Engine operating method and piston with non-reentrant combustion bowl and anti-carbon-accumulation ramp

Abstract

Operating an internal combustion engine involves delivering a spray of directly injected fuel from a swirl bag within a combustion bowl in a piston, and causing the fuel to impinge on an anti-deposit ramp that transitions between a radially inner shelf surface of the combustion bowl and a radially outer extrusion surface of the piston. The shelf surface is spaced axially (FA) from a plane defined by the extrusion surface by a distance of 1% to 2% of the piston's outer diameter (OD). Impinging the fuel on the anti-deposit ramp guides the fuel upward from the extrusion surface to limit wet walls within the combustion cylinder.

Description

Technical Field

[0001] This disclosure generally relates to engine operating methods and piston geometries for reducing smoke or soot production, and more specifically to a piston with an anti-carbon deposit ramp for redirecting injected fuel leaving the combustion bowl to limit wet walls. Background Technology

[0002] Internal combustion engines are commonly used across a wide range of industries to power machinery and equipment. Examples of industries using such machinery and equipment include marine, earthmoving, construction, mining, locomotives, and agriculture, to name just a few. There is an increasing demand for internal combustion engines with higher power density in various applications. These engines are sometimes challenged by the high levels of soot and high valve temperatures or other high cylinder head component temperatures they produce under rated engine conditions. Strategies that improve one performance parameter (such as reduced soot production) often have negative or unpredictable effects on other performance parameters (such as nitrogen oxides or "NOx" production), requiring engineers to balance sometimes competing considerations.

[0003] For decades, research and development have progressed on ways in which fuel supply, exhaust gas recirculation (EGR), turbocharging, variable valve actuation, variable geometry turbines, the use of wastegates, and many other factors can be altered to produce different results. Beyond altering these and other operating parameters, a significant amount of research and performance testing has focused on engine components, particularly pistons in recent years, which can be shaped and scaled to achieve a range of desired outcomes. As mentioned above, one driving force behind progress in combustion science is the desire to reduce and / or balance the relative amounts of certain emissions in engine exhaust. Improving or optimizing engine fuel efficiency, as well as managing component wear and / or fatigue, also remain important objectives. The increasing demand for power density exacerbates some of these challenges and increases the unpredictability of secondary effects from attempting to manipulate any one of these performance parameters. For such reasons, designs and strategies built specifically for one application may reveal themselves to be less suitable for other applications.

[0004] U.S. Patent Application Publication No. 2016 / 0169152 by Burger et al. discloses a piston having a top grooved ridge surface with a height dimension. The piston has a nominal outer diameter such that a predetermined ratio is achieved between the height and the inner diameter of the engine bore, apparently intended to improve engine operation by increasing power output, reducing fuel consumption, and reducing emissions. Summary of the Invention

[0005] In one aspect, a method of operating an internal combustion engine includes reciprocating a piston defining a piston outer diameter (OD) dimension within a combustion cylinder of the engine. The method further includes injecting liquid fuel directly into the combustion cylinder of the engine from a plurality of nozzles in a fuel injector defining a longitudinal axis, and propelling a spray plume of the injected liquid fuel outward and downward through the plurality of nozzles through a combustion bowl having a non-concave profile on the piston. The method further includes conveying the fuel spray plume from a vortex bag of the combustion bowl into a shelf volume of the combustion bowl, the combustion bowl being formed between a plane defined by a radially outer extrusion surface and a radially inner shelf surface spaced apart from the plane by an axial (FA) distance of 1% to 2% of the OD dimension. The method further includes causing the fuel spray plume exiting the shelf volume of the combustion bowl to impinge on an anti-carbon deposit ramp transitioning between the radially inner shelf surface and the radially outer extrusion surface. The method further includes guiding the fuel spray plume away from the shelf volume upward from the extrusion surface based on the impact of fuel on the anti-carbon deposit ramp, in order to limit the wet walls within the combustion cylinder.

