Abstract: A synchronous belt drive system having: a synchronous belt with a tensile cord of high-modulus fiber such as glass, carbon, PBO, or aramid; a driver sprocket and at least one driven sprocket, at least one of which is an obround sprocket; and a tensioner having: a base having a cylindrical portion extending axially with a radially outer surface and a receiving portion, an eccentric arm pivotally engaged with the radially outer surface, a torsion spring disposed within the receiving portion, the torsion spring applying a biasing force to the eccentric arm, and a pulley journalled to the eccentric arm. Preferably, no one of the eccentric arm, pulley, or torsion spring is axially displaced along an axis A-A from the others. The obround sprocket has a toothed surface and at least one linear portion disposed between two arcuate portions having a constant radius, the linear portion having a predetermined length.

Abstract: A synchronous belt drive system comprising a first obround sprocket having a toothed surface and at least one linear portion disposed between two arcuate portions, the arcuate portions having a constant radius, the linear portion having a predetermined length, a sprocket having a toothed surface, the sprocket engaged to the first obround sprocket by an endless toothed member, and the first obround sprocket having a magnitude and a phase such that an angular displacement timing error between the sprocket and the first obround sprocket is less than 1.5 degree peak to peak.

Abstract: A synchronous belt drive system having: a synchronous belt with a tensile cord of high-modulus fiber such as glass, carbon, PBO, or aramid; a driver sprocket and at least one driven sprocket, at least one of which is an obround sprocket; and a tensioner having: a base having a cylindrical portion extending axially with a radially outer surface and a receiving portion, an eccentric arm pivotally engaged with the radially outer surface, a torsion spring disposed within the receiving portion, the torsion spring applying a biasing force to the eccentric arm, and a pulley journalled to the eccentric arm. Preferably, no one of the eccentric arm, pulley, or torsion spring is axially displaced along an axis A-A from the others. The obround sprocket has a toothed surface and at least one linear portion disposed between two arcuate portions having a constant radius, the linear portion having a predetermined length.

Abstract: A synchronous belt drive system comprising a first obround sprocket having a toothed surface and at least one linear portion disposed between two arcuate portions, the arcuate portions having a constant radius, the linear portion having a predetermined length, a sprocket having a toothed surface, the sprocket engaged to the first obround sprocket by an endless toothed member, and the first obround sprocket having a magnitude and a phase such that an angular displacement timing error between the sprocket and the first obround sprocket is less than 1.5 degree peak to peak.

Abstract: A timing error correction system comprising a three element linkage having at least one element pivotally mounted to a mounting surface, a timing belt engaged between a driver and a driven, a first element of the three element linkage in contact with a timing belt slack side, a second element of the three element linkage in contact with a timing belt tight side, and a spring imparting a load to the three element linkage.

Abstract: A tensioner comprising a base, a shaft connected to the base, an eccentric adjuster coaxially engaged with the shaft, an arm pivotally engaged with the shaft, a pulley journalled to the arm, a torsion spring engaged between the arm and the base, the arm comprising a first receiving portion and a second receiving portion disposed axially opposite from the first receiving portion, a first damping member disposed between the arm and the base, the first damping member frictionally engaged with the base and engaged with first receiving portion, a second damping member disposed between the arm and the eccentric adjuster having a member engaged with the second receiving portion, and a biasing member disposed between the first damping member and the arm for applying a normal force to the first damping member and to the second damping member.

Abstract: A tensioner comprising a base, a shaft connected to the base, an eccentric adjuster coaxially engaged with the shaft, an arm pivotally engaged with the shaft, a pulley journalled to the arm, a torsion spring engaged between the arm and the base, the arm comprising a first receiving portion and a second receiving portion disposed axially opposite from the first receiving portion, a first damping member disposed between the arm and the base, the first damping member frictionally engaged with the base and engaged with first receiving portion, a second damping member disposed between the arm and the eccentric adjuster having a member engaged with the second receiving portion, and a biasing member disposed between the first damping member and the arm for applying a normal force to the first damping member and to the second damping member.

Abstract: A tensioner comprising a base, a shaft connected to the base, an eccentric adjuster coaxially engaged with the shaft, an arm pivotally engaged with the shaft, a pulley journalled to the arm, a torsion spring engaged between the arm and the base, the arm comprising a first receiving portion and a second receiving portion disposed axially opposite from the first receiving portion, a first damping member disposed between the arm and the base, the first damping member frictionally engaged with the base and engaged with first receiving portion, a second damping member disposed between the arm and the eccentric adjuster having a member engaged with the second receiving portion, and a biasing member disposed between the first damping member and the arm for applying a normal force to the first damping member and to the second damping member.

Abstract: A tensioner comprising a base, a shaft connected to the base, an eccentric adjuster coaxially engaged with the shaft, an arm pivotally engaged with the shaft, a pulley journalled to the arm, a torsion spring engaged between the arm and the base, the arm comprising a first receiving portion and a second receiving portion disposed axially opposite from the first receiving portion, a first damping member disposed between the arm and the base, the first damping member frictionally engaged with the base and engaged with first receiving portion, a second damping member disposed between the arm and the eccentric adjuster having a member engaged with the second receiving portion, and a biasing member disposed between the first damping member and the arm for applying a normal force to the first damping member and to the second damping member.

Abstract: A synchronous belt drive system comprising an obround sprocket (10) having a toothed surface and at least one linear portion (16) disposed between two arcuate portions (14,15), the arcuate portions having a constant radius (R1, R2), the linear portion having a predetermined length, a second sprocket (300) having a toothed surface, the second sprocket engaged to the obround sprocket by an endless toothed member (200), the second sprocket connected to a rotary load, the rotary load having cyclic torque fluctuations, and a radius (R1) of the obround sprocket (10) oriented at a belt entry point (201) which coincides with a maximum amplitude of a cyclic torque fluctuation such that a span length (SL) of the endless toothed member is made to vary in a manner that substantially cancels the cyclic torque fluctuations.

Abstract: A synchronous belt drive system comprising an obround sprocket (10) having a toothed surface and at least one linear portion (16) disposed between two arcuate portions (14,15), the arcuate portions having a constant radius (R1, R2), the linear portion having a predetermined length, a second sprocket (300) having a toothed surface, the second sprocket engaged to the obround sprocket by an endless toothed member (200), the second sprocket connected to a rotary load, the rotary load having cyclic torque fluctuations, and a radius (R1) of the obround sprocket (10) oriented at a belt entry point (201) which coincides with a maximum amplitude of a cyclic torque fluctuation such that a span length (SL) of the endless toothed member is made to vary in a manner that substantially cancels the cyclic torque fluctuations.

Abstract: A belt drive system having a belt having a belt body. A tensile cord disposed in the belt body running along a longitudinal axis. A plurality of belt teeth disposed on an outer surface of the belt body, the belt teeth oriented transverse to the longitudinal axis. A belt land disposed between the belt teeth. A driver sprocket attached to an engine crankshaft, the engine having a plurality of cylinders. A driven sprocket. The number of grooves on the driver sprocket being an integer multiple of the number of engine cylinders divided by two. The number of grooves on the driven sprocket being an integer multiple of the number of grooves in the driver sprocket. The number of belt teeth, land length and sprocket groove spacing is dependent on the number of engine firing events per crankshaft revolution thereby reducing the frequency of the belt/pulley meshing to a level within the orders of engine frequencies.