Method to test for a leak in a fuel tank system
First Claim
1. A method of testing for a leak in a fuel tank system of a motor vehicle, comprising:
- cutting off a fuel tank during an overrun by at least one cutoff device and acquiring a pressure that builds up in the fuel tank within a specifiable time interval; and
when a specifiable maximum pressure or a specifiable vacuum threshold is unrealized,opening the at least one cutoff device and closing the at least cutoff device again after a specifiable time period,producing and acquiring a vacuum in a subsequent vacuum phase,determining and evaluating a first parameter that characterizes leak tightness from the vacuum achieved within a specifiable time period and an achieved overpressure,when the specifiable maximum pressure is realized,determining a second parameter characterizing leak tightness from the overpressure and a specifiable overpressure threshold and comparing the second parameter with a specifiable reference value,upon the second parameter being found less than the reference value, suggesting a leak-proof fuel tank system; and
when the determined second parameter is greater than the specifiable reference value,opening the cutoff device,producing and acquiring a vacuum in the fuel tank in a subsequent vacuum phase, wherein a leak-proof fuel tank system is suggested when a specifiable vacuum threshold is achieved and the test for a leak is concluded, and whereby the test for a leak is then concluded if the vacuum threshold is not achieved within a specifiable time period, and thereby a parameter characterizing leak tightness is evaluated.
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Accused Products
Abstract
A method to test for a leak in a fuel tank system of a motor vehicle includes a fuel tank is cut off during the overrun by means of at least one cutoff device, and the pressure, which builds up in the fuel tank within a specifiable time interval is acquired; if a specifiable maximum pressure or a specifiable vacuum threshold is not achieved, said cutoff device is opened and closed again after a specifiable time period, and a vacuum is produced and acquired in a subsequent vacuum phase, and a parameter, which characterizes the leak tightness, is determined and evaluated from the vacuum achieved within a specifiable time period and the overpressure, which is achieved, and the test for a leak is concluded; if the specifiable maximum pressure is achieved, a parameter characterizing the leak tightness is determined from the acquired overpressure and the specifiable overpressure threshold and is compared with a specifiable reference value and for the case that the determined parameter is smaller than the reference value, a leak-proof fuel tank system is suggested and the test for a leak is concluded, and if the determined parameter is greater than the specifiable reference value, the cutoff device is opened and a vacuum is produced and acquired in the fuel tank in a subsequent vacuum phase, whereby a leak-proof fuel tank system is then suggested if a specifiable vacuum threshold is achieved, and hence the test for a leak is concluded, and whereby the test for a leak is then concluded if the vacuum threshold is not achieved within a specifiable time period, and hence the parameter characterizing the leak tightness is evaluated.
9 Citations
3 Claims
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1. A method of testing for a leak in a fuel tank system of a motor vehicle, comprising:
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cutting off a fuel tank during an overrun by at least one cutoff device and acquiring a pressure that builds up in the fuel tank within a specifiable time interval; and when a specifiable maximum pressure or a specifiable vacuum threshold is unrealized, opening the at least one cutoff device and closing the at least cutoff device again after a specifiable time period, producing and acquiring a vacuum in a subsequent vacuum phase, determining and evaluating a first parameter that characterizes leak tightness from the vacuum achieved within a specifiable time period and an achieved overpressure, when the specifiable maximum pressure is realized, determining a second parameter characterizing leak tightness from the overpressure and a specifiable overpressure threshold and comparing the second parameter with a specifiable reference value, upon the second parameter being found less than the reference value, suggesting a leak-proof fuel tank system; and when the determined second parameter is greater than the specifiable reference value, opening the cutoff device, producing and acquiring a vacuum in the fuel tank in a subsequent vacuum phase, wherein a leak-proof fuel tank system is suggested when a specifiable vacuum threshold is achieved and the test for a leak is concluded, and whereby the test for a leak is then concluded if the vacuum threshold is not achieved within a specifiable time period, and thereby a parameter characterizing leak tightness is evaluated. - View Dependent Claims (2, 3)
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Specification