[0006] On the other hand, a piston configured to reciprocate in a combustion cylinder of an internal combustion engine includes an annular body comprising a crown defining a longitudinal axis and having a radially outer lip defining a plane oriented perpendicular to the longitudinal axis. The crown further includes a combustion bowl having a radially inner shelf portion spaced apart from the plane by a first axial (FA) distance and a bottom surface spaced apart from the plane by a second axial (SA) distance. The piston further includes an outer surface defining a piston outer diameter (OD) dimension, wherein the ratio of the FA distance to the OD dimension is 1% to 2%, and the ratio of the FA distance to the SA distance is 7% to 11%. The combustion bowl forms a non-concave profile, and the crown further includes an anti-carbon deposit ramp transitioning between the radially inner shelf portion and the radially outer lip to redirect the injected fuel flow exiting the combustion bowl upward from the radially outer lip, thereby limiting the wet walls in the combustion cylinder.

[0007] In another aspect, the piston for an internal combustion engine includes an annular crown body defining a longitudinal axis and having a radially outer lip defining a plane oriented perpendicular to the longitudinal axis. The annular crown body further includes a combustion bowl having a radially inner shelf portion spaced from the plane by a first axial (FA) distance, a bottom concave surface spaced from the plane by a second axial (SA) distance, and an outer bowl surface defining a tangent forming an acute angle with the plane, the acute angle opening in a radially inward direction. The piston further includes a piston skirt attached to the annular crown body and defining a piston outer diameter (OD) dimension of 169 mm to 170 mm, and a FA distance of 1.9 mm to 2.5 mm. The radially outer lip includes a planar extrusion surface, the radially inner shelf portion includes a planar shelf surface, and an anti-carbon deposit ramp transitions between the planar shelf surface and the planar extrusion surface and has a concave curved profile. Attached Figure Description

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

[0009] Figure 2 This illustrates a piston according to one embodiment. Figure 1 A sectional side view of an internal combustion engine;

[0010] Figure 3 yes Figure 2 An enlarged sectional side view of the piston;

[0011] Figure 4 yes Figure 3 Another sectional side view of the piston in the image;

[0012] Figure 5 This is a CFD (Computational Fluid Dynamics) diagram showing the fluid leaving the combustion bowl in the piston being guided away from the combustion cylinder wall according to one embodiment;

[0013] Figure 6 This is an improved CFD-based bar graph showing the temperature of the exhaust valve according to one embodiment;

[0014] Figure 7 This shows an improved CFD-based bar graph of the cover plate temperature according to one embodiment; and

[0015] Figure 8 This is an improved CFD-based bar graph showing the generation of smoke or soot according to one embodiment. Detailed Implementation

[0016] This document discloses various embodiments of pistons that can be used in internal combustion engines and crowns or piston crowns having piston cup geometry according to various embodiments of this disclosure. As will further become apparent from the following description, when the associated internal combustion engine is operating at its rated load, the pistons according to this disclosure are expected to provide increased power density, reduced smoke or soot emissions, and lower cylinder head component temperatures.

[0017] See now Figure 1 An internal combustion engine 100 is shown, which can be implemented in various ways and with different piston geometries according to the principles set forth herein. The engine 100 may include a piston ( Figure 1 An engine block 102 and a cylinder head 104 (not shown) reciprocate therein. The cylinder head may contain various engine components for introducing fluid into bores / combustion cylinders located in the engine block 102. The engine 100 may include any number of combustion cylinders and pistons in any suitable arrangement, such as a V-shaped or inline configuration.

[0018] Also refer to Figure 2 The diagram shows a cross-sectional view of a portion of an engine 100, including a combustion chamber or cylinder 106, which may have a generally cylindrical shape defined within a cylinder bore 108 formed within a crankcase or engine block 102 of the engine 100. The combustion cylinder 106 is further defined at one end by a flame plate surface 110 of a cylinder head 104 and at the other end by a piston crown 400 or piston crown 402 configured to reciprocate within the bore 108 and connected to a connecting rod 124 coupled to a crankshaft (not shown). A fuel injector 112 is mounted in the cylinder head 104. The injector 112 has a tip 114 that protrudes through the flame plate surface 110 within the combustion cylinder 106, allowing it to directly inject fuel into the combustion cylinder 106. Engine 100 may be a compression ignition engine, which causes piston 400 to reciprocate to compress a mixture containing directly injected liquid fuel, such as diesel fraction fuel, to the auto-ignition threshold in a conventional four-stroke mode.

