Microprocessor-based liquid sensor and ice detector

• US 20020100318A1
• Filed: 05/01/2001
• Published: 08/01/2002
• Est. Priority Date: 03/31/1995
• Status: Active Grant

• Current Assignee: Josef Maatuk
• Original Assignee: Josef Maatuk
• Inventors: Maatuk, Josef
• Granted Patent: US 6,776,037 B2
• Time in Patent Office: Days
• US Class Current: 73/295
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing
• CPC Class Codes: B64D 37/005 Accessories not provided for in the groups B64D37/02 - B64D37/28
• CPC Class Codes: G01F 23/22 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water involving the use of floats G01F23/30
• CPC Class Codes: G01F 23/247 for discrete levels
• CPC Class Codes: G01F 23/248 Constructional details; Mounting of probes

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.

Claims

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.

2. ) The apparatus recited in claim 1, whereby the Constantan strip and the Copper elements can be of other combination of thermocouple elements.

3. ) The apparatus recited in claim 1, wherein said constantan strip is an electrically pulsed heater and the common wire for said thermocouples.

4. ) A data acquisition comprising:

two multiplexers for odd and even thermocouples;

wiring of said multiplexers to a single differential amplifier;

said differential amplifier wired to a microprocessor;

said microprocessor wired to the apparatus recited in claim 1, and a display through a serial and digital to analog input/output;

said microprocessor connected to a power supply capable of having a power switched on and off.

8. ) Apparatus for detecting ice on horizontal and vertical surfaces, said apparatus comprising:

apparatus of claim 1;

a dome over one of the thermocouples of the apparatus of claim 1.

9. ) A method for accurately detecting ice on one of horizontal and vertical and inclined surfaces, said method comprising the steps of:

determining the presence of ice on any section of said surfaces from any of three parameters of said differential voltage and temperature from each said thermocouples;

existence of a time-delay of said differential voltage time behavior of each thermocouple will indicate the presence of ice on the location of such thermocouple;

a steady-state differential voltage for each thermocouple close to the steady-state voltage of the thermocouple under the dome of claim 8 will indicate the presence of ice on such thermocouple;

a response time of the differential voltage for each thermocouple close to the response time of the voltage of the thermocouple under the dome of claim 8 will indicate the presence of ice on such thermocouple.

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.

6. ) software of said data acquisition, capable of determining absolute temperature of each said thermocouples using said differential voltages.

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.

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:

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.