Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
1998-05-05
2001-02-20
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S649000, C073S659000, C073S660000, C073S661000
Reexamination Certificate
active
06189384
ABSTRACT:
BACKGROUND
FIELD OF THE INVENTION
In general, the present invention relates to a method of detecting and monitoring ultrasonic waves. In particular, the present invention relates to a route based method of monitoring equipment that utilizes a central base computer and a portable ultrasonic monitoring instrument to analyze and store information about detected ultrasonic waves and surface temperatures in order to locate leaks and machinery defects.
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 route based ultrasonic monitoring system and method for use in detecting ultrasonic signals. The route based method monitors a mechanical system with a monitoring system that includes a portable sensing device, a portable processing and storage unit, and a central processing location.
In accordance with the method, a list is created that contains the location of each machine or device to be tested, the tests to be performed on each machine or device, and the times at which the tests should be performed. The list is stored in the central processing location. In order to keep accurate records of the tests to be performed and the results of the tests, each machine to be measured and each measurement to be taken is assigned an identification code. The identification code is stored in the central processing location for later reference. Alarm levels indicating conditions that may require immediate attention are determined for each measurement taken. When the time arrives to perform the tests, a list of the tests that currently need to be performed, the alarm levels for each measurement and the configuration information needed to perform the list of tests are loaded into the portable processing and storage unit from the central processing location. The operator of the system is then prompted to proceed to a first measurement location with the portable sensing device and the portable processing and storage device. Instructions concerning the particular types of tests to be performed at the first measurement location are provided to the operator. The configuration information related to the performance of the particular tests and the alarm levels for the tests are provided from the portable storage and processing unit to the portable sensing means. Thus, the system eliminates the need for the operator to keep track of any special settings needed to most accurately monitor a particular machine.
When the device is properly configured, the tests are performed with the portable sensing device and the test results are obtained. At a convenient time, the test results are downloaded from the portable sensing device to the portable processing and storage unit. Once a test has been performed, the operator is prompted to proceed to the next measurement location along the route of testing locations and perform the tests indicated by the portable processing and storage device. The operator continues to perform the tests indicated by the portable processing and storage device in the manner described above until all of the tests on the list of tests have been performed. The test results stored in the portable processing and storage unit are transferred to the central processing station where they can be stored and analyzed The test results from the most current set of measurements may then be compared to the stored test results from any previous measurements to determine if any trends in the data indicate a condition that warrants further investigation.
The above described method overcomes the disadvantages of the prior art by providing an automated method for monitoring a set of machines producing ultrasonic sound. By automatically configuring the devices in the same manner each time a test is performed and consistently providing detailed information to an operator on how to best perform the