COMBUSTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A combustion system for an internal combustion engine includes combustion chamber that is defined between a cylinder head and a top surface of a piston. The combustion system also includes a fuel injector having an injector tip. The injector tip defines a nozzle disposed in fluid communication with the combustion chamber for dispensing a fuel jet into the combustion chamber. A bluff body is positioned within the combustion chamber such that an axis of the dispensed fuel jet is incident on an anterior portion of the bluff body proximal to the injector tip. The anterior portion has a contour that is adapted to split the dispensed fuel jet into at least two turbulent fuel streams and facilitate mixing of each fuel stream with an oxidant present in the combustion chamber.

Claims

1. A combustion system for an internal combustion engine, the combustion system comprising: a combustion chamber defined between a cylinder head and a top surface of a piston; a fuel injector having an injector tip defining a nozzle, the nozzle disposed in fluid communication with the combustion chamber to dispense a fuel jet into the combustion chamber; and a bluff body positioned within the combustion chamber such that an axis of the dispensed fuel jet is incident on an anterior portion of the bluff body proximal to the injector tip, the anterior portion having a contour adapted to split at least a portion of the dispensed fuel jet into at least two turbulent fuel streams and facilitate mixing of each fuel stream with an oxidant present in the combustion chamber.

2. The combustion system of claim 1, wherein the bluff body has a posterior portion defining a first orifice transverse to the axis of the dispensed fuel jet and a second orifice distal from the injector tip and parallel to the axis of the dispensed fuel jet.

3. The combustion system of claim 2, wherein the first orifice is in fluid communication with the second orifice via a passageway such that the first orifice is configured to entrain an oxidant from a portion of the combustion chamber adjacent the first orifice and communicate the entrained oxidant to a portion of the combustion chamber adjacent the second orifice via the passageway.

4. The combustion system of claim 3, wherein a contour of the posterior portion is at least one of: convergent and divergent from the axis of the dispensed fuel jet.

5. The combustion system of claim 1, wherein the contour of the anterior portion is convex opposing a flow direction of the fuel jet.

6. The combustion system of claim 5, wherein a maximum perimeter of the anterior portion is one of: at least equal to and smaller than a perimeter associated with a spray pattern of the dispensed fuel jet that is incident on the anterior portion.

7. The combustion system of claim 1, wherein the contour of the anterior portion includes an apex opposing a flow direction of the fuel jet.

8. The combustion system of claim 1, wherein the bluff body is at least one of: oblong, spherical, and polyhedral in shape.

9. The combustion system of claim 8, wherein the polyhedral shape of the bluff body defines a plurality of concave and convex portions in an alternating arrangement about the axis of the dispensed fuel jet.

10. The combustion system of claim 9, wherein the first orifice is located on at least one of: the concave and convex portions of the bluff body.

11. The combustion system of claim 1, wherein the bluff body is positioned at a pre-determined distance from the nozzle of the injector tip to impart turbulence by generating a wake in the incident fuel jet.

12. The combustion system of claim 1, wherein the bluff body is a screen mesh having a plane angularly disposed to the axis of the fuel jet.

13. The combustion system of claim 12, wherein the screen mesh comprises a plurality of wires, each wire from the plurality of wires being disposed at a pre-specified distance from an adjacent one of the wires to render the screen mesh with a pre-determined porosity.

14. The combustion system of claim 13, wherein each wire has at least one of an oblong, circular, and polygonal cross-section.

15. The combustion system of claim 13, wherein the screen mesh is positioned at a pre-determined distance from the injector tip to facilitate at least one wire from the plurality of wires in imparting turbulence by generating a wake in the incident fuel jet.

16. The combustion system of claim 12, wherein the screen mesh is positioned adjacent to the nozzle on the injector tip of the fuel injector.

17. The combustion system of claim 12, wherein a contour of the screen mesh is adapted to correspond with a contour of the injector tip.

18. The combustion system of claim 12, further comprising a duct disposed within the combustion chamber, wherein the screen mesh is attached to an end of the duet distal from the nozzle.

19. An internal combustion engine comprising: a piston slidably disposed within a cylinder such that a top surface of the piston and a cylinder head adjoining the cylinder are in reciprocally opposing relation to one another for defining the combustion chamber therebetween; and a combustion system associated with the combustion chamber, the combustion system comprising: a fuel injector having an injector tip defining a nozzle, the nozzle disposed in fluid communication with the combustion chamber to dispense a fuel jet into the combustion chamber; and a bluff body positioned within the combustion chamber such that an axis of the dispensed fuel jet is incident on an anterior portion of the bluff body proximal to the injector tip, the anterior portion having a contour adapted to split at least a portion of the dispensed fuel jet into at least two turbulent fuel streams and facilitate mixing of each fuel stream with an oxidant present in the combustion chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a diagrammatic front sectional view of an exemplary internal combustion engine having a combustion chamber and a combustion system having an exemplary bluff body that is associated with the combustion chamber, in accordance with an embodiment of the present disclosure;

[0014] FIGS. 2A-2C illustrate positioning of the exemplary bluff body in relation to a flame lift-off length associated with fuel, according to certain embodiments of the present disclosure;

[0015] FIGS. 3-8 illustrate a perspective view of exemplary bluff bodies that can be employed for use in the combustion system of FIG. 1, in accordance with embodiments of the present disclosure;

[0016] FIG. 9 illustrates a perspective view of another exemplary bluff body having first and second orifices in communication with each other with the help of a passageway, in accordance with an embodiment of the present disclosure;

[0017] FIGS. 10-12 show states of fuel and oxidant interaction with use of the bluff body from FIG. 9 in the combustion system;

[0018] FIG. 13 is a diagrammatic front view of a bluff body that is embodied in the form of a screen mesh having wires, in accordance with another embodiment of the present disclosure;

[0019] FIG. 14 is a diagrammatic front sectional view of the internal combustion engine showing the combustion system employing the screen mesh of FIG. 13, in accordance with an embodiment of the present disclosure;

[0020] FIG. 15 is a diagrammatic front view of a fuel injector showing a screen mesh adapted to conform with a contour of the injector tip, in accordance with an alternative embodiment of the present disclosure;

[0021] FIG. 16 is a diagrammatic top view of a combustion system showing screen meshes being used in conjunction with ducts, in accordance with yet another alternative embodiment of the present disclosure; and

[0022] FIGS. 17-19 illustrate different exemplary cross-sections of a wire that can be used either by itself as a bluff body, or to form the screen mesh of FIG. 13, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

[0023] Reference numerals appearing in more than one figure indicate the same or corresponding parts in each of them. References to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims. In the accompanying drawings,

[0024] FIG. 1 illustrates an exemplary internal combustion engine 10 (hereinafter referred to as the engine and denoted by identical numeral 10) having a combustion chamber 12 and a combustion system 14 associated with the combustion chamber 12, in accordance with an embodiment of the present disclosure. As shown, the engine 10 is embodied as a compression ignition engine, for example, a diesel engine. However, in other embodiments, the engine 10 could be embodied as a spark-ignited engine, for example, a direct-injection gasoline fueled engine, a gas fueled engine with direct-injection of gas, or a dual fuel engine system in which at least one of a pilot fuel and a main fuel are directly injected into a combustion chamber thereof.

[0025] Referring to FIG. 1, the engine 1.0 includes a piston 16 that is slidably disposed within a cylinder 18 such that a top surface 20 of the piston 16 and a cylinder head 22 adjoining the cylinder 18 are in a reciprocally opposing relation to one another for defining the combustion chamber 12 therebetween. Further, the piston 16 is shown connected to a crankshaft 24 of the engine 10 via a connecting rod 26 for converting its linear reciprocal motion within the cylinder 18 into a rotary motion of the crankshaft 24.

[0026] Although a single-cylinder engine is used to depict the engine 10, in other embodiments, the engine 10 could include two or more combustion chambers so that the engine 10 be embodied as a multi-cylinder engine. It will be acknowledged that aspects of the present disclosure can be applied similarly in a multi-cylinder engine without deviating from the spirit of the present disclosure.

[0027] As shown in FIG. 1, the combustion system 14 also includes a fuel injector 28 having an injector tip 30. The injector tip 30 defines a nozzle 32 that is disposed in fluid communication with the combustion chamber 12 for dispensing a fuel jet 34 into the combustion chamber 12. Further, as shown in FIG. 1, a bluff body 36 is positioned within the combustion chamber 12 such that an axis AA of the dispensed fuel jet 34 is incident on an anterior portion 38 of the bluff body 36 proximal to the injector tip 30. In embodiments of this disclosure, the bluff body 36 also includes a posterior portion 40 that extends from the anterior portion 38 and is distally located from the injector tip 30.

