Thermistor-based fuel sensor
First Claim
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1. A fuel level sensing system for use in conjunction with a fuel tank, the sensing system comprising:
- a plurality of temperature sensors adapted to be positioned at different heights of an internal fuel tank surface;
an energy source coupled to inputs of each of the plurality of temperature sensors; and
a controller coupled to outputs of each of the plurality of temperature sensors, the controller operative to determine an initial temperature of each temperature sensor before each temperature sensor is heated, to energize each sensor with a supply of constant voltage from the energy source for at least a predetermined stabilizing time period, to determine a stabilized temperature of each temperature sensor after the stabilizing time period has elapsed while each sensor is still being energized and heated by said supply of constant voltage, and to determine whether each temperature sensor is immersed in fuel as a function of each sensor'"'"'s stabilized temperature.
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Abstract
A system for sensing a fuel level includes sensors that sense the fuel level and a voltage source that applies a constant voltage to the sensors for a predetermined time. The system includes a control module that measures outputs of the sensors at a beginning and at an end of the predetermined time. The control module determines a number of the sensors that are submersed in fuel or air based on the outputs and calculates the fuel level based on the number of the sensors that are submersed in fuel or air.
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Citations
18 Claims
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1. A fuel level sensing system for use in conjunction with a fuel tank, the sensing system comprising:
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a plurality of temperature sensors adapted to be positioned at different heights of an internal fuel tank surface; an energy source coupled to inputs of each of the plurality of temperature sensors; and a controller coupled to outputs of each of the plurality of temperature sensors, the controller operative to determine an initial temperature of each temperature sensor before each temperature sensor is heated, to energize each sensor with a supply of constant voltage from the energy source for at least a predetermined stabilizing time period, to determine a stabilized temperature of each temperature sensor after the stabilizing time period has elapsed while each sensor is still being energized and heated by said supply of constant voltage, and to determine whether each temperature sensor is immersed in fuel as a function of each sensor'"'"'s stabilized temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for sensing fuel level in a fuel tank, comprising:
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positioning a plurality of temperature sensors at different heights of an interior surface of the fuel tank; determining an initial temperature of each sensor before each sensor is heated; energizing each sensor with an energy source providing a supply of constant voltage for at least a predetermined stabilizing time period; determining a stabilized temperature of each sensor after the stabilizing time period has elapsed while each sensor is still being energized and heated by said supply of constant voltage; and determining whether each sensor is immersed in fuel as a function of each sensor'"'"'s stabilized temperature. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification