Rosemount Aerospace Limited

Eric David Haugen

Charles George Huss

Greg Allen Seidel

Derrick David Hongerholt

Jeffrey P Danicich

Mark R Koosmann

Stephen R Meyer

Gary A Willms

A built-in test system for an ultrasonic liquid level sensor that includes a transducer assembly having an ultrasonic transducer, and a switch that will be actuated when the ultrasonic transducer is in intimate contact with a surface of a tank in which level is to be determined. Once the switch is actuated to indicate that the ultrasonic transducer is properly coupled to the surface, a test sequence is initiated to determine that the level of ultrasonic transmissions are above a certain desired threshold for a selected period of time, and after which the circuit looks for echoes to determine the depth of the liquid in the tank. Thereafter, the test sequence is repeated for each cycle of level sensing.

Built-in test procedure for non-intrusive ultrasonic level sensing

For use with a high gain receiver circuit which receives echo pulses of frequencies within a predetermined bandwidth and at times within interpulse periods of a predetermined pulse repetition rate and amplifies the echo pulses for measurement purposes, the receiver circuit susceptible to electrical noise within the frequency bandwidth of the received echo pulses to create false echo pulses, a method of eliminating substantially the false echo pulses without affecting substantially the amplified echo pulses by accepting only echo pulses which occur synchronously among interpulse periods. The pulse repetition rate may be varied to eliminate false echo pulses that are synchronous to the interpulse periods.

Method and apparatus for eliminating substantially false echoes produced by electrical noise induced into high gain receiver circuits

A liquid level sensor used for determining liquid levels in a sealed container includes a heat source bonded to the container, a first temperature sensor mounted on the container adjacent the heat source, and a second temperature sensor mounted on the container spaced from the heat source. The temperatures at the first and second temperature sensors are sensed while the heat source is operating, and the differential in the temperatures is measured and used to control power to the heater. Changes in the differential in temperature between the first and second temperature sensors indicates when the heat conductivity between the first and second temperature sensors changes, due to presence or absence of a liquid in the container at the level of the temperature sensors.

Apparatus and method to non-intrusively measure the level of liquid in a sealed container

A sensor for measuring the height of fluid in a vessel, the sensor including a mounting base shaped to be coupled to an exterior surface of a vessel. The sensor further includes a transducer having a pulse source for sending pulses into the vessel and an echo detector for detecting echoes of pulses emitted by the pulse source. The sensor further has a dry couplant located between the transducer and the mounting base, and a processor connected to the transducer for calculating the height of fluid in the vessel based at least in part upon the time elapsed between the pulses sent by the transducer and echoes detected by the echo detector.

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Farmington, MN, United States of America

Eric David Haugen