Patent ID: 6401701
Filing Date: 2002-06-11
Classification: F01M,F02B

Abstract:
A four-stroke cycle internal combustion engine whose inside is lubricated using a mixed fuel composed of fuel and lubricant added thereto, said engine comprising:a combustion chamber; an intake port which opens toward said combustion chamber; an air intake passage in communication with said intake port, a fuel supply device for supplying said mixed fuel to said air intake passage; a downstream side air intake passage which bifurcates from said air intake passage and is located on a downstream side of said fuel supply device; a crank chamber; a crank shaft disposed within said crank chamber; a branch passage for placing said downstream side air intake passage in communication with said crank chamber; a valve chamber; a valve system disposed within said valve chamber, said valve system including an intake valve and an exhaust valve; a communication passage for placing said crank chamber in communication with said valve chamber; a circulation passage for providing communication between said valve chamber and said air intake passage; a first valve disposed within said branch passage for opening and closing said branch passage and an upstream side air intake passage located on an upstream side of said fuel supply device of said air intake passage; and wherein said circulation passage places said valve chamber in communication with said upstream side air intake passage.