[0019] During operation of engine 100, when one or more intake valves 117 (one shown) open during the intake stroke, air, along with other intake gases such as recirculated exhaust gases, is allowed to enter combustion cylinder 106 via intake passage 115. In known configurations, high-pressure fuel, such as diesel fraction fuel, is allowed to flow through nozzle openings / ports in tip 114 to form a fuel jet or fuel spray plume entering combustion cylinder 106. Each nozzle opening produces a fuel spray plume 118, which is generally dispersed to produce a predetermined fuel / air mixture, which, in a compression-ignition engine, spontaneously combusts and burns. The fuel spray plume 118 can be supplied from injector 112 at an angle β, for example, between 110° and 150°, but other angles may also be used. After combustion, when one or more exhaust valves 122 open during the exhaust stroke, exhaust gases are discharged from combustion cylinder 106 through exhaust passage 120.

[0020] See now Figure 3 The image shows piston 400, with further details shown. Piston 400 can be made of steel, cast aluminum alloy, forged aluminum alloy, or other suitable, durable, and corrosion-resistant materials. The geometry of the crown can be formed during casting or forging, and then roughing and / or finishing can be performed if necessary. Suitable machining processes can include milling, turning, electrical discharge machining, or other processes.

[0021] Piston 400 may include an annular body 404, the annular body including a crown 402 and defining a longitudinal axis 406, a radial direction 408 perpendicular to the longitudinal axis 406, and a plane including the longitudinal axis 406 and the radial direction 408 (e.g., Figure 3 (The cross-section shown). Crown 402 may also include a corrugated combustion bowl 410. Crown 402 also includes a radially outer lip 412, and the corrugated combustion bowl 410 includes a radially inner shelf portion 414, which is spaced apart from the radially outer lip 412 and the plane thus defined by a first axial (FA) distance 416 as further discussed herein.

[0022] The vortex bag 418 extends radially inward (e.g., directly or indirectly) from the radially inner shelf portion 414 and defines a lower axial end 420, which is axially spaced from the radially outer lip 412 and the plane defined therefrom by a second axial (SA) distance 422 greater than the FA distance 416. The combustion bowl 410 has a non-concave profile, and the vortex bag 418 may define a tangent 424 extending in a radially outward direction, which forms an acute angle 426 with the radially outer lip 412 in a plane including the longitudinal axis 406 and the radial direction 408, ranging from 70° to 80° (e.g., 75.0°). The angle 426 may be defined by the outer bowl surface 434 and open in a radially inward direction. A peak 448 may extend from the surface 438 (e.g., tangentially). The peak 448 can be centered at the longitudinal axis 406 and can be axially offset from the extrusion surface 429 by an axial offset distance 450, which is projected onto a plane containing the longitudinal axis 406 and the radial direction 408, ranging from 3.5 mm to 6 mm (e.g., 5.5 mm).

[0023] The crown 402 can be defined solely by rotating the geometry of the radially outer lip 412 and the corrugated combustion bowl 410 360° about the longitudinal axis 406 in a plane containing the longitudinal axis 406 and the radial direction 408. Therefore, the cross-sectional geometry of the crown 402 is identical in any plane containing the longitudinal axis 406 and the radial direction 408. See also... Figure 4 As can be seen, the radially outer lip 412 includes a planar extrusion surface 428 (e.g., which may be perpendicular to the longitudinal axis 406, so that when the piston 400 approaches the cylinder head, this surface extrudes or squeezes the fluid in the orifice), and the radially inner shelf portion 414 may include a planar shelf surface 430 (e.g., which may be parallel to the planar extrusion surface), which is axially spaced from the planar extrusion surface 428 by a distance FA 416. The extrusion surface 428 defines a plane 458 as described above, and the shelf volume is axially defined between the plane 458 and the shelf surface 430.

[0024] The vortex bag 418 may include a bottom concave arcuate surface or bowl bottom surface 432 defining a lower axial end 420 of the vortex bag 418, the lower axial end of the vortex bag being axially spaced apart from the planar extrusion surface 428 and the plane 458 by a distance SA 422. As used herein, "arc" includes any shape that is not straight or flat, including radii, ellipses, polynomials, splines, etc. The vortex bag 418 may further include an outer surface 434 extending radially and axially (e.g., directly or indirectly) from the planar shelf surface 430 and defining a tangent 424 forming an acute angle 426 with the plane 458, the angle 426 opening in a radially inward direction.

