Measuring instrument that senses heat transfer along a probe

A measuring instrument that senses heat transfer along a probe that is inserted at least partially into an environment, the heat transfer occurring between the probe and the environment, comprising:

• a metallic tubular sheath having a U-shape with two parallel side-by-side upright spaced apart legs, said legs having top ends and bottom ends, and a lower transverse connecting segment connecting the bottom ends of said legs;
• a heater circuit having a heater cable segment disposed in and along the length of said first leg;
• an electrical insulator disposed inside said sheath, having an elongate heater passageway disposed at least in said first leg for receiving said heater circuit and having a plurality of elongate sensor passageways extending through said first leg, said connecting segment and said second leg;
• a first sensor wire extending through said one of said sensor passageways from the top end of said first leg to the top end of said second leg, said first sensor wire having a heated thermocouple junction disposed in said first leg and a non-heated thermocouple junction disposed in said second leg at a position perpendicularly across from the heated thermocouple junction, a voltage potential being produced across said first sensor wire that is proportional to the temperature of said heated thermocouple junction relative to the temperature of said non-heated thermocouple junction;
• at least a second sensor wire extending through one of said sensor passageways from the top end of said first leg to the top end of said second leg, said sensor wire having a heated thermocouple junction disposed in said first leg at a position along said first leg different from the position of said heated thermocouple junction of said first sensor wire and having a non-heated thermocouple junction disposed in said second leg perpendicularly across from said heated thermocouple junction of said second sensor wire, a voltage potential being produced across said second sensor wire that is proportional to the temperature of said heated thermocouple junction of said second sensor wire relative to the temperature of said non-heated thermocouple junction thereof;
• and
• circuit means connected to said first and second sensor wires for producing an output signal indicating the voltage potentials produced by said first and second sensor wires.

A measuring instrument that senses heat transfer along a probe inserted at least partially into a liquid in a vessel to measure to the level of the liquid, comprising:

• a metallic tubular sheath having a U-shape with two parallel side-by-side upright spaced apart legs for being disposed vertically in a vessel, said legs having top ends and bottom ends, and a lower transverse connecting segment connecting the bottom ends of said legs;
• a heater circuit having a heater cable segment disposed in and along the length of at least said first leg;
• an electrical insulator disposed inside said sheath, having an elongate heater passageway disposed at least in said first leg for receiving said heater circuit and having a plurality of elongate sensor passageways extending through said first leg, said connecting segment and said second leg;
• a first sensing wire extending through one of said sensor passageways from the top end of said first leg to the top end of said second leg, said first sensor wire including a first elongate resistor extending along at least a portion of the length of said first leg and having a resistance that varies with the temperature of said first elongate resistor for sensing liquid levels at a plurality of positions vrtically along said first leg;
• a second sensor wire extending through one of said sensor passageways from the top end of said first leg to the top end of said second leg, said second sensor wire including a second elongate resistor extending along at least a portion of the length of said second leg and having a resistance that varies with the temperature of said second elongate resistor for sensing ambient temperatures at a plurality of positions vertically along said second leg;
• and
• circuit means connected to said first and second elongate sensor wires for producing at least one output signal indicating the resistances of said first and second sensor wires.