To improve the oil separation performance in an oil separation device for an internal combustion engine. The oil separation device (10) comprises a gas liquid separation passage (56) internally defined by a lower wall, an upper wall and a pair of side walls, and extending in a horizontal direction, a gas inlet (54) and a gas outlet (63) provided on either end of the gas liquid separation passage, a plurality of lower partition walls (56H) projecting upward from the lower wall, and a plurality of upper partition walls (56J) projecting downward from the upper wall. The lower partition walls and the upper partition wall are tilted with respective the length wise direction in plan view so as to define a spiral passage. The lower wall is inclined with respect to a horizontal plane such that an upstream part of the lower wall is lower than a downstream part of the lower wall with respect to a direction of the swirl flow.

The present invention discloses an energy-saving and emission-reducing multistage throttling expansion method for engine. In a crevice passage disposed between the combustion chamber and the crankcase, a multistage throttling is disposed for converting pressure energy of the high-pressure blow-by gas into kinetic energy and momentum, and a multistage expansion is disposed for expanding and dissipating the incoming kinetic energy and momentum of the high-velocity blow-by gas into heat, so that to realize the multistage throttling and expansion method, reduce the leaking of the unburned fuel-air mixture and the burned gas, the hydrocarbon emissions hidden in the intra-cylinder carbon deposition and exhaust gas emissions of the engine, and also improve the engine efficiency and the overall performance of the engine.

The present invention discloses an energy-saving and emission-reducing multistage throttling expansion method for engine. In a crevice passage disposed between the combustion chamber and the crankcase, a multistage throttling is disposed for converting pressure energy of the high-pressure blow-by gas into kinetic energy and momentum, and a multistage expansion is disposed for expanding and dissipating the incoming kinetic energy and momentum of the high-velocity blow-by gas into heat, so that to realize the multistage throttling and expansion method, reduce the leaking of the unburned fuel-air mixture and the burned gas, the hydrocarbon emissions hidden in the intra-cylinder carbon deposition and exhaust gas emissions of the engine, and also improve the engine efficiency and the overall performance of the engine.

A leakage detection device detects leakage in a PCV passage that at least includes a scavenging line that communicates between a crank chamber of an engine and a portion of an intake passage of the engine that is on a downstream side of a throttle valve and a fresh air line that communicates between the crank chamber and a portion of the intake passage that is on an upstream side of the throttle valve. The leakage detection device includes a pressure measurement, a first valve and a leakage determination unit. The pressure measurement unit measures pressure in the PCV passage. The first valve opens/closes the fresh air line. The leakage determination unit determines presence or absence of leakage in the PCV passage on a basis of the pressure in the PCV passage at a time when the first valve is closed.

A leakage detection device detects leakage in a PCV passage that at least includes a scavenging line that communicates between a crank chamber of an engine and a portion of an intake passage of the engine that is on a downstream side of a throttle valve and a fresh air line that communicates between the crank chamber and a portion of the intake passage that is on an upstream side of the throttle valve. The leakage detection device includes a pressure measurement, a first valve and a leakage determination unit. The pressure measurement unit measures pressure in the PCV passage. The first valve opens/closes the fresh air line. The leakage determination unit determines presence or absence of leakage in the PCV passage on a basis of the pressure in the PCV passage at a time when the first valve is closed.

A canister arrangement structure for a saddle-ride type vehicle in which a canister for adsorbing evaporated fuel in a fuel tank is disposed below a step floor on which an occupant's foot is placed, the step floors are configured as a left and right pair and are supported from below by left and right step frames that extend back and forth at a position on the side of the main frame of the vehicle. The canister is supported by the one step frame.

A canister arrangement structure for a saddle-ride type vehicle in which a canister for adsorbing evaporated fuel in a fuel tank is disposed below a step floor on which an occupant's foot is placed, the step floors are configured as a left and right pair and are supported from below by left and right step frames that extend back and forth at a position on the side of the main frame of the vehicle. The canister is supported by the one step frame.

An intake structure of a vehicle is provided to prevent engine oil from flowing back along a nipple. The structure includes an intake hose which is mounted between an air cleaner and a compressor of a turbo charger. A pocket part, in which the oil comprised in a blow-by gas through the nipple is collected, is formed on the inner sidewall surface of the intake hose. The intake structure prevents the oil existing in the recirculated blow-by gas from flowing into a fresh air nipple.

A crankcase ventilation device features a closing valve with a valve body, the valve body executes a positioning movement between a closed and an opened position. A sensor device for detecting the positioning movement of the valve body is disposed in the housing.

A crankcase ventilation device features a closing valve with a valve body, the valve body executes a positioning movement between a closed and an opened position. A sensor device for detecting the positioning movement of the valve body is disposed in the housing.