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1. WO2020202137 - VENTING SYSTEMS AND METHODS

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[ EN ]

CLAIMS:

1. A venting system for a fuel system, the fuel system including a fuel tank connected to a vapor recovery canister via a main conduit, the venting system comprising:

an electrically actuated vent control valve configured for being installed in the main conduit to thereby enable selectively opening or closing fluid communication between the fuel tank and the vapor recovery canister;

a plurality of sensors for providing data indicative of conditions relating to the tank;

a control unit coupled to the sensors and to the electrically actuated vent control valve, the control unit configured for operating the electrically actuated vent control valve to open or close said fluid communication according to first predetermined criteria, wherein said first predetermined criteria include minimizing risk of liquid carry over (LCO) from the fuel tank to the vapor recovery canister.

2. The venting system according to claim 1, further comprising a direct venting valve for directly venting fuel vapors from the tank to an engine.

3. The venting system according to any one of claims 1 to 2, said main conduit comprises a first main conduit portion providing fluid communication between the tank and the vent control valve, and a second main conduit portion providing fluid communication between the vapor recovery canister and the vent control valve.

4. The venting system according to claim 3, wherein the fuel system comprises a plurality of mechanically actuable valves providing selective fluid communication between said first main conduit portion and the tank, and wherein selective fluid communication between the tank and the second main conduit portion via said plurality of mechanically actuable valves is exclusively via said vent control valve.

5. The venting system according to any one of claims 1 to 4, wherein the control unit is configured for determining whether a fuel level in the tank, as sensed by at least one said sensor, exceeds a baseline level of fuel, wherein said baseline level of fuel corresponds to a maximum liquid carry over safe level of fuel in the tank.

6. The venting system according to claim 5, wherein the control unit is configured for maintaining the vent control valve open if the fuel level is not greater than the baseline level.

7. The venting system according to claim 6, wherein the control unit is further configured for determining the acceleration/deceleration of the tank.

8. The venting system according to claim 7, wherein the control unit is further configured for maintaining the vent control valve open if:

- the acceleration/deceleration of the tank does not exceed a respective baseline acceleration, and,

- the control unit determines that the rate of change of said acceleration/deceleration of the tank does not exceed a baseline acceleration rate.

9. The venting system according to claim 7 or claim 8, wherein the control unit is further configured for closing the vent control valve open if:

- the control unit determines that the acceleration/deceleration of the tank exceeds a respective baseline acceleration, or, if the control unit determines that the rate of change of said acceleration/deceleration of the exceeds a baseline acceleration rate; and

- the control unit determines that a tank pressure is less than a maximum pressure corresponding to an over pressure limit for the tank which should not be exceeded.

10. The venting system according to any one of claims 2 to 9, comprising a conduit directly connecting the fuel tank with the engine, wherein:

the direct venting valve is electrically actuated and configured for being installed in the conduit to thereby enable selectively opening or closing fluid communication between the fuel tank and the engine; and

the control unit is coupled to the sensors and to the direct venting valve, the control unit being configured for operating the direct venting valve to open or close said fluid communication according to second predetermined criteria related to said data. 11. The venting system according to claim 10, wherein said second predetermined criteria include at least pressure conditions in an airspace within the tank being considered desirable for venting to the engine.

12. The venting system according to claim 11, wherein said pressure conditions comprise a first pressure in the airspace being greater than a second pressure in a portion of said conduit between the direct venting valve and the engine.

13. The venting system according to claim 12, wherein said first pressure is greater than said second pressure by at least 3 kPa.

14. The venting system according to any one of claims 10 to 13, wherein said second predetermined criteria further include temperature conditions in an airspace within the tank being considered desirable for venting to the engine.

15. The venting system according to claim 14, wherein said temperature conditions include a temperature of greater than 30°C.

16. The venting system according to any one of claims 10 to 15, wherein said second predetermined criteria further include fuel vapor quantity conditions in an airspace within the tank being considered desirable for venting to the engine.

