Abstract: It is proposed a method for determining a quantity of a liquid in a tank, the tank comprising: a first ultrasound subsystem capable of measuring level of liquid present above a predetermined threshold level within the tank; and at least one second ultrasound subsystem, said second ultrasound subsystem being associated with a sensing area within the tank and being configured to measure a parameter characteristic of the liquid, said sensing area being located below the predetermined threshold level. The method comprises in the steps of: —checking the validity of the measurement performed by said first ultrasound subsystem (S10); —when it is detected that the measurement of said first ultrasound system is not valid: (a) checking (S22) the validity of the measurement performed by said second ultrasound subsystem; (b) determining (S24, S25, S26) a quantity of liquid, which quantity being based on a result of the validity check at step (a).

Abstract: A method for estimating a volume of thawed liquid in a motor vehicle tank, wherein the following operations are executed at regular time intervals: obtaining a temperature of the ambient air outside the tank using a thermometer; determining, according to said temperature outside the tank and by a first pre-established relation, a thermal energy transfer between the contents of the tank and the outside environment; determining, as a function of the power produced by a heating element, and by a second pre-established relation, a thermal energy transfer between the heating element and the contents of the tank; determining, as a function of the energy transfers, and by a third pre-established relation, an amount of thawed or refrozen liquid, during said time interval; the amounts of thawed and refrozen liquid are added during the preceding consecutive time intervals to estimate a volume of thawed liquid present in the tank.

Abstract: A method for estimating a volume of thawed liquid in a motor vehicle tank, wherein the following operations are executed at regular time intervals: obtaining a temperature of the ambient air outside the tank using a thermometer; determining, according to said temperature outside the tank and by a first pre-established relation, a thermal energy transfer between the contents of the tank and the outside environment; determining, as a function of the power produced by a heating element, and by a second pre-established relation, a thermal energy transfer between the heating element and the contents of the tank; determining, as a function of the energy transfers, and by a third pre-established relation, an amount of thawed or refrozen liquid, during said time interval; the amounts of thawed and refrozen liquid are added during the preceding consecutive time intervals to estimate a volume of thawed liquid present in the tank.

Abstract: It is proposed a method for determining a quantity of a liquid in a tank, the tank comprising: a first ultrasound subsystem capable of measuring level of liquid present above a predetermined threshold level within the tank; and at least one second ultrasound subsystem, said second ultrasound subsystem being associated with a sensing area within the tank and being configured to measure a parameter characteristic of the liquid, said sensing area being located below the predetermined threshold level. The method comprises in the steps of: checking the validity of the measurement performed by said first ultrasound subsystem (S10); when it is detected that the measurement of said first ultrasound system is not valid: (a) checking (S22) the validity of the measurement performed by said second ultrasound subsystem; (b) determining (S24, S25, S26) a quantity of liquid, which quantity being based on a result of the validity check at step (a).