Engine Crankcase Breathing Passage With Flow Diode
An internal combustion engine is disclosed which includes an improved crankcase drain back system. A set of drain flow diodes are disposed in each of the drain lines to direct fluid flow in a direction from the head portion to the crankcase. Likewise, a set of breather flow diodes are disposed in the breather lines to direct fluid flow in a second direction from the cylinder portion to the head portion. The flow diodes include a series of stacked flow diode elements which allow flow in one direction, while resisting flow in the opposite direction.
1 . An oil drain back system for an internal combustion engine comprising:
a drain line extending between an upper region and a lower region of an engine, the drain line having a preferred direction of drain flow from the upper region to the lower region;
a breather line extending between the lower region and the upper region, the breather line having a preferred direction of breather flow from the lower region to the upper region; and
a preferential flow passageway associated with at least one of the drain line and the breather line, the preferential flow passageway having a flow diode disposed therein and oriented to direct fluid flow in the preferred direction of the at least one of the drain line and the breather line;
wherein a pressure differential across the flow diode for flow in preferred direction is less than the pressure differential across the flow diode for flow in a direction opposite the preferred direction.
2 . The crankcase drain back system of claim 1 wherein the flow diode comprises a plurality of diode elements stacked in the preferential flow passageway such that a Q value for the flow diode is greater than the Q value for any of the plurality of diode elements.
3 . The crankcase drain back system of claim 1 wherein the flow diode has a Q value greater than or equal to 1.1.
4 . The crankcase ventilation system of claim 1 wherein the flow diode comprises an inlet having an inlet cross-sectional area and an outlet having an outlet cross-sectional area which is less than the inlet cross-sectional area.
5 . The crankcase drain back system of claim 4 wherein the flow diode comprises a tapered wall extending from the inlet to the outlet.
6 . The crankcase drain back system of claim 4 wherein the tapered wall comprises a fin extending from a sidewall of the preferential flow passageway toward a centerline thereof.
7 . The crankcase drain back system of claim 4 wherein the tapered wall comprises a frusto-conical surface formed in a sidewall of the preferential flow passageway.
8 . The crankcase ventilation system of claim 1 further comprising:
a first preferential flow passageway associated with the drain line and having a first flow diode disposed therein and oriented to direct fluid flow in the preferred direction of drain flow; and
a second preferential flow passageway associated with the breather line and having a second flow diode disposed therein and oriented to direct fluid flow in the preferred direction of breather flow.
9 . The crankcase drain back system of claim 8 wherein each of the first flow diode and the second flow diode have a Q value greater than or equal to 1.1.
10 . The crankcase drain back system of claim 8 further comprising:
a first plurality of diode elements stacked in the first preferential flow passageway such that a Q value for the first flow diode is greater than the Q value for any of the first plurality of diode elements; and
a second plurality of diode elements stacked in the second preferential flow passageway such that a Q value for the second flow diode is greater than the Q value for any of the second plurality of diode elements.
11 . An internal combustion engine in combination with a crankcase drain back system comprising:
an engine block including a crankcase, a cylinder portion, and a head portion, the engine block having a drain line extending between the head portion and the crankcase and a breather line extending between an upper region of the cylinder portion and the head portion;
first flow directing means for directing fluid flow in a first preferred direction from the head portion to the crankcase, the first flow directing means being formed in a first preferential flow passageway associated with the drain line; and
second flow directing means for directing fluid flow in a second preferred direction from the cylinder portion to the head portion, the second flow directing means being formed in a second preferential flow passageway associated with the breather line.
12 . The combination of claim 11 further comprising:
a plurality of first diode elements stacked in the first preferential flow passageway in the first preferred direction to define the first flow directing means; and
a plurality of second diode elements stacked in the second preferential flow passageway in the second preferred direction to define the second flow directing means.
13 . An internal combustion engine having a crankcase drain back system comprising:
an engine block including a crankcase, a cylinder portion, and a head portion;
a plurality of drain lines, each drain line extending between the head portion and the crankcase and having a preferred direction of drain flow from the head portion to the crankcase;
a plurality of breather lines, each breather line extending between an upper region of the cylinder portion and the head portion and having a preferred direction of breather flow from the head portion to the crankcase; and
a preferential flow passageway associated with at least one drain line and/or breather line, the preferential flow passageway having a flow diode disposed therein and oriented to direct fluid flow in the preferred direction thereof;
wherein a pressure differential across the flow diode for flow in preferred direction is less than the pressure differential across the flow diode for flow in a direction opposite the preferred direction.
14 . The internal combustion engine of claim 13 wherein the flow diode comprises a plurality of diode elements stacked in the drain line in the preferred direction of drain flow and forming a drain flow diode.
15 . The internal combustion engine of claim 13 wherein the flow diodes comprises a plurality of diode elements stacked in the breather line in the preferred direction of breather flow and forming a breather flow diode.
16 . The internal combustion engine of claim 13 wherein the preferential flow passageway comprises:
a first preferential flow passageway associated with the drain line and having a drain flow diode disposed therein and oriented to direct fluid flow in the preferred direction of drain flow; and
a second preferential flow passageway associated with the breather line and having a breather flow diode disposed therein and oriented to direct fluid flow in the preferred direction of breather flow.
17 . The internal combustion engine of claim 16 wherein the drain flow diode has a Q value greater than or equal to 1.1.
18 . The internal combustion engine of claim 17 wherein the breather flow diode has a Q value greater than or equal to 1.1.
19 . The internal combustion engine of claim 16 wherein the breather flow diode has a Q value greater than or equal to 1.1.
20 . The internal combustion engine of claim 17 further comprising:
a plurality of diode elements stacked in the drain line in the preferred direction of drain flow and forming the first flow diode; and
a plurality of diode elements stacked in the breather line in the preferred direction of breather flow and forming the second flow diode.