Internal combustion engine and piston with stepped combustion pocket having a non-axisymmetric profile

Abstract

An internal combustion engine system includes an engine housing having a combustion cylinder, and a piston movable within the combustion cylinder to increase pressure therein to a self-ignition threshold for injection of fuel. The piston includes a piston crown having a combustion face that forms a combustion pocket, and whose profile is altered to form an inter-jet interaction limiter at a location that is offset from a fuel injector to deviate a fuel injection jet path. The inter-jet interaction limiter includes a pocket component and a step component that protrude within the combustion pocket and a step, respectively, that transitions between the combustion pocket and a circumferential edge of the piston. Limiting inter-jet interaction limits the production of soot in exhaust gas produced by the engine.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to a piston for an internal combustion engine, and more particularly to a piston having a combustion face geometry for limiting interaction between injection jets of combustion fuel. BACKGROUND

[0002] For many years, engineering and combustion science research has worked to understand the relationship between factors such as fuel delivery, turbocharging, variable valve actuation, exhaust gas recirculation (EGR), and the like, and emissions and efficiency. In addition to engine operating characteristics such as these that can be actively controlled, in recent years, research and testing efforts have focused on different ways in which engine components, particularly pistons, can be shaped and proportioned to achieve different combustion results. One driving advance in combustion science has been the desire to reduce and / or balance the relative amounts of certain emissions in engine exhaust, including particulate matter such as soot and nitrogen oxides or NOx, without unduly affecting other parameters, such as fuel efficiency and performance. It is now well understood that factors such as efficiency and emissions can be significantly affected by seemingly minor changes in component design or operating parameters, and the effects are often unpredictable. Designs and strategies built for one application purpose can be less suitable for other applications. U.S. Patent No. 8,978,621 to Easley et al. relates to a piston having a combustion bowl shaped to balance combustion efficiency and emissions characteristics. The piston proposed by Easley has features that together desirably affect emissions such as particulate matter and NOx without unduly sacrificing fuel efficiency. SUMMARY

[0003] In one aspect, a piston for an internal combustion engine includes a piston crown defining a piston center axis extending between a first piston axial end to a second piston axial end having a combustion face. The combustion face forms a combustion bowl having a central cone and a bowl periphery, a circumferential rim having an inner rim periphery and an outer rim periphery, and a step having a first step surface transitioning from the bowl periphery and a second step surface transitioning from the rim periphery. The combustion face has a rotational profile about the piston center axis that is altered to form jet-to-jet interaction limiters at spaced apart angular orientations about the piston center axis. The jet-to-jet interaction limiters each include a bowl component that protrudes within the combustion bowl to limit interaction between adjacent injection jets of combustion fuel traveling radially outward through the combustion bowl. The jet-to-jet interaction limiters each further include a step component that protrudes within the step to limit interaction between adjacent injection jets of combustion fuel once the combustion fuel travels from the combustion bowl into the step and spreads in an azimuthal direction.

[0004] In another aspect, an internal combustion engine system includes an engine housing having a combustion cylinder formed therein and a fuel injector supported in the engine housing and having a plurality of injection orifices formed therein, each injection orifice defining an injection jet path. The internal combustion engine system further includes a piston located within the combustion cylinder and having a piston crown, the piston crown defining a piston center axis extending between a first piston axial end and a second piston axial end having a combustion face. The combustion face forms a combustion bowl having a center cone and a bowl perimeter, a circumferential rim having an inner rim perimeter and an outer rim perimeter, and a step having a first step surface transitioning from the bowl perimeter and a second step surface transitioning from the inner rim perimeter. The combustion face has a rotational profile about the piston center axis that is altered to form inter-jet interaction limiters. The inter-jet interaction limiters are arranged at locations offset from the injection jet paths and each include a bowl component projecting within the combustion bowl and a step component projecting within the step to limit interaction between adjacent injection jets of combustion fuel injected from the plurality of injection orifices.