[0028] The anterior portion 38 has a contour that is adapted to split at least a portion of the dispensed fuel jet 34 into at least two turbulent fuel streams and facilitate mixing of each fuel stream with an oxidant (as represented by empty circles in the views of FIGS. 10-12 and 14-15), in the combustion chamber 12. The oxidant may be, for example, air, or particularly, oxygen from the air that may be present in the combustion chamber 12.

[0029] In the present disclosure, although the terms fuel jet or dispensed fuel jet has been used, it should be noted that a positioning of the bluff body 36 is not necessarily limited to locations in the combustion chamber 12 where the fuel is merely in a fuel-only phase. Rather, as exemplarily illustrated in the views of FIGS. 2A-2C, the bluff body 36 may be located within the combustion chamber 12 at any position in relation to a flame lift-off length L that is associated with the fuel being dispensed at a pre-specified velocity and pressure. In the exemplary diagrammatic views of FIGS. 2A-2C, the lift-off length L associated with the fuel jet 34 is a length along the fuel jot 34 before which the fuel jet 34 can be regarded as being in its fuel-only phase 27 and after which the fuel jet 34 would ignite into a flame 29.

[0030] In the exemplary drawing of FIG. 2A, the bluff body 36 is positioned in the path of the fuel jet 34 where the fuel jet 34 is in its fuel-only phase 27, in the exemplary drawing of FIG. 2B, the bluff body 36 is positioned such that at least some portion of the bluff body 36 is disposed along the flame lift-off length L i.e., the bluff body 36 is located partway between the fuel-only zone 27 and the flame zone 29. In the exemplary drawing of FIG. 2C, the bluff body 36 is shown positioned fully in the flame zone 29. Hence, the terms fuel jet or dispensed fuel jet used herein are not only being inclusive of the fuel when the fuel is in its fuel-only phase, rather, it should be understood that such terms are to be construed broadly as they refer to scenarios where the fuel is at least partly, or fully, ignited with a flame along or after the flame lift-off length L.

[0031] In the illustrated embodiment of FIG. 3, the bluff body 36 is configured to exhibit a pyramidal shape having a square base 42 and an apex 44, or a prismatic shape having a rectangular base 46 and an opposing wedge-shaped end 48 as shown in the illustrated embodiment of FIG. 4.

[0032] Although the pyramidal shape of the bluff body 36 is depicted in FIG. 3, it may be noted that the square base 42 of the bluff body 36 is merely exemplary in nature, and hence, non-limiting of this disclosure. Rather, other polygonal shapes can be contemplated in lieu of the square base 42 of the bluff body 36 disclosed in FIG. 3. For example, the bluff body 36 may be configured to exhibit a pentagonal pyramid shape, a hexagonal pyramid shape, or other polyhedral shapes that are known to persons skilled in the art for having either an apex 44 or a wedge-shaped end 48 as shown in the views of FIGS. 3 and 4 respectively.

[0033] In other embodiments of this disclosure, other shapes such as a conical shape as shown in the view of FIG. 5, an oblong shape as shown in the view of FIG. 6, an oblong shape with a rear apex 57 as shown in the view of FIG. 7, or a spherical shape as shown in the view of FIG. 8 could be used for forming the bluff body 36 disclosed herein. In embodiments of this disclosure, it is hereby contemplated that a shape and material of the bluff body 36 would be selected such that the anterior portion 38 or the posterior portion 40 of the bluff body 36 impede an axial momentum of the dispensed fuel jet 34 as minimally as possible after the fuel jet 34 is incident on the anterior portion 38 of the bluff body 36. Also, as disclosed earlier herein, the contour that would be associated with the anterior portion 38 of the bluff body 36 would he so selected that the anterior portion 38 can split the dispensed fuel jet 34 into two or more turbulent fuel streams.

