Leak detection method and associated valve and fuel system
First Claim
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1. A method of detecting a leak in a fuel system comprising a fuel tank and an orifice with a controlled section between the tank and the atmosphere, according to which:
- a) the controlled section is set to a value A1 at a time T1 and a pressure differential Δ
p1 between the inside of said fuel tank and the atmosphere is measured at least after an interval of time Δ
T from T1, for a constant fuel flow out of said fuel tank;
b) the controlled section is set to a value A2 at a time T2 and a pressure differential Δ
p2 between the inside of said fuel tank and the atmosphere is measured at least after the same interval of time Δ
T from T2, for the same constant fuel flow;
c) a ratio of said pressure differentials Δ
p1 and Δ
p2 is computed and is compared to a reference pressure differential ratio Δ
pL obtained with the same fuel system but comprising a calibrated leak; and
d) a leak bigger than said calibrated leak is detected if said ratio computed at stage c) is smaller than said reference ratio Δ
pL.
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Abstract
Method of detecting a leak in a fuel system comprising a fuel tank and an orifice with a controlled section between the tank and the atmosphere, according to which
- a) the controlled section is set to a value Al at a time T1 and a pressure differential Δp1 between the inside of the tank and the atmosphere is measured at least after an interval of time ΔT from T1, for a constant fuel flow out of the tank;
- b) the controlled section is set to a value A2 at a time T2 and a pressure differential Δp2 between the inside of the tank and the atmosphere is measured at least after the same interval of time ΔT from T2, for the same constant fuel flow;
- c) a ratio of the pressure differentials Δp1 and Δp2 is computed and is compared to a reference pressure differential ratio ΔpL obtained with the same fuel system but comprising a calibrated leak.
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Citations
12 Claims
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1. A method of detecting a leak in a fuel system comprising a fuel tank and an orifice with a controlled section between the tank and the atmosphere, according to which:
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a) the controlled section is set to a value A1 at a time T1 and a pressure differential Δ
p1 between the inside of said fuel tank and the atmosphere is measured at least after an interval of time Δ
T from T1, for a constant fuel flow out of said fuel tank;b) the controlled section is set to a value A2 at a time T2 and a pressure differential Δ
p2 between the inside of said fuel tank and the atmosphere is measured at least after the same interval of time Δ
T from T2, for the same constant fuel flow;c) a ratio of said pressure differentials Δ
p1 and Δ
p2 is computed and is compared to a reference pressure differential ratio Δ
pL obtained with the same fuel system but comprising a calibrated leak; andd) a leak bigger than said calibrated leak is detected if said ratio computed at stage c) is smaller than said reference ratio Δ
pL. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A fuel system equipped with leak detection means, said fuel system comprising:
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a) a fuel tank; b) an orifice with a controlled section between the tank and the atmosphere; c) means for varying said controlled section between at least two values; d) means for measuring a pressure differential between the inside of the tank and the atmosphere at said at least two values of said controlled section; and e) means for computing a ratio between two pressure differentials measured by the means for measuring a pressure differential at stage d) and for comparing said ratio with a reference pressure differential ratio obtained with the same fuel system but with a calibrated leak and the atmosphere. - View Dependent Claims (12)
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Specification