Water Cooled Plastic Oil Pan

The invention relates to oil pans for internal combustion engines.

The invention provides improvements in oil pan construction, including a plastic oil pan with reinforcing structure increasing the mechanical strength of same to enable a plastic oil pan to support the engine when the latter rests on the oil pan during installation or repair procedures.

The invention also provides improvements in engine cooling. A conduit extends through the oil pan and passes engine coolant therethrough to cool engine oil.

FIG. 1 shows a marine drive having an internal combustion engine with an oil pan in accordance with the invention.

FIG. 2 is a top elevation view of the oil pan of FIG. 1 removed from the engine.

FIG. 3 is a side sectional view of the oil pan of FIG. 1.

FIG. 4 is a sectional view taken along line 4--4 of FIG. 3.

FIG. 5 is a bottom elevation view of the oil pan of FIG. 1.

FIG. 6 is a side elevation view of the oil pan of FIG. 1.

FIG. 7 is a left end elevation view of the oil pan of FIG. 6.

FIG. 8 is a right end elevation view of the oil pan of FIG. 6.

FIG. 9 schematically shows a further embodiment of the invention.

FIG. 10 is an enlarged view of a portion of FIG. 4.

FIG. 1 shows a marine drive 12 having an internal combustion engine 14 with a lower oil pan 16. Oil pan 16 is a plastic member having an upper lip 18, FIGS. 2-6, for mating with the engine in sealing relation, sidewalls 21, 22, 23, 24 extending downwardly below lip 18, and a bottom 26 extending between the sidewalls below the lip to provide a closed-bottom receptacle for holding engine oil. A plurality of internal reinforcing walls are integrally formed along the internal surface of respective longitudinal sidewalls 21 and 23 and increase the mechanical strength of the sidewalls to enable the plastic oil pan to support the engine when the latter rests on the oil pan during installation or repair procedures. Reinforcing walls 28 and 30 extend laterally inwardly from respective sidewalls 21 and 23 and substantially protrude into the interior of oil pan 16. Reinforcing walls 28 and 30 extend integrally upwardly from bottom 26, such that each reinforcing wall has a given width and height extending in a plane transverse to its respective sidewall. Reinforcing walls 28 and 30 are coplanar and extend toward eachother and have a gap 32 therebetween permitting oil flow therethrough. The reinforcing walls also provide baffle walls preventing rapid flow of oil therepast, which is desirable in marine applications to prevent sloshing of oil back and forth during turbulent operating conditions. The height of reinforcing walls 28 and 30 is less than the height of sidewalls 21 and 23.

Sidewalls 21-24, including opposed longitudinal sidewalls 21 and 23, and opposed lateral sidewalls 22 and 24, extend downwardly below bottom 26 such that when the oil pan and engine rest on a horizontal surface, the sidewalls support and space the bottom 26 of the oil pan above the surface, such that the weight of the engine is supported by the sidewalls of the oil pan. A plurality of legs 34 extend integrally downwardly from bottom 26 in a gridwork or waffle pattern for engaging the horizontal support surface and spacing the bottom 26 of the oil pan above such surface and helping to support the weight of the engine.

Reinforcing walls are also provided by a plurality of external struts such as 36, 38, 40 integrally formed along the exterior surface of respective sidewalls and extending laterally outwardly therefrom and extending from upper lip 18 downwardly along the sidewalls. The external integral struts are tapered along their length to have their narrowest width at the bottom of the sidewalls and their widest width at the top of the sidewalls. The struts further increase the mechanical strength of the sidewalls to enable the plastic oil pan to support the engine when the latter rests on the oil pan during installation or repair procedures.

Upper lip 18 of the oil pan includes a horizontal flange having an upper surface 42 with a raised rib 44, FIG. 10, formed thereon for mating with the engine in sealing relation to form a gasket, without the need for a separate gasket. Oil pan 16 is formed in a first molding operation. In a second molding operation, rib 44 is molded in situ in groove 46 in flange 18 of the oil pan. Flange 18 has a plurality of bolt holes therethrough, such as 48, FIG. 2. Rib 44 comprises a plurality of annuli such as 50, each circumscribing a respective bolt hole, and a plurality of connecting sections such as 52, each between respective adjacent annuli.

A conduit 54, FIGS. 2 and 3, extends through oil pan 16 and passes engine coolant therethrough to cool engine oil. Conduit 54 extends in a serpentine pattern as shown at 56 along a generally horizontal plane substantially conforming to the bottom 26 of the oil pan. Reinforcing walls 28 and 30 have the above noted gap 32 therebetween, through which conduit 54 extends. Conduit 54 has an inlet portion 58 extending through gap 32 and engaging reinforcing wall 28, and an outlet portion 60 extending through gap 32 and engaging reinforcing wall 30. The central portion of the conduit is provided by serpentine portion 56 on the right side of walls 28 and 30. Inlet and outlet conduit portions 58 and 60 extend through oil pan sidewall 24 and are on the left side of reinforcing walls 28 and 30. Inlet and outlet conduit portions 58 and 60 extend through respective apertures 62 and 64 in the oil pan sidewall, and the sidewall is formed and molded with increased stock thickness 66 and 68 around apertures 62 and 64 to enhance support of inlet and outlet conduit portions 58 and 60. Oil pan 16 has a shallow portion 70 and a deep portion 72. Lateral sidewall 24 provides the bottom of shallow portion 70, and sidewall portion 24a provides the transition between shallow portion 70 and deep portion 72. Inlet and outlet conduit portions 58 and 60 extend through sidewall portion 24a, such that conduit 54 is in deep portion 72. Drain plugs 74 and 76 are provided in deep portion 72 for draining engine oil. In one possible alternate embodiment, conduit 54 has fins extending from or along one or more sections thereof.

Serpentine portion 56 of conduit 54 provides the central portion of the conduit and does the bulk of the cooling. One or more thermostats 78 and 80, FIG. 9, are provided in conduit 54, and have a first condition passing coolant from inlet portion 58 directly to outlet portion 60, and have a second condition passing coolant from inlet portion 58 to central portion 56. Thermostats 78 and 80 are in the oil pan 16 and respond to the temperature of the engine oil therein, such that at low oil temperature during cold engine operation, engine coolant flows from inlet portion 58 to outlet portion 60 and bypasses central portion 56 such that the latter does not cool the engine oil and hence allows the temperature of the engine oil to rise. At higher engine oil temperature after the engine is warmed up, coolant flows from inlet portion 58 through central portion 56 to outlet portion 60, such that central portion 56 cools the engine oil in oil pan 16. Thermostat 78 is connected between inlet portion 58 and outlet portion 60 in parallel with central portion 56. Thermostat 80 is connected in series with central portion 56 between central portion 56 and the junction 82 of thermostat 78 with inlet portion 58, or between central portion 56 and the junction 84 of thermostat 78 with outlet portion 60. Thermostat 78 is open at low oil temperature, and closed at high oil temperature. Thermostat 80 is closed at low oil temperature and open at high oil temperature. It is preferred that the engine coolant be obtained from the output of the sea water pick-up pump, for example at output line 12 of pump 14 in Widmer et al U.S. Pat. No. 4,768,492, incorporated herein by reference, or from thermostat 16 in said Widmer patent, though other sections of the engine cooling system may be tapped into as convenient, for example Mercury Marine Service Training Notebook 90-90593 5-1286, Brunswick Corp., pp. 127-132, 1986.

It is recognized that various equivalents, alternatives and modifications are possible within the scope of the appended claims.