a known variation of direct injection. With staged injection, during a given working cycle, two pulses of main fuel F1 are directly injected into cylinder 102. In some applications, staged injection is employed such that a first portion of the main fuel F1 is injected into combustion chamber 110 before the intake valve closes, and a second portion of the main fuel F1 is injected after the intake valve closes.
[0044] In Figure 170, crank angle is shown in arbitrary units on the horizontal axis, and cylinder pressure is shown in arbitrary units on the vertical axis. Figure 170 includes curves 172 and 174. Curve 172 depicts the cylinder pressure of combustion system 100 as a function of crank angle when main fuel F1 is injected normally. Curve 174 depicts the cylinder pressure of combustion system 100 as a function of crank angle when main fuel F1 is injected in stages. Referring to curves 172 and 174, it is clear that using a staged injection strategy can help reduce peak cylinder pressure in cylinder 102. In the case of staged injection, the peak cylinder pressure is relatively low, resulting in improved performance of internal combustion engine 50.
[0045] While specific elements, embodiments, and applications of the invention have been shown and described, it should be understood that the invention is not limited thereto, as modifications can be made by those skilled in the art without departing from the scope of this disclosure, particularly inspired by the foregoing teachings.
Claims
1. A combustion system for an internal combustion engine, the combustion system comprising: A cylinder that extends along a longitudinal axis; Cylinder head, the cylinder head being disposed on the cylinder; A piston configured to reciprocate within a cylinder along a longitudinal axis between top dead center and bottom dead center, the piston including a piston cup including a dome extending conically to a dome tip, the dome tip including a ridge, an annular protrusion and an annular recessed surface, the annular protrusion being spaced apart from and surrounding the ridge, the annular recessed surface being disposed between the ridge and the annular protrusion, wherein each of the ridge and the annular protrusion extends upward from the annular recessed surface such that the ridge, the annular protrusion and the annular recessed surface define an annular groove between the ridge, the annular protrusion and the annular recessed surface; Combustion chamber, the combustion chamber being defined by the cylinder, the cylinder head, and the piston; and A fuel injector for directly introducing ignition fuel and main fuel into the combustion chamber, the fuel injector being mountable in the cylinder head, the fuel injector including a nozzle that extends at least partially into the combustion chamber, the nozzle including a nozzle tip, a single ignition orifice, and a plurality of main orifices, the nozzle tip facing a dome tip, the ignition orifice being disposed at the nozzle tip and configured to discharge an ignition jet of the ignition fuel into the combustion chamber, the plurality of main orifices being angularly spaced from each other and configured to discharge corresponding plurality of main jets of the main fuel into the combustion chamber, wherein each of the plurality of main orifices is spaced apart from the nozzle tip.
2. The combustion system according to claim 1, wherein, The raised portion is centrally located on the end of the dome and aligned with the central axis of the piston.
3. The combustion system according to claim 2, wherein, The ignition hole extends along the ignition axis, which is aligned with the central axis of the piston.
4. The combustion system according to claim 2, wherein, The dome tip is symmetrical about the central axis of the piston.
5. The combustion system according to claim 1, wherein, The raised portion is convex relative to the annular recessed surface.
6. The combustion system according to claim 1, wherein, The annular protrusion is provided along the periphery of the end of the dome.
7. The combustion system according to claim 1, wherein, The annular protrusion includes an angled surface extending from the annular recessed surface, the angled surface forming an inclination angle with the horizontal plane, the horizontal plane being orthogonal to the central axis of the piston.
8. The combustion system according to claim 7, wherein, The tilt angle is between -30 degrees and 45 degrees.
9. The combustion system according to claim 1, wherein, The annular recessed surface is planar.
10. The combustion system according to claim 1, wherein, The dome has conical side surfaces that extend at an angle from the end of the dome.
11. The combustion system according to claim 1, wherein, The piston bowl also includes an annular surface surrounding the dome.
12. The combustion system according to claim 1, wherein, The dome tip is configured to receive the ignition jet from the nozzle tip and guide the ignition jet toward the plurality of main jets discharged from the plurality of main orifices.
13. The combustion system according to claim 1, wherein, The dome tip is configured to receive the ignition jet from the nozzle tip and deflect the ignition jet into a cone-shaped spray surface.
14. The combustion system according to claim 1, wherein, The ignition orifice has an ignition orifice diameter, and wherein, when the piston is at the top dead center, the distance between the nozzle tip and the bulge along the longitudinal axis of the cylinder is greater than 30 times the ignition orifice diameter.
15. The combustion system according to claim 1, wherein, The ignition hole has an ignition cross-sectional area, wherein each main hole has a main cross-sectional area, and wherein the ignition cross-sectional area is less than 2% of the main cross-sectional area.
16. The combustion system according to claim 1, wherein, The nozzle further includes a plurality of bridging orifices spaced at an angle to each other and disposed at an angle relative to the central axis of the fuel injector between the ignition orifice and the plurality of main orifices, wherein the plurality of bridging orifices are configured to discharge corresponding bridging jets of the main fuel.
17. The combustion system according to claim 16, wherein, Each main orifice has a main outlet through which the corresponding main jet exits the nozzle, wherein each of the plurality of bridging orifices has a bridging outlet through which the corresponding bridging jet exits the nozzle, and wherein the bridging outlet of each bridging orifice is disposed between the nozzle tip and the main outlet of each main orifice relative to the central axis of the fuel injector.
18. The combustion system according to claim 16, wherein, The ignition hole extends along the ignition axis, wherein each main hole extends along the main axis, the main axis being inclined at a main tilt angle relative to the ignition axis, wherein each of the plurality of bridging holes extends along the bridging axis, and wherein the bridging axis is inclined at a bridging tilt angle relative to the ignition axis, the bridging tilt angle being smaller than the main tilt angle.
19. The combustion system according to claim 18, wherein, The bridging tilt angle is between 20% and 90% of the main tilt angle.
20. The combustion system according to claim 18, wherein, The ignition axis is aligned with the central axis of the fuel injector.
21. The combustion system according to claim 16, wherein, Each main hole has a main cross-sectional area, wherein each bridging hole has a bridging cross-sectional area, and wherein the bridging cross-sectional area is between 5% and 100% of the main cross-sectional area.
22. The combustion system according to claim 16, wherein, The number of the plurality of bridging holes is equal to the number of the plurality of main holes.
23. The combustion system according to claim 1, wherein, The fuel injector also includes an ignition needle valve that controls the discharge of the ignition jet through the ignition orifice.
24. The combustion system according to claim 1, wherein, The fuel injector also includes a main needle valve that controls the discharge of the corresponding main jet through each main orifice.
25. The combustion system according to claim 24, wherein, During each injection cycle of the fuel injector, the main needle valve is configured to have an open duration of 0.5 milliseconds to 3 milliseconds to allow the discharge of the corresponding main jet through each main orifice.
26. The combustion system according to claim 1, wherein, The ignition fuel is a liquid fuel.
27. The combustion system according to claim 1, wherein, The timing of the injection of the ignition fuel allows at least 50% of the ignition fuel to evaporate before impacting the piston.
28. The combustion system according to claim 1, wherein, The main fuel is a gaseous fuel.