Evaporative fuel-processing system for internal combustion engines

An evaporative fuel-processing system for an internal combustion engine including a fuel tank having a main body, and a fuel supply pipe extending from an interior of said main body and having an inlet end, comprising:

• a canister accommodating an adsorbent therein, for adsorbing evaporative fuel generated in said fuel tank;
• a charging passage connecting between said canister and said fuel tank;
• shutter valve means arranged in said fuel supply pipe in the vicinity of said inlet end thereof, for isolating an interior of said fuel supply pipe from the atmosphere, said shutter valve means being disposed to be opened by a tip of a refueling gun when said refueling gun is inserted into said fuel supply pipe;
• pressure-intake port means arranged in said fuel supply pipe at a side of said shutter valve means closer to said main body of said fuel tank, for taking in pressure within said fuel supply pipe;
• and
• diaphragm valve means arranged in said charging passage, said diaphragm valve means having a casing, a diaphragm defining an interior of said casing into a first chamber and a second chamber, a valve element displaceable together with said diaphragm, an evaporative fuel outlet disposed to be opened and closed by said valve element for communication with and disconnection from an interior of said canister, and means urging said valve element in a direction of closing said evaporative fuel outlet, said first chamber communicating with said pressure-intake port means, said second chamber communicating with an interior of said fuel tank.