METHOD AND SYSTEM FOR FUEL TANK CAP DETECTION

Abstract

A method may verify that a fuel tank cap is present and properly closed after refueling of a motor vehicle fuel tank. The method may include, in response to a request for refueling: (a1) enabling refueling of the motor vehicle fuel tank by opening a first vent valve connected in series in a vent line, downstream from a first port of a recirculation line coupled to the vent line, so that to vent the motor vehicle fuel tank to the atmosphere through a fuel vapor canister; (b1) disabling refueling of the motor vehicle fuel tank by closing the first vent valve; (c1) monitoring the internal pressure within the motor vehicle fuel tank when the refueling request is finished; and (d1) concluding that the fuel tank cap is deemed present and properly closed when the internal pressure increases and/or remains higher than the atmospheric pressure.

Claims

1. A method for verifying that a fuel tank cap is present and properly closed after refueling of a motor vehicle fuel tank, the method comprising, in response to a request for refueling: (a1) enabling refueling of the motor vehicle fuel tank by opening a first vent valve connected in series in a vent line, downstream from a first port of a recirculation line coupled to the vent line, so that to vent the motor vehicle fuel tank to the atmosphere through a fuel vapor canister, (b1) disabling refueling of the motor vehicle fuel tank by closing the first vent valve, (c1) monitoring the internal pressure within the motor vehicle fuel tank when the refueling request is finished; and (d1) concluding that the fuel tank cap is deemed present and properly closed when the internal pressure increases and/or remains higher than the atmospheric pressure.

2. The method of claim 1, which proceeds to the disabling (b1) when the refueling request is finished.

3. The method of claim 1, which proceeds to the disabling (b1) when fuel volume has reached a target fuel volume.

4. The method of claim 3, further comprising, after the disabling (b1): (a2) enabling refueling of the motor vehicle fuel tank by sequentially opening and closing the first vent valve; (b2) incrementing a counter value by one; (c2) determining whether the counter value has reached a threshold value, if the counter value has reached the threshold value, then proceeding to the monitoring (c1); otherwise, proceeding to the concluding (d2); and (d2) determining whether additional fuel has been introduced into the motor vehicle fuel tank, if additional fuel has been introduced into the motor vehicle fuel tank, then returning to the enabling (a2); otherwise, proceeding to the monitoring (c1).

5. The method of claim 1, further comprising at the enabling (a1): opening a second vent valve connected in series in the vent line, upstream from the first port of the recirculation line coupled to the vent line.

6. The method of claim 5, further comprising, after the enabling (a1): (a3) determining whether the volume of fuel contained within the motor vehicle fuel tank has reached a target fuel volume; (b3) disabling refueling of the motor vehicle fuel tank by closing the second vent valve when the fuel volume has reached the target fuel volume; (c3) opening the second vent valve and proceeding to the disabling (b1).

7. The method of claim 6, which proceeds to the opening (c3) when the refueling request is finished.

8. The method of claim 6, further comprising, after the disabling (b3): (a4) enabling refueling of the motor vehicle fuel tank by sequentially opening and closing the second vent valve; (b4) incrementing a counter value by one; (c4) determining whether the counter value has reached a threshold value, if the counter value has reached the threshold value, then proceeding to the opening (c3), otherwise proceeding to (d4); and (d4) determining whether additional fuel has been introduced into the motor vehicle fuel tank, if additional fuel has been introduced into the motor vehicle fuel tank, then returning to the enabling (a4), otherwise, proceeding to the opening (c3).

9. The method of claim 5, wherein the second vent valve is an electrically actuated tank isolation valve.

10. The method of claim 1, wherein the first vent valve is an electrically actuated system isolation valve.

11. A recirculation line for a fuel tank assembly for a motor vehicle, comprising: a first port at one end and a second port at the other end, wherein the first port of the recirculation line is configured to be coupled to a vent line of a fuel tank assembly between an electrically actuated tank isolation valve and a fuel vapor canister, and wherein the second port of the recirculation line is configured to be coupled to a filler pipe of the fuel tank assembly.

12. A fuel tank assembly suitable for a motor vehicle, the fuel tank assembly comprising: the recirculation line of claim 11, a motor vehicle fuel tank fillable with fuel through a filler pipe; a vent line having a first port at one end and a second port at the other end, the first port of the vent line being coupled to the motor vehicle fuel tank and the second port of the vent line communicating with the atmosphere; a fuel vapor canister connected in series in the vent line and coupled between the first and second ports of the vent line; an electrically actuated tank isolation valve connected in series in the vent line and coupled between the motor vehicle fuel tank and the fuel vapor canister (7), wherein the first port of the recirculation line is coupled to the vent line between the electrically actuated tank isolation valve and the fuel vapor canister and the second port of the recirculation line is coupled to the filler pipe.

13. The fuel tank assembly of claim 12, wherein the motor vehicle fuel tank is sealable and at a pressure higher than atmospheric pressure.

