Patent ID: 7186196
Filing Date: 2007-03-06
Classification: F16H

Abstract:
1. A belt tensioner with integral damping for use in conjunction with a pulley assembly for tensioning an endless drive belt of a drive system, said belt tensioner comprising: a housing, a pivot shaft, a pivot bushing, a spring element, a disc-shaped spring bushing, a lever arm assembly, a friction element, an armplate, and a pulley assembly; wherein said housing comprises a cup-shaped body having a closed circumferential end, a cylindrical wall extending perpendicularly from said circumferential end along a longitudinal axis, and an open circumferential end opposite said closed circumferential end, said closed circumferential end including a plurality of ribs radially disposed on an inner surface thereof, said plurality of ribs including securing means for securing said pivot bushing to said housing wherein said pivot shaft comprises a cylindrical member having a proximal end, a distal end and an outer surface extending axially from said proximal end to said distal end, said pivot shaft further comprising a coupling means on said distal end thereof for fixedly mounting said armplate onto said distal end of said pivot shaft, said pivot shaft being fixedly secured to said closed circumferential end of said housing along said longitudinal axis, said coupling means configured to prevent axial rotation of said armplate with respect to said pivot shaft; wherein said pivot bushing comprises a cylindrical body portion having an outer cylindrical wall surface, said pivot bushing further comprising a flared end, said flared end facing said closed circumferential end of said housing, said pivot bushing further comprising a plurality of grooves extending the longitudinal length of said pivot bushing, said pivot bushing being axially disposed on said outer cylindrical surface of said pivot shaft and secured to said housing by said securing means; wherein said spring element is disposed in said housing between said cylindrical body portion of said pivot bushing and said cylindrical wall of said housing, a first end of said spring element being operatively connected to said housing and a second end of said spring element being operatively connected to said lever arm; wherein said disc-shaped spring bushing is axially disposed between said spring element and said lever arm, said spring bushing having an outer circumferential surface commensurate with the circumferential surface of the outer edge of the circumferential wall of said housing, and a central circular opening having an inner circumferential surface commensurate with the outer circumferential wall of the tubular proximal end of said lever arm; wherein said lever arm is pivotally mounted on said outer surface of said pivot bushing, said lever arm comprising a distal end and a proximal end, said proximal end including a cup-shaped damping cavity having an open end extending longitudinally from said distal end for accepting said armplate and said friction element, said proximal end further comprising a tubular member extending oppositionally from said cup-shaped damping cavity and longitudinally onto and operatively connected to said pivot bushing, whereby said lever arm is pivoted about said longitudinal axis in a belt tensioning direction, said lever arm further having, wherein said friction element comprises a first cup-shaved cavity having a flat bottom surface and a circumferential side surface, said friction element further including a centrally located aperture in said circumferential surface configured to prevent axial rotation of said friction element with respect to said lever arm, said friction element further comprising a cylindrical wall extending perpendicularly outward from said circumferential surface along a longitdinal axis, said friction element further comprising a cut-out portion extending from an outer rim of said cylindrical wall of said friction element to said centrally located aperture in said circumferential surface, such that said friction element tensionally fits into said cup-shaped damper cavity, said friction element providing a contact area having a high degree of damping on said cup-shaped damping cavity; wherein said armplate comprises a second cup-shaved cavity having a flat bottom surface and a circumferential edge, said circumferential edge having a plurality of spaced apart finger elements extending radially outward from said circumferential edge and angularly with respect to said flat bottom surface, each of said finger elements having a surface area exhibiting one or more angular contours configured to enhance spring-like characteristics of said finger elements and provide a more uniform and enduring pressure as well as increased damping on said damping cavity in a radial direction, said armplate further comprising a centrally located aperture in said flat bottom surface, said aperture configured to mate with said coupling means on said axial end of said pivot shaft to prevent axial rotation of said armplate with respect to said lever arm; and wherein said pulley assembly is mounted on said distal end of said lever arm, said pulley assembly including a pulley for receiving an endless drive belt and applying a tensioning force on said endless drive belt upon pivoting said lever arm in said belt tensioning direction, and wherein said damping is independent of the axial force of said tensioner and said spring element.