Ultrasonic sensing array system and method

Abstract

A system and method for detecting leaks in substantially closed objects, such as automobiles, airplanes, tanks, and other vehicles, using an ultrasonic transmitter and an array of ultrasonic sensors or receivers positioned or mounted on a frame. As the objects are passed through the frame, ultrasonic amplitude readings obtained from the sensors are processed to determine if they are representative of a defective or leaking object. The position of the leak may be determined by examining the readings from individual sensors. The system is particularly well-adapted for use in detecting defects and leaks in automobiles on an assembly line without interrupting the assembly process or damaging the automobile.

1 . A system for detecting a liquid or gas leak in a substantially enclosed object, said system comprising:
 an ultrasonic transmitter positioned in said enclosed object for producing ultrasonic frequency sound waves as said object moves through a frame;   a plurality of ultrasonic sensors positioned around the internal perimeter of said frame for detecting said ultrasonic frequency sound waves and producing ultrasonic frequency signals;   an analog-to-digital converter for converting said ultrasonic frequency signals to digital data; and   a computing device coupled to said analog-to-digital converter for receiving, analyzing and storing said digital data.   
   
   
       2 . The system of  claim 1 , further comprising a receiver for receiving the ultrasonic frequency signals from said sensors and converting said ultrasonic frequencies signals to lower frequency signals which are in turn provided to said analog-to-digital converter. 
   
   
       3 . The system of  claim 1 , wherein said computer terminal compares a strength of a received ultrasonic frequency signal to a predetermined alarm threshold and produces an alarm if said threshold is exceeded. 
   
   
       4 . The system of  claim 1 , wherein said internal perimeter of said frame corresponds to an outline of said substantially enclosed object. 
   
   
       5 . The system of  claim 1 , further comprising at least one object position sensor for sensing a position of said object with respect to said frame. 
   
   
       6 . The system of  claim 1 , wherein said computer terminal determines a location of a potential leak based upon a detected amplitude of said ultrasonic frequency sound waves. 
   
   
       7 . The system of  claim 1 , wherein said frame is constructed to minimize ultrasonic reflections. 
   
   
       8 . The system of a  claim 1 , wherein said receiver further comprises a Hartley oscillator for converting the ultrasonic frequency signals to a lower frequency. 
   
   
       9 . A method of locating leaks in a substantially enclosed object, said method comprising:
 placing an ultrasonic transmitter inside of said substantially enclosed object wherein said ultrasonic transmitter produces ultrasonic sound waves at a predetermined frequency;   moving said object at a predetermined speed through an ultrasonic sensing array of ultrasonic sensors mounted on a frame;   obtaining a series of ultrasonic sensor readings from said ultrasonic sensing array as said object moves through said ultrasonic sensing array; and   comparing an amplitude of said ultrasonic sensor readings to a threshold amplitude level to determine if said threshold amplitude level has been exceeded and determining if a leak is present in said object based upon said comparison.   
   
   
       10 . The method of  claim 9 , further comprising converting ultrasonic frequency signals from said peripheral ultrasonic sensing array to signals having a lower frequency. 
   
   
       11 . The method of  claim 10 , further comprising converting said lower frequency signals into digital data. 
   
   
       12 . The method of  claim 9 , further comprising mounting said ultrasonic sensing array on a frame wherein said frame is constructed to minimize ultrasonic reflections and signal interference. 
   
   
       13 . The method of  claim 9 , further comprising altering a frequency of said transmitter based upon a physical structure of said object or the presence of interference at said predetermined frequency. 
   
   
       14 . The method of  claim 9 , further comprising the step of displaying an image of said object wherein said displayed image contains a visual indication of the amplitude of at least some of said ultrasonic sensor readings and a location on said object from which they were obtained.