Combustion system for an engine having a swirl inducing combustion chamber

A combustion chamber of an internal combustion engine includes a contoured surface that defines a plurality of deflection foils. The contoured surface distributes fuel spray into portions directed toward one of the deflection foils. Each deflection foil re-directs their respective portion of the fuel spray into a combined radial path that swirls about a center of the combustion chamber. Each of the deflection foils defines a flow path and a foil axis. The flow path includes an entrance segment and an exit segment. The entrance segment directs a portion of the fuel spray radially away from the center of the combustion chamber, and the exit segment directs the portion of the fuel spray substantially tangential relative to the combined radial path of the re-directed portions of the fuel spray.

TECHNICAL FIELD

The invention generally relates to a combustion chamber for an internal combustion engine.

BACKGROUND

Modern engine assemblies, including but not limited to diesel engines, may include a direct injection fuel system having a fuel injector that directly injects a stream of fuel, i.e., a fuel spray, into a combustion chamber of the engine assembly. The fuel spray mixes with air within the combustion chamber prior to combustion. The degree of mixture achieved between the fuel spray and the air within the combustion chamber affects the fuel economy and the hydrocarbon emissions of the internal combustion engine.

SUMMARY

An internal combustion engine is provided. The internal combustion engine includes an engine assembly defining a bore that extends along a central bore axis. A piston is disposed within the bore. The piston is moveable in a reciprocating motion within the bore along the central bore axis. The piston and the engine assembly cooperate to define a combustion chamber. The internal combustion engine further includes a direct injection fuel system having a fuel injector for injecting a fuel spray into the combustion chamber. The fuel spray is injected into the combustion chamber along a path. The combustion chamber includes a contoured surface that defines a plurality of deflection foils. The contoured surface receives and re-distributes the path of the fuel spray into a plurality of portions, with each portion of the fuel spray directed toward one of the plurality of deflection foils. Each of the plurality of deflection foils re-directs their respective portion of the fuel spray into a combined radial path that swirls about a center of the combustion chamber.

A combustion chamber of an internal combustion engine is also provided. The combustion chamber includes a contoured surface that defines a plurality of deflection foils. The contoured surface is shaped for receiving and distributing an injected fuel spray into a plurality of portions. Each portion of the fuel spray is directed toward one of the plurality of deflection foils. Each of the plurality of deflection foils re-directs their respective portion of the fuel spray into a combined radial path that swirls about a center of the combustion chamber. Each of the plurality of deflection foils include a foil axis that extends radially outward from the center of the combustion chamber through a center of each deflection foil, and a flow path. The flow path includes an entrance segment, an exit segment, and a transition segment. The entrance segment forms an entrance angle with the respective foil axis of the deflection foil. The exit segment forms an exit angle with the respective foil axis of the deflection foil. The transition segment transitions between the entrance segment and the exit segment. The entrance angle is between 7° and 20°, and the exit angle is between 30° and 60°. The exit angle is larger than the entrance angle. The entrance segment of the flow path of each deflection foil directs a respective portion of the fuel spray radially away from the center of the combustion chamber, and the exit segment of the flow path of each deflection foil directs the respective portion of the fuel spray substantially tangential relative to the combined radial path of the re-directed portions of the fuel spray.

Accordingly, the deflection foils are angularly spaced about the central bore axis, with each of the deflection foils re-directing a portion of the fuel spray into the combined radial path of the re-directed portions of the fuel spray. The separation of the fuel spray into portions, and the following re-direction of each portion and recombining of the individual portions into a single, combined radial path that swirls around the center of the combustion chamber, increases the mixing between the fuel spray and the air within the combustion chamber, thereby improving fuel efficiency, as well as hydrocarbon, soot and carbon monoxide emissions.

DETAILED DESCRIPTION

Referring to the Figures, wherein like numerals indicate like parts throughout the several views, an internal combustion engine is generally shown at20inFIG. 1. The internal combustion engine20may include but is not limited to a gasoline engine or a diesel engine.

