Patent ID: 8978631
Filing Date: 2015-03-17
Classification: F01M

Abstract:
1. An engine in which lubricating oil is stored in a crankcase and which is equipped with a breather mechanism for causing blow-by gas of the crankcase to flow out of the crankcase, the breather mechanism comprising: a single breather passage opening into the crankcase; a single breather chamber communicating with the crankcase via the single breather passage; the breather passage having an outlet end portion, the breather chamber having an inlet end portion to which the outlet end portion of the breather passage is connected; a breather valve provided at the inlet end portion of the breather chamber and configured to open to allow the blow-by gas to flow out of the crankcase into the breather chamber via the breather passage when an inner pressure of the crankcase exceeds a predetermined value; the breather passage being directly connected to the breather chamber and the crankcase; the breather passage being configured to prevent the lubricating oil from entering the breather chamber when the engine is placed in a laterally laid-down position; the outlet end portion of the breather passage, opening into the breather chamber, being located above an inlet end portion of the breather passage, opening into the crankcase, when the engine is in a vertical upright position; and a return passage provided separately from the breather passage for returning the lubricating oil, having flown into the breather chamber through the breather passage, back to the crankcase, the return passage having one end portion connected to the breather chamber and an opposite end portion disposed within the crankcase, the opposite end portion of the return passage being always disposed above a level of the lubricating oil stored in the crankcase regardless of whether the engine is in the vertical upright position or in the laterally laid-down position.