TORSIONAL VIBRATION DAMPERS HAVING A HUB WITH SPOKES ACTING AS A SECOND SPRING IN SERIES WITH AN ELASTOMERIC MEMBER
Torsional vibration dampers for rotating shafts are disclosed that have a hub or a hub portion of a pulley-hub monolithic body that has an innermost sleeve defining a bore, an outermost ring concentric with and spaced radially outward from the innermost sleeve, and a plurality of spokes connecting the innermost sleeve to the outermost ring that each have torsional flexibility to act as a first spring to attenuate torsional vibrations. The dampers include an elastomeric member positioned concentrically against the outermost ring or the innermost sleeve of the hub, where the elastomeric member acts as a second spring to attenuate torsional vibrations, and an inertia member positioned concentrically against the elastomeric member, which places the first spring and second spring in series. The dampers may be crankshaft, driveline, or direct drive dampers, and the equivalent spring rate for the first and second springs is governed by the elastomeric member.
1 . A torsional vibration damper for a rotating shaft comprising:
a hub configured for connection to a rotating shaft, the hub having a plurality of spokes that have torsional flexibility to act as a first spring to attenuate torsional vibrations; and
an inertia member operatively coupled to the hub for rotation therewith by an elastomeric member that acts as a second spring to attenuate torsional vibrations;
wherein the first spring and the second spring are in series.
2 . The torsional vibration damper of claim 1 , wherein the elastomeric member is positioned concentrically against a radially outermost surface of the hub with the inertia member radially concentric about the elastomeric member or concentrically against a radially innermost surface of the hub with the inertia member radially concentric inward of the elastomeric member.
3 . The torsional vibration damper of claim 1 , wherein the equivalent spring rate (k eq ) for the first and second springs in series is governed by the elastomeric member.
4 . The torsional vibration damper of claim 3 , wherein the elastomeric member has a thickness of about 2 mm to about 10 mm.
5 . The torsional vibration damper of claim 1 , wherein the plurality of spokes define a plurality of labyrinth windows axially through the hub.
6 . The torsional vibration damper of claim 1 , wherein the plurality of spokes comprise a plurality of first partial spokes extending radially outward from an innermost sleeve of the hub and a plurality of partial spokes extending radially inward from an outermost ring of the hub, and are connected to one another by a continuous serpentine web.
7 . The torsional vibration damper of claim 1 , wherein the inertia member has an outermost belt-engaging surface, and the bore of the hub is configured to receive a crankshaft.
8 . The torsional vibration damper of claim 1 wherein the hub is part of a pulley-hub monolithic body comprising a belt engaging surface on the radially outermost surface of the pulley portion thereof.
9 . The torsional vibration damper of claim 8 , wherein the inertia member is operatively coupled to a back side of the pulley portion opposite the belt engaging surface placing the elastomeric member in compression radially.
10 . The torsional vibration damper of claim 8 , wherein the inertia member is axially positioned to axially compress the elastomeric member against the pulley-hub monolithic body.
11 . The torsional vibration damper of claim 1 , wherein the plurality of spokes comprise a first plurality of partial spokes extending from an innermost sleeve toward an outermost ring of the hub.
12 . The torsional vibration damper of claim 11 , wherein the first plurality of partial spokes each comprise a generally T-shaped member interconnected to one another by a generally annular connecting member.
13 . The torsional vibration damper of claim 12 , wherein the plurality of spokes further comprise a second plurality of partial spokes extending from the outermost ring toward the innermost sleeve.
14 . The torsional vibration damper of claim 13 , wherein the second plurality of partial spokes are each a generally T-shaped member interconnected with the T-shaped members of the first plurality of partial spokes by the generally annular connecting member.
15 . The torsional vibration damper of claim 1 , wherein the hub and the inertia member include opposing annular recesses in which the elastomer is seated.
16 . The torsional vibration damper of claim 15 , wherein one of the annular recesses is deeper than the other.
17 . The torsional vibration damper of claim 1 , wherein the elastomeric member is press-fit between the hub and the inertia member or is mold bonded to one of the hub or inertia member.
18 . The torsional vibration damper of claim 1 , wherein the elastomeric member comprises a plurality of elastomeric members each having a first width that is less and a second width of the radial outermost surface of the hub, concentric about an axis of rotation of the hub and positioned a distance apart in an axial direction from one another or abutting against an adjacent elastomeric member.
19 . The torsional vibration damper of claim 1 , wherein the hub is configured to couple to a driveline shaft.
20 . A front end accessory drive system comprising the torsional vibration damper of claim 1 .