17. The venting system according to claim 16, wherein said fuel vapor quantity conditions is correlated to a predetermined fuel level within the tank.

18. The venting system according to claim 17, wherein said predetermined fuel level within the tank corresponds to a volume of fuel in the tank that is not greater than 80% of the volume of fuel when the tank is considered to be full.

19. A fuel system comprising the venting system, vapor recovery canister and fuel tank as defined in any one of claims 1 to 18.

20. An assembly of an engine and a fuel system, the fuel system being as defined in claim 19, wherein the main conduit is connected to the fuel tank and to the vapor recovery canister.

21. A vehicle comprising an assembly as defined in claim 20.

22. A method for venting a fuel system, the fuel system comprising at least a fuel tank and a vapor recovery canister, the fuel tank being connected to the vapor recovery canister via a main conduit, and further comprising an electrically actuated vent control valve installed in said main conduit to thereby enable selectively opening or closing fluid communication between the fuel tank and the vapor recovery canister, the method comprising selectively operating the electrically actuated vent control valve to:

- prevent venting of the tank to the vapor recovery canister under predetermined conditions including at least a first said condition indicative of potential liquid carry over from the tank to the vapor recovery canister.

23. The method according to claim 22, further comprising the step of directly venting fuel vapors from the tank to an engine.

24. The method according to any one of claims 22 to 23, comprising determining whether a fuel level in the tank exceeds a baseline level of fuel, wherein said baseline level of fuel corresponds to a maximum liquid carry over safe level of fuel in the tank. 25. The venting system according to claim 24, wherein the vent control valve is maintained open if the fuel level is not greater than the baseline level.

26. The method according to claim 25, further comprising determining the acceleration/deceleration of the tank.

27. The method according to claim 26, further comprising maintaining the vent control valve open if:

- the acceleration/deceleration of the tank does not exceed a respective baseline acceleration, and,

- the control unit determines that the rate of change of said acceleration/deceleration of the tank does not exceed a baseline acceleration rate.

28. The method according to claim 26 or claim 27, comprising closing the vent control valve open if:

- the acceleration/deceleration of the tank exceeds a respective baseline acceleration, or, if the rate of change of said acceleration/deceleration of the exceeds a baseline acceleration rate; and

- a tank pressure is less than a maximum pressure corresponding to an over pressure limit for the tank which should not be exceeded.

29. The method according to any one of claims 22 to 28, comprising selectively operating the electrically actuated vent control valve to allow venting the tank to the vapor recovery canister responsive to a pressure in the tank being greater than a first predetermined threshold.

30. The method according to any one of claims 23 to 29, wherein the fuel tank is connected to the engine via a conduit, different from said main conduit, and wherein an electrically actuated direct venting valve installed in the conduit to thereby enable selectively opening or closing direct fluid communication between the fuel tank and the engine, the method further comprising

- providing data indicative of conditions relating to the tank;

- selectively operating the direct venting valve to allow venting the tank directly to the engine according to predetermined criteria related to said data.

31. The method according to claim 30, wherein said conditions include fuel air ratio conditions in an airspace within the tank, and wherein said predetermined criteria include said pressure conditions considered desirable for venting the tank directly to the engine. 32. The method according to claim 31, wherein said pressure conditions comprise a first pressure in the airspace being greater than a second pressure in a portion of said conduit between the direct venting valve and the engine.

33. The method according to claim 32, wherein said first pressure is greater than said second pressure by at least 3 kPa.

34. The method according to any one of claims 30 to 33, wherein said predetermined criteria further include temperature conditions in an airspace within the tank being considered desirable for venting to the engine.

35. The method according to claim 34, wherein said temperature conditions include a temperature of greater than 30°C.

36. The method according to any one of claims 30 to 35, wherein said predetermined criteria further include fuel vapor quantity conditions in an airspace within the tank being considered desirable for venting to the engine.

