Positive crankcase ventilation in an engine having a cyclically varying crankcase volume

An apparatus further for providing positive crankcase ventilation for the crankcase of a four-stroke engine having one or more reciprocating pistons exposed on a bottom side thereof to the crankcase, whereby the crankcase and bottom side of the one or more reciprocating pistons define a crankcase volume that varies cyclically with reciprocation of the one or more pistons, the apparatus comprising:

• a crankcase air inlet, a crankcase air outlet, and a control element utilizing the cyclically varying crankcase volume resulting from reciprocation of the one or more pistons for generating a unidirectional flow of air through the crankcase from the crankcase air inlet to the crankcase air outlet, wherein the apparatus varies the flow of air through the crankcase substantially in direct proportion to engine speed;
• an inlet control device attached to the crankcase air inlet for allowing a flow of air into the crankcase through the when the crankcase volume is increasing, and restricting flow out of the crankcase when the crankcase volume is decreasing;
• and
• an outlet control device to the crankcase air outlet for allowing a flow of air to escape from the crankcase when the crankcase volume is decreasing, and restricting flow in to the crankcase through the outlet control device when the crankcase volume is increasing.

A four-stroke engine comprising:

• a crankcase and one or more reciprocating pistons exposed on a bottom side thereof to the crankcase, whereby the crankcase and bottom side of the one or more reciprocating pistons define a crankcase volume that varies cyclically with reciprocation of the one or more pistons;
• and
• a positive crankcase ventilation (PCV) apparatus including:
• a crankcase air inlet;
• a crankcase air outlet;
• and
• a control element having an inlet control device attached to the crankcase air inlet for allowing a flow of air into the crankcase through the when the crankcase volume is increasing, and restricting flow out of the crankcase when the crankcase volume is decreasing, and an outlet control device attached to the crankcase air outlet for allowing a flow of air to escape from the crankcase when the crankcase volume is decreasing, and restricting flow in to the crankcase through the outlet control device when the crankcase volume is increasing, wherein the control element utilizes the cyclically varying crankcase volume resulting from reciprocation of the one or more pistons for generating a unidirectional flow of air through the crankcase from the crankcase air inlet to the crankcase air outlet, and wherein the PCV apparatus varies the flow of air through the crankcase substantially in direct proportion to engine speed.