Resonance tension reducing sprocket with combined radial variation and sprocket wrap

A chain and sprocket drive system comprising:

• a chain having a plurality of links interconnected by joints including a link pin so that the links are pivotable around a link pin axis relative to each other, the chain having teeth;
• and
• at least one sprocket having a central axis of rotation and a plurality of sprocket teeth, the sprocket teeth having engagement surfaces disposed to engage the chain teeth, the sprocket teeth and sprocket engagement surfaces spaced about the periphery of the sprocket,
• the sprocket engagement surfaces spaced a distance from the sprocket central axis effective to dispose the chain at a pitch radius defined by the distance between the sprocket central axis and the link pin axis of a chain link which has teeth engaged by the sprocket engagement surfaces,
• the sprocket engagement surfaces of the at least one of the sprockets disposed to engage the chain teeth to provide a sequence of at least a minimum pitch radius, at least a maximum pitch radius, and at least one intermediate pitch radii therebetween, the distance between adjacent link pin axes of links having teeth engaged with the sprocket substantially constant, and
• a pitch radii sequence including the minimum and the maximum pitch radii and an intermediate pitch radii continually repeating itself at least twice with each rotation of the sprocket,
• the chain not wrapped around the sprocket at an average wrap angle outside the average wrap angle defined by the equation
• average wrap angle=360N/Order±120/Order,
• where N=1, 2, . . . Order −1, and Order means sprocket order as a result of tensioning events which originate outside the chain and/or sprocket,
• the wrap angle, the sequence of pitch radii and order of the sprocket being coordinated to be effective to reduce maximum chain tensions during operation of the sprocket when operated with a chain at resonance conditions relative to where the sprocket is a straight sprocket operated with a chain operating at resonance conditions.

A method of distributing tensions imparted to a chain having links looped around a sprocket, the chain and sprocket operating at variable speeds, the method comprising:

• providing a sprocket having a central axis, a plurality of sprocket teeth and a plurality of sprocket engagement surfaces, the sprocket engagement surfaces spaced at a distance from the central axis to dispose the chain at a pitch radius defined by the distance between the sprocket central axis and a pin axis of a chain link engaged by the sprocket engagement surfaces;
• providing the sprocket engagement surfaces so that they engage the chain to provide a sequence of at least a minimum pitch radius, at least a maximum pitch radius and at least an intermediate pitch radius therebetween, the sprocket engagement surfaces maintaining distances between adjacent pin axes of links engaged with the sprocket engagement surfaces constant;
• arranging the sprocket engagement surfaces to provide a sequence in the different pitch radii so that the sequence continually repeats itself at least two times,
• the wrap angle, the sequence of pitch radii and order of the sprocket being coordinated to be effective to reduce maximum chain tensions during operation of the sprocket when operated with a chain at resonance conditions relative to where the sprocket is a straight sprocket operated with a chain operating at resonance conditions.

A chain and sprocket drive system comprising:

• a chain having a plurality of links interconnected by joints so that the links are pivotable around a link pin axis relative to each other;
• and
• at least one sprocket having a central axis of rotation and a plurality of sprocket teeth and sprocket engagement surfaces between the teeth,
• the sprocket teeth and the sprocket engagement surfaces spaced about the sprocket, the sprocket engagement surfaces disposed to engage the chain,
• the sprocket engagement surfaces spaced a distance from the sprocket central axis and are effective to dispose the chain at a pitch radius defined by the distance between the sprocket central axis and the link pin axes of the chain links,
• the sprocket engagement surfaces of the at least one of the sprockets disposed to engage the chain to provide a sequence of at least a minimum pitch radius, at least a maximum pitch radius, and at least a intermediate pitch radii therebetween,
• the sprocket engagement surfaces maintaining constant the distance between adjacent link pin axes of links, and
• the pitch radii sequence uninterruptedly and continually repeating itself at least twice with each rotation of the sprocket for imparting tensions to the chain timed with respect to tension loads imparted to the system from other sources,
• the chain wrapped around the sprocket at an average wrap angle defined by the equation
• wrap angle=360N/Order±120/Order,
• where N=1, 2, . . . Order−1, and Order means sprocket order as a result of tensioning events which originate outside the chain and/or sprocket,
• the wrap angle, the sequence of pitch radii and order of the sprocket being coordinated to be effective to reduce maximum chain tensions during operation of the sprocket when operated with a chain at resonance conditions relative to where the sprocket is a straight sprocket operated with a chain operating at resonance conditions.

A chain and sprocket drive system comprising:

• a chain having a plurality of links interconnected by joints so that the links are pivotable around a link pin axis relative to each other;
• and
• at least one sprocket having a central axis of rotation and a plurality of sprocket teeth and sprocket engagement surfaces between the teeth, the sprocket teeth and the sprocket engagement surfaces spaced about the sprocket,
• the sprocket engagement surfaces disposed to engage the chain at the link pin axes of the chain,
• the sprocket engagement surfaces spaced a distance from the sprocket central axis and are effective to dispose the chain at a pitch radius defined by the distance between the sprocket central axis and the link pin axes of the chain links,
• the sprocket engagement surfaces of the at least one of the sprockets disposed to engage the chain to provide a sequence of at least a minimum pitch radius, at least a maximum pitch radius, and at least a intermediate pitch radii therebetween,
• the sprocket engagement surfaces maintaining constant the distance between adjacent link pin axes of links, and
• the pitch radii sequence repeating with each rotation of the sprocket in a way that the sequence is effective for imparting tensions to the chain timed with respect to tension loads imparted to the system from other sources,
• the chain not wrapped around the sprocket at an average wrap angle outside the average wrap angle defined by the equation
• wrap angle=360N/Order±120/Order,
• where N=1, 2, . . . Order−1, and Order means sprocket order as a result of tensioning events which originate outside the chain and/or sprocket,
• the wrap angle, the sequence of pitch radii, sprocket order and timing of the tensions provided by the pitch radii effective to reduce maximum chain tensions during operation of the sprocket when operated with a chain at resonance conditions relative to where the sprocket is a straight sprocket operated with a chain operating at resonance conditions.