A structural or support ring for an overmolded pulley, the ring placed between a bearing and outer radial surface of the pulley, providing structural support across a width of the pulley.
1. An overmolded pulley for an accessory drive of an internal combustion engine comprising;
a bearing comprising;
an inner ring having a raceway on a radially outer circumference;
an outer ring having a raceway on a radially inner circumference;
a plurality of rolling elements arranged between the inner and outer ring raceways;
an overmolded portion retained on an outer radial surface of the bearing comprising;
a belt contact interface on a radially outer surface;
a plurality of structural ribs distributed on each axial end face, each rib having a first radial end face, a second opposing radial end face and an axial end face;
a plurality of concavities formed by the first radial end face and second radial end face of adjacent ribs, the concavities having a radially outer wall, radially inner wall, a first wall perpendicular to the radial walls and a second wall perpendicular to the radial walls, opposite the first wall;
the overmolded portion having a material thickness between the belt contact interface and the radially outer wall of the concavities, and a width extending from one axial end of the overmolded portion to the opposite end, greater than the maximum width of the structural ribs;
a ring;
the ring having a hollow cylindrical form extending around an entire circumference of the overmolded portion;
the ring positioned between the radially outer surface of the bearing and the belt contact interface of the overmolded portion, radially outward from the radially outer walls of the plurality of concavities;
there being a minimum material thickness from the radially outer surface of the ring to the belt contact interface of the overmolded portion, the thickness no less than required to support contact stresses.
2. The pulley of claim 1 , wherein, the ring has straight cross section.
3. The pulley of claim 1 , wherein, the ring has an I shaped cross section, comprising a first radially outer axially extending member, a second radially inner axially extending member and a radially extending member connecting the first and the second member.
4. The pulley of claim 1 , wherein, the ring has a U shaped cross section, comprising a first axially extending member and first and second radially extending protrusions at axially opposite ends of the first axially extending member.
5. The pulley of claim 1 , wherein, the ring has a rectangular cross section comprising a first radially outer axially extending member, a second radially inner axially extending member and first and second radially extending axial members at opposite ends of the first and second axially extending members, and connecting the axially extending members, forming a hollow cavity.
6. The pulley of claim 1 , wherein, the ring has surface retention features for overmolding.
7. The pulley of claim 6 , wherein, the features are selected from the group waves, knurls or notches.
8. The pulley of claim 1 , wherein, the ring has at least one perforation extending through a thickness of the ring, for flow of overmolding material into the perforation to provide retention.
9. The pulley of claim 1 , wherein, the overmolded portion is made of a plastic.
10. The pulley of claim 1 , wherein, the ring extends across the entire width of the overmolded portion.
11. The pulley of claim 1 , wherein, the ring extends no more than three quarters of the width of the overmolded portion.
12. An overmolded pulley for an accessory drive of an internal combustion engine comprising;
a bearing comprising;
an inner ring having a raceway on a radially outer circumference;
an outer ring having a raceway on a radially inner circumference;
a plurality of rolling elements arranged between the inner and outer ring raceways;
an overmolded portion retained on an outer radial surface of the bearing comprising;
a belt contact interface on a radially outer surface;
the overmolded portion having a material thickness extending radially inward from the belt contact interface; and,
a ring having;
a hollow cylindrical form extending around an entire circumference of the overmolded portion;
the ring positioned between the radially outer surface of the bearing and the belt contact interface of the overmolded portion, encased within the material thickness;
wherein there is a minimum thickness from the radially outer surface of the ring to the belt contact interface of the overmolded portion, the thickness no less than required to support contact stresses.