Crankshaft gear torsional vibration isolator assembly for an engine

An engine drive train including a crankshaft gear torsional vibration isolator assembly for damping torsional vibrations in an internal combustion engine, comprising:

• a crankshaft mounted for rotation and having a natural resonant frequency;
• a crank gear connected to the crankshaft for transmitting a drive force to an associated engine gear train, said engine gear train including a camshaft for operating engine components in timed relationship to the rotation of said crankshaft, a cam gear mounted on said camshaft and an intermediary gear for transferring the drive force from said crank gear to said cam gear, further including a lash controller positioned along the engine gear train for minimizing the lash between said intermediary gear and said crank and cam gears, said lash controller including a first set of scissors gears positioned in meshing relationship between said crank gear and said intermediary gear and a second set of scissors gears positioned in meshing relationship between said intermediary gear and said cam gear;
• a damper connected to a first end of said crankshaft for damping torsional vibrations transmitted by said crankshaft, said damper capable of damping torsional vibrations occurring at said natural resonant frequency of said crankshaft;
• and
• an isolator for resiliently connecting said crank gear to said crankshaft, said isolator capable of absorbing torsional vibrations transmitted from said crankshaft when the engine operates at approximately said natural resonant frequency of said crankshaft so as to minimize the torsional vibrations transmitted from said crankshaft to said crank gear.

An engine drive train including a crankshaft gear torsional vibration isolator assembly for damping torsional vibrations in an internal combustion engine, comprising:

• a crankshaft mounted for rotation and having a natural resonant frequency;
• a crank gear connected to the crankshaft for transmitting a drive force to an associated engine gear train,
• a damper connected to a first end of the crankshaft for damping torsional vibrations transmitted by said crankshaft, the damper capable of damping torsional vibrations occurring at the natural resonant frequency of the crankshaft;
• and
• an isolator for resiliently connecting the crank gear to the crankshaft, the isolator capable of absorbing torsional vibrations transmitted from the crankshaft when the engine operates at approximately the natural resonant frequency of the crankshaft so as to minimize the torsional vibrations transmitted from the crankshaft to the crank gear;
• a driving ring for connection to the crankshaft, the driving ring including a plurality of radial recesses and projections;
• a driven ring for connection with the crank gear, the driven ring being positioned annularly within the driving ring, the driven ring including a plurality of radial recesses and projections, each recess of the driven ring being positioned for accepting a radial projection of the driving ring and forming a plurality of cavities, each radial projection of the driven ring being positioned for acceptance by a recess of the driving ring forming a plurality of cavities;
• spring means in the form of resilient elements torsionally connecting the driving and driven rings, one of the resilient elements being positioned in each cavity, each resilient element having two radial side surfaces positioned in continuous abutting contact against a radial side surface of one of the radial projections of the driven or driving ring and against a radial side surface of the other driven or driving ring recesses, each resilient member having circumferential thickness less than one-half of the circumferential thickness of the driving ring radial projections or the driven ring radial projections, each of the resilient elements being prestressed circumferentially at least ten percent, each resilient member being positioned within the cavity such that there is a radially inward and radially outward expansion volume portions of the cavity, the volume portions circumferentially traversing the cavity and wherein the resilient rotational movement between the crankshaft and the crank gear while substantially preventing further relative rotational movement greater than the limited predetermined amount of relative rotational movement to ensure accurate control of an engine operation by the associated engine gear train, and wherein relative rotational movement of the driving ring and the driven ring causes compression of at least one of the plurality of the resilient elements to form expanded portions of the resilient element whereby the radially inward and radially outward expansion volumes have a predetermined volume capable of being fully occupied by the expanded portions of the resilient element upon the predetermined limited amount of relative rotational movement between the driving and driven rings during operation of the engine thereby substantially preventing further relative rotational movement.