[0025] The first transition blend 436 connects the outer surface 434 to the shelf surface 430. The first transition blend 436 may define a radius of curvature ranging from 1 mm to 10 mm, for example, 2 mm. As used herein, the term "blend" may include any suitable geometry, including radii or other arcuate curve segments. The vortex bag 418 may also include a second surface 438 that is conical and extends from the bottom surface 432 toward the longitudinal axis 406, forming an external obtuse angle 440 ranging from 110° to 130° projected onto a plane including the longitudinal axis 438 and the radial direction 408. Angle 440 may be approximately 124.0° (+ / - 10.0°).

[0026] The piston 400 and combustion bowl 410 may further include an anti-deposition ramp 442 extending axially upward from the shelf surface 430 in a tangential direction toward the extrusion surface 428. The anti-deposition ramp 442 transitions between the shelf surface 430 and the extrusion surface 429 and may define a concave ramp radius of curvature ranging from 5 mm to 10 mm (e.g., 7 mm) in a plane including the longitudinal axis 406 and the radial direction 408. The anti-deposition ramp 442 connects to the extrusion surface 428 at a apex 444 (i.e., without tangency). The anti-deposition ramp 442 redirects the injected fuel flow away from the combustion bowl 418 upward from the radially outer lip 412, thereby limiting the wet walls in the associated combustion cylinder, as discussed further herein.

[0027] Still referencing Figure 4 The crown 402 may include an annular crown body, and as Figure 4 As shown, crown 402 includes combustion bowl 410, and radially inner shelf portion 414 is part of combustion bowl 418. Piston skirt 405 is attached to crown 402 and includes piston outer surface 466. Shelf portion 414 includes shelf surface 430 and extends circumferentially about longitudinal axis 406. Crown 402 also includes radially outer lip 412, which includes extrusion surface 428 and extends circumferentially about longitudinal axis 406. Radially outer lip 412, more specifically extrusion surface 428, defines plane 458, which is oriented perpendicular to longitudinal axis 406 and is generally located at the axial uppermost end of crown 402 and piston 400 itself.

[0028] Crown 402 also includes a top groove 464, one or more additional grooves (not labeled), and a top annular groove 468 configured to receive a piston ring and formed between the top groove 464 and a second additional groove among the additional grooves. Piston 400 defines an outer diameter (OD) dimension 454, which may be the widest point of piston 400. In an embodiment, an outer surface 466 on piston skirt 405 defines OD dimension 454. OD dimension 454 may be located in / defined by said piston skirt 405, although this disclosure is not limited thereto. OD dimension 454 may be 169 mm to 170 mm, and in one improvement may be 169.5 mm to 169.9 mm. As further discussed herein, certain geometric, dimensional, and proportional properties of piston 400 may contribute to achieving the goals of reducing or limiting the increase in engine valve temperature, limiting wet walls and thus reducing soot production, and increasing power density.

[0029] Shelf portion 414, i.e., shelf surface 430, is spaced apart from plane 458 by a distance FA 416, and bottom surface 432 is spaced apart from plane 458 by a distance SA 422. The ratio of FA distance 416 to SA distance 422 can be 7% to 11%, and in one improvement, it can be 7.6% to 10.8%. FA distance 416 can be 1.9 mm to 2.5 mm, and in one improvement, it can be 2.5 mm. The ratio of FA distance 416 to OD size 454 can be 1% to 2%, and in one improvement, it can be 1.1% to 1.5%. The ratio of SA distance 422 to OD size 454 can be 13% to 15%, and in one improvement, it can be 13.6% to 14.8%. SA distance 422 can be from 23 mm to 25 mm, and in one improvement, it can be 25 mm.

[0030] The anti-carbon buildup ramp 442 connects to the lip 412 at a apex 444, and the apex 444 defines the combustion bowl inner diameter (ID) dimension 456. The ID dimension 456 can be from 155 mm to 157 mm, and in one improvement, it can be 156.5 mm. The ratio of the FA distance 416 to the ID dimension 456 can be from 1.2% to 1.6%, and the ratio of the SA distance 422 to the ID dimension 456 can be from 14.7% to 16.1%. The bottom surface 432 defines a bottom radius of curvature, and the ratio of the bottom radius of curvature to the OD dimension 454 can be from 8% to 15%. The bottom radius of curvature can be from 15 mm to 25 mm, and in one improvement, it can be 22 mm. The ratio of the ramp radius of curvature defined by the anti-carbon buildup ramp 242 to the OD dimension 454 can be from 3% to 6%.