[0005] In another aspect, a piston crown for a piston in an internal combustion engine includes a piston crown body having a piston outer surface with a crown land and extending circumferentially about a piston center axis, a cooling gallery surface formed on a first axial side of the piston crown body, and a combustion face formed on a second axial side of the piston crown body. The combustion face forms a combustion bowl having a center cone and a bowl perimeter, a circumferential rim extending radially outward to the piston outer surface, and a step transitioning between the combustion bowl and the circumferential rim. The combustion face has a rotational profile about the piston center axis that is altered to form inter-jet interaction limiters at spaced apart angular orientations about the piston center axis. The inter-jet interaction limiters each include a bowl component projecting within the combustion bowl and a step component projecting within the step to limit interaction between adjacent injection jets of combustion fuel located within the combustion bowl and the step. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 is a partial cross-sectional side view illustration of an internal combustion engine system according to one embodiment;

[0007] Figure 2 is a diagrammatic view of a piston crown of a piston according to one embodiment;

[0008] Figure 3 is Figure 2 is another diagrammatic view of the piston crown of

[0009] Figure 4 is Figure 2 and Figure 3A cross-sectional diagram of a portion of the piston crown;

[0010] Figure 5 This is a top view of the piston, showing the jet of fuel combustion during one stage of combustion;

[0011] Figure 6 Is it through Figure 5 A cross-sectional view of a portion of the piston;

[0012] Figure 7 It is a schematic view of the piston, showing the jet of fuel combustion in another stage of combustion;

[0013] Figure 8 Is it through Figure 7 A cross-sectional view of a portion of the piston;

[0014] Figure 9 It is a schematic view of the piston, showing the jet of fuel combustion in another stage of combustion;

[0015] Figure 10 Is it through Figure 9 A cross-sectional view of a portion of the piston;

[0016] Figure 11 This is another schematic view of the piston, showing the jet of fuel combustion in yet another stage of combustion; and

[0017] Figure 12 Is it through Figure 11 A cross-sectional view of a portion of the piston. Detailed Implementation

[0018] See also Figure 1 The diagram illustrates an internal combustion engine system 8 according to one embodiment, comprising an internal combustion engine 10 having an engine housing 12 having a cylinder block 14 and an engine cylinder head 16. The engine housing 12 has a combustion cylinder 26 formed therein. A first gas exchange valve 18 and a second gas exchange valve 20 are supported in the engine cylinder head 16 and are movable to open and close a first gas exchange duct 22 and a second gas exchange duct 24, respectively. The first gas exchange valve 18 may include an intake valve, and the second gas exchange valve 20 may include an exhaust valve; each valve may be an exhaust valve, or each valve may be an intake valve. Typically, intake air compressed by a turbocharger compressor is delivered to the combustion cylinder 26 via one of the gas exchange ducts 22 and 24, and exhaust gas is delivered to the exhaust system in a conventional manner via the other of the gas exchange ducts 22 and 24.

[0019] The combustion cylinder 26 can comprise one of a number of combustion cylinders arranged in any suitable manner, such as a V-type, an inline-type, or another type. A fuel injector 28 is supported in the engine housing 12 and, in the illustrated case, is mounted in the engine cylinder head 16 for injecting fuel directly into the combustion cylinder 26. The fuel injector 28 defines an injector axis 29 and has a plurality of injection orifices 30 formed therein and positioned within the combustion cylinder 26. The injection orifices 30 define a plurality of injection jet paths 31 that travel radially outward and axially outward relative to the injector axis 29 into the combustion cylinder 26. By "axially outward" is meant a line segment away from the center point of the axis, while "axially inward" has the opposite meaning. Radially inward and radially outward are terms used conventionally herein. A piston is positioned within the combustion cylinder 26 and is movable between a bottom dead center position and a top dead center position to increase fluid pressure in the combustion cylinder 26 to a self-ignition threshold for injecting fuel. The internal combustion engine system 8 can operate in a conventional four-stroke cycle, however, the present disclosure is not limited thereto. A piston pin 64 is mounted in the piston 32 and is coupled with a connecting rod 66, which is understood to be coupled with a crankshaft in a generally conventional manner. The engine 12 can be configured to operate with a suitable compression ignition fuel, such as a diesel distillate fuel. As will be further apparent from the following description, the internal combustion engine system 8 can be uniquely configured, including through the geometry of the piston 32, for reducing the amount of soot in exhaust gas produced by fuel combustion in the combustion cylinder 26 and any other cylinders of the engine 12 as compared to certain known strategies.

