Method and computer for controlling the pressure inside a motor vehicle fuel tank

Patent metadata

Field	Value
Publication number	US-10399434-B2
Application number	US-201615737348-A
Country	US
Kind code	B2
Filing date	Jun 23, 2016
Priority date	Jun 25, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

Disclosed is a method for controlling the pressure inside a fuel tank of a motor vehicle, the motor vehicle including a fuel vapor vent circuit connecting the tank to a fuel vapor canister, the vent circuit including an isolation valve for isolating the tank and a rollover valve. The pressure control method includes steps of: determining an activation duration required for the isolation valve to transition from a closed state to a fully open state, referred to as the “full opening duration”, when a predefined rollover valve closure risk criterion is satisfied: controlling the isolation valve in repeated activations of respective durations that are shorter than the full opening duration.

First claim

The invention claimed is:

1. Method ( 50 ) for controlling the pressure inside a fuel tank ( 10 ) of a motor vehicle, said motor vehicle comprising a fuel vapor vent circuit ( 20 ) connecting the tank ( 10 ) to a canister ( 23 ), the vent circuit ( 20 ) comprising an isolation valve ( 22 ) for isolating the tank ( 10 ) and a rollover valve ( 21 ), the pressure inside the tank ( 10 ) being controlled by controlling the isolation valve ( 22 ), wherein said method ( 50 ) comprises steps of:
( 51 ) determining an activation duration required for the isolation valve ( 22 ) to transition from a closed state to a fully open state, referred to as the “full opening duration”,
when a predefined rollover valve ( 21 ) closure risk criterion is satisfied: ( 55 ) controlling the isolation valve ( 22 ) in repeated activations of respective durations that are shorter than the full opening duration.

2. Method ( 50 ) according to claim 1 , wherein it comprises the steps of:
( 52 ) determining a closure-initiating flow rate of the rollover valve ( 21 ),
( 53 ) determining a maximum instantaneous flow rate (Qinst) of the isolation valve ( 22 ) in the fully open state,

and wherein the predefined rollover valve ( 21 ) closure risk criterion is satisfied when the closure-initiating flow rate of the rollover valve ( 21 ) is less than the maximum instantaneous flow rate of the isolation valve ( 22 ).

3. Method ( 50 ) according to claim 2 , wherein the duration of an activation of the isolation valve ( 22 ), when the rollover valve ( 21 ) closure risk criterion is satisfied, is determined as a function of the ratio R between the closure-initiating flow rate and the maximum instantaneous flow rate (Qinst).

4. Method ( 50 ) according to claim 3 , wherein the duration Ton of an activation of the isolation valve ( 22 ), when the rollover valve ( 21 ) closure risk criterion is satisfied, is determined according to the following expression:
T on= K·T min+ R·T open

where:
Tmin is the activation duration required for the isolation valve ( 22 ) to begin to open from the closed state,
Topen is the activation duration required for the isolation valve ( 22 ) to fully open, starting from the moment when said isolation valve began to open,
K is a positive coefficient less than or equal to one.

5. Method ( 50 ) according to claim 4 , wherein the maximum instantaneous flow rate (Qinst) is determined as a function of the pressure Pt inside the tank ( 10 ) and the pressure Pc in the vent circuit ( 20 ) after the isolation valve ( 22 ).

6. Method ( 50 ) according to claim 4 , wherein, when the rollover valve ( 21 ) closure risk criterion is satisfied, the time separating the end of one activation of the isolation valve ( 22 ) and the beginning of the next activation is greater than the time required for said isolation valve to transition from the fully open state to the closed state.

7. Method ( 50 ) according to claim 4 , wherein, when the rollover valve ( 21 ) closure risk criterion is not satisfied, the isolation valve ( 22 ) is activated continuously.

8. Method ( 50 ) according to claim 3 , wherein the maximum instantaneous flow rate (Qinst) is determined as a function of the pressure Pt inside the tank ( 10 ) and the pressure Pc in the vent circuit ( 20 ) after the isolation valve ( 22 ).

9. Method ( 50 ) according to claim 3 , wherein, when the rollover valve ( 21 ) closure risk criterion is satisfied, the time separating the end of one activation of the isolation valve ( 22 ) and the beginning of the next activation is greater than the time required for said isolation valve to transition from the fully open state to the closed state.

10. Method ( 50 ) according to claim 3 , wherein, when the rollover valve ( 21 ) closure risk criterion is not satisfied, the isolation valve ( 22 ) is activated continuously.

11. Method ( 50 ) according to claim 2 , wherein the maximum instantaneous flow rate (Qinst) is determined as a function of the pressure Pt inside the tank ( 10 ) and the pressure Pc in the vent circuit ( 20 ) after the isolation valve ( 22 ).

12. Method ( 50 ) according to claim 11 , wherein the maximum instantaneous flow rate Qinst is determined according to the following expression:

Qinst
=

295
·
Cv
·

Pt
2

-

Pc
2

ρ
·
T

where:
Cv is the coefficient of the isolation valve,
ρ is the density of the fuel vapors relative to air,
T is the temperature inside the tank ( 10 ).

13. Method ( 50 ) according to claim 12 , wherein, when the rollover valve ( 21 ) closure risk criterion is satisfied, the time separating the end of one activation of the isolation valve ( 22 ) and the beginning of the next activation is greater than the time required for said isolation valve to transition from the fully open state to the closed state.

14. Method ( 50 ) according to claim 11 , wherein, when the rollover valve ( 21 ) closure risk criterion is satisfied, the time separating the end of one activation of the isolation valve ( 22 ) and the beginning of the next activation is greater than the time required for said isolation valve to transition from the fully open state to the closed state.

15. Method ( 50 ) according to claim 2 , wherein, when the rollover valve ( 21 ) closure risk criterion is satisfied, the time separating the end of one activation of the isolation valve ( 22 ) and the beginning of the next activation is greater than the time required for said isolation valve to transition from the fully open state to the closed state.

16. Method ( 50 ) according to claim 2 , wherein, when the rollover valve ( 21 ) closure risk criterion is not satisfied, the isolation valve ( 22 ) is activated continuously.

17. Method ( 50 ) according to claim 1 , wherein, when the rollover valve ( 21 ) closure risk criterion is satisfied, the time separating the end of one activation of the isolation valve ( 22 ) and the beginning of the next activation is greater than the time required for said isolation valve to transition from the fully open state to the closed state.

18. Method ( 50 ) according to claim 1 , wherein, when the rollover valve ( 21 ) closure risk criterion is not satisfied, the isolation valve ( 22 ) is activated continuously.

19. Electronic computer ( 30 ) for a motor vehicle, comprising means configured to control the pressure, inside a fuel tank ( 10 ) of said motor vehicle, in accordance with a method according to claim 1 .

20. Motor vehicle comprising an electronic computer ( 30 ) according to claim 19 .

Assignees

• Continental Automotive France
• Continental Automotive Gmbh
• Audi Ag

Inventors

• Grunwald Oliver
• Collet Thierry
• Groussard Aurelien

Classifications

• B60K2015/03576

  Venting during filling the reservoir · CPC title

• B60K2015/03561

  Venting means working at specific times · CPC title

• B60K2015/03514

  with vapor recovery means · CPC title

• B60K2015/03302

  Electromagnetic valves · CPC title

• B60K15/03519

  Valve arrangements in the vent line · CPC title