Apparatus for monitoring the level of liquid by resistive wire

Claim 1

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially immersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said resistive wire probe; means for detecting an electrical parameter in said resistive wire probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said resistive wire probe; means for monitoring any variation in said electrical parameter from its initial value and for generating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said tables being associated with initial values of said parameters being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value.

Claim 2

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially immersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said resistive wire probe; means for detecting an electrical parameter in said resistive wire probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said resistive wire probe; means for monitoring any variation in said electrical parameter from its initial value and for generating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said tables being associated with initial values of said parameters being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value.

Claim 3

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially submersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said probe; means for detecting an electrical parameter of said probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; means for comparing said electrical parameter with a reference value and for calculating a differential parameter representative of an elapsed time taken for said electrical parameter to reach said reference value, said differential parameter being related to the level of said liquid; converting means for converting said differential parameter into digital value; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameters being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value; memory means for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; means for determining from said memory means a digital liquid level value corresponding to said corrected differential parameter digital value; display means for displaying said digital liquid level value.

Claim 4

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially submersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said probe; means for detecting an electrical parameter of said probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; means for comparing said electrical parameter with a reference value and for calculating a differential parameter representative of an elapsed time taken for said electrical parameter to reach said reference value, said differential parameter being related to the level of said liquid; converting means for converting said differential parameter into digital value; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameters being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value; memory means for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; means for determining from said memory means a digital liquid level value corresponding to said corrected differential parameter digital value; display means for displaying said digital liquid level value.

Claim 5

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially submersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for supplying electrical energy to said probe; means for limiting the amount of energy supplied to said probe to a predetermined amount; means for detecting an electrical parameter of said probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; means for determining when the energy applied to said probe equals said predetermined amount; means for monitoring any variation in said electrical parameter from its initial value until said energy supplied equals said predetermined amount and for calculating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of said liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values converted by said converting means, said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameters being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value converted by said converting means, and for generating a corrected differential parameter digital value; memory means for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; means for determining from said memory means a digital liquid level value corresponding to said corrected differential parameter digital value; display means for displaying said digital liquid level value.

Claim 6

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially submersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for supplying electrical energy to said probe; means for limiting the amount of energy supplied to said probe to a predetermined amount; means for detecting an electrical parameter of said probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; means for determining when the energy applied to said probe equals said predetermined amount; means for monitoring any variation in said electrical parameter from its initial value until said energy supplied equals said predetermined amount and for calculating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of said liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values converted by said converting means, said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameters being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value converted by said converting means, and for generating a corrected differential parameter digital value; memory means for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; means for determining from said memory means a digital liquid level value corresponding to said corrected differential parameter digital value; display means for displaying said digital liquid level value.

Claim 7

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially submersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said probe through a series resistance; means for detecting an electrical parameter of said probe and of said resistance; means for memorizing initial values of said electrical parameter of said probe and said resistance when electrical energy is applied to said probe and resistance; means for monitoring any variation in said electrical parameter of said probe and resistance from said initial values and for calculating a differential parameter representative of the variation in said electrical parameters, said differential parameter being related to the level of said liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial values of said electrical parameter of said probe and resistance; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value; memory means for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; means for determining from said memory means a digital liquid level value corresponding to said corrected differential parameter digital value; display means for displaying said digital liquid level value.

Claim 8

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially submersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said probe through a series resistance; means for detecting an electrical parameter of said probe and of said resistance; means for memorizing initial values of said electrical parameter of said probe and said resistance when electrical energy is applied to said probe and resistance; means for monitoring any variation in said electrical parameter of said probe and resistance from said initial values and for calculating a differential parameter representative of the variation in said electrical parameters, said differential parameter being related to the level of said liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial values of said electrical parameter of said probe and resistance; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value; memory means for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; means for determining from said memory means a digital liquid level value corresponding to said corrected differential parameter digital value; display means for displaying said digital liquid level value.

Claim 12

A method for determining a level of a liquid in a tank using a temperature sensitive resistive wire probe at least partially immersed in said liquid, in a generally vertical orientation in said tank comprising: supplying electrical energy to said probe; limiting the amount of energy supplied to said probe to a predetermined amount; detecting an electrical parameter of said probe; memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; determining when the energy applied to said probe equals said predetermined amount; monitoring any variation in said electrical parameter from its initial value until said energy supplied equals said predetermined amount; calculating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of said liquid; converting said differential parameter into digital values; storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said correspondence tables being associated with initial values of said parameter being detected; selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value; generating a corrected differential parameter digital value; storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; determining from said table of correspondence a digital liquid level value corresponding to said corrected differential parameter digital value; and displaying said digital liquid level value.

