Bottom up contact type ultrasonic continuous level sensor

1. 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.

2. The sensor as claimed in claim 1 further comprising a cap having said reflector that is mounted at said end of said probe to mount said reflector first surface within said probe opposite an ultrasonic energy transmitting and receiving part of said transducer.

3. The sensor as claimed in claim 1 and further comprising an electronics module that supplies electrical signals to said transducer for conversion to ultrasonic energy and uses the supplied electrical signals and signals returned from said transducer after reflection from the liquid-air interface in the probe to measure the round trip travel time of the ultrasonic energy in the liquid in said probe.

4. The sensor as claimed in claim 1 further comprising a member on which said transducer is mounted and which said member seals the end of said tube.

5. The sensor as claimed in claim 4 wherein said cap has openings to admit liquid into the probe interior.

6. The sensor as claimed in claim 1 wherein each of said reflector first and second surfaces is flat and said surfaces are connected in has a generally conical V shape.

7. The sensor as claimed in claim 1 and further comprising a pin reflective to ultrasonic energy mounted within said probe at a fixed distance from said transducer, wherein ultrasonic energy transmitted by said transducer to said reflector first surface is reflected to said reflector second surface and then to said pin from which it is reflected back to said reflector second surface from which it is reflected to said reflector second surface and is directed back to said transducer to be used to measure the round-trip transit time of the ultrasonic energy from said transducer to said pin.

8. The sensor as claimed in claim 7 wherein said transducer has two sectors, one said sector being substantially aligned with said pin.

9. The sensor as claimed in claim 8 and further comprising an electronics module that supplies electrical signals to said two sectors of said transducer for conversion to ultrasonic energy and uses the respectively supplied electrical signals and signals returned from each of said two transducer sectors after reflection respectively from the said pin and the liquid-air interface in the probe to measure the round trip travel time of the ultrasonic energy to said pin and in the liquid in said probe to the air-liquid interface.