Method and device for detecting the fluid level in a tank

Claim 1

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; and if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes obtaining the pressure change in form of a build-up of partial vacuum in the tank with a tank venting system by closing a shut-off valve in a venting line of an adsorption filter connected to the tank and opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle.

Claim 2

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; and if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes obtaining the pressure change in form of a build-up of partial vacuum in the tank with a tank venting system by closing a shut-off valve in a venting line of an adsorption filter connected to the tank and opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle.

Claim 8

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes obtaining the pressure change in form of a build-up of partial vacuum in the tank with a tank venting system by closing a shut-off valve in a venting line of an adsorption filter connected to the tank, and opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle; and detecting a build-up gradient occurring during the build-up of partial vacuum, and using it as the pressure change gradient parameter for determining the fluid level.

Claim 9

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes obtaining the pressure change in form of a build-up of partial vacuum in the tank with a tank venting system by closing a shut-off valve in a venting line of an adsorption filter connected to the tank, and opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle; and detecting a build-up gradient occurring during the build-up of partial vacuum, and using it as the pressure change gradient parameter for determining the fluid level.

Claim 10

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes obtaining the pressure change in form of a build-up of partial vacuum in the tank with a tank venting system by closing a shut-off valve in a venting line of an adsorption filter connected to the tank, and opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle; detecting a build-up gradient occurring during the build-up of partial vacuum; and detecting a reduction gradient occurring during the reduction in the partial vacuum, and combining the build-up gradient and the reduction gradient mathematically in such a way that an influence of the fluid level is apparent as clearly as possible and a combination parameter is produced and used as the pressure change gradient parameter for determining the fluid level.

Claim 11

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes obtaining the pressure change in form of a build-up of partial vacuum in the tank with a tank venting system by closing a shut-off valve in a venting line of an adsorption filter connected to the tank, and opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle; detecting a build-up gradient occurring during the build-up of partial vacuum; and detecting a reduction gradient occurring during the reduction in the partial vacuum, and combining the build-up gradient and the reduction gradient mathematically in such a way that an influence of the fluid level is apparent as clearly as possible and a combination parameter is produced and used as the pressure change gradient parameter for determining the fluid level.

Claim 13

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes achieving the pressure change in form of a reduction in partial vacuum in the tank wit a tank venting system by closing a shutoff valve in a venting line of an adsorption filter connected to the tank, opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle until at least one predetermined pressure is reached, and then closing the tank venting valve again and thereafter reducing the partial vacuum in the tank; and detecting a build-up gradient occurring during the build-up of partial vacuum; detecting a reduction gradient occurring during the reduction in the partial vacuum, and combining the build-up gradient and the reduction gradient mathematically in such a way that an influence of the fluid level is apparent as clearly as possible and a combination parameter is produced and used as the pressure change gradient parameter for determining the fluid level.

Claim 14

A method for detecting a fluid level of fuel in a tank of a motor vehicle, the method comprising the steps of assessing tank conditions whether the tank at least achieves a predetermined leaktightness and whether the fuel vaporized less than corresponds to a predetermined value; if the conditions are fulfilled, detecting a fuel level, said detecting including subjecting a volume of the tank to pressure changes, determining an associated value of a pressure change gradient parameter from at least one achieved pressure change and one time period associated therewith due to said pressure changes, and estimating an instantaneous value of the fluid level from a known interrelation between the pressure change gradient parameter and the fluid level, said subjecting includes achieving the pressure change in form of a reduction in partial vacuum in the tank wit a tank venting system by closing a shutoff valve in a venting line of an adsorption filter connected to the tank, opening a tank venting valve in a valve line between the adsorption filter and an intake line of an internal combustion engine of the motor vehicle until at least one predetermined pressure is reached, and then closing the tank venting valve again and thereafter reducing the partial vacuum in the tank; and detecting a build-up gradient occurring during the build-up of partial vacuum; detecting a reduction gradient occurring during the reduction in the partial vacuum, and combining the build-up gradient and the reduction gradient mathematically in such a way that an influence of the fluid level is apparent as clearly as possible and a combination parameter is produced and used as the pressure change gradient parameter for determining the fluid level.

Claim 16

A device for detecting a fluid level of fuel in a tank of a motor vehicle, comprising tank leaktightness testing means; gas evaluation testing means for testing whether the fuel in the tank vaporizes; pumping-out/sequence control means for subjecting the tank to a pressure change with respect to time; gradient detecting means for detecting a value of a pressure change gradient parameter from at least one pressure change and one time period associated therewith; and fluid level output means which receives signals from said tank leaktightness testing means, said gas evaluation testing means, and said gradient detecting means in order to output an instantaneous value of the fluid level with the aid of a known interrelationship between the pressure change gradient parameter and the fluid level whenever the tank is sufficiently leaktight and the vaporization of the fuel is sufficiently low.

Claim 17

A device for detecting a fluid level of fuel in a tank of a motor vehicle, comprising tank leaktightness testing means; gas evaluation testing means for testing whether the fuel in the tank vaporizes; pumping-out/sequence control means for subjecting the tank to a pressure change with respect to time; gradient detecting means for detecting a value of a pressure change gradient parameter from at least one pressure change and one time period associated therewith; and fluid level output means which receives signals from said tank leaktightness testing means, said gas evaluation testing means, and said gradient detecting means in order to output an instantaneous value of the fluid level with the aid of a known interrelationship between the pressure change gradient parameter and the fluid level whenever the tank is sufficiently leaktight and the vaporization of the fuel is sufficiently low.