Claim 13

A method for determining a level of a liquid in a tank using a temperature sensitive resistive wire probe at least partially immersed in said liquid, in a generally vertical orientation in said tank comprising: supplying electrical energy to said probe; limiting the amount of energy supplied to said probe to a predetermined amount; detecting an electrical parameter of said probe; memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; determining when the energy applied to said probe equals said predetermined amount; monitoring any variation in said electrical parameter from its initial value until said energy supplied equals said predetermined amount; calculating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of said liquid; converting said differential parameter into digital values; storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said correspondence tables being associated with initial values of said parameter being detected; selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value; generating a corrected differential parameter digital value; storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital liquid level values; determining from said table of correspondence a digital liquid level value corresponding to said corrected differential parameter digital value; and displaying said digital liquid level value.

Claim 14

A method for determining a level of a liquid in a tank using a temperature dependent resistive wire probe at least partially immersed in said liquid, in a generally vertical orientation in said tank comprising: applying electrical energy to said probe through a series resistance; detecting an electrical parameter of said probe and of said resistance; memorizing initial values of said electrical parameter of said probe and said resistance when electrical energy is applied; monitoring any variation in said electrical parameter of said probe and resistance from said initial values; calculating a differential parameter representative of the variation in said electrical parameters, said differential parameter being related to the level of said liquid; converting said differential parameter into digital values; storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said correspondence tables being associated with initial values of said parameter being detected; selecting the associated one of said plurality of correspondence tables depending upon the memorized initial values of said electrical parameter of said probe and resistance; determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value; generating a corrected differential parameter digital value; storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital level values; determining from said table of correspondence a digital liquid level value corresponding to said corrected differential parameter digital value; and displaying said digital liquid level value.

Claim 15

A method for determining a level of a liquid in a tank using a temperature dependent resistive wire probe at least partially immersed in said liquid, in a generally vertical orientation in said tank comprising: applying electrical energy to said probe through a series resistance; detecting an electrical parameter of said probe and of said resistance; memorizing initial values of said electrical parameter of said probe and said resistance when electrical energy is applied; monitoring any variation in said electrical parameter of said probe and resistance from said initial values; calculating a differential parameter representative of the variation in said electrical parameters, said differential parameter being related to the level of said liquid; converting said differential parameter into digital values; storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said correspondence tables being associated with initial values of said parameter being detected; selecting the associated one of said plurality of correspondence tables depending upon the memorized initial values of said electrical parameter of said probe and resistance; determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value; generating a corrected differential parameter digital value; storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital level values; determining from said table of correspondence a digital liquid level value corresponding to said corrected differential parameter digital value; and displaying said digital liquid level value.

Claim 16

A method for determining a level of a liquid in a tank using a temperature dependent resistive wire probe at least partially immersed in the liquid, in a generally vertical orientation in said tank comprising: applying electrical energy to said probe; detecting an electrical parameter in said probe; memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; monitoring any variation in said electrical parameter from its initial value and calculating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting said differential parameter into digital values; storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said correspondence tables being associated with initial values of said parameter being detected; selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value; generating a corrected differential parameter digital value; storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital level values; determining from said table of correspondence a digital level value corresponding to the corrected differential parameter digital value; and displaying the corrected digital level value.

Claim 17

A method for determining a level of a liquid in a tank using a temperature dependent resistive wire probe at least partially immersed in the liquid, in a generally vertical orientation in said tank comprising: applying electrical energy to said probe; detecting an electrical parameter in said probe; memorizing an initial value of said electrical parameter when electrical energy is applied to said probe; monitoring any variation in said electrical parameter from its initial value and calculating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting said differential parameter into digital values; storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means, said correspondence tables being associated with initial values of said parameter being detected; selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value; generating a corrected differential parameter digital value; storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital level values; determining from said table of correspondence a digital level value corresponding to the corrected differential parameter digital value; and displaying the corrected digital level value.

Claim 18

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially immersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said resistive wire probe; means for detecting an electrical parameter in said resistive wire probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said resistive wire probe; means for monitoring any variation in said electrical parameter from its initial value and for generating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value; a second memory for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital level values; means for determining from said second memory means a digital level value corresponding to the corrected differential parameter digital value; and display means for displaying the corrected digital level value.

Claim 19

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially immersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said resistive wire probe; means for detecting an electrical parameter in said resistive wire probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said resistive wire probe; means for monitoring any variation in said electrical parameter from its initial value and for generating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said tables being associated with initial values of said parameter being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value; a second memory for storing a table of correspondence between possible digital values of said corrected differential parameter and associated digital level values; means for determining from said second memory means a digital level value corresponding to the corrected differential parameter digital value; and display means for displaying the corrected digital level value.