Ultrasonic Liquid Level Sensing Systems

Abstract

An ultrasonic sensor probe ( 100 ) and controller ( 109 ). The controller ( 109 ) is operationally configured to determine and display wet and dry status of each of a plurality of ultrasonic sensors ( 156 ) positioned in the barrel ( 123 ) of the probe ( 100 ). The controller ( 109 ) may change the status of a sensor ( 156 ) from wet to dry or dry to wet if certain conditions are met, such as the sensor ( 156 ) consistently indicates the new status over multiple readings or over a predetermined period of time. The controller ( 109 ) preferably includes a two-wire output capable of producing a stepped analog or digital signal that indicates the fluid level in a container in which the probe ( 100 ) is positioned.

1 . A system comprising for determining the level of a fluid in a container, the system comprising:
 a controller;   an ultrasonic probe comprising a fitting assembly adapted to be attached to the container, a barrel extending downwardly from the fitting assembly, and a plurality of ultrasonic sensors located within the barrel, each of the plurality of ultrasonic sensors being electrically linked to the controller and adapted to receive electronic signals sent from the controller, emit sound waves in response to the electronic signals sent from the controller, detect sound waves, and transmit electronic signals to the controller indicative of the detected sound waves, the ultrasonic probe being shaped and configured to be inserted into the container;   wherein the controller is operationally configured to send electrical pulses a first frequency and to direct the electrical pulses to each of the plurality of ultrasonic sensors in a first sequence;   wherein the controller is operationally configured to determine a fluid level in the container based on the transmitted electronic signals from each of the plurality of ultrasonic sensors;   wherein the controller is operatively configured to generate an output signal for communication to one or more external devices in electrical communication with the controller, the output signal being representative of the fluid level in the container determined by the controller.   
     
     
         2 . The system of claim  13 , wherein the output signal is a stepped analog output. 
     
     
         3 . The system of claim  14 , wherein the stepped analog output has a current, the current being directly proportional to the fluid level. 
     
     
         4 . The system of claim  14 , wherein the stepped analog output has a voltage, the voltage being directly proportional to the fluid level. 
     
     
         5 . The system of claim  13 , wherein the output signal is a digital output that is directly proportional to the fluid level. 
     
     
         6 . The system of claim  13 , wherein a two-wire interface provides the electrical communication between the controller and the one or more external devices and the controller is operationally configured to generate the output signal through the two-wire interface. 
     
     
         7 . An ultrasonic probe having an internal volume, the ultrasonic probe comprising:
 a multi conductor shielded cable comprising an first shield, a second shield, and a plurality of conductors, the first shield comprising an outer shield, each of the plurality of conductor being individually insulated but not individually shielded;   a plurality of ultrasonic sensors disposed within the internal volume;   wherein each ultrasonic sensor of the plurality of ultrasonic sensors is electrically connected to a separate one of the plurality of conductors and to the first shield and the second shield comprises a ground path of the multi conductor shielded cable.   
     
     
         8 . The ultrasonic probe of claim  19 , wherein the second shield comprises an earth ground path of the multi conductor shielded cable. 
     
     
         9 . The ultrasonic probe of claim  19 , wherein the second shield is an outermost shield of the multi conductor shielded cable.