Referring toFIG. 1, the internal combustion engine20includes an engine assembly22. The engine assembly22includes but is not limited to an engine block24and a cylinder head26. The engine block24defines a bore28that extends along a central bore axis30. The cylinder head26is attached to the engine block24above and adjacent the bore28. A piston32is disposed within the bore28, and is reciprocally moveable within the bore28along the central bore axis30to drive rotation of a crankshaft34. The piston32includes a radial center36that is aligned and coaxial with the central bore axis30. The piston32and the engine assembly22, and particularly the piston32, the engine block24and the cylinder head26, cooperate to define a combustion chamber38therebetween.

The internal combustion engine20further includes a direct injection fuel system40. The direct injection fuel system40includes a fuel injector42in fluid communication with the combustion chamber38. The fuel injector42injects a stream of fuel, i.e., fuel spray44, into the combustion chamber38. The fuel spray44is injected into the combustion chamber38along a linear path46. While it should be appreciated that the injected fuel spray44may fan out over a distance to define a plume of injected fuel spray44, a centerline of the plume extends along the straight, non-curving, linear path46. Once injected into the combustion chamber38, the fuel spray44may mix with combustion air to form a fuel/air mixture. The direct injection fuel system40further includes a fuel pump48. The fuel pump48provides the fuel injector42with pressurized fuel. For example, the fuel pump48may provide the fuel to the fuel injector42at a pressure of at least 120 MPa, and more preferably greater than 200 MPA.

As shown inFIGS. 1 through 4, the fuel injector42is positioned relative to the bore28and the piston32to inject the fuel spray44into the combustion chamber38such that the linear path46is approximately parallel with the central bore axis30. The fuel injector42is positioned so that the centerline of the fuel spray44is positioned approximately co-axial with the central bore axis30, at a center of the combustion chamber38. As such, the centerline of the linear path46of the fuel spray44is centered at the radial center36of the piston32.

The combustion chamber38includes a contoured surface50. Preferably and as shown, the contoured surface50is defined by an axial end surface52of the piston32, facing the cylinder head26. However, it should be appreciated that the contoured surface50may be defined, for example, by a lower vertical surface54of the cylinder head26, disposed directly above the bore28and facing the axial end surface52of the piston32.

Referring toFIG. 2, the contoured surface50defines a plurality of deflection foils56. As shown inFIGS. 2 and 4, the contoured surface50defines six deflection foils56. However, it should be appreciated that the number of deflection foils56may be greater than or less than the six deflection foils56shown in the exemplary embodiment. Each deflection foil56includes a foil axis58that extends from the center of the combustion chamber38, i.e., the central bore axis30, outward through a center60of the deflection foil56and toward a radial edge62of the piston32. The deflection foils56, and their respective foil axis58, are angularly spaced about the central bore axis30an equal angle from each other. Accordingly, the deflection foils56and their respective foil axis58are angularly spaced equidistant from each other about the central bore axis30and the center of the combustion chamber38.

Referring toFIGS. 2 and 3, the contoured surface50of the combustion chamber38is shaped and/or formed to distribute the fuel spray44from the fuel injector42into a plurality of approximately equal portions, generally indicated by reference numeral64. Each portion64of the fuel spray44is directed toward one of the deflection foils56. Each of the deflection foils56defines a flow path66to receive and re-direct the portion64of the fuel spray44directed thereto. The flow path66of each of the deflection foils56re-directs their respective portion64of the fuel spray44into a combined radial path68that swirls about a center of the combustion chamber38, i.e., about the central bore axis30. Accordingly, the combined radial path68of the re-directed portions64of the fuel spray44is approximately concentric with the radial center36of the piston32.

Each of the deflection foils56re-directs their respective portion64of the fuel spray44in a common rotational direction about the central bore axis30. As shown, each of the deflection foils56re-directs their respective portion64of the fuel spray44in a clockwise direction of rotation relative to the central bore axis30, so that the combined radial path68circulates in the clockwise direction about the central bore axis30. It should be appreciated that the deflection foils56may be reversed so that all of the deflection foils56re-directs their respective portion64of the fuel spray44in a counter-clockwise direction of rotation relative to the central bore axis30, so that the combined radial path68circulates in the counter-clockwise direction about the central bore axis30.

