Engine apparatus with blow-by gas handling device

1. An engine apparatus comprising:

an engine;

a blow-by gas returning device configured to return a leakage of blow-by gas from a combustion chamber to an intake system;

in a head cover disposed in an upper surface of a cylinder head of the engine, an expansion chamber into which the blow-by gas is introduced through a gas pressure regulation valve, in which expansion chamber lubricant contained in the blow-by gas is isolated, and from which expansion chamber the blow-by gas is returned through a blow-by gas exit to an intake side of the engine;

an exit conduit of the gas pressure regulation valve disposed inside the head cover, adjacent to a center of right-left width of a portion of the head cover and connected above the expansion chamber;

a plurality of maze conduits defined by a plurality of partition walls, which are disposed in the expansion chamber; and

wherein the blow-by gas exit is adjacent to the center of the right-left width of the portion of the head cover where the expansion chamber is disposed, so as to return the blow-by gas from the expansion chamber to the intake side of the engine through the blow-by gas exit, the partition walls being sufficiently wide in a front-rear direction of the engine apparatus to partition off the exit conduit of the gas pressure regulation valve and the blow-by gas exit from each other; and further comprising:

a shielding plate closing off a bottom of the expansion chamber;

a lubricant return opening provided in the shield plate to return the lubricant separated in the expansion chamber into the engine;

a plate spring secured to a lower surface of the shield plate and overlying the lubricant return opening and openable and closable to function as a non-return valve; and

wherein the lubricant return opening opens into one of the plurality of maze conduits positioned nearest the blow-by gas exit.