Air-pollution preventing system

Claim 2

An air-pollution preventive system for an internal combustion engine having a crankcase, a carburetor, and a fuel tank for storing a liquid fuel to be supplied to said engine, which system comprises, in combination, first means to recirculate the blow-by gases in said crankcase to said engine when pressures prevail in said crankcase, second means to suck in atmospheric air into said crankcase when substmospheric pressures prevail in said crankcase thereby to scavange said blow-by gases in said crankcase, said second means including a first passage vented from the atmosphere and a first check valve mounted in said first passage, and third means to introduce evaporative gases emitted from said fuel tank into said carburetor through said crankcase, said third means including a second check valve mounted in said first passage for controlling the flow of said evaporative gases, and a second passage for delivering the evaporative gases, said second passage communicating with said first passage at a position intermediate said first and second check valves and with said fuel tank, said check valves being responsive to pressure differences between pressures in said fuel tank and in said crAnkcase, so that when the pressure in said fuel tank exceeds the pressure in said crankcase, said first check valve opens to admit the evaporative gases to said crankcase and concurrently said second check valve closes to prevent the evaporative gases from escaping to the atmosphere and when the pressure in said fuel tank is lower than in said crankcase, said second check valve opens to admit atmospheric pressure into the fuel tank and concurrently said first check valve closes to prevent contamination.

Claim 3

In combination with an internal combustion engine having a crankcase, a carburetor, and a fuel tank for storing a liquid fuel to be supplied to said engine, said air-pollution preventive system comprising a ventilation air inlet provided in said crankcase and opened to the atmosphere, a ventilation air check valve mounted in said ventilation air inlet, a blow-by gas mixture outlet provided in said crankcase, a blow-by gas mixture passage connecting said outlet to the carburetor, a blow-by gas mixture check valve mounted in said blow-by mixture passage, an evaporative gas passage communicating with said fuel tank and with said ventilation air inlet for discharging evaporative gas from said fuel tank into said crankcase, and an evaporative gas check valve mounted in said ventilation air inlet and associated with said ventilation air check valve, said evaporative gas passage intersecting said ventilation air inlet at a point intermediate said ventilation air check valve and said evaporative gas check valve, said ventilation air check valve and said evaporative gas check valve being responsive to differences between pressures in said fuel tank and in said crankcase, so that when the pressure in said fuel tank exceeds the pressure in said crankcase, said ventilation air check valve opens to admit evaporative gases to said crankcase and concurrently said evaporative gas check valve closes to prevent the evaporative gases from escaping to the atmosphere and when the pressure in said fuel tank is lower than in said crankcase, said evaporative gas check valve opens to admit atmospheric pressure into the fuel tank and concurrently said ventilation air check valve closes to prevent contamination.

Claim 4

In combination with an internal combustion engine having a crankcase, a carburetor, and a fuel tank for storing a liquid fuel to be supplied to said engine, said air-pollution preventive system comprising a ventilation air inlet provided in said crankcase and opened to the atmosphere, a ventilation air check valve mounted in said ventilation air inlet, a blow-by gas mixture outlet provided in said crankcase, a blow-by gas mixture passage connecting said outlet to the carburetor, a blow-by gas mixture check valve mounted in said blow-by mixture passage, an evaporative gas passage communicating with said fuel tank and with said ventilation air inlet for discharging evaporative gas from said fuel tank into said crankcase, and an evaporative gas check valve mounted in said ventilation air inlet and associated with said ventilation air check valve, said evaporative gas passage intersecting said ventilation air inlet at a point intermediate said ventilation air check valve and said evaporative gas check valve, said ventilation air check valve and said evaporative gas check valve being responsive to differences between pressures in said fuel tank and in said crankcase, so that when the pressure in said fuel tank exceeds the pressure in said crankcase, said ventilation air check valve opens to admit evaporative gases to said crankcase and concurrently said evaporative gas check valve closes to prevent the evaporative gases from escaping to the atmosphere and when the pressure in said fuel tank is lower than in said crankcase, said evaporative gas check valve opens to admit atmospheric pressure into the fuel tank and concurrently said ventilation air check valve closes to prevent contamination.

Claim 5

An air-pollution preventing system according to claim 2, further comprising a branch passage branched from said blow-by gas mixture passage before said blow-by gas mixture check valve and communicating with said carburetor downstream of the throttle valve of the carburetor, said branch passage having a restricting means mounted therein for restricting the flow of blow-by gases passing therethrough.

Claim 6

An air-pollution preventing system according to claim 2, further comprising a vapor adsorption means provided in said evaporative gas passage for adsorbing evaporative gases passing therethrough.