Shock-absorbing sprocket, drive assembly, and the like

A torsional vibration absorbing power transmission drive adapted to smooth and dampen torque pulses generated by an engine operable at low engine speeds, to which the vibration absorbing drive is connected, comprising a rotary driver member, a rotary driven member, an endless power transmission member trained about the rotary members in driving relationship, at least one of the rotary members being shock-absorbing and having a hub member having at least two lugs, an outer rim member having at least two radially inwardly extending ears adapted to matingly engage the lugs through torque-transmitting resilient elastomeric cushions interposed therebetween, characterized in that the shock-absorbing rotary member has outer flange bearings attached to and sandwiching the hub on either side thereof, and ring surfaces attached to the rim and disposed axially on either side thereof respectively forming radial bearing surfaces with each of the flange bearings, and the cushions occupy a portion of captive volumes defined within the shock-absorbing rotary member (under no load), the portion of the captive volume unoccupied by a cushion material defining void volume which is at least about 20 percent of the total captive volume, whereby upon rotation of the hub relative to the rim member, in addition to the inherent hysteresis of the elastomeric cushion members the damping properties of the vibration absorbing device are enhanced by frictional forces generated as the cushions are deflected into the unoccupied volume of the captive volumes and slide along wall portions of such captive volumes.

In a shock-absorbing power transmission sprocket assembly, adapted to be used with a positive drive power transmission belt, the sprocket assembly having a hub with at least one radially protruding lug, the lug including a marginal end thereof, a rim with circumferentially disposed teeth and at least one inwardly extending ear adapted to mate with the lug of the hub, and cushioning means interposed between the lug and ear to transmit torque therebetween, the improvement comprising:

• a pair of outer flange bearings integral with and having a radial dimension at least coextensive with the marginal end of the protruding lug of the hub member, sandwiching the hub on either side thereof;
• a pair of ring surfaces integral with the rim and disposed axially on either side thereof, respectively forming radial bearing surfaces with each of the flange bearings to accommodate limited, smoothed and dampened rotative motion between the hub and rim portions of the assembly;
• said ring surfaces having radial extensions which serve as flanges to retain the power transmission belt in meshing engagement with the teeth of the sprocket;
• and
• said cushioning means comprising elastomeric bodies so configured relative to the adjoining rim, flange bearings and hub to define a void volume of at least about 20 percent of the total captive volume defined between the hub, flange bearings and rim surfaces under no load condition, to accommodate in use a large angular deflection of the hub relative to the rim.

A power transmission drive comprising a driver sprocket, a driven sprocket, and a positive drive synchronous power transmission belt linking the sprockets in driving relationship and having teeth of desired pitch spaced along the inward driving surfaces of the belt meshing with mating teeth of the sprockets, at least one of the sprockets being a shock-absorbing sprocket assembly having a hub with at least one radially protruding lug, the lug including a marginal end thereof;

• a rim with at least one inwardly extending ear adapted to mate with the lug of the hub;
• cushioning means interposed between the lug and ear to transmit torque therebetween;
• a pair of outer flange bearings integral with and having a radial dimension at least coextensive with the marginal end of the protruding lug of the hub member, sandwiching the hub on either side thereof;
• a pair of ring surfaces integral with the rim disposed axially on either side thereof, respectively forming radial bearing surfaces with each of the flange bearings to accommodate limited, smoothed and dampened rotative motion between the hub and rim portions of the assembly, the rim carrying circumferentially disposed teeth positioned between the pair of ring surfaces;
• and said cushioning means comprising elastomeric bodies so configured relative to the adjoining rim, flange bearings and hub to define a void volume of at least about 20 percent of the total captive volume defined between the hub, flange bearings and rim surfaces under no load condition, to accommodate in use a large angular deflection of the hub relative to the rim.

