Liquid sensor and ice detector

• US 20070113646A1
• Filed: 12/18/2006
• Published: 05/24/2007
• Est. Priority Date: 12/16/2003
• Status: Active Grant

• Current Assignee: Josef Maatuk
• Original Assignee: Josef Maatuk
• Inventors: Maatuk, Josef
• Granted Patent: US 7,334,471 B2
• Time in Patent Office: Days
• US Class Current: 73/295
• CPC Class Codes: G01F 23/246 thermal devices
• CPC Class Codes: G01F 23/247 for discrete levels

Abstract

An improved apparatus and a method of measuring and interpreting reliably, simply and accurately the information on continuous liquid level, liquid temperature and other liquid properties within a vessel. The apparatus is suited for economical manufacturing and could be made of a powered heater element and temperature sensors that can be screen-printed, vacuum deposited, etched, welded, soldered or plated on one or both sides of a single rigid or a flexible substrate. The apparatus is compact and light weight and can be installed in relatively small liquid containers if necessary; Various parallel and serial configurations of thermocouples or temperature sensors can be used to measure the temperature along a heater. Simultaneous measurements from all the temperature sensors, before and after heat is applied, are used to generate accurate temperature profiles for the entire heater. Different features of the temperature profiles will determine accurately the liquid level, liquid temperature and other liquid properties.

Claims

1. ) A liquid level sensor comprising:

a substrate;

a common heater wire;

temperature sensors;

said common heater and temperature sensors are secured along the said substrate;

said sensor is positioned within a vessel containing a volume of liquid with said substrate partially immersed in said liquid such that the temperature sensors will generate a signal indicative of the level of liquid within said vessel.

2. ) A liquid level sensor as set forth in claim 1 wherein said substrate is a single layer or a multi-layer;

3. ) A liquid level sensor as set forth in claim 1 wherein said common heater having uniform or non-uniform cross-section.

4. ) A liquid level sensor as set forth in claim 1 wherein said temperature sensors are serially connected thermocouples;

5. ) A liquid level sensor as set forth in claim 4 wherein cold junctions of said thermocouples are connected by an isothermal block.

6. ) A liquid level sensor as set forth in claim 1 wherein said temperature sensors are thermocouples connected in a parallel configuration.

7. ) A liquid level sensor as set forth in claim 1 wherein said temperature sensors are located at strategic vertically spaced points and located very close to the common heater on either side of said substrate.

8. ) A liquid level sensor as set forth in claim 1 further comprising means for applying power to heat said common heater wire, controlled by a power control switch and power circuitry, wherein both ends of said common heater wire are connected to said electrical power applying means for heating by continuous or discrete electrical pulses of said common heater.

9. ) A liquid level sensor as set forth in claim 8 wherein said power circuitry is mounted on said substrate.

10. ) A liquid level sensor as set forth in claim 1 wherein a signal conditioning circuitry filters and amplifies said signal from said thermocouples.

11. ) A liquid level sensor as set forth in claim 10 wherein said signal conditioning circuitry is mounted on said substrate.

12. ) A liquid level sensor as set forth in claim 1, further comprising a signal processing software, capable of eliminating non-random electronic hardware errors and minimizing random errors in differential voltage reading of said thermocouples.

13. ) A liquid level sensor as set forth in claim 1, further comprising of a signal processing software capable of determining absolute temperature of each said thermocouples using said differential voltages.

14. ) A liquid level sensor as set forth in claim 1 further comprising a thermally conductive, electrically insulating, chemically inert, slippery and liquid impermeable, encapsulating coating of said sensor.

15. ) A method for accurately determining the density and pressure change of compressible fluid and the liquid parameters of level, absolute temperature and viscosity degradation in a three dimensional liquid container, said method comprising of three components on a monotonic 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;

reading of a point or a few points along each of said three components will be used to construct said profile

adding, averaging or interpolation of said readings from said points determine with different accuracy the said density and pressure changes, liquid level, absolute temperature and viscosity degradation.

16. ) The method recited in claim 15 wherein said monotonic profile is a voltage or temperature profile, each of its three components is constructed from reading of one or more hot thermocouple junctions after power is applied to the heater and after zeroing one of the voltage and the temperature reading from all of the hot thermocouple junctions while the cold junctions temperature remains equal and constant for all of the cold thermocouple junctions.

17. ) The method recited in claim 16 wherein the said monotonic profile is used to detect the presence of two or more different stratified liquids, such as oil and water, and determining the level of each liquid.

18. ) The method recited in claim 16 wherein the said monotonic profile is used to detect the level at pre-set points at one of the bottom and top of liquid containers such as oil pans, fuel tanks and coolant reservoir.

19. ) The method recited in claim 16 wherein the said monotonic profile is used to determine 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.