Federal-mogul World Wide, Inc.

Federal-mogul Corporation

Roberto Bueno Nigro

Randall R Gaiser

Carmo Ribeiro

Eduardo Matsuo

Xiluo Zhu

Kai Wang

Eric Allan Highum

A piston assembly and connecting rod therefor is provided. The connecting rod has an elongate body extending to an end for operable attachment to a piston. The end has a wrist pin bore extending between opposite sides of the body. The wrist pin bore has a wavy profile extending between the sides. The wavy profile has at least one concave surface with a valley extending along a circumferential direction of the wrist pin bore and convex surfaces having peaks extending along a circumferential direction of the wrist pin bore on laterally opposite sides of the valley. The peaks and valleys cooperate to form a smooth load gradient and uniform lubrication flow across the interface region between the wrist pin bore and the wrist pin extending therethrough.

Piston assembly and connecting rod having a profiled wrist pin bore therefor

A piston assembly and wrist pin therefor provide a method for controlling rotation of the wrist pin with respective piston pin bores and connecting rod small end wrist pin bore. The wrist pin has a cylindrical body with opposite end portions spaced axially from one another by a central portion and a through bore of varying internal diameter. The through bore has first diameter and second diameters, wherein the first diameter is less than the second diameter. The first diameter is defined in one of the central portion or the opposite end portions, while the second diameter is defined in the other of the central portion or the opposite end portions. The first diameter transitions to the second diameter generally between the small end of the connecting rod and the pin bores of the piston.

Piston assembly and wrist pin therefor providing a method of controlling rotation of the wrist pin within corresponding piston pin bores and connecting rod wrist pin bore

A wrist pin for a heavy-duty piston assembly has a body with an axis of rotation and a generally cylindrical outer surface. The outer surface is adapted for pivotal connection to both a pair of laterally spaced pin bores and a small end of a connecting rod generally between the pin bores. The outer surface has a surface roughness equal to or less than 0.10 &#x3bc;m. The outer surface has a Kurtosis value that is inversely proportional with the surface roughness such that a product of the Kurtosis value and the surface roughness is between about 0.30 &#x3bc;m to 0.60 &#x3bc;m. The outer surface has a skewness of about &#x2212;1.0 to 0.0 and a lay angle relative to the axis of about 85 to 95 degrees.

Wrist pin

A monobloc piston has at least two steel parts welded together to define an inner cooling gallery. An outer ring belt is spaced from an inner annular support wall and is joined by a combustion bowl and a lower wall. A pair of pin bosses have axially aligned pin bores. A skirt is formed as one immovable piece with the pin bores. The piston has the following dimensional relationships:

Monobloc piston

An articulated piston includes a crown and a separate skirt joined in articulated manner to the pin bosses of the crown by a wrist pin. The skirt has opposing thrust surfaces which contact the wall of a cylinder bore of an engine when the piston experiences side loading during operation. The thrust surfaces have a vertical profile which is generally symmetrical about a center plane containing the axis of a pin bore of the skirt. The profile includes tapered end sections and a wide, shallow central depressed region. Under normal operation, the depressed region channels lubricant to the pin bores. The twin peaked profile distributes side loads and stress above and below the pin bore plane and under heavy load, the depressed region bows outwardly presenting a flat, full contact surface between the peaked regions for decreasing the wear load on the thrust surfaces.

Growing community of inventors

Ann Arbor, MI, United States of America

Roberto Bueno Nigro