Tensioner with expanding spring for radial frictional asymmetric damping

摘要

A tensioner is disclosed that may be part of a power system where the tensioner provides tension to an endless power transmitting element such as a belt, chain, or other continuous loop. The tensioner has an arm that is rotatable about a first axis and includes an arm arbor having a window therethrough, a bushing having a protrusion and being positioned adjacent the arm arbor with the protrusion received in the arm arbor's window, and a spring coupled to the arm urging the arm to rotate about the first axis into tensioning engagement with a power transmitting element. The spring is positioned where it can radially expand into contact with the protrusion of the bushing as the arm is rotated in a direction opposite the direction of tensioning engagement such that the bushing is urged radially outward relative to the arm arbor to provide frictional damping.

主权项

1. A tensioner comprising:
an arm rotatable about a first axis, the arm comprising an arm arbor having a slot through a portion thereof and having a spring support; a bushing having a protrusion wherein the bushing includes a longitudinal slit that allows radial expansion and splits the protrusion into a first part and a second part; a spring coupled to the arm urging the arm to rotate about the first axis into tensioning engagement with an endless power transmitting element; a cap having a spring abutment feature, the cap enclosing the spring within the tensioner; wherein the bushing surrounds the arm arbor and is positioned with the protrusion extending through the slot of the arm arbor; wherein the spring has a first end coupled to the arm and a second end coupled to the cap and is positioned to radially expand into contact with the protrusion of the bushing as the arm is rotated in a direction opposite the direction of tensioning engagement such that the bushing is urged radially outward relative to the arm arbor to provide frictional damping; wherein the slot of the arm arbor is positioned about 30 degree from the spring abutment feature of the cap, and the spring support of the arm arbor is positioned at or between 90 degree through 180 degrees from the spring abutment feature of the cap, thereby providing damping of about 60 in-lb to about 80 in-lb with a tensioner torque of between about 150 in-lb to about 200 in-lb.