A power transmission drive comprising a driver sprocket, a driven sprocket, a positive drive synchronous power transmission belt linking the sprockets in driving relationship and having teeth of desired pitch spaced along the inward driving surfaces of the belt meshing with mating teeth of the sprockets, at least one of the sprockets being a vibration resistant torsionally elastic sprocket assembly having a hub with at least two lugs protruding radially therefrom;

• a rim with circumferentially disposed teeth and at least two inwardly extending ears adapted to matingly engage the lugs of the hub;
• resilient cushioning means interposed between the lugs and ears to transmit torque therebetween;
• outer flange bearings integral with and sandwiching the hub on either side thereof;
• ring surfaces integral with the rim and disposed axially on either side of the teeth, respectively forming radial bearing surfaces with each of the flange bearings to accommodate limited, smoothed and dampened rotative motion between the hub and rim portions of the sprocket assembly;
• said radial bearing surfaces being positioned symmetrically in the axial direction of either side of the teeth;
• and said cushioning means comprising elastomeric bodies so configured relative to the adjoining rim, flange bearings and hub to define a void volume of at least about 20 percent of the total captive volume defined between the hub, flange bearings and rim surfaces under no load condition, to accommodate in use an angular deflection of at least 9.degree. of the hub relative to the rim.

A power transmission drive comprising a driver sprocket, a driven sprocket, and an endless chain linking the sprockets in driving relationship, at least one of the sprockets being a shock-absorbing sprocket assembly having a hub with at least one radially protruding lug, the lug including a marginal end thereof;

• a rim with at least one inwardly extending ear adapted to mate with the lug of the hub;
• cushioning means interposed between the lug and ear to transmit torque therebetween;
• a pair of outer flange bearings integral with and having a radial dimension at least coextensive with the marginal end of the protruding lug of the hub member, sandwiching the hub on either side thereof;
• a pair of ring surfaces integral with the rim disposed axially on either side thereof, respectively forming radial bearing surfaces with each of the flange bearings to accommodate limited, smoothed and dampened rotative motion between the hub and rim portions of the assembly, the rim carrying circumferentially disposed teeth meshing with the chain and positioned between the pair of ring surfaces;
• and said cushioning means comprising elastomeric bodies so configured relative to the adjoining rim, flange bearings and hub to define a void volume of at least about 20 percent of the total captive volume defined between the hub, flange bearings and rim surfaces under no load condition, to accommodate in use a large angular deflection of the hub relative to the rim.

A power transmission drive comprising a driver sprocket, a driven sprocket, and an endless chain linking the sprockets in driving relationship, at least one of the sprockets being a vibration resistant torsionally elastic sprocket assembly having a hub with at least two lugs protruding radially therefrom;

• a rim with circumferentially disposed teeth meshing with the chain and at least two inwardly extending ears adapted to matingly engage the lugs of the hub;
• resilient cushioning means interposed between the lugs and ears to transmit torque therebetween;
• outer flange bearings integral with and sandwiching the hub on either side thereof;
• ring surfaces integral with the rim and disposed axially on either side of the teeth, respectively forming radial bearing surfaces with each of the flange bearings to accommodate limited, smoothed and dampened rotative motion between the hub and rim portions of the sprocket assembly;
• said radial bearing surfaces being positioned symmetrically in the axial direction of either side of the teeth;
• and said cushioning means comprising elastomeric bodies so configured relative to the adjoining rim, flange bearings and hub to define a void volume of at least about 20 percent of the total captive volume defined between the hub, flange bearings and rim surfaces under no load condition, to accommodate in use an angular deflection of at least 9.degree. of the hub relative to the rim.

A power transmission drive comprising a rotary driver member, a rotary driven member, an endless power transmission member linking the rotary members in driving relationship, at least one of the rotary members being a shock-absorbing power transmission assembly having a hub with at least one radially protruding lug;

• a rim with at least one inwardly extending ear adapted to mate with the lug of the hub;
• cushioning means interposed between the lug and ear to transmit torque therebetween;
• a pair of outer flange bearings integral with and sandwiching the hub on either side thereof;
• a pair of ring surfaces integral with the rim and disposed axially on either side thereof, respectively forming radial bearing surfaces with each of the flange bearings;
• and said cushioning means comprising elastomeric bodies so configured relative to the adjoining rim, flange bearings and hug to define a relatively large void volume under no load condition, to accommodate in use a relatively large angular deflection of the hub relative to the rim.