[0020] The piston 32 includes a piston crown 34 defining a piston center axis 38 extending between a first piston axial end 40 and a second piston axial end 42 having a combustion face 44. The first piston axial end 40 can include or be formed by a piston skirt 62 that is attached to the piston crown 34, such as by welding. The piston crown 34 further includes a piston outer surface having a land 58 extending circumferentially about the piston center axis 38. One or more piston rings 60 are positioned in ring grooves extending circumferentially about the piston center axis 38 below the land 58. Referring now to Figure 2 and Figure 3The piston crown 34 includes a crown body 36. Descriptions and discussions herein of the piston crown 34 or the piston crown body 36 or the piston 32 itself are to be understood as interchangeably referring to any of these. The combustion face 44 forms a combustion bowl 46 having a center cone 48 and a bowl rim 50. The combustion face 44 further forms a circumferential rim 52 having an inner rim 54 and an outer rim 56. The combustion face 44 also forms a step 70 that transitions between the combustion bowl 46 and the circumferential rim surface 52 and has a first step surface 72 that transitions with the bowl rim 50 and a second step surface 74 that transitions with the inner rim 54. The circumferential rim 52 extends radially outward to a piston outer surface / crown land 88. It is to be understood that descriptions herein of the combustion bowl 46 and the step 70 relate to the areas or volumes formed by these features, not their individual surfaces.

[0021] The combustion face 44 has a changed rotational profile about the piston center axis 38, meaning that the combustion bowl 46 and the step 70 are not axisymmetric. The changed rotational profile of the combustion face 44 forms inter-jet interaction limiters 76 at spaced apart angular orientations about the piston center axis 38. From Figure 2 It can also be noted that the injection jet paths 31 are shown and are arranged alternately with the inter-jet interaction limiters 76. The inter-jet interaction limiters 76 are arranged at locations offset from the injection jet paths 31, meaning that injection jets of fuel will align with locations between the inter-jet interaction limiters 76. The injection jet paths 31 can intersect the piston 32 in axial projection at locations equidistant from adjacent inter-jet interaction limiters 76. It has been found that, in at least some cases, limiting interaction between injection jets of combustion fuel can advantageously limit soot production. As discussed further herein, the limitation of interaction can include limiting the merging of soot pockets formed or formed within individual injection jets of combustion fuel, or limiting the merging of regions of injection jets of combustion fuel where soot formation is possible or can be expected.

[0022] In one practical implementation, the number of inter-jet interaction limiters 76 is 3 to 8. In one refinement, the number of inter-jet interaction limiters 76 is 5 to 7, and in the illustrated embodiment is 6. The inter-jet interaction limiters 76 can be regularly spaced about the piston center axis 38, so in the illustrated embodiment the locations of the inter-jet interaction limiters 76 are offset from one another by 60°. Similarly, the injection jet paths 31 can be regularly spaced circumferentially about the injector axis 29, and can be arranged so that each injection jet path 31 aligns with an intermediate location on the piston 32 between adjacent inter-jet interaction limiters 76.

[0023] As can be seen from these illustrations, the inter-jet interaction limiter 76 can be partially formed within the combustion cavity 46 and partially formed within the step 70. It has been determined that limiting inter-jet interaction during the initial injection phase of the jet and after the jet has traveled to and entered the step 70, during which the fuel-burning jet is located within the combustion cavity 46. Furthermore, this approach is considered to optimize the contact between the fuel and available oxygen within the combustion space, rather than allowing oxygen access to be restricted and thus contributing to the merging and expansion of areas where soot production occurs. To this end, each of the inter-jet interaction limiters 76 includes a cavity member 78 protruding within the combustion cavity 46 to limit the interaction between adjacent fuel-burning jets traveling radially outward through the combustion cavity 46. Each of the jet interaction limiters 76 further includes a stepped component 80 that protrudes within the step 70 to limit the interaction between adjacent jets of the combustion fuel once the combustion fuel has traveled from the combustion cavity 46 into the step 70 and spread out in the azimuth angle. The phenomena and mechanisms relating to limiting the inter-jet interaction of the combustion fuel jets will become more apparent through the following discussion.