[0031] Industrial applicability

[0032] Referring generally to the accompanying drawings, operating the engine 100 may include causing the piston described herein to reciprocate, including... Figure 3 and Figure 4 Example piston 400. Fuel can be directly injected into combustion cylinder 106, such that the spray plume of the injected fuel is propelled outward and downward through multiple nozzles and combustion bowl 418. See details. Figure 5 As can be seen, a computational fluid dynamics (CFD) description of the fuel spray plume and fuel flow pattern during the expansion stroke in the example engine cycle can be viewed, where the directly injected spray plume 460, as described, has been propelled outward and downward within the combustion bowl 410. It is recollected that the combustion bowl 410 may have a non-concave profile.

[0033] The non-concave profile of the combustion bowl 410 can result in some fuel from the spray plume being delivered or overflowing from the vortex bag 418 into the shelf volume of the combustion bowl 410 formed between the plane 458 and the shelf surface 430. Some fuel travels into the shelf volume along an example fuel travel path shown by reference numeral 462, and then further outward, such that the fuel leaving the shelf volume impacts the anti-deposit ramp 442. The fuel from the spray plume can leave the shelf volume and be redirected so that it flows upward from the extrusion surface 428 based on the impact on the anti-deposit ramp 442, thereby avoiding reaching and wetting the walls 470 in the combustion cylinder. In some cases, the impact of the fuel on the anti-deposit ramp 242 can begin before a crank angle position in the engine, which is 20° after the piston's top dead center position during the expansion stroke.

[0034] Attempting to increase the power density in an internal combustion engine may require burning a relatively larger amount of fuel in a given engine cycle to enable the engine to produce more power within a given engine configuration and component size. However, burning a relatively large amount of fuel can cause the combustion gases to heat the engine valves and / or fire plates to temperatures that can ultimately lead to fatigue or performance degradation. According to this disclosure, using a non-concave combustion bowl allows some unburned and still-burning fuel spray to overflow from and exit the combustion bowl in a radially outward and axially upward direction, limiting the extreme temperatures experienced by the engine valves and fire plates.

[0035] The term "wet wall" refers to the phenomenon where liquid fuel spray contacts the relatively cold walls of the combustion cylinder, typically formed by the cylinder liner, leading to incomplete combustion of the fuel and the production of smoke or soot. If left unmitigated, fuel leaving the combustion bowl can thus cause or exacerbate the wet wall phenomenon. Also according to this disclosure, providing an anti-smoke ramp can help redirect fuel and other fluids leaving the combustion bowl shelf volume away from the combustion cylinder walls, thereby limiting wet walls. Therefore, this disclosure can be understood as providing piston geometry solutions that limit excessively high temperatures of engine valves and fire plates to achieve increased power density, while mitigating the increased incidence of wet walls and consequently soot production that may result from these piston geometry solutions. In some cases, the pistons according to this disclosure can also be adapted for a relatively late injection termination for various purposes, or to maintain a relatively late injection termination without other compensation, which may be feasible with other pistons such as non-concave pistons without anti-smoke ramps. Using a piston as disclosed herein, the fuel injected near the end of injection is less likely to travel over the top of the piston and wet the wall than when using a piston without a shelf surface / volume or anti-carbon ramp.

