Engine front cover with rotational support insert

An engine front cover assembly includes a plastic engine cover. A metal insert is secured within the plastic engine cover and defines a bore configured to receive a rotating engine component. A seal is located in a seal seat defined within the bore of the metal insert and configured to sealingly engage the rotating engine component. The metal insert is overmolded within the plastic engine cover and serves as a datum point to properly locate the seal relative to the rotating engine component.

FIELD

The present disclosure relates to an engine assembly, and more particularly, to an engine front or rear cover made from plastic and having a molded-in metal insert defining a bore for receiving a rotating engine component.

BACKGROUND

Currently, engine covers (front or rear) are produced from aluminum castings or steel stampings. The aluminum castings provide a flexibility in design, but the cost and mass of aluminum are significant and it is desirable to use a significantly lower mass component.

SUMMARY

The present disclosure is directed to an engine front cover assembly including a plastic engine cover. A metal insert is secured within the plastic engine cover and defines a bore configured to receive a rotating engine component. A seal is located in a seal seat defined within the bore of the metal insert and configured to sealingly engage the rotating engine component. The metal insert can include a radially extending flange portion defining reinforcing ribs that are overmolded by plastic reinforcing ribs of the plastic engine cover. The flange portion can be a mesh or textured surface to provide enhanced surface area contact between the plastic front cover and the metal insert.

DETAILED DESCRIPTION

Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

With reference toFIGS. 1-5, the plastic engine front cover assembly10according to the principles of the present disclosure will now be described. The engine front cover assembly10includes a plastic engine cover12defining an aperture14configured to receive a rotating engine component16such as a crankshaft, camshaft, or idler shaft, therethrough. A metal insert18is secured within the plastic engine cover and defines a seal bore20configured to receive the rotating engine component16. A seal22is located within a seal seat24defined within the seal bore20of the metal insert18and configured to sealingly engage the rotating engine component16.

Even though the plastic materials have performance characteristics approximately equivalent to aluminum, obtaining tolerances around the crank seal is very difficult. To resolve this, the crankshaft center is set as the datum point and the metal insert18with the shaft seal seat24is overmolded at the centered location creating a final dimensionally correct part that is lighter in weight than conventional steel or aluminum engine covers. Should there be additional adjustments, the metal insert18can be machined to requirements.

The metal insert18can be overmolded within the plastic engine cover12. The plastic engine cover12is configured to fit over an end of an engine block26and can include a plurality of mounting apertures28for mounting the cover12to the engine block26and/or other components of the engine assembly such as the cylinder heads, and intake manifolds and oil pans, if desired. The plastic engine cover12can also include additional apertures30to receive additional pulley hubs/tensions and cam shafts. The plastic engine cover12can also include a plurality of intersecting reinforcing ribs32on at least one face34thereof. The reinforcing ribs32can intersect with annular ribs36that can surround the mounting apertures28as well as the aperture14and additional apertures30, as shown inFIGS. 1 and 2. It is noted that inFIG. 1only a portion of the detail of the reinforcing ribs32and36are shown for simplicity, while it should be understood that the reinforcing ribs32,36are intended to extend along the entire surface of the cover10.

With reference toFIGS. 2-4, the metal insert18can include a generally planar wall portion40defining the circular bore20therein. An annular wall portion42extends axially from the planar wall portion40and is coaxial with the bore20for defining the seal seat24, wherein the seal22seats against the annular wall portion42and the planar wall portion40. A plurality of radially extending reinforcing ribs46can extend radially outward from the annular wall portion42in a spoke-like fashion and terminate at a second annular wall portion48. Additional reinforcing ribs50can extend radially outward from the second annular wall portion48and can be overmolded by the reinforcing ribs32of the plastic engine cover12, as best shown inFIG. 3. A section44of the planar wall portion40can optionally be provided with a mesh-like portion defining holes60(FIG. 5A) or waffle-type recesses62(FIG. 5B) or other surface irregularities64(FIG. 5C) that are overmolded by the plastic engine cover12and therefore provide additional surface area contact between the metal insert18and the plastic engine cover12.

With reference toFIG. 6, the planar wall portion40of the metal insert18can extend laterally or vertically to encompass mounting apertures28on opposites sides of the seal bore20to help to stabilize the position of the seal22in the as-built condition as the plastic expands and contracts with temperature variations. As the cover heats up, the metal insert18holds the seal22in its proper position with the perimeter bolt bosses28. According to one embodiment, the metal insert can extend a sufficient distance to encompass at least a pair of bolt bosses28on opposite sides of the seal bore20.

The additional reinforcing ribs50of the metal insert18can have a height of 30-70% of the final overmolded rib height. The ribs50of the metal insert18can have a thickness of 30-60% of the final overmolded rib thickness, and more preferably 40-50% of the final overmolded rib thickness. The length of the reinforcing ribs can be at least 25 mm and up to approximately 75 mm long. The thickness of the planar section44A of the flange portion44can be between 0.75 and 2 mm. The size of the holes in the mesh or the recesses in the waffle-like pattern can be from 0.5 to 3.2 mm, and more preferably, 1-2 mm in diameter. The insert18can be made from brass, aluminum, steel, magnesium, pressed metal, or other materials. The plastic front engine cover12can be made from high performance thermoplastic or thermoset resins enhanced with fiberglass or other filler types at levels of from 30-60%. Also, the material should be able to withstand continuous temperatures of 130° C.