[0024] See also Figure 4 In the illustrated embodiment, the cavity component 78 and the stepped component 80 in each jet interaction limiter 76 are symmetrical about a common plane of symmetry 100 that is parallel to and intersects the piston central axis 38. Figure 4 The diagram shows a dashed line illustrating the plane of symmetry of the subject matter, and it should be understood that, in the top view, in axial projection, each jet interaction limiter 76 is approximately symmetrical about plane 100. Plane 100 includes and intersects the piston central axis 38. It should also be noted that the cavity component 78 and the stepped component 80 are circular in axial projection and may have a generally semi-circular profile in axial projection. Figure 4 Oil passage 83 is also shown, which is partially formed on its first axial side by the piston crown 34 and also partially by the piston skirt 62. Combustion surface 44 is located on the second axial side of the piston crown 44. Backside cooling surface 84 is positioned opposite to combustion cavity 46 such that the heat of combustion is dissipated through the material thickness of piston crown 34 between combustion cavity 46 and cooling passage 82.

[0025] This can also be seen from the attached diagram, especially... Figure 4In the embodiment shown, the combustion surface 44 has a combustion surface profile at the location of the inter-jet interaction limiter 76 and at a circumferential location between the inter-jet interaction limiters 76. In the illustrated embodiment, the combustion surface profile includes a limiter profile at the location of the inter-jet interaction limiter and a base profile at a circumferential location between the inter-jet interaction limiters 76. The limiter profile can be understood as, for example, a profile rotating about the piston central axis 38 at a location in plane 100. The base profile is approximately in… Figure 4 The profile can be observed at the cross-sectional plane shown. In the illustrated embodiment, the limiter profile is consistent with the base profile. Consistency means substantially consistent, although not necessarily perfectly consistent. Therefore, it will be further understood that the combustion surface profile can be substantially the same at the location of the inter-jet interaction limiter 76 and at locations between inter-jet interaction limiters 76, but with displacement in the radial direction. In other embodiments, the limiter profile and the base profile can differ. For example, in some cases, it may be desirable to provide relatively more or less volume within step 70, and the arcuate path or other shape of the second step surface 74 can vary between adjacent inter-jet interaction limiters 76 to provide more or less volume scooped out from the piston 32 adjacent to the circumferential edge 52. It may also be desirable to change the shape of the transition between the cavity member 78 and the step member 80.

[0026] The cavity component 78 and the stepped component 80 may be separate, as shown, or they may be joined and continuous between the cavity base plate 86 and the circumferential edge 52. The combustion cavity 46 includes a cavity base plate 86 and a cavity outer wall 88 extending between the cavity base plate 86 and the cavity periphery 50. The cavity outer wall 88 may extend from the cavity base plate 86 to the cavity periphery 50. The cavity component 78 of each of the jet interaction limiters 76 may extend axially between the cavity base plate 86 and the cavity periphery 50, and extend radially inward from the cavity outer wall 88. The cavity component 78 may further extend axially from the cavity base plate 86 to the cavity periphery 50. The stepped component 80 may extend axially between a first stepped surface 72 and an inner periphery 54, and extend radially inward from a second stepped surface 74. The stepped component 80 may further extend completely from the first stepped surface 72 to the inner periphery 54. Therefore, it can be seen that in the illustrated embodiment, the first stepped surface 72 is partially formed on the cavity component 78 of each jet interaction limiter 76. The circumferential edge 52 is partially formed on the stepped component 80 of each jet interaction limiter 76. The protruding portion 94 of the first stepped surface 72 is shown in... Figure 4 On the recessed component 78. The protruding portion 96 of the circumferential rim 52 is shown in Figure 2The first step surface 72 can be planar and can be oriented perpendicular to the piston center axis 38. The second step surface 74 can be rounded and can be oriented parallel to the piston center axis 38.

