Patent ID: 8248888

Claim:
A contact type ultrasonic bottom up sensor to measure the level of liquid in a vessel, comprising: an elongated tubular probe having an end to be located near the vessel bottom and an opening though which the vessel liquid can enter the probe interior; a tube within said probe having an end spaced from said end of said probe; a transducer that converts electrical energy signals to ultrasonic energy mounted at or near said end of said tube to transmit and receive ultrasonic energy though liquid in the probe in directions generally along the probe longitudinal axis; and a generally conical shaped reflector at said end of said probe opposing said transducer having first and second opposing surfaces that reflects ultrasonic energy, said reflector first surface being opposite to an ultrasonic energy emitting and receiving part of said transducer to reflect ultrasonic energy transmitted downwardly from said transducer within said probe to said reflector second surface which directs the ultrasonic energy reflected from said reflector first surface upwardly to an air-liquid interface in the probe from which it is directed downwardly back to said reflector second surface and reflected to said reflector first surface from which the energy reflected from the interface is reflected upwardly back to said transducer for conversion to an electrical signal to be used for measuring the round-trip travel time of the ultrasonic energy from said transducer to the air liquid interface within the probe.