Leak detection system

Patent metadata

Field	Value
Publication number	US-12140503-B2
Application number	US-202017780386-A
Country	US
Kind code	B2
Filing date	Nov 30, 2020
Priority date	Nov 29, 2019
Publication date	Nov 12, 2024
Grant date	Nov 12, 2024

Abstract

The invention relates to a leak detection system on board of a vehicle comprising a fuel tank ( 301, 401 ), a filler pipe ( 302, 402 ), a venting line ( 303, 403 ) for recirculating fuel vapors from the tank to the filler pipe, said system having a combination pressure and temperature sensor mounted in the vapor dome of the fuel tank, and a pressure sensor located in the recirculation line above the highest possible liquid level that could be present in the recirculation line and to methods to detect said leak.

First claim

The invention claimed is:

1. A sealed fuel system for a vehicle, comprising:
a fuel tank,
a filler pipe,
a venting line for recirculating fuel vapors from the tank to the filler pipe, and
a leak detection device,
wherein the leak detection device comprises:
a first pressure sensor provided to measure a pressure in a vapor dome of the fuel tank,
a second pressure sensor, and
a controller,

wherein:
the filler pipe has a sealing means located near the fuel tank,
a part of the venting line forms a sump, and
the second pressure sensor is configured to measure a pressure in the venting line above a predetermined maximum threshold after the sump.

2. The sealed fuel system for a vehicle according to claim 1 , wherein the sealing means is an Inlet Check Valve.

3. The sealed fuel system for a vehicle according to claim 1 , wherein the leak detection device further comprises a temperature sensor to measure a temperature in the vapor dome of the fuel tank.

4. The sealed fuel system for a vehicle according to claim 1 , wherein the part of the venting line forming a sump has a shape selected from the group consisting of a U-shape, a V-shape, and a J-shape.

5. A method for detecting a leak in a sealed fuel system of a vehicle comprising a fuel tank, a filler pipe, and a venting line for recirculating fuel vapors from the tank to the filler pipe, wherein a part of the venting line forms a sump, the method comprising:
a) measuring and storing a pressure and a temperature in a vapor dome of a tank of the fuel tank at predetermined time points;
b) measuring a pressure in the venting line of the fuel system above a predetermined maximum threshold after the sump at the predetermined time points;
c) comparing the measured pressure in the vapor dome of a tank of the fuel tank and the measured pressure in the venting line of the fuel system above the predetermined maximum threshold after the sump at a same predetermined time point; and
d) detecting a leak using a result obtained in step c).

6. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 5 , wherein steps c) and d) comprise:
e) comparing an absolute value of a difference between the two measured pressures to a first threshold;
f) when the absolute value of the difference is lower than the first threshold, comparing the measured temperatures and the measured pressures in the vapor dome of the fuel tank measured at the predetermined time points;
g) when a difference of the temperatures measured at a first time and at a second later time is higher than a temperature threshold, calculating a pressure expected in the fuel system at the second time, based on a temperature evolution measured between the first time and the second time and the pressure obtained at the first time, and a coefficient that represents a natural evolution of pressure in the fuel system over time; and
h) detecting a leak by comparing the calculated expected pressure and the pressure obtained at the second time to at least one predetermined second threshold.

7. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 5 , wherein steps c) and d) comprise:
i) comparing an absolute value of a difference between the two measured pressures to a first threshold;
j) when the absolute value of the difference is higher than the first threshold, comparing an absolute value of the pressure in the vapor dome of a tank of the fuel system to a third threshold and comparing an absolute value of the pressure in the venting line of the fuel system above the predetermined maximum threshold after the sump to a fourth threshold;
k) when the absolute value of the pressure in the vapor dome of a tank of the fuel system is lower than the third threshold, concluding an impossibility to detect a leak;
l) When the absolute value of the pressure in the venting line of the fuel system above the predetermined maximum threshold after the sump is higher than the fourth threshold (Th 4 ), concluding the fuel system is leak tight; and
m) when the absolute value of the pressure in the venting line of the fuel system above the predetermined maximum threshold after the sump is lower than the fourth threshold, concluding the fuel system has a leak.

8. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 6 , wherein the first threshold is defined based on a precision and an accuracy of:
a first pressure sensor configured to measure the pressure in the vapor dome of the fuel tank, and
a second pressure sensor configured to measure the pressure in the venting line above the predetermined maximum threshold after the sump.

9. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 6 , wherein the second threshold is chosen in a range of 5 mbar and 35 mbar, and the temperature threshold is chosen between 1° C. and 5° C.

10. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 7 , wherein the third threshold is adapted to a potential maximum hydraulic pressure of the liquid in the sump of the venting line as a function of a sign of a value of the pressure in the vapor dome.

11. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 7 , wherein the fourth threshold is defined based on an accuracy and a precision of a pressure sensor configured to measure the pressure in the venting line above the predetermined maximum threshold after the sump, the pressure sensor being located in the filler pipe above the the predetermined maximum threshold after the sump.

12. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 7 , wherein the third threshold and the fourth threshold are augmented by a temperature evolution between two predetermined time points when the temperature evolution is greater than the temperature threshold.

13. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 6 , wherein the method is started when a temperature evolution measured by a temperature sensor is higher than the temperature threshold.

14. A method for detecting a malfunctioning of a pressure sensor in a sealed fuel system for a vehicle according to claim 1 , wherein the method comprises:
measuring a pressure in the vapor dome of a tank of the fuel tank at predetermined time points;
measuring a pressure in the venting line of the fuel system above the predetermined maximum threshold after the sump at the predetermined time points;
comparing the pressure value in the vapor dome of a tank of the fuel tank and the pressure value (P 2 ) in the filler pipe of the fuel system or in the venting line of the fuel system above the predetermined maximum threshold after the sump; and
detecting the malfunctioning of a pressure sensor selected from the first pressure sensor and the second pressure sensor.

15. The method for detecting a leak in a sealed fuel system of a vehicle according to claim 9 , wherein the temperature threshold is chosen between 2° C. and 3° C.

Assignees

• Plastic Omnium Advanced Innovation & Res

Inventors

• Hill David
• Chaussinand Antoine
• Baja Mihai

Classifications

• G01M3/3263

  using a differential pressure detector (G01M3/3245, G01M3/3272 take precedence) · CPC title

• G01L27/007

  Malfunction diagnosis, i.e. diagnosing a sensor defect · CPC title

• B60K2015/03538

  the venting tube being connected with the filler tube · CPC title

• B60K15/03504 Primary

  adapted to avoid loss of fuel or fuel vapour, e.g. with vapour recovery systems · CPC title

• B60Y2400/306

  Pressure sensors · CPC title