Patent Application
20110239983
The present disclosure relates to internal combustion engines including direct injection fuel systems.
This section provides background information related to the present disclosure which is not necessarily prior art.
Engine assemblies may include direct engine fuel systems providing a fuel supply directly to a combustion chamber of the engine. Typically, the direct injection fuel systems may include a centrally located fuel injector. During the injection, the fuel injector may provide multiple radial fuel jets directed toward the combustion chamber walls. The orientation of the fuel injector and the resulting fuel spray may result in the fuel hitting the combustion chamber walls and therefore limiting mixing within the combustion chamber.
An engine assembly may include an engine structure, a piston, and a direct injection fuel system. The engine structure may define a cylinder bore and an intake port in communication with the cylinder bore and adapted to mitigate intake air swirl within the cylinder bore. The piston may be disposed within the cylinder bore for a reciprocal stroke between a top dead center position and a bottom dead center position. The piston may define an annular recess portion in an axial end surface thereof. The direct injection fuel system may include a fuel injector that provides a fuel spray to a combustion chamber defined by the piston and the engine structure. The fuel spray may define an annular plume intersecting the annular recess portion in the piston when the piston is in an injection position within twenty percent of the reciprocal stroke from the top dead center position.
A method may include providing a direct injection fuel injector in communication with a combustion chamber of an internal combustion engine defined by a cylinder bore in an engine structure and a piston disposed in the cylinder bore for a reciprocal stroke between a top dead center position and a bottom dead center position. The method may further include providing intake air flow to the combustion chamber and mitigating intake air swirl within the combustion chamber. A fuel spray may be injected from the fuel injector directly into the combustion chamber. The fuel injected into the combustion chamber may define an annular plume directed toward an annular recess portion in an axial end surface of the piston when the piston is in an injection position within twenty percent of the reciprocal stroke from the top dead center position.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
When an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
With reference to
The piston 16 and the engine structure 12 cooperate to define a combustion chamber 32. The direct injection fuel system 14 includes a fuel pump 34 providing a pressurized fuel supply to a direct injection fuel injector 36. In the present non-limiting example, the fuel provided to the direct injection fuel injector 36 may be at an operating pressure of at least one hundred mega Pascal (100 MPa). The direct injection fuel injector 36 is in direct communication with the combustion chamber 32 forming a direct injection arrangement. The direct injection fuel injector 36 may be incorporated into a fuel rail (not shown) having a plurality of direct injection fuel injectors.
The direct injection fuel injector 36 may extend axially into the combustion chamber 32. The piston 16 may define a torroidal combustion bowl 38 in an axial end surface 40 facing the direct injection fuel injector 36. The torroidal combustion bowl 38 may include an annular recess portion 42 defined radially between inner and outer radial surfaces 43, 45. The direct injection fuel injector 36 may be located centrally relative to the combustion chamber 32 and may direct a fuel spray (F1) into the annular recess portion 42 when the piston 16 is in an injection position within twenty percent of the reciprocal stroke from the TDC position. The fuel spray (F1) may define an annular plume.
In a first non-limiting example, the fuel spray (F1) includes multiple plumes. The multiple plumes may be generated by a multi-hole nozzle 44 of the direct injection fuel injector 36 defining a plurality of apertures 46 as illustrated in
In either arrangement, the annular plume formed by the fuel spray (F1) defines an annular centerline (C1) between inner and outer radial peripheries (P1i, P1o) of the fuel spray (F1). The annular centerline (C1) of the fuel spray (F1) may extend into the torroidal combustion bowl 38 between an annular center (C2) of the annular recess portion 42 and the inner radial surface 43 of the annular recess portion 42. The annular center (C2) may define a torroid center for the torroidal combustion bowl 38.
A line (L1) perpendicular to the annular centerline (C1) of the fuel spray (F1) and through the annular center (C2) may intersect the inner radial surface 43 at a point (P2). The fuel spray (F1) may define a spray angle (θ1). The spray angle (θ1) may be defined as the included angle of the annular centerline (C1). The inner radial periphery (P1i) may extend in a direction toward the piston 16 at an angle of (θ2) relative to the annular centerline (C1) and the outer radial periphery (P1o) may extend toward the piston 16 at the angle (θ2) relative to the annular centerline (C1).
The spray angle (θ1) may be adjusted to have the inner radial periphery (P1i) extend in a direction toward the piston 16 and radially between the annular centerline (C1) and the point (P2). By way of non-limiting example, the inner radial periphery (P1i) may extend in a direction toward the piston 16 intersecting the point (P2) on the inner radial surface 43 of the piston 16 when the piston is in the injection position. It is understood that the spray angle (θ1) may be adjusted to a position for a desired overall operation at all loads and speeds as a result of the angle (θ2) varying slightly with injection pressure and the fuel-air mass in the combustion chamber 32 (combustion chamber charge density).
An alternate engine assembly 110 is shown in
The high operating pressure of the fuel spray (F1) and the orientation of the fuel spray (F1) relative to the combustion chamber 32 may create a rolling fuel spray pattern (rolling torroidal flow) within the combustion chamber 32 and provide mixing. The fuel spray (F1) may form a rotational fuel spray, rotating about the annular center (C2) of the annular recess portion 42 in a rotational direction (R1) from the inner radial surface 43 of the annular recess portion 42 axially toward the piston 16 and to the outer radial surface 45 of the annular recess portion 42. The rotational direction (R1) may be defined about an axis generally perpendicular to the reciprocal direction of the piston 16. By way of non-limiting example, the fuel delivered to the combustion chamber at the start of the injection event may travel at least three hundred and sixty degrees in the rotational direction (R1) by the end of the injection event for a corresponding combustion event (in-cylinder combustion corresponding to a power stroke) under high load operation.
The intake port 28 may be arranged to minimize swirl flow generated by intake air flow. In the non-limiting example of
The equal and opposite orientation of the first intake port 228, 328 relative to the second intake port 229, 329 counteracts the tendency for intake air swirl within the combustion chamber 232, 332. Therefore, the mixing of air and fuel within the combustion chamber is primarily generated by the fuel spray (F1).
