Patent ID: 8695563

Claim:
A lubrication system for a four-stroke engine configured to lubricate components in a crank chamber and in a valve-operating chamber with oil by supplying the oil by utilizing changes in pressure inside the crank chamber caused by reciprocating movement of a piston while circulating the oil, the oil being stored in an oil reservoir provided separately from the crank chamber, the valve-operating chamber accommodating intake and exhaust valve mechanisms therein and configured to discharge blow-by gas in an oil circulation path from the valve-operating chamber to a combustion chamber characterized by: an oil feeding passage for communicating the oil reservoir with the crank chamber to deliver the oil stored in a liquid form in the oil reservoir to the crank chamber when a negative pressure is created in the crank chamber; a communication passage for communicating the crank chamber with the oil reservoir to deliver oil mist generated in the crank chamber to the oil reservoir when a positive pressure is created in the crank chamber; liquefying means provided in the oil reservoir for liquefying the oil mist delivered from the communication passage to the oil reservoir to decrease a concentration of the oil mist, the liquefying means including (i) a tubular punched metal plate disposed around the opening end of the communication passage, and (ii) a collision plate disposed at a bottom portion of the tubular punched metal plate so as to be located on the front side of the opening end in a protruding direction of the communication passage; and a supply passage for supplying the oil mist from the oil reservoir to the valve-operating chamber through the liquefying means, the supply passage being provided separately from the oil feeding passage.