[0034] It is hereby further contemplated that the shape and material of the bluff body 36 are also selected such that the anterior portion 38 or the posterior portion 40 of the bluff body 36 minimally impedes the momentum of the fuel streams that are firmed upon splitting the dispensed fuel jet 34. To that effect, in certain embodiments of this disclosure, it is further contemplated that a contour of the posterior portion 40 could also be made convergent towards the axis AA of the dispensed fuel jet 34 as shown in FIGS. 6, 7 and 8 instead of being divergent from the axis AA of the dispensed fuel jet 34 as shown in FIGS. 3-5. Due to these aspects, it is envisioned that as the split fuel streams are facilitated to travel with minimal impediment to their momentum, the split fuel streams can now access an increased amount of oxidant within the combustion chamber 12.

[0035] In another embodiment as shown in FIGS. 6-8, the contour of the anterior portion 38 could be merely convex in a direction opposing a flow of the fuel jet 34. In such embodiments, it may be noted that although the contour of the anterior portion 38 could be merely convex in a direction opposing a flow of the fuel jet 34, a maximum perimeter M.sub.p of the anterior portion 38 would be kept at least equal to, or preferably, smaller than a perimeter that is associated with a spray pattern of the dispensed fuel jet 34 that would be incident on the anterior portion 38. This way, the anterior portion 38 would not only be configured to offer a separation plane to the dispensed fuel jet 34 for splitting the dispensed fuel jet 34 but would also be configured to reduce the amount of impediment to the axial momentum of the dispensed fuel jet 34 and the split fuel streams that are obtained upon splitting of the dispensed fuel jet 34.

[0036] In a further embodiment as shown in FIG. 9, the posterior portion 40 of the bluff body 36 may be configured to define a first orifice 50 that is transverse to the axis AA of the dispensed fuel jet 34. In this embodiment, the posterior portion 40 may be further configured to define a second orifice 52 that is disposed parallel to the axis AA of the dispensed fuel jet 34 and located distally away from the injector tip 30. The first orifice 50 would be disposed in fluid communication with the second orifice 52 via a passageway 54 such that the first orifice 50 can entrain an oxidant, for instance, air from a portion of the combustion chamber 12 adjacent the first orifice 50 and communicate the entrained oxidant to a portion of the combustion chamber 12 adjacent the second orifice 52 via the passageway 54.

[0037] It is contemplated that during operation of the engine 10, due to the presence of the bluff body 36, a low-pressure region may exist in the portion of the combustion chamber 12 underlying the posterior portion 40 of the bluff body 36. Moreover, as the fuel jet 34 would be dispensed from the nozzles 32 of the injector tip 30 at a relatively high velocity, this high-velocity fuel would, upon being split at the anterior portion 38 of the bluff body 36, result in two or more fuel streams that would continue as high-velocity fuel streams with a minimal momentum loss.

[0038] In embodiments of the present disclosure, it is contemplated that the bluff body 36 is positioned at a pre-determined distance D.sub.1 from the nozzle 32 of the injector tip 30 to impart turbulence in the split fuel streams by generating a wake in the dispensed fuel jet 34 when the dispensed fuel jet 34 is incident upon the anterior portion 38 of the bluff body 36. As each split fuel stream passes over the bluff body 36, the split fuel streams can tend to push some of the oxidant present in the combustion thanker 12 into the first orifice 50 as shown in FIG. 10. This oxidant may be communicated to the second orifice 52 via the passageway 54 as shown in FIG. 11. As shown in FIG, 12, upon exiting the second orifice 52, the oxidant can now mix with the fuel streams that are in a state of high turbulent mixing at the portion of the combustion chamber 12 adjacent to the second orifice 52.

[0039] In this manner, it is envisioned that if a core of the dispensed fuel jet 34 is rich in fuel, such a core would first be split by the anterior region of the bluff body 36 to help the fuel from the core gain access to the oxidant in the combustion chamber 12. Besides, due to the presence of the first and the second orifices 50, 52 being connected by the passageway 54, oxidant from the portion of the combustion chamber 12 adjacent the first orifice 50 could now be pulled by the high velocity split fuel streams adjacent to the bluff body 36 to enter the first orifice 50, and exit the second orifice 52 to efficiently mix with the fuel (that was split from the fuel rich core) at the portion of the combustion chamber 12 adjacent to the second orifice 52.