[0036] The currently disclosed ratio ranges, along with example dimensions and size ranges, reflect a balance between design and performance considerations while still achieving the aforementioned objectives. For example, when the engine is operating under rated conditions, the ratio range of the FA distance to the SA distance provides a shelf volume and shelf surface position to accommodate a sufficient amount of injected fuel leaving the combustion bowl, thereby reducing excessive engine valve and / or fire plate temperatures. However, the ratio of the FA distance to the SA distance is not so large that the size and shape of the combustion bowl are affected to such an extent that, for example, the compression ratio or other structural properties are altered or difficult to maintain. In other words, if the FA distance is too small relative to the SA distance, the piston's ability to prevent soot formation may be negatively affected or rendered ineffective. If the FA distance is too large relative to the SA distance, the combustion gas and / or fuel spray flow, the size or shape of the combustion bowl, or other piston dimensions, proportions, or functional properties may be negatively affected or subject to unforeseen influences. The ratios of the FA distance, SA distance, bowl bottom radius, and ramp radius to the OD size and / or ID size, as well as other properties of the disclosed piston 400, such as the size of the concave angle, also provide a combustion bowl profile advantageously suited for use in relatively large bores and large piston engines with the said OD size range, although this disclosure is not strictly limited thereto. The ratios given herein can be understood as specified quantities within measurement error. Dimensions can be understood as specified quantities within tolerances of ±0.1 mm. Thus, the 5 mm specification ranges from 4.9 mm to 5.1 mm, while the 2.5 mm specification ranges from 2.4 mm to 2.6 mm.

[0037] Figure 6 This indicates that even with an increase in the number of holes in the fuel injector, the temperature of the exhaust valve decreases when using a piston as described in this disclosure. Figure 7 It is shown that when using a piston as described in this disclosure, the cover temperature unexpectedly decreases as the number of injector holes increases. Figure 8 The use of a piston as described in this disclosure is shown to reduce soot production when the number of injector orifices is increased.

[0038] This specification is for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Therefore, those skilled in the art will understand that various modifications can be made to the embodiments currently disclosed without departing from the full and fair scope and spirit of this disclosure. Other aspects, features, and advantages will become apparent upon review of the accompanying drawings and claims. As used herein, the article “a / an” is intended to include one or more items and is interchangeable with “one or more.” The term “a” or similar language is used where only one item is intended. Furthermore, as used herein, the terms “has / have / having” and the like are intended to be open-ended terms. Additionally, unless expressly stated otherwise, the phrase “based on” is intended to mean “at least partially based on.”

Claims

1. A method of operating an internal combustion engine (100), comprising: The piston (400), which defines the outer diameter (OD) of the piston, reciprocates in the combustion cylinder (106) of the engine (100); Liquid fuel is injected directly from multiple nozzles in a fuel injector (112) that defines a longitudinal axis into the combustion cylinder (106) in the engine (100); The spray plume of the injected liquid fuel is propelled outward and downward from the plurality of nozzles through the combustion bowl (410) with a non-concave profile of the piston (400). The fuel of the spray plume is delivered from the vortex bag (418) of the combustion bowl (410) to the shelf volume of the combustion bowl (410), the combustion bowl being formed between a plane defined by a radially outer extrusion surface (428) and a radially inner shelf surface (430) spaced apart from the plane by a first axial (FA) distance, the first axial (FA) distance being 1% to 2% of the piston outer diameter; The fuel spray plume exiting the shelf volume of the combustion bowl (410) impacts the anti-carbon deposit ramp (442) between the radially inner shelf surface (430) and the radially outer extrusion surface (428); and Based on the impact of the fuel on the anti-carbon deposit ramp (442), the fuel is guided upward from the extrusion surface away from the spray plume of the shelf volume to limit the wet walls in the combustion cylinder (106). The impact of the fuel in the spray plume includes the fuel impact starting before the crank angle position in the engine (100), the crank angle position being 20° after the top dead center position of the piston (400). Delivering the fuel from the spray plume out of the vortex bag (418) includes guiding the fuel along the outer surface (434) of the combustion bowl (410), the outer surface defining an acute angle of 70° to 80° with the plane, the acute angle opening in a radially inward direction; and The propulsion of the spray plume includes advancing the spray plume along the bottom surface (432) of the combustion bowl (410), the bottom surface defining a concave radius of curvature that is 8% to 15% of the piston outer diameter.

2. The method according to claim 1, wherein: The bottom surface (432) is spaced apart from the plane by a second axial (SA) distance, and the ratio of the first axial distance to the second axial distance is 7% to 11%; Each of the radially outer extrusion surface (428) and the radially inner shelf surface (430) is planar, and the impact of the fuel further includes impacting the fuel against a curved profile anti-carbon deposit ramp (442) that is recessed into the radially outer extrusion surface (428) and the radially inner shelf surface (430); and The piston has an outer diameter of 169 mm to 170 mm.