14. A fuel tank cap detection system suitable for verifying that a fuel tank cap is present and properly closed after refueling of a motor vehicle fuel tank, the fuel tank cap detection system comprising: the fuel tank assembly of claim 12; a fuel tank cap to tightly close off the filler pipe; a fuel door to permit access to the fuel tank cap, a pressure sensor to monitor the internal pressure of the motor vehicle fuel tank; a fuel level sensor to determine the volume of fuel contained within the motor vehicle fuel tank; a fuel door sensor to determine whether the fuel door is open or closed; an electrically actuated system isolation valve connected in series in the vent line and coupled between the fuel vapor canister and the second port of the vent line.

15. A non-transitory computer-readable medium comprising instructions for verifying that a fuel tank cap is present and properly closed after refueling of a motor vehicle fuel tank, which, when executed by a processor, cause the processor to perform the method of claim 1.

16. A motor vehicle, comprising: the fuel tank cap detection system of claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1a-1d are flow diagrams of a fuel tank cap detection method according to the invention;

[0067] FIG. 2 is a diagrammatic view of a fuel tank cap detection system according to an embodiment of the present invention;

[0068] FIG. 3 is a view similar to FIG. 2 showing a prior art recirculation line;

[0069] FIG. 4 is a view similar to FIG. 2 of another embodiment of the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0070] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0071] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0072] FIG. 1a to 1d show an example method 100 for verifying that a fuel tank cap is present and properly closed after refueling of a motor vehicle fuel tank in various conditions in accordance with the present disclosure. At step Start, method 100 starts. At step a1, in response to a request for refueling, method 100 enables refueling of a motor vehicle fuel tank 2 by opening a first vent valve 3 connected in series in a vent line 4, downstream from a first port 5a of a recirculation line 5 coupled to the vent line 4, so that to vent the motor vehicle fuel tank 2 to the atmosphere 50 through a fuel vapor canister 7. At step b1, method 100 disables refueling of the motor vehicle fuel tank 2 by closing the first vent valve 3. At step c1, method 100 monitors the internal pressure within the motor vehicle fuel tank 2 when the refueling request is finished. At step d1, method 100 concludes that the fuel tank cap 1 is deemed present and properly closed when the internal pressure increases and/or remains higher than the atmospheric pressure. Method 100 may then end.

[0073] Method 100 proceeds to step b1 when the refueling request is finished or, alternatively, when the fuel volume has reached a target fuel volume.

[0074] When the fuel volume has reached a target fuel volume, method 100 may proceed to step a2. At step a2, method 100 enables refueling of the motor vehicle fuel tank 2 by sequentially opening and closing the first vent valve 3. At step b2, method 100 increments a counter value by one. At step c2, method 100 determines whether the counter value has reached a threshold value, if the counter value has reached the threshold value, then the method proceeds to step c1; otherwise, the method proceeds to step d2. At step d2, method 100 determines whether additional fuel has been introduced into the motor vehicle fuel tank 2, if additional fuel has been introduced into the motor vehicle fuel tank 2, then the method returns to step a2; otherwise, the method proceeds to step c1.

[0075] At step a1, method 100 may open a second vent valve 6 connected in series in the vent line 4, upstream from the first port 5a of the recirculation line 5 coupled to the vent line 4, for enabling refueling of the motor vehicle fuel tank 2.

[0076] After step a1, method 100 may proceed to step a3. At step a3, method 100 determines whether the volume of fuel contained within the motor vehicle fuel tank 2 has reached a target fuel volume. At step b3, method 100 disables refueling of the motor vehicle fuel tank 2 by closing the second vent valve 6 when the fuel volume has reached the target fuel volume. At step c3, method 100 opens the second vent valve 6 and proceeding to step b1.

[0077] Method 100 proceeds to step c3 when the refueling request is finished.

[0078] After step b3, method 100 may proceed to step a4. At step a4, method 100 enables refueling of the motor vehicle fuel tank 2 by sequentially opening and closing the second vent valve 6. At step b4, method 100 increments a counter value by one. At step c4, method 100 determines whether the counter value has reached a threshold value, if the counter value has reached the threshold value, then the method proceeds to step c3; otherwise the method proceeds to step d4. At step d4, method 100 determines whether additional fuel has been introduced into the motor vehicle fuel tank 2, if additional fuel has been introduced into the motor vehicle fuel tank, then the method returns to step a4, otherwise, the method proceeds to step c3.

[0079] Method 100 may use an electrically actuated system isolation valve as first vent valve 3 and an electrically actuated tank isolation valve as second vent valve 6.

[0080] Method 100 may be carried out by an ECU and may be stored at the ECU as executable instructions in non-transitory memory. Instructions for carrying out method 100 and the test routines of the method included herein may be executed by the ECU based on instructions stored on the memory of the ECU and in conjunction with signals received from sensors and actuators of the system.