37. The method according to claim 36, wherein said fuel vapor quantity conditions is correlated to a predetermined fuel level within the tank.

38. The method according to claim 37, wherein said predetermined fuel level within the tank corresponds to a volume of fuel in the tank that is not greater than 80% of the volume of fuel when the tank is considered to be full.

39. A venting system for a fuel system of an engine, the fuel system including a fuel tank connectable directly to the engine via a conduit, the venting system comprising: an electrically actuated direct venting valve configured for being installed in the conduit to thereby enable selectively opening or closing fluid communication between the fuel tank and the engine;

a plurality of sensors for providing data indicative of conditions relating to the tank;

a control unit coupled to the sensors and to the direct venting valve, the control unit configured for operating the direct venting valve to open or close said fluid communication according to first predetermined criteria related to said data.

40. The venting system according to claim 39, wherein said first predetermined criteria include at least pressure conditions in an airspace within the tank being considered desirable for venting to the engine.

41. The venting system according to claim 40, wherein said pressure conditions comprise a first pressure in the airspace being greater than a second pressure in a portion of said conduit between the direct venting valve and the engine.

42. The venting system according to claim 41, wherein said first pressure is greater than said second pressure by at least 3 kPa.

43. The venting system according to any one of claims 39 to 42, wherein said first predetermined criteria further include temperature conditions in an airspace within the tank being considered desirable for venting to the engine.

44. The venting system according to claim 43, wherein said temperature conditions include a temperature of greater than 30°C.

45. The venting system according to any one of claims 39 to 44, wherein said first predetermined criteria further include fuel vapor quantity conditions in an airspace within the tank being considered desirable for venting to the engine.

46. The venting system according to claim 45, wherein said fuel vapor quantity conditions is correlated to a predetermined fuel level within the tank.

47. The venting system according to claim 46, wherein said predetermined fuel level within the tank corresponds to a volume of fuel in the tank that is not greater than 80% of the volume of fuel when the tank is considered to be full.

48. The venting system according to any one of claims 39 to 47, further comprising a main conduit for connecting the tank to a vapor recovery canister, and an electrically

actuated vent control valve configured for being installed in the main conduit to thereby enable selectively opening or closing fluid communication between the fuel tank and the vapor recovery canister.

49. The venting system according to claim 48, wherein the control unit is coupled to the sensors and to the electrically actuated vent control valve, the control unit being further configured for operating the electrically actuated vent control valve to open or close said fluid communication according to second predetermined criteria, wherein said second predetermined criteria include minimizing risk of liquid carry over (LCO) from the fuel tank to the vapor recovery canister.

50. The venting system according to claim 49, wherein the control unit is configured for causing the electrically actuated vent control valve to be closed concurrently with the direct venting valve being open.

51. The venting system according to any one of claims 48 to 50, wherein the control unit is configured for determining whether a fuel level in the tank, as sensed by at least one said sensor, exceeds a baseline level of fuel, wherein said baseline level of fuel corresponds to a maximum liquid carry over safe level of fuel in the tank.

52. The venting system according to claim 51, wherein the control unit is configured for maintaining the vent control valve open if the fuel level is not greater than the baseline level.

53. The venting system according to claim 52, wherein the control unit is further configured for determining the acceleration/deceleration of the tank.

54. The venting system according to claim 53, wherein the control unit is further configured for maintaining the vent control valve open if:

- the acceleration/deceleration of the tank does not exceed a respective baseline acceleration, and,

- the control unit determines that the rate of change of said acceleration/deceleration of the tank does not exceed a baseline acceleration rate.

55. The venting system according to claims 48 to 54, for example, the control unit is further configured for closing the vent control valve open if:

- the control unit determines that the acceleration/deceleration of the tank exceeds a respective baseline acceleration, or, if the control unit determines

that the rate of change of said acceleration/deceleration of the exceeds a baseline acceleration rate; and

- the control unit determines that a tank pressure is less than a maximum pressure corresponding to an over pressure limit for the tank which should not be exceeded

56. A fuel system comprising the venting system and tank as defined in any one of claims 39 to 55.

57. An assembly of an engine and a fuel system, the fuel system being as defined in claim 56, wherein the conduit is connected to the fuel tank and to the engine.

