Method for checking the operability of a tank-venting system
First Claim
1. A method of checking the operability of a tank-venting system of a motor vehicle, the tank-venting system including a tank, an adsorption filter and a tank-venting valve, the adsorption filter having a venting line and being connected to the tank via a connecting line, the tank-venting valve being connected to the adsorption filter via a valve line, the method comprising the steps of:
- utilizing a pressure source to introduce a pressure into said tank-venting system which is an overpressure compared to atmospheric pressure and said system or said pressure source having at least one operating variable which can be detected;
providing a stored reference time-dependent trace of said one variable which is characteristic for a diagnostic trace;
detecting said operating variable while introducing said overpressure during a first standstill of said vehicle to form a first time-dependent trace of said one variable and determining whether a leak is present;
detecting said operating variable while introducing said overpressure during a second standstill of said vehicle to form a second time-dependent trace of said one variable and determining whether a leak is present;
comparing said first and second time-dependent traces to said stored reference time-dependent trace;
outputting a fault announcement only when;
(a) a conclusion is drawn as to the presence of a leak from both of said first and second time-dependent traces and when said first and second traces deviate from said stored reference time-dependent trace by a pregiven value; and
,(b) when, between said first and second standstills of said vehicle, one of the following does not exceed a predetermined threshold;
(i) fuel consumption;
(ii) distance traveled;
or,(iii) another index which permits a conclusion to be drawn that no tanking operation is taking place during said second standstill.
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Accused Products
Abstract
The invention is directed to a method for checking the operability of a tank-venting system of a motor vehicle. The tank-venting system includes a tank, an adsorption filter and a tank-venting valve. The adsorption filter has a venting line and is connected to the tank via a connecting line. The tank-venting valve is connected to the adsorption filter via a valve line. In the method, a pressure source introduces a pressure into the tank-venting system which is an overpressure compared to atmospheric pressure and the pressure source has at least one operating variable. A first time-dependent trace of the one variable is provided and this trace is characteristic for a diagnostic trace undisturbed by a tanking operation. A second time-dependent trace of the one variable is detected during standstill of the vehicle and is compared to the first time-dependent trace. An output of a fault announcement is inhibited when the second time-dependent trace deviates from the first time-dependent trace by a pregiven value.
30 Citations
5 Claims
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1. A method of checking the operability of a tank-venting system of a motor vehicle, the tank-venting system including a tank, an adsorption filter and a tank-venting valve, the adsorption filter having a venting line and being connected to the tank via a connecting line, the tank-venting valve being connected to the adsorption filter via a valve line, the method comprising the steps of:
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utilizing a pressure source to introduce a pressure into said tank-venting system which is an overpressure compared to atmospheric pressure and said system or said pressure source having at least one operating variable which can be detected; providing a stored reference time-dependent trace of said one variable which is characteristic for a diagnostic trace; detecting said operating variable while introducing said overpressure during a first standstill of said vehicle to form a first time-dependent trace of said one variable and determining whether a leak is present; detecting said operating variable while introducing said overpressure during a second standstill of said vehicle to form a second time-dependent trace of said one variable and determining whether a leak is present; comparing said first and second time-dependent traces to said stored reference time-dependent trace; outputting a fault announcement only when; (a) a conclusion is drawn as to the presence of a leak from both of said first and second time-dependent traces and when said first and second traces deviate from said stored reference time-dependent trace by a pregiven value; and
,(b) when, between said first and second standstills of said vehicle, one of the following does not exceed a predetermined threshold; (i) fuel consumption; (ii) distance traveled;
or,(iii) another index which permits a conclusion to be drawn that no tanking operation is taking place during said second standstill. - View Dependent Claims (2)
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3. A method of checking the operability of a tank-venting system of a motor vehicle, the tank-venting system including a tank, an adsorption filter and a tank-venting valve, the adsorption filter having a venting line and being connected to the tank via a connecting line, the tank-venting valve being connected to the adsorption filter via a valve line, the method comprising the steps of:
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utilizing a pressure source to introduce a pressure into said tank-venting system which is an overpressure compared to atmospheric pressure and said pressure source having at least one operating variable; providing a first time-dependent trace of said one variable which is characteristic for a diagnostic trace undisturbed by a tanking operation; detecting a second time-dependent trace of said one variable during standstill of said vehicle; comparing said second time-dependent trace to said first time-dependent trace; and
,inhibiting an output of a fault announcement when said second time-dependent trace deviates from said first time-dependent trace by a pregiven value. - View Dependent Claims (4, 5)
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Specification