Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1999-12-10
2001-06-19
Chapman, John E. (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S632000
Reexamination Certificate
active
06247353
ABSTRACT:
BACKGROUND
1. Field of the Invention
In general, the present invention relates to a digital device for detecting and monitoring ultrasonic waves. In particular, the present invention relates to a portable ultrasonic monitoring instrument that utilizes a microprocessor to analyze and store information about detected ultrasonic waves in order to locate leaks and machinery defects.
2. Background of the Invention
The normal frequency range for human hearing is roughly 20 to 20,000 hertz. Ultrasonic sound waves are sound waves that are above the range of human hearing and, thus, have a frequency above about 20,000 hertz. Any frequency above 20,000 hertz may be considered ultrasonic. Most industrial processes, including almost all sources of friction, create some ultrasonic noise. For example, leaks in pipes, machinery defects and electrical arcing produce ultrasonic sound waves that have a frequency that is too high for the human ear to detect. In the past, analog ultrasonic sensors have been used in industrial settings to sense these ultrasonic sound waves. To monitor the ultrasonic sound waves produced by operating machinery, an operator would use an ultrasonic sensor to obtain a reading indicating the strength of the ultrasonic sound waves near the machine. If the ultrasonic sound levels generated by one machine were larger than those produced by another similar machine, the operator would investigate further to determine if a problem existed with the noisy machine. If the ultrasonic sound levels were approximately equal to those produced by a properly functioning machine, the operator would assume the machine was properly functioning and simply proceed to the next machine. Some of the prior art ultrasonic sensors used to monitor machines were semi-permanently mounted on individual machines so that ultrasonic readings could be obtained by simply checking the output of the ultrasonic sensors. However, other ultrasonic detectors were portable to allow the operator to monitor many machines. These portable ultrasonic detectors were especially useful in locating small leaks in pipes carrying pressurized gasses. Because ultrasonic sound waves attenuate very rapidly, the location of the sound waves is usually the location of the leak. Therefore, in order to locate a leak, the user simply moved the ultrasonic detector over the surface until the strength of the ultrasonic sound waves rapidly increased. The user then investigated further by placing soapy water on the location where it was suspected that there was a leak. If a leak was present, bubbles would form in the soapy water where the gas was escaping.
These analog ultrasonic instruments suffer from many drawbacks. For example, the analog instruments do not provide a quantitatively referenced power level of the signal to the user. Instead, the analog ultrasonic units simply provide a relative indication of the ultrasonic sound waves' strength in one location compared to another location. Typically, this information is provided to the user by a needle on a dial with an adjustable volume. The volume is set so that the needle is at a reference point when an ultrasonic measurement is taken in a particular location. If the needle rises above that point when a reading is taken in another location, the ultrasonic noise level is higher at the second location than the reference point and vice versa. This is undesirable because it makes it difficult to compare readings taken at one point in time to readings taken at a later point in time. Also, prior art analog instruments did not employ analog to digital converters or microprocessors, making it difficult for them to perform advanced signal analysis techniques on the ultrasonic electrical signals.
SUMMARY OF THE INVENTION
The present invention eliminates the oversights, difficulties, and disadvantages of the prior art by providing an automated digital ultrasonic monitoring system for use by an operator in detecting ultrasonic signals. The digital monitoring system allows reliable referenced signal strength measurements to be obtained and recorded. In addition, advanced signal processing techniques can be used to analyze the digital data produced.
In accordance with the present invention, a digital ultrasonic sound and temperature detection and analysis device for measuring surface temperatures of an object and detecting ultrasonic sounds produced by sources such as leaks in pipes, arcing, electrical corona and machinery defects is provided. An elongate housing encloses the digital ultrasonic device. The elongate housing has a grip that is designed to provide a handle that allows a user to carry and point the digital ultrasonic device like a pistol. A barrel shaped portion is attached to the grip at one end and has a sensor socket located in the other end. A trigger located at the junction of the barrel and the grip is used to control the functioning of the digital ultrasonic device.
A set of sensors including a temperature sensor; an ultrasonic sensor, and a combination temperature and ultrasonic sensor are provided for use with the ultrasonic monitoring device. A sensor socket located in the barrel shaped portion of the ultrasonic device is designed to interchangeably receive a sensor from the set of sensors. The sensor socket that receives the sensor from the set of sensors has a cylindrical shaped cavity having walls and a bottom portion. A set of pins located in the bottom portion of the sensor socket provides electrical contacts between a plurality of electrical contacts on the sensor installed in the sensor socket and the ultrasonic device. A pair of spaced apart L-shaped grooves are located in the walls of the cylindrical shaped cavity. Each of the L-shaped grooves has an open receiving portion that begins at the rim of the cylindrical shaped cavity and extends a distance down the cavity walls to an ending position and a leg portion that extends perpendicularly from the ending position of the open receiving portion. A pair of protrusions are fixedly attached to the sides of each of the sensors in the set of sensors. The protrusions are shaped and positioned to be received in the L-shaped grooves in a manner that removably secures the sensor in the sensor socket. Installation guide means prevent a sensor from the set of sensors from being improperly installed in the sensor socket. An identification circuit, that contains identification and configuration information concerning the sensor, is located on each sensor in the set of sensors.
A received signal strength indicator receives ultrasonic electrical signals from a sensor installed in the sensor socket that correspond to the ultrasonic sounds detected by the sensor and produces a signal indicative of the strength of the ultrasonic electrical signals. A first voltage controlled amplifier also receives the ultrasonic electrical signals from the installed sensor and amplifies the ultrasonic electrical signals to produce amplified ultrasonic electrical signals. A mixer receives the amplified ultrasonic electrical signals from the first voltage controlled amplifier and local oscillator frequency signals from a variable frequency sine wave oscillator and heterodynes the amplified ultrasonic electrical signals to produce audible frequency range signals that correspond to the amplified ultrasonic electrical signals but are in the audible frequency range of a human being. A low pass filter receives the audible frequency range signals from the mixer and removes any above audible range frequency signals in the audible frequency range signals received from the mixer. Next, a second voltage controlled amplifier receives and amplifies the audible frequency range signals after the audible frequency range signals have passed through the low pass filter. From there, the amplified audible frequency range signals are sent to a headphone jack located on the base of the grip. A pair of headphones have a headphone plug that receives the amplified audible frequency range signals from the headphone jack when the headphone plug is inserted into the head
Battenberg Rexford A.
Carpenter Terry G.
Johnson William S.
Piety Kenneth R.
Puterbaugh Kenneth C.
Chapman John E.
CSI Technology, Inc.
Luedeka Neely & Graham P.C.
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