[0040] In an alternative embodiment as shown in FIG. 13, the bluff body 36 may be a screen mesh 62. As shown in FIG. 13, the screen mesh 62 may include wires 64, and each wire 64 may be disposed at a pre-specified distance d from an adjacent one of the wires 64 to render the screen mesh 62 with a pre-determined amount of porosity.

[0041] The screen mesh 62 could be positioned within the combustion chamber 12 such that a plane of the screen mesh 62 is angularly disposed, for example, at 45 degrees, exactly transverse i.e., at 90 degrees, or 60 degrees to the axis AA of the dispensed fuel jet 34 as shown in the view of FIG. 14. Further, as shown in the illustrated embodiment of FIG. 14, the screen mesh 62 may be positioned at a pre-determined distance D from the nozzle 32 of the injector tip 30 to facilitate at least one wire 64 from the set of wires 64 to impart turbulence by generating a wake in the incident fuel jet 34.

[0042] Alternatively, in another embodiment as shown in the view of FIG. 15, the screen mesh 62 could be positioned adjacent to the nozzle 32 on the injector tip 30 of the fuel injector 28. In this configuration, a contour of the screen mesh 62 may be adapted to correspond with a contour of the injector tip 30.

[0043] In another embodiment as shown in FIG. 16, a duct 66 may be disposed within the combustion chamber 12 and the screen mesh 62 may be attached to an outlet end 68 of the duct 66 that is distal from the nozzle 32. In this embodiment, when high-velocity fuel is injected through an inlet 70 of the duct 66, it is envisioned that subsequent to a flow of the high-velocity fuel through the duct 66, the duct 66 would entrain air from the combustion chamber 12 and urge the entrained air to follow the high-velocity fuel. The fuel and the entrained air can now be forced into a wake from turbulence created by the wires 64 of the screen mesh 62 at the outlet end 68 of the duct 66, thereby facilitating a more uniform mixing of the fuel and air with one another.

[0044] Although one possible configuration of the bluff body 36 has been disclosed in the embodiment in which the bluff body 36 has been explained as being embodied as a screen mesh 62, it will be acknowledged that references made to the screen mesh 62 in totality is non-limiting of this disclosure. Rather, it will be appreciated by persons skilled in the art that each wire 64 that is present on the screen mesh 62 could also be regarded as an individual bluff body 36 by itself as each wire 64 from the screen mesh 62 can be used to perform functions that are consistent with the present disclosure. Therefore, for purposes of the present disclosure, it has been contemplated that in embodiments herein, a wire 64 having an oblong cross-section as shown in the view of FIG, 17, a circular cross-section as shown in the view of FIG. 18, or a polygonal cross-section, for example, a hexagonal cross-section as shown in the view of FIG. 19 can be regarded as the bluff body 36, or multiple wires 64 of an oblong, circular, or polygonal cross-section may be grouped or meshed to define interstitial spaces between adjacently located wires 64 to define the bluff body 36 of the present disclosure.

[0045] Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., associated, provided, disposed, in communication and the like are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.

[0046] Additionally, all numerical terms, such as, but not limited to, first, second, or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and; or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to or over another element, embodiment, variation and/or modification.

[0047] It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims.

INDUSTRIAL APPLICABILITY

[0048] The present disclosure has applicability for use and implementation in reducing soot emissions with combustion of fuel in an engine. The present disclosure is directed to an internal combustion engine 10 and more particularly, to a combustion system 14 for an internal combustion engine that is configured to help reduce an amount of soot that would otherwise typically be produced without the use of embodiments disclosed herein.

[0049] With use of the embodiments herein, fuel jets having a rich fuel core are oxidized by helping the rich fuel core to gain access to oxidants from within the combustion chamber of the engine. As these fuel jets and their fuel rich cores are split with use of the bluff body 36, the split fuel jets can be oxidized for accomplishing combustion with reduced soot emissions.

[0050] Moreover, by providing the first and second orifices 50, 52 together with the passageway 54, a pressure within the combustion chamber 12 may be normalized to help entrain the oxidant within the first orifice 50 and direct the entrained oxidant towards the second orifice 52 to mix with the split fuel streams, thereby facilitating a greater amount of oxidation and assisting in the reduction of the amount of soot from combustion. Due to this, detrimental effects caused by soot such as sludging of lubricants, or other fluids in an internal combustion engine can be reduced.

[0051] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems, methods and processes without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.