Patent ID: 6464604
Filing Date: 2002-10-15
Classification: F16H

Abstract:
A combination comprising:a vehicle engine adapted to thermally expand from an initial condition at an ambient temperature to a hot engine condition due to an increase in engine temperature during engine operation; an endless flexible driving element driven by said engine; a tensioner comprising: a fixed structure mounted on said engine; a pivot structure pivotally mounted on said fixed structure for pivotal movement about a pivot axis; spring structure constructed and arranged to apply a tensioning torque to said pivot structure that tends to pivot said pivot structure in a tension applying direction; a rotatable member rotatably mounted on said pivot structure for rotation about a rotational axis spaced radially from said pivot axis by a radius, said rotatable member engaging said driving element in a tension applying relationship such that said driving element is tensioned and in reaction applies a hub load force to said rotatable member at an angle with respect to said radius; said tensioner being mounted on said engine such that when said engine is in said initial condition said pivot structure is angularly positioned at an initial angular position spaced from a perpendicular angular position at which said hub load force would be applied to said rotatable member perpendicular to said radius, said initial angular position being spaced from said perpendiculer angular position in a return direction opposite said tension applying direction, said spring structure applying said tensioning torque to said pivot structure such that said driving element is tensioned to a first mean dynamic tension when said pivot structure is in said initial angular position thereof; said engine and said driving element being constructed and arranged such that as said engine thermally expands to said hot engine condition the mean dynamic tension in said driving element increases so that the hub load force applied by said driving element pivots said pivot structure in said return direction away from said initial angular position thereof to a hot engine angular position, said spring structure applying said tensioning torque to said pivot structure such that said driving element is tensioned to a second mean dynamic tension greater than said first mean dynamic tension when said pivot structure is in said hot engine angular position thereof; said tensioner being constructed and arranged such that, as said pivot structure is pivoted from said initial angular position thereof to said hot engine angular position thereof, the angle between said hub load force and said radius continually increases and said spring structure is continually increasingly stressed so that the mean dynamic tension in said driving element continually increases from said first mean dynamic tension to said second mean dynamic tension during the thermal expansion of said engine; said tensioner being constructed and arranged such that the mean dynamic tension of said driving element required to continue pivoting said pivot structure in said return direction from said hot engine position thereof continually increases as a result of the angle between said hub load force and said radius continually increasing and said spring structure being continually increasingly stressed the further said pivot structure is pivoted in said return direction from said hot engine position.