Determining the size of a leak in a fuel tank system

Patent metadata

Field	Value
Publication number	US-12188425-B2
Application number	US-202217807031-A
Country	US
Kind code	B2
Filing date	Jun 15, 2022
Priority date	Dec 16, 2019
Publication date	Jan 7, 2025
Grant date	Jan 7, 2025

Abstract

The disclosure relates to a method for determining a size of a leak in a fuel tank system. The method includes: starting an internal combustion engine; calculating a stoppage time for a vehicle and/or a temperature difference between the fuel in the fuel tank system and the environment; and checking whether at least one of a plurality of diagnostic conditions is fulfilled. A first diagnostic condition is fulfilled when the stoppage time is longer than a predetermined minimum stoppage time. A second diagnostic condition is fulfilled when the temperature difference is smaller than a predetermined maximum temperature difference. Additionally, when at least one of the plurality of diagnostic conditions is fulfilled, the method includes: evacuating the fuel tank system; recording a time profile of the pressure in the fuel tank system; and determining the size of a leak based on the recorded time profile of the pressure.

First claim

What is claimed is:

1. A method for determining a size of a leak in a fuel tank system of a vehicle having an internal combustion engine, the method comprising:
starting the internal combustion engine;
determining a stoppage time for the vehicle, the stoppage time being a length of time the vehicle was switched off before starting;
calculating a temperature difference between the fuel in the fuel tank system and a vehicle environment;
checking whether at least two of a plurality of diagnostic conditions are fulfilled, wherein:
a first diagnostic condition of the plurality of diagnostic is fulfilled when the stoppage is longer than a predetermined minimum stoppage time,
a second diagnostic condition of the plurality of diagnostic conditions is fulfilled when the temperature difference is smaller than a predetermined maximum temperature difference, and
when the at least two of the plurality of diagnostic conditions are fulfilled, carrying out the following steps:
shutting off the fuel tank system,
waiting until a predetermined waiting time has elapsed,
evacuating the fuel tank system,
recording a time profile of a pressure in the fuel tank system; and
determining the size of a leak in the fuel tank system based on the recorded time profile of the pressure.

2. The method of claim 1 , wherein the determination of the size of the leak comprises calculating a gradient of the time profile of the pressure.

3. The method of claim 1 , wherein the evacuation of the fuel tank system is carried out when the pressure in the fuel tank system is reduced by a predetermined amount.

4. The method of claim 3 , wherein the predetermined amount is between 5 mbar and 15 mbar.

5. The method of claim 1 , wherein the evacuation take place via suction by the internal combustion engine or a scavenging air pump.

6. The method of claim 1 , wherein a third diagnostic condition of the plurality of diagnostic conditions is checked, the third diagnostic condition is fulfilled when an idling phase with a predetermined duration is implemented.

7. The method of claim 1 , wherein a fourth diagnostic condition of the plurality of diagnostic conditions is checked, the fourth diagnostic condition is fulfilled when the internal combustion engine is operated in idling mode and stop-start prevention is realized.

8. A computer program having computer-executable commands which, when executed by a processor, are developed for carrying out the method as claimed in claim 1 .

9. An engine controller for a vehicle having an internal combustion engine, which is developed for carrying out a method for determining a size of a leak in a fuel tank system of a vehicle having an internal combustion engine, the method comprising:
starting the internal combustion engine;
determining a stoppage time for the vehicle, the stoppage time being a length of time the vehicle was switched off before starting;
calculating a temperature difference between the fuel in the fuel tank system and a vehicle environment;
checking whether at least two of a plurality of diagnostic conditions are fulfilled, wherein:
a first diagnostic condition of the plurality of diagnostic conditions is checked, the first diagnostic condition is fulfilled when the stoppage is longer than a predetermined minimum stoppage time,
a second diagnostic condition of the plurality of diagnostic conditions is fulfilled when the temperature difference is smaller than a predetermined maximum temperature difference, and
when the at least two of the plurality of diagnostic conditions are fulfilled, carrying out the following steps:
shutting off the fuel tank system,
waiting until a predetermined waiting time has elapsed,
evacuating the fuel tank system,
recording a time profile of a pressure in the fuel tank system; and
determining the size of a leak in the fuel tank system based on the recorded time profile of the pressure.

10. A method for determining a size of a leak in a fuel tank system of a vehicle having an internal combustion engine, the method comprising:
starting the internal combustion engine;
calculating a temperature difference between the fuel in the fuel tank system and a vehicle environment; and
checking whether at least one of a plurality of diagnostic condition is fulfilled, the at least one diagnostic condition of the plurality of diagnostic conditions is fulfilled when the temperature difference is smaller than a predetermined maximum temperature difference, wherein
when the at least one of the plurality of diagnostic conditions is fulfilled, carrying out the following steps:
shutting off the fuel tank system,
waiting until a predetermined waiting time has elapsed,
evacuating the fuel tank system,
recording a time profile of a pressure in the fuel tank system; and
determining the size of a leak in the fuel tank system based on the recorded time profile of the pressure.

Assignees

• Vitesco Tech Gmbh

Inventors

• Zhang Hong
• Haft Gerhard

Classifications

• G01M3/3272

  for verifying the internal pressure of closed containers · CPC title

• F02D2200/0606

  Fuel temperature · CPC title

• F02D2200/0602

  Fuel pressure · CPC title

• F02D2041/225

  Leakage detection · CPC title

• F02D41/22 Primary

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title