Patent ID: 7895937

Claim:
A piston assembly comprising: a head with an integrally formed and unitary ring belt having a plurality of ring grooves and centered on a central longitudinal axis; first and second skirts integrally formed and unitary with said head and extending along said axis, each of said first and second skirts having a top edge adjacent said ring belt and a bottom edge spaced from said top edge along said axis and being radially narrower than said top edge and first and second side edges; first and second pin bosses integrally formed and unitary with said head and extending along said axis, said first and second pin bosses being mirror images of one another across said axis and being spaced radially inward from said ring belt to define a short-pin support arrangement, and formed with respective first and second pin bores axially aligned on a pin bore axis perpendicular to said central longitudinal axis; a plurality of panels integrally formed and unitary with said head and each extending between one of said first and second pin bosses and one of said first and second skirts, said plurality of panels including first and second panels being mirror images of one another across a first plane containing said central longitudinal axis and perpendicular to said pin bore axis and also including third and fourth panels being minor images of one another across said first plane, wherein said first and third panels are mirror images of one another across a second plane containing both said central longitudinal axis and said pin bore axis, and wherein said second and fourth panels are minor images of one another across said second plane, and wherein each of said panels include a top portion spaced closest to said head and bottom portion spaced furthest said head and a middle portion disposed substantially equally spaced from said top and bottom portions, and wherein each of said panels extends away from one of said pin bosses in a direction perpendicular to said second plane and over a rectilinear length to merge with one of said skirts, and wherein each of said panels twists along said length such that a ratio defined by a first distance between said top portion of said panel and said first plane over a second distance between said bottom portion of said panel and said first plane increases along at least part of said length; and wherein such said ratio increases because said first distance increases over at least part of said length and said second distance decreases over at least part of said length.