Accordingly, Referring toFIG. 3, as the fuel spray44is injected into the combustion chamber38, the fuel spray44moves along the linear path46, orthogonally toward the piston32, until the fuel spray44contacts the contoured surface50. Referring toFIG. 2, once the fuel spray44initially contacts the contoured surface50, the contoured surface50directs the stream of the fuel spray44into the portions64, which are directed radially outward relative to the central bore axis30, toward one of the deflection foils56. Each of the deflection foils56further re-directs the flow of the fuel spray44received therein into the combined radial path68, which swirls or circles about the central bore axis30. The splitting of the injected fuel spray44into the portions64, the re-direction of the portions64, and the re-joining of the individual portions64of the fuel spray44into the combined radial path68, increases fuel/air mixing to provide a more uniformly and thoroughly mixed fuel/air mixture.

Referring toFIG. 2, the flow path66of each portion64of the fuel spray44includes an entrance segment70, an exit segment72, and a transition segment74. The entrance segment70of each portion64of the fuel spray44is directed from the linear path46of injection, radially outward toward the radial edge62of the piston32and away from the radial center36of the piston32. The exit segment72of each portion64of the fuel spray44is directed inward into the combustion chamber38, along a substantially tangential path relative to the combined radial path68of the re-directed portions64of the fuel spray44. The transition segment74transitions the direction of flow of the portion64of the fuel spray44between the entrance segment70and the exit segment72.

Referring toFIG. 2, the entrance segment70of the flow path66and the foil axis58of each deflection foil56form an entrance angle76therebetween, having a vertex approximately located at the radial center36of the piston32. The exit segment72of the flow path66and the foil axis58of each deflection foil56form an exit angle78therebetween, having a vertex81approximately located at an outer radial edge80of the combustion chamber38. Accordingly, the entrance angle76and the exit angle78open in opposing directions. The exit angle78is larger than the entrance angle76. Preferably, the entrance angle76is between the range of 7° and 20° , and the exit angle78is between the range of 30° and 60° . The sum of the entrance angle76and the exit angle78is less than ninety degrees)(90° ).

Referring toFIG. 3, each deflection foil56includes an edge wall82. The edge wall82of each deflection foil56extends generally parallel with the central bore axis30. Referring toFIGS. 2 and 4, the edge wall82includes a first wall portion84, a second wall portion86, and an entrance portion87. The first wall portion84re-directs the portion64of fuel spray44from the entrance segment70of the flow path66to the exit segment72of the flow path66. The second wall portion86re-directs the portion64of the fuel spray44along the exit segment72of the flow path66toward and into the combined radial path68of the re-directed portions64of the fuel spray44.

The first wall portion84of the edge wall82may include a curved cross section perpendicular to the central bore axis30, or a linear cross section perpendicular to the central bore axis30. The second wall portion86of the edge wall82may include a curved cross section perpendicular to the central bore axis30, or a linear cross section perpendicular to the central bore axis30.FIG. 2shows the edge wall82of each deflection foil56having a curved first wall portion84, and a linear second wall portion86.FIG. 4shows the edge wall82of each deflection foil56having a linear first wall portion84, and a curved second wall portion86. It should be appreciated that the edge wall82may be configured in a different manner than shown and described herein that is capable of directing the portion64of the fuel spray44from the entrance segment70to the exit segment72of the flow path66, and toward the combined radial path68.

The entrance angle76may be chosen such that the entrance segment70of each portion64of the fuel spray44enters the first wall portion84of the deflection foil56with the entire spray located between the center60of the deflection foil56and the entrance portion87of the edge wall82. The entrance angle76may be adjusted experimentally or analytically relative to the width of the fuel spray44entering the deflection foil56and any preexisting level of swirl or air motion that may exist in the combustion chamber38. In the preferred embodiment, the entrance segment70of each portion64of the fuel spray44is biased toward the entrance portion87of the edge wall82of the deflection foil56.