[0081] FIG. 2 is a diagrammatic view of a fuel tank cap detection system according to an embodiment of the invention. In this embodiment, the fuel tank cap detection system comprises a recirculation line 5 for a fuel tank assembly for a motor vehicle. The recirculation line 5 comprises a first port 5a at one end and a second port 5b at the other end. The first port 5a of the recirculation line 5 is coupled to a vent line 4 of a fuel tank assembly between an electrically actuated tank isolation valve 6 and a fuel vapor canister 7 and the second port 5b of the recirculation line 5 is coupled to a filler pipe 8 of the fuel tank assembly.

[0082] The recirculation line 5 is part of a fuel tank assembly for a motor vehicle comprising a motor vehicle fuel tank 2 fillable with fuel through the filler pipe 8. The vent line 4 has a first port 4a at one end and a second port 4b at the other end. The first port 4a of the vent line 4 is coupled to the motor vehicle fuel tank 2 and the second port 4b of the vent line 4 communicates with the atmosphere 50. The fuel vapor canister 7 is connected in series in the vent line 4 and coupled between the first 4a and second 4b ports of the vent line 4. The electrically actuated tank isolation valve 6 is connected in series in the vent line 4 and coupled between the motor vehicle fuel tank 2 and the fuel vapor canister 7.

[0083] In an example, the motor vehicle fuel tank 2 is sealable and at a pressure higher than atmospheric pressure.

[0084] The fuel tank assembly is part of the fuel tank cap detection system which further comprises a fuel tank cap 1 to tightly close off the filler pipe, a fuel door 9 to permit access to the fuel tank cap 1, a pressure sensor 10 to monitor the internal pressure of the motor vehicle fuel tank 2, a fuel level sensor 11 to determine the volume of fuel contained within the motor vehicle fuel tank 2, a fuel door sensor 14 to determine whether the fuel door 9 is open or closed, an electrically actuated system isolation valve 3 connected in series in the vent line 4 and coupled between the fuel vapor canister 7 and the second port 4b of the vent line 4.

[0085] The fuel level sensor 11 comprises a pivotable arm 12 having a float 13 attached at a free end of the pivotable arm 12. The filler pipe 8 comprises an upper part for receiving fuel from a refueling dispenser and a lower part for discharging the received fuel in the fuel tank 2. A filler head 15 is coupled to the upper part of the filler pipe 8 and an inlet check valve 19 is coupled to the lower part of the filler pipe 8. The fuel tank cap 1 is screwed on the filler head 15. The fuel tank assembly further comprises a fuel pump 17 associated with a fuel suction point 18, roll-over-valves 22 and a refueling control valve 16. The fuel pump 17 and the pump level sensor 11 are part of a fuel delivery module comprising a flange 20 and a fuel outlet 21 connecting the fuel pump 17 to a fuel feed line for the internal combustion engine (not shown).

[0086] The fuel tank cap detection system assembly is part of a motor vehicle (not shown).

[0087] FIG. 3 is a view similar to FIG. 2 showing a prior art recirculation line. The recirculation line 5′ of the prior art comprises a first port 5a′ at one end and a second port 5b′ at the other end. The first port 5a′ of the recirculation line 5′ is coupled to an opening located on the top of the fuel tank 2 and the second port 5b′ of the recirculation line 5′ is coupled to the filler pipe 8 of the fuel tank assembly. The drawback of this arrangement is that the internal pressure within the fuel tank cannot be maintained by closing the electrically actuated tank isolation valve 6 when the filler pipe is not closed.

[0088] FIG. 4 is a view similar to FIG. 2 of another embodiment of the present invention. In this alternative embodiment, the electrically actuated system isolation valve 3 and the electrically actuated tank isolation valve 6 are combined in one single valve device 30. The valve device 30 is set to simultaneously close the electrically actuated system isolation valve and open the electrically actuated tank isolation valve.

LIST OF REFERENCES

[0089] 1: fuel tank cap [0090] 2: motor vehicle fuel tank [0091] 3: first vent valve, electrically actuated system isolation valve [0092] 4: vent line [0093] 4a: first port of the vent line [0094] 4b: second port of the vent line [0095] 5: recirculation line [0096] 5a: first port of the recirculation line 5 [0097] 5b: second port of the recirculation line 5 [0098] 5′: recirculation line [0099] 5a′: first port of the recirculation line 5′ [0100] 5b′: second port of the recirculation line 5′ [0101] 6: second vent valve, electrically actuated tank isolation valve [0102] 7: fuel vapor canister [0103] 8: filler pipe [0104] 9: fuel door [0105] 10: pressure sensor [0106] 11: fuel level sensor [0107] 12: pivotable arm [0108] 13: float [0109] 14: fuel door sensor [0110] 15: filler head [0111] 16: refueling control valve [0112] 17: fuel pump [0113] 18: fuel suction point [0114] 19: inlet check valve [0115] 20: flange of the fuel delivery module [0116] 21: fuel outlet of the fuel delivery module [0117] 22: roll-over-valve [0118] 30: valve device [0119] 50: atmosphere [0120] 100: fuel tank cap detection method