Low frequency torsional vibration damper having a formed hub
A low frequency torsional vibration damper has an annular inertia member defining an annular recess for receiving an elastomeric O-ring in a radial outer surface or a radial inner surface thereof and defining opposing annular recesses for receiving elastomeric O-rings, one each, in the top and bottom surfaces thereof, an elastomeric O-ring seated in each annular recess, and a hub defining an annular receptacle with opposing sidewalls that each comprise a plurality of spaced apart tabs permanently deformed against the plurality of elastomeric O-rings, thereby operatively coupling the hub to the inertia member for rotation together. When the inertia member defines the outer diameter of the torsional vibration damper, the hub is mountable on a shaft, and when the inertia member defines the inner diameter of the torsional vibration damper, the hub is mountable inside a shaft.
1. A frequency torsional vibration damper comprising:
an annular inertia member defining a first annular recess for receiving an elastomeric O-ring in a radial outer surface or a radial inner surface thereof and defining generally opposing secondary annular recesses for receiving elastomeric O-rings in opposing top and bottom surfaces thereof, the opposing secondary annular recesses being positioned proximate whichever of the radial outer surface or the radial inner surface has the first annular recess;
a plurality of elastomeric O-rings, one each seated in the first annular recess and the opposing secondary annular recesses; and
a hub defining an annular receptacle with opposing sidewalls that each comprise a plurality of spaced apart tabs;
wherein the annular inertia member is seated in the annular receptacle with the plurality of spaced apart tabs permanently deformed against the plurality of elastomeric O-rings, thereby operatively coupling the hub to the inertia member for rotation together;
wherein when the inertia member defines the outer diameter of the torsional vibration damper, the hub is mountable on a shaft, and when the inertia member defines the inner diameter of the torsional vibration damper, the hub is mountable inside a shaft.
2. The torsional vibration damper of claim 1 , wherein the inertia member has a first portion with a primary axial width and a second portion with a secondary axial width, wherein the second portion is seated in the annular receptacle defined by the hub and the secondary axial width is smaller than the primary axial width.
3. The torsional vibration damper of claim 1 , wherein the plurality of elastomeric O-rings are seated in the first annular recess and the opposing secondary annular recesses without an adhesive.
4. The torsional vibration damper of claim 1 , wherein there is no adhesive or fastener attaching the hub to the inertia member.
5. The torsional vibration damper of claim 1 , wherein finite element modeling demonstrates that the torsional vibration damper has a first mode of vibration that is torsional and a second mode of vibration that is radial.
6. The torsional vibration damper of claim 5 , wherein finite element modeling demonstrates that the second mode of vibration is decoupled from the first mode of vibration by at least 20 Hz.
7. The torsional vibration damper of claim 1 , wherein the annular receptacle of the hub defines annular recesses that align one each with the first annular recess and the opposing secondary annular recesses of the inertia member.
8. A method of making the torsional vibration damper of claim 1 , the method comprising:
providing an inertia member defining a first annular recess for receiving an elastomeric O-ring in a radial outer surface or a radial inner surface thereof and defining generally opposing secondary annular recesses for receiving elastomeric O-rings in opposing top and bottom surfaces thereof, the opposing secondary annular recesses being positioned proximate whichever of the radial outer surface or the radial inner surface has the annular recess, and having an elastomeric O-ring, one each, in the first annular recess and the opposing secondary annular recesses;
providing an annular hub precursor comprising an annular band having a first plurality of spaced apart tabs and a second plurality of spaced apart tabs both extending outward therefrom in opposing directions from two parallel circular bases of the annular band or from two parallel cylindrical surfaces of the annular band, wherein each tab of the first and second plurality of spaced apart tabs has a first thickness substantially the same as a second thickness of the annular band as measured from a longitudinal cross-section of the hub precursor;
permanently bending the first plurality of spaced apart tabs and the second plurality of spaced apart tabs around the inertia member in contact with each of the elastomeric O-rings;
wherein the elastomeric O-rings operatively couple the hub to the inertia member for rotation therewith.
9. The method of claim 8 , further comprising providing the inertia member and the elastomeric O-rings in an unassembled state and placing one each of an elastomeric O-ring in the first annular recess and the opposing secondary annular recesses of the annular inertia member, thereby forming an inertia member intermediate.
10. The method of claim 8 , wherein permanently bending the first plurality of spaced apart tabs and the second plurality of spaced apart tabs around the inertia member comprises:
first, permanently bending the first plurality of spaced apart tabs to define a first flange and form a hub precursor intermediate having a first angle matable to a bottom surface of the inertia member;
seating the inertia member intermediate against the hub precursor intermediate with the first angle of the first flange mated against the bottom surface of the inertia member with at least a first and a second O-ring positioned between the hub precursor intermediate and the inertia member intermediate;
permanently bending the second plurality of spaced apart tabs against the inertia member intermediate with a third O-ring therebetween to operatively couple the hub to the inertia member for rotation therewith.
11. The method of claim 8 , wherein the hub precursor is a generally flat annular disc.
12. The method of claim 11 , wherein the second plurality of spaced apart tabs define the inner diameter of the disc and are each generally wedge-shaped.
13. The method of claim 12 , wherein the first plurality of spaced apart tabs define the outer diameter of the disc and are each generally wedge-shaped.
14. The method of claim 13 , wherein each generally wedge-shaped tab of the first plurality of spaced apart tabs is narrowest at its junction to the annular band portion of the hub precursor, and each generally wedge-shaped tab of the second plurality of spaced apart tabs is widest at its junction to the annular band portion of the hub precursor.
15. The method of claim 11 , further comprising hydroforming the hub precursor.
16. The method of claim 8 , wherein the first plurality of spaced apart tabs and the second plurality of spaced apart tabs are mirror images of one another.
17. The method of claim 8 , wherein the first plurality of spaced apart tabs are staggered offset from the second plurality of spaced apart tabs.
18. The method of claim 8 , wherein the hub precursor is a cylindrical tube having a height greater than the second thickness, and the method further comprises forming the hub precursor by cutting slits into two parallel circular bases of a metal cylindrical tube.
19. The method of claim 18 , wherein the first plurality of spaced apart tabs and the second plurality of spaced apart tabs are mirror images of one another.