Engine Crankcase Breathing Passage With Flow Diode

Abstract

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.

What is claimed is: 
     
         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.