Piston having combustion bowl shaped to balance combustion efficiency and emission properties

摘要

A piston for a compression ignition internal combustion engine includes a piston body having a combustion face defining a combustion bowl, and the combustion face including a compound bowl surface and a compound rim surface. The combustion face is profiled to balance a combustion efficiency property of the piston with emissions properties of the piston, and includes a profile of rotation defining a convex curve segment bisected by the longitudinal axis, and a plurality of concave curve segments outboard of the convex curve segment. The profile of rotation further includes a compound rim profile defining a plurality of convex curve segments corresponding to an inner rim surface. The convex curve segment of the compound bowl profile defines a relatively small radius of curvature, and the plurality of convex curve segments corresponding to the inner rim surface define a relatively large radius of curvature. The combustion face includes an abrupt transition from the compound bowl surface to the compound rim surface.

主权项

1. A piston for a compression ignition internal combustion engine, the piston comprising:
a piston body including
an outer cylindrical surface defining a longitudinal axis,a combustion face defining a combustion bowl, the combustion face including a compound bowl surface having an inner bowl surface and an outer bowl surface, anda compound rim surface having an outer rim surface adjoining the outer cylindrical surface and an inner rim surface adjoining the compound bowl surface; the combustion face further including a profile of rotation about the longitudinal axis, the profile of rotation including a compound bowl profile defining a bowl convex curve segment corresponding to the inner bowl surface and being bisected by the longitudinal axis, and further defining a plurality of concave curve segments outboard of the bowl convex curve segment and corresponding to the outer bowl surface, a radius of curvature of the bowl convex curve segment being smaller than a radius of curvature of the plurality of concave curve segments; the profile of rotation further including a compound rim profile defining a plurality of linear curve segments corresponding to the outer rim surface, and further defining a plurality of rim convex curve segments corresponding to the inner rim surface, each convex curve segment of the plurality of rim convex curve segments adjoining one linear curve segment of the plurality of linear curve segments, a radius of curvature of the plurality of rim convex curve segments being larger than the radius of curvature of the plurality of concave curve segments; the combustion face further including a first continuous transition from the inner bowl surface to the outer bowl surface, a second continuous transition from the inner rim surface to the outer rim surface, and an abrupt transition from the compound bowl surface to the compound rim surface; and the plurality of concave curve segments including a first concave curve segment and a second concave curve segment, a radius of curvature of the first concave curve segment being different from a radius of curvature of the second concave curve segment.