Fuel evaporative emission treatment system
First Claim
1. A fuel evaporative emission treatment system for use with an engine fuel system including a fuel tank having a filler neck, the fuel tank having an upper space defined therein above the level of fuel contained therein, the system comprising:
- a canister for adsorbing evaporative fuel produced in the fuel system;
a vent passage connecting the upper space of the fuel tank and said canister, said vent passage having a first effective area; and
a vent circulation passage connecting the upper space of the fuel tank and the filler neck, said vent circulation passage having a second effective area,the ratio of the second effective area to the first effective area being set to a value such that internal pressure of the filler neck during refueling falls within a predetermined pressure range, and the second effective area being smaller than the first effective area.
3 Assignments
0 Petitions
Accused Products
Abstract
A fuel evaporative emission treatment system installed in an engine fuel system has a canister for adsorbing evaporative fuel, a vent hose connecting a fuel tank and the canister, and a vent circulation hose connecting the vent hose and a filler neck of the fuel tank, and the sectional areas of the vent hose and vent circulation hose are set so that the ratio thereof may be a proper value. The negative pressure produced in the filler neck due to aspiration induced by refueling is canceled out by the pressure of fuel gas circulated to the filler neck through the vent circulation hose, whereby the internal pressure of the filler neck is controlled to a value appropriately smaller than the atmospheric pressure. Thus, inflow of the outside air into the filler neck, and thus generation of evaporative fuel gas, can be suppressed, and also the outflow of evaporative fuel gas from the filler neck is suppressed.
48 Citations
20 Claims
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1. A fuel evaporative emission treatment system for use with an engine fuel system including a fuel tank having a filler neck, the fuel tank having an upper space defined therein above the level of fuel contained therein, the system comprising:
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a canister for adsorbing evaporative fuel produced in the fuel system; a vent passage connecting the upper space of the fuel tank and said canister, said vent passage having a first effective area; and a vent circulation passage connecting the upper space of the fuel tank and the filler neck, said vent circulation passage having a second effective area, the ratio of the second effective area to the first effective area being set to a value such that internal pressure of the filler neck during refueling falls within a predetermined pressure range, and the second effective area being smaller than the first effective area. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 18, 19, 20)
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2. A fuel evaporative emission treatment system for use with an engine fuel system including a fuel tank having a filler neck, the fuel tank having an upper space defined therein above the level of fuel contained therein, the system comprising:
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a canister for adsorbing evaporative fuel produced in the fuel system; a vent passage connecting the upper space of the fuel tank and said canister, said vent passage having a first effective area; a vent circulation passage connecting the upper space of the fuel tank and the filler neck; and an orifice formed in said vent circulation passage for reducing the effective area thereof, a portion of said vent circulation passage at which said orifice is formed having a second effective area, the ratio of the second effective area to the first effective area being set to a value such that internal pressure of the filler neck during refueling falls within a predetermined pressure range. - View Dependent Claims (3)
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13. A fuel evaporative emission treatment system for use with an engine fuel system including a fuel tank having a filler neck, the fuel tank having an upper space defined therein above the level of fuel contained therein, the system comprising:
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a canister for adsorbing evaporative fuel produced in the fuel system; a vent passage connecting the upper space of the fuel tank and said canister; a vent circulation passage connecting the upper space of the fuel tank and the filler neck; and a control valve arranged in said vent circulation passage for varying the effective area thereof. - View Dependent Claims (14, 15, 16, 17)
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Specification