Evaporative emission control system for internal combustion engines

In an evaporative emission control system for an internal combustion engine including a fuel tank having a tank main body, and a filler pipe extending from said tank main body, said filler pipe having an inlet end portion, said evaporative emission control system including a canister for adsorbing evaporative fuel generated in said fuel tank, and an evaporative fuel passage extending between said canister and said fuel tank,

• the improvement comprising:
• a housing;
• a diaphragm partitioning said housing into a first chamber and a second chamber;
• a pressure-detecting port provided in said first chamber and communicated with said inlet end portion of said filler pipe;
• an evaporative fuel inlet port provided in said second chamber and communicated with an interior of said tank main body;
• an evaporative fuel outlet port provided in said second chamber and communicated with an interior of said canister, said evaporative fuel outlet port having an opening;
• a first valve element disposed for displacement together with said diaphragm, for opening and closing said opening of said evaporative fuel outlet port;
• a first spring for biasing said first valve element in a direction of closing said opening of said evaporative fuel outlet port;
• a communication passage extending between said first chamber and said second chamber, said communication passage having an outlet;
• a second valve element arranged at said outlet of said communication passage;
• and
• a second spring for biasing said second valve element in a direction of closing said outlet of said communication passage.

In an evaporative emission control system for an internal combustion engine including a fuel tank having a tank main body, and a filler pipe extending from said tank main body, said filler pipe having an inlet end portion, said evaporative emission control system including a canister for adsorbing evaporative fuel generated in said fuel tank, and an evaporative fuel passage extending between said canister and said fuel tank,

• the improvement comprising:
• a housing;
• a first diaphragm partitioning said housing into a first chamber and a second chamber;
• a second diaphragm partitioning said housing into said second chamber and a third chamber;
• a pressure-detecting port provided in said first chamber and communicated with said inlet end portion of said filler pipe;
• an evaporative fuel inlet port provided in said second chamber and communicated with an interior of said tank main body;
• first and second evaporative fuel outlet ports formed in said second chamber and communicated with an interior of said canister, said first and second evaporative fuel outlet ports having first and second openings, respectively;
• an atmospheric pressure port provided in said third chamber and communicated with atmosphere;
• a first valve element disposed for displacement together with said first diaphragm, for opening and closing said first opening of said first evaporative fuel outlet port;
• a first spring for biasing said first valve element in a direction of closing said first opening of said first valve element;
• a second valve element disposed for displacement together with said second diaphragm, for opening and closing said second opening of said second evaporative fuel outlet port;
• a second spring for biasing said second valve element in a direction of closing said second opening of said second valve element, said second spring having a biasing force stronger than a biasing force of said first spring;
• a communication passage extending between said first chamber and said second chamber, said communication passage having an outlet;
• a third valve element arranged at said outlet of said communication passage;
• and
• a third spring for biasing said third valve element in a direction of closing said outlet of said communication passage.