[0027] Figure 4 A first radius of curvature 90 defined by the pocket perimeter 50 and a second radius of curvature 92 defined by the inner edge perimeter 54 are further shown. The second radius of curvature 92 can be greater than the first radius of curvature 90. It has been found that a sharp radius of curvature at the pocket perimeter can help the injection jet of combusting fuel to break away from the combustion face 44, thereby facilitating mixing with available oxygen, as further discussed herein. Thus, the first radius of curvature 90 can be quite small, e.g., 2 millimeters or less, and in some embodiments can include a deburred edge. The combustion pocket 46 can also re-enter in concert with principles that promote the partial breakaway of the injection jet of combusting fuel and avoid the injection jet from exiting the stop 70 and traveling toward the cylinder liner wall.

[0028] Figure 3 and Figure 4 Certain dimensional and proportional properties of the piston 32 are also shown. The first step surface 72 can extend from the pocket perimeter 50 to the second step surface 74 and define a step width dimension 102. The second step surface 74 extends from the first step surface 72 to the inner edge perimeter 54 and defines a step depth dimension 104. The crown 58 extends circumferentially about the piston center axis 38, thus defining a piston diameter dimension 106. Each of the step width dimension 102 and the step depth dimension 104 can be about 3% to about 8% of the piston diameter dimension 106. These proportional properties are believed to provide sufficient volume of the step 70 to participate in the combustion process in concert with the principles set forth herein, without unduly interfering with compression ratio or creating other challenges. As used herein, the term “about” is understood to mean generally or approximately. For example, about 3 can mean 2.5 to 3.4, in concert with conventional rounding to a consistent number of significant digits. The relative proportions associated with the step 70 can be expected to scale to relatively larger piston sizes as well as relatively smaller piston sizes.

[0029] INDUSTRIAL APPLICABILITY

[0030] Referring now to Figure 5 A view of the piston 32 is shown, as can be apparent in the figure, with a plurality of injection jets 131 of combusting fuel having been injected into the combustion cylinder 26 and traveling outward in the combustion pocket 60. As Figure 5The depicted conditions occur at engine timing that can vary depending on factors such as injection timing, engine speed, injection pressure, boost pressure, etc., but can be observed a few degrees before the top dead center position of the piston 32 on the compression stroke. The injection jet 131 has traveled radially outward and axially downward from the injection hole 30 and has begun to move upward along the outer wall 88 from the pocket floor 86. See Figure 6 , which shows a cross-sectional view of the conditions that can be observed within the injection jet 131 corresponding to Figure 5 The hotter central region 135 of the injection jet 131 is generally surrounded by a cooler second region 133. As can also be seen in Figure 5 , the lift length of the injection jet 131 is shown at 139 and represents fuel that has not yet burned, while the remainder of the injection jet 131 can be understood to be actively burning.

[0031] In Figure 7 and Figure 8 , a subsequent stage can be seen in which the injection jet 131 has begun to travel away from the combustion pocket 46 and is approaching or beginning to enter the step 70. It can be seen that some azimuthal development of the injection jet 131 is occurring. From Figure 8 It can also be noted that soot regions 137 have begun to form and the injection jet 131 has begun to separate from the combustion face 44. The inter-jet interaction limiter 76 prevents the interaction between injection jets 131 that might otherwise be observed.

[0032] In Figure 9 and Figure 10 , at a further subsequent stage it can be seen that additional azimuthal development has occurred in the step 70, with the injection jet 131 beginning to encounter the pocket component 78 and step component 80 of the inter-jet interaction limiter 76. The soot pocket 137 has expanded somewhat, still largely surrounded by actively burning injection fuel. Roughly as shown in Figure 9 and Figure 10 , as the jet emerges on the pocket periphery 50, the injection jet 131 begins to develop in all directions, including more aggressively in azimuth into the step 70. The admission of air in the step 70 helps to maintain combustion and soot oxidation. Although the soot region 137 has expanded somewhat further from the previous stage, soot region inter-jet coalescence is still prevented.

[0033] In Figure 11 and Figure 12In the middle, another subsequent phase is depicted that can be observed a few degrees after top dead center position of the piston 32, the inter-jet interaction limiter 76 continues to help maintain separation between the jets so that the high soot regions in the injection jet 131 do not interact. It can be observed that portions of the injection jet 131 travel on the circumferential edge 52, however, it can be noted that the combustion remains substantially within the combustion pocket 46 and the step 70.