58. The assembly according to claim 47, wherein the conduit connects the fuel tank to an intake of the engine.

59. A vehicle comprising an assembly as defined in claim 57 or claim 58.

60. A method for venting a fuel system of an engine, the fuel system comprising at least a fuel tank and connected to the engine via a conduit, and further comprising an electrically actuated direct venting valve installed in the conduit to thereby enable selectively opening or closing direct fluid communication between the fuel tank and the engine, the method comprising

- providing data indicative of conditions relating to the tank;

- selectively operating the direct venting valve to allow venting the tank directly to the engine according to first predetermined criteria related to said data.

61. The method according to claim 60, wherein said conditions include fuel air ratio conditions in an airspace within the tank, and wherein said first predetermined criteria include said pressure conditions considered desirable for venting the tank directly to the engine.

62. The method according to claim 61, wherein said pressure conditions comprise a first pressure in the airspace being greater than a second pressure in a portion of said conduit between the direct venting valve and the engine.

63. The method according to claim 62, wherein said first pressure is greater than said second pressure by at least 3 kPa.

64. The method according to any one of claims 60 to 63, wherein said first predetermined criteria further include temperature conditions in an airspace within the tank being considered desirable for venting to the engine.

65. The method according to claim 64, wherein said temperature conditions include a temperature of greater than 30°C.

66. The method according to any one of claims 60 to 65, wherein said first predetermined criteria further include fuel vapor quantity conditions in an airspace within the tank being considered desirable for venting to the engine.

67. The method according to claim 66, wherein said fuel vapor quantity conditions is correlated to a predetermined fuel level within the tank.

68. The method according to claim 67, wherein said predetermined fuel level within the tank corresponds to a volume of fuel in the tank that is not greater than 80% of the volume of fuel when the tank is considered to be full.

69. The method according to any one of claims 60 to 68, the fuel system comprising at least the fuel tank and a vapor recovery canister, the fuel tank being connected to the vapor recovery canister via a main conduit, and further comprising an electrically actuated vent control valve installed in said main conduit to thereby enable selectively opening or closing fluid communication between the fuel tank and the vapor recovery canister, the method further comprising selectively operating the electrically actuated vent control valve to prevent venting of the tank to the vapor recovery canister under predetermined conditions including at least a first said condition indicative of potential liquid carry over from the tank to the vapor recovery canister.

70. The method according to claim 69, further comprising selectively operating the electrically actuated vent control valve to allow venting the tank to the vapor recovery canister responsive to a pressure in the tank being greater than a first predetermined threshold.

71. The method according to claim 69 or claim 70, comprising determining whether a fuel level in the tank exceeds a baseline level of fuel, wherein said baseline level of fuel corresponds to a maximum liquid carry over safe level of fuel in the tank.

72. The method according to any one of claims 69 to 71, wherein the vent control valve is maintained open if the fuel level is not greater than the baseline level.

73. The method according to any one of claims 69 to 72, comprising determining the acceleration/deceleration of the tank.

74. The method according to claim 73, comprising maintaining the vent control valve open if:

- the acceleration/deceleration of the tank does not exceed a respective baseline acceleration, and,

- the control unit determines that the rate of change of said acceleration/deceleration of the tank does not exceed a baseline acceleration rate.

75. The method according to claim 73 or claim 74, comprising closing the vent control valve open if:

- the acceleration/deceleration of the tank exceeds a respective baseline acceleration, or, if the rate of change of said acceleration/deceleration of the exceeds a baseline acceleration rate; and

- a tank pressure is less than a maximum pressure corresponding to an over pressure limit for the tank which should not be exceeded.