Engine operating method and piston having non-reentrant combustion bowl and anti-sooting ramp
AssigneeCaterpillar Inc.
InventorsEric Lee Schroeder, Jonathan Kevin Tooker, Adam Joseph Clute
Life of this patent
Estimating the term…
Abstract
Operating an internal combustion engine includes conveying fuel of spray plumes of directly injected fuel out of a swirl pocket in a combustion bowl in a piston, and impinging the fuel upon an anti-sooting ramp transitioning between a radially inner shelf surface of the combustion bowl and a radially outer squish surface of the piston. The shelf surface is spaced an axial distance (FA) from a plane defined by the squish surface that is from 1% to 2% of an outer diameter (OD) dimension of the piston. Impinging the fuel upon the anti-sooting ramp directs the fuel upwardly from the squish surface to limit wall-wetting in the combustion cylinder.
Claims19
A method of operating an internal combustion engine comprising:
- reciprocating a piston defining a piston outer diameter (OD) dimension, in a combustion cylinder in the engine;
- directly injecting a liquid fuel from a plurality of spray orifices in a fuel injector defining a longitudinal axis into the combustion cylinder in the engine;
- advancing spray plumes of the injected liquid fuel outwardly and downwardly from the plurality of spray orifices through a combustion bowl of the piston having a non-reentrant profile;
- conveying fuel of the spray plumes out of a swirl pocket of the combustion bowl into a shelf volume of the combustion bowl formed between a plane defined by a radially outer squish surface, and a radially inner shelf surface spaced an axial (FA) distance from the plane that is from 1% to 2% of the OD dimension;
- impinging fuel of the spray plumes exiting the shelf volume of the combustion bowl upon an anti-sooting ramp transitioning between the radially inner shelf surface and the radially outer squish surface;
- and
- directing the fuel of the spray plumes exiting the shelf volume upwardly from the squish surface based on the impingement of the fuel upon the anti-sooting ramp so as to limit wall-wetting in the combustion cylinder.
A piston configured to reciprocate in a combustion cylinder in an internal combustion engine comprising:
- an annular body including a crown portion defining a longitudinal axis and having a radially outer lip portion defining a plane oriented normal to the longitudinal axis;
- the crown portion further including a combustion bowl having a radially inner shelf portion spaced a first axial (FA) distance from the plane, and a bottom surface spaced a second axial (SA) distance from the plane;
- the annular body further including an outer surface defining a piston outer diameter (OD) dimension, and a ratio of the FA distance to the OD dimension is from 1% to 2%, and a ratio of the FA distance to the SA distance is from 7% to 11%;
- and
- the combustion bowl forms a non-reentrant profile, and the crown portion further includes an anti-sooting ramp transitioning between the radially inner shelf portion and the radially outer lip portion to redirect a flow of injected fuel exiting the combustion bowl upwardly from the radially outer lip portion, such that wall-wetting in the combustion cylinder is limited.
A piston for an internal combustion engine comprising:
- an annular crown body defining a longitudinal axis and having a radially outer lip portion defining a plane oriented normal to the longitudinal axis;
- the annular crown body further including a combustion bowl having a radially inner shelf portion spaced a first axial (FA) distance from the plane, a bottom surface spaced a second axial (SA) distance from the plane, and an outer surface defining a tangent forming an acute angle with the plane opening in a radially inward direction;
- the a piston skirt attached to the annular crown body defining a piston outer diameter (OD) dimension that is from 169 millimeters to 170 millimeters, and the FA distance is from 1.9 millimeters to 2.5 millimeters;
- and
- the radially outer lip portion includes a planar squish surface and the radially inner shelf portion includes a planar shelf surface, and an anti-sooting ramp transitions between the planar shelf surface and the planar squish surface and has a concave curvilinear profile.
Dependencies are inferred from the claim text.