3. A piston (400) configured to reciprocate in a combustion cylinder (106) of an internal combustion engine (100), comprising: The annular body (404) includes a crown (402) that defines a longitudinal axis and has a radially outer lip (412) that defines a plane oriented perpendicular to the longitudinal axis. The crown (402) further includes a combustion bowl (410) having a radially inner shelf portion (414) spaced apart from the plane by a first axial (FA) distance and a bottom surface (432) spaced apart from the plane by a second axial (SA) distance. The annular body (404) further includes an outer surface (434) defining the piston outer diameter (OD) dimension, and the ratio of the first axial distance to the piston outer diameter dimension is 1% to 2%, and the ratio of the first axial distance to the second axial distance is 7% to 11%; and The combustion bowl (410) forms a non-concave profile, and the crown (402) further includes an anti-carbon deposit ramp (442) transitioning between the radially inner shelf portion (414) and the radially outer lip portion (412) to redirect the injected fuel flow away from the combustion bowl (410) upward from the radially outer lip portion (412), thereby limiting the wet walls in the combustion cylinder (106). The radial inner shelf portion (414) includes a flat shelf surface (430), the radial outer lip portion (412) includes a flat extrusion surface (428), and the anti-carbon deposit ramp (442) has a curved profile and is recessed into the flat shelf surface (430) and the flat extrusion surface (428); The ratio of the first axial distance to the piston outer diameter is 1.1% to 1.5%, the ratio of the second axial distance to the piston outer diameter is 13.6% to 14.8%, and the ratio of the first axial distance to the second axial distance is 7.6% to 10.8%. The combustion bowl (410) includes an outer surface (434) that defines a tangent forming an acute angle of 70° to 80° with the plane, the acute angle opening in a radially inward direction; The bottom surface (432) defines a bottom radius of curvature, and the ratio of the bottom radius of curvature to the piston outer diameter is 8% to 15%; and The anti-carbon deposit ramp (442) defines the ramp curvature radius, and the ratio of the ramp curvature radius to the piston outer diameter is 3% to 6%.

4. The piston (400) according to claim 3, wherein: The anti-carbon buildup ramp (442) is connected to the radial outer lip (412) at the apex (444) that defines the inner diameter (ID) of the combustion bowl, the ratio of the first axial distance to the inner diameter of the combustion bowl being 1.2% to 1.6%, and the ratio of the second axial distance to the inner diameter of the combustion bowl being 14.7% to 16.1%.

5. The piston (400) according to claim 3, wherein: The piston has an outer diameter of 169 mm to 170 mm. The inner diameter of the combustion bowl is 155 mm to 157 mm; The first axial distance is 1.9 mm to 2.5 mm; The second axial distance is 23 mm to 25 mm; and The radius of curvature of the ramp is 5 to 10 millimeters.

6. A piston (400) for an internal combustion engine (100), comprising: An annular crown body (404) defines a longitudinal axis and has a radially outer lip (412) defining a plane oriented perpendicular to the longitudinal axis. The annular crown body (404) further includes a combustion bowl (410) having a radially inner shelf portion (414) spaced apart from the plane by a first axial (FA) distance, a bottom surface (432) spaced apart from the plane by a second axial (SA) distance, and an outer surface (434) defining a tangent forming an acute angle with the plane, the acute angle opening in a radially inward direction. A piston skirt (405) is attached to the annular crown body (404) and defines a piston outer diameter (OD) dimension of 169 mm to 170 mm, and the first axial distance is 1.9 mm to 2.5 mm; and The radial outer lip (412) includes a planar extrusion surface (428), and the radial inner shelf portion (414) includes a planar shelf surface (430), and the anti-carbon deposit ramp (442) transitions between the planar shelf surface (430) and the planar extrusion surface (428) and has a concave curve profile.

7. The piston (400) according to claim 6, wherein: The piston has an outer diameter of 169.5 mm to 169.9 mm; The anti-carbon buildup ramp (442) connects to the radial outer lip (412) at a apex (444), the apex defining a combustion bowl inner diameter (ID) dimension of 155.5 mm to 156.5 mm.

8. The piston (400) according to claim 6, wherein: The second axial distance is 23 mm to 25 mm; The anti-carbon buildup ramp (442) is defined with a ramp curvature radius of 5 mm to 10 mm; and The bottom surface (432) defines a radius of curvature of 15 mm to 25 mm.

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