Microprocessor-based liquid sensor and ice detector
First Claim
1. ) Apparatus for determining accurately the level in a liquid container, said apparatus comprising:
- a constantan strip secured along the longitudinal extent of the face of an elongated substrate or plastic sheet;
a plurality of copper pads secured to said substrate, each pad having one end electrically connected to said constantan strip to form a plurality of thermocouples, said thermocouples being spaced apart over the longitudinal extent of said constantan strip;
a thin dielectric film secured to said substrate covering said thermocouples for electrically isolating said thermocouples from air or liquid;
means for applying electrical power to said constantan strip, controlled by a power control switch, wherein both ends of said constantan strip are connected to said electrical power applying means for heating by electrical pulses of said constantan strip;
display means for indicating the liquid level in said liquid container;
a data acquisition means comprising a microprocessor connected to said thermocouples and display means for indicating said liquid level from temperatures sensed by said thermocouples.
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Accused Products
Abstract
Apparatus and a method of operating any structural configuration of a heater and array of temperature sensors to measure with high accuracy, the level of stratified liquids like water and oil or water and gasoline and non-stratified liquids, liquid temperature, and other liquid properties and detect ice formation on aircraft surfaces. Thin and narrow strips of dissimilar material will be used for the heater, array of temperature sensors, mount, and coating. The connecting wires to and from the apparatus will be from the same material. Simultaneous measurements from all the temperature sensors, before and after heat is applied, will be used to generate accurate temperature profiles for the entire configuration and not just from two adjacent temperature sensors. Different features of the temperature profiles will determine accurately the liquid level, liquid temperature and other liquid properties. Apparatus of the invention may also be used to detect ice formation.
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Citations
10 Claims
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1. ) Apparatus for determining accurately the level in a liquid container, said apparatus comprising:
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a constantan strip secured along the longitudinal extent of the face of an elongated substrate or plastic sheet;
a plurality of copper pads secured to said substrate, each pad having one end electrically connected to said constantan strip to form a plurality of thermocouples, said thermocouples being spaced apart over the longitudinal extent of said constantan strip;
a thin dielectric film secured to said substrate covering said thermocouples for electrically isolating said thermocouples from air or liquid;
means for applying electrical power to said constantan strip, controlled by a power control switch, wherein both ends of said constantan strip are connected to said electrical power applying means for heating by electrical pulses of said constantan strip;
display means for indicating the liquid level in said liquid container;
a data acquisition means comprising a microprocessor connected to said thermocouples and display means for indicating said liquid level from temperatures sensed by said thermocouples. - View Dependent Claims (2, 3, 4, 8, 9)
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5. ) software used with the microprocessor of said data acquisition, capable of eliminating non-random electronic hardware errors and minimizing random errors in differential voltage reading of said thermocouples.
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6. ) software of said data acquisition, capable of determining absolute temperature of each said thermocouples using said differential voltages.
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7. ) software of said data acquisition, capable of determining the kind of liquid based on curvature of the temperature profile and the rise of temperature of the thermocouples in liquid, and thermocouples in air.
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10. ) A method for accurately determining the liquid parameters of level, temperature and viscosity in a three dimensional liquid container, said method comprising of three components on the temperature profile, namely:
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a line along most of the lineal dimension of the sensor that is immersed in liquid;
a line along a significant portion of the lineal dimension of the sensor that is in air or other medium above the liquid;
a steep or shallow curved line connecting said two lines.
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Specification