[0034] According to Figure 11 and Figure 12 The portions of the injection jet 131 that have remained in the combustion pocket 46 and the step 70 can begin to be directed back toward the center of the combustion cylinder 26 by the inter-jet interaction limiter 76, as depicted in the state in the middle. The injection jet 131 will eventually merge with adjacent or neighboring injection jets in the combustion pocket 46 and in the step 70, however the inter-jet interaction limiter 76 prevents the high soot regions, more soot rich regions, of the injection jet 131 from merging with adjacent jets, particularly with adjacent high soot regions, thereby helping to better entrain air into the combustion pocket 46 above the step 70 and between the injection jets 131. By limiting inter-jet interaction according to the principles discussed herein, it is believed that total soot production will be reduced compared to combustion that would occur in a conventional axisymmetric combustion pocket.

[0035] This description is for illustrative purposes, and should be construed be limiting on any manner. Accordingly, those skilled in the art will appreciate that the embodiments disclosed herein can be practiced with variations of the embodiments disclosed herein without departing from the complete and true spirit and scope of the present application. Other aspects, features, and advantages will become apparent to those of ordinary skill in the art, upon reading the following claims and description of the preferred embodiments. As used herein, the articles "a" and "an" are intended to include one or more items, and can be used interchangeably with "one or more." Where only one item is intended, the term "one" or similar language is used. Also, as used herein, the terms "has," "have," "having," or the like are intended to be open-ended terms. Further, the phrase "based on" is intended to mean "based, at least in part, on" unless explicitly stated otherwise.

Claims

1. A piston for an internal combustion engine, comprising: a piston crown defining a piston center axis extending between a first piston axial end and a second piston axial end having a combustion face; the combustion face forming a combustion bowl having a center cone and a bowl periphery, a circumferential rim having an inner rim periphery and an outer rim periphery, and a step having a first step surface transitioning from the bowl periphery and a second step surface transitioning from the inner rim periphery; the combustion face having a rotational profile about the piston center axis that is altered to form inter-jet interaction limiters at spaced apart angular orientations about the piston center axis; the inter-jet interaction limiters each including a bowl component projecting within the combustion bowl to limit interaction between adjacent injection jets of combustion fuel traveling radially outward through the combustion bowl; and the inter-jet interaction limiters each further including a step component projecting within the step to limit interaction between the adjacent injection jets of combustion fuel once the combustion fuel travels from the combustion bowl into the step and spreads in an azimuthal direction, the first step surface being formed partially on the bowl component of each of the inter-jet interaction limiters and the circumferential rim being formed partially on the step component of each of the inter-jet interaction limiters.

2. The piston of claim 1 wherein, the bowl component and the step component are circular in axial projection and the bowl component and the step component in each of the inter-jet interaction limiters are symmetric about a common plane of symmetry that is parallel to and intersects the piston center axis.

3. The piston of claim 1, wherein: the first step surface extends from the bowl periphery to the second step surface and defines a step width dimension; the second step surface extends from the first step surface to the inner rim periphery and defines a step depth dimension; a crown extends circumferentially about the piston center axis and defines a piston diameter dimension; the step component extends axially between the first step surface and the inner rim periphery and radially inwardly from the second step surface.

4. The piston of claim 3 wherein, each of the step width dimension and the step depth dimension is 3% to 8% of the piston diameter dimension.

5. The piston of any one of claims 1 to 4, wherein: the number of inter-jet interaction limiters is 3 to 8 and the inter-jet interaction limiters are regularly distributed about the piston center axis; and the bowl periphery defines a first radius of curvature and the inner rim periphery defines a second radius of curvature that is greater than the first radius of curvature.

6. An internal combustion engine system, comprising: an engine housing having a combustion cylinder formed therein; a fuel injector supported in the engine housing and having a plurality of injection orifices formed therein, each of the injection orifices defining an injection jet path; a piston located within the combustion cylinder and including a piston crown defining a piston center axis extending between a first piston axial end and a second piston axial end having a combustion face; the combustion face forms a combustion bowl having a central cone and a bowl periphery, a circumferential rim having an inner rim periphery and an outer rim periphery, and a step having a first step surface transitioning from the bowl periphery and a second step surface transitioning from the inner rim periphery; the combustion face has a rotational profile about the piston center axis that is altered to form inter-jet interaction limiters; and the inter-jet interaction limiters are arranged at locations offset from the injection jet paths and each include a bowl component projecting within the combustion bowl to limit interaction between adjacent injection jets of combustion fuel traveling radially outward through the combustion bowl and a step component projecting within the step to limit interaction between adjacent injection jets of combustion fuel injected from the plurality of injection orifices as the combustion fuel spreads in an azimuthal direction upon traveling from the combustion bowl into the step, the combustion face profile includes a limiter profile at locations of the inter-jet interaction limiters and a base profile at circumferential locations between the inter-jet interaction limiters, the first step surface is formed partially on the bowl component of each of the inter-jet interaction limiters and the circumferential rim is formed partially on the step component of each of the inter-jet interaction limiters.

7. The internal combustion engine system of claim 6, wherein: the number of injection orifices and the number of inter-jet interaction limiters are each from 3 to 8 and the injection jet paths and the inter-jet interaction limiters are circumferentially alternatingly arranged about the piston center axis; the first step surface extends from the bowl periphery to the second step surface and defines a step width dimension; the second step surface extends from the first step surface to the inner rim periphery and defines a step depth dimension; a crown extends circumferentially about the piston center axis and defines a piston diameter dimension; each of the step width dimension and the step depth dimension is from 3% to 8% of the piston diameter dimension; the bowl component and the step component have a circular shape in axial projection and the bowl component and the step component in each of the inter-jet interaction limiters are symmetric about a common plane of symmetry that is parallel to and intersects the piston center axis; and the injection jet paths intersect the piston in axial projection at locations equidistant from adjacent ones of the inter-jet interaction limiters.

8. The internal combustion engine system of claim 6 or 7, wherein: the combustion bowl includes a bowl floor and a bowl outer wall extending from the bowl floor to the bowl periphery; The cavity component of each of the inter-jet interaction limiters extends axially between the cavity floor and the cavity periphery, and extends radially inwardly from the cavity outer wall; The step component extends axially between the first step surface and the inner edge periphery, and extends radially inwardly from the second step surface.

9. A piston crown for a piston in an internal combustion engine, comprising: a piston crown body including a piston outer surface having a crown land and extending circumferentially about a piston center axis; a cooling gallery surface formed on a first axial side of the piston crown body, and a combustion face formed on a second axial side of the piston crown body; the combustion face forms a combustion cavity having a central cone and a cavity periphery, a circumferential edge extending radially outwardly to the piston outer surface and having an inner edge periphery and an outer edge periphery, and a step transitioning between the combustion cavity and the circumferential edge, the step having a first step surface transitioning with the cavity periphery and a second step surface transitioning with the inner edge periphery; the combustion face has a rotational profile about the piston center axis that is altered to form inter-jet interaction limiters at spaced apart angular orientations about the piston center axis; and the inter-jet interaction limiters each include a cavity component projecting into the combustion cavity and a step component projecting into the step to limit interaction between adjacent jet streams of combustion fuel located within the combustion cavity and the step, the first step surface is formed partially on the cavity component of each of the inter-jet interaction limiters, and the circumferential edge is formed partially on the step component of each of the inter-jet interaction limiters.

10. The piston crown of claim 9, wherein: the combustion face profile includes a limiter profile at locations of the inter-jet interaction limiters, and a base profile at circumferential locations between the inter-jet interaction limiters; and the crown land defines a piston diameter dimension, and the step defines a step width dimension and a step depth dimension, and the step width dimension and the step depth dimension are each 3% to 8% of the piston diameter dimension.

11. The piston crown of claim 9 or 10, wherein: the combustion cavity includes a cavity floor, and a cavity outer wall extending from the cavity floor to the cavity periphery; the cavity component of each of the inter-jet interaction limiters extends axially between the cavity floor and the cavity periphery, and extends radially inwardly from the cavity outer wall; and the step component extends axially between the first step surface and the inner edge periphery, and extends radially inwardly from the second step surface.

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