US 5,710,377 A · Ultrasonic leak detection system

Abstract

A system for detecting ultrasonic vibrations, such as those generated by a small leak in a pressurized container, vessel, pipe, or the like, comprises an ultrasonic transducer assembly and a processing circuit for converting transducer signals into an audio frequency range signal. The audio frequency range signal can be used to drive a pair of headphones worn by an operator. A diode rectifier based mixing circuit provides a simple, inexpensive way to mix the transducer signal with a square wave signal generated by an oscillator, and thereby generate the audio frequency signal. The sensitivity of the system is greatly increased through proper selection and matching of the system components, and the use of noise rejection filters and elements. In addition, a parabolic collecting horn is preferably employed which is mounted on the transducer assembly housing. The collecting horn increases sensitivity of the system by amplifying the received signals, and provides directionality which facilitates easier location of an ultrasonic vibration source.

Claims20

Dependent claims

A system for detecting ultrasonic vibrations comprising:

a) a first housing;
b) an ultrasonic transducer disposed in said housing for detecting ultrasonic vibrations and generating an electrical signal in response thereto, said transducer including an output for transmitting a transducer signal generated thereby;
c) a parabolic collecting horn attached to said housing and positioned for collecting and focusing said ultrasonic vibrations onto said transducer;
and
d) a processing circuit electrically connected to said output of said transducer for converting said transducer signal into an audio frequency signal having a magnitude proportional to a magnitude of said transducer signal.

2 more elements

A system for detecting ultrasonic vibrations comprising:

a) an ultrasonic transducer for detecting ultrasonic vibrations and generating an electrical signal in response thereto, said transducer including an output for transmitting a transducer signal generated thereby;
and
b) a processing circuit electrically connected to said output for converting said transducer signal into an audio frequency signal, said processing circuit comprising:
i) an oscillator for generating an oscillating signal;
ii) means for forming a weighted sum of said oscillating signal and said transducer signal;
and
iii) a mixing circuit for multiplying an oscillating signal component of the weighted sum and a transducer signal component of the weighted sum, and thereby generating said audio frequency signal having a frequency equal to a difference between a frequency of said transducer signal and a frequency of said oscillating signal, said mixing circuit comprising a diode bridge rectifier generating first and second complimentary outputs, and a differential amplifier having a first, positive input connected to the first output of said diode bridge rectifier, and a second, negative input connected to the second output of said diode bridge rectifier, said differential amplifier generating said audio frequency signal.

4 more elements

Dependencies are inferred from the claim text.

Ultrasonic leak detection system

Life of this patent

Ultrasonic leak detection system

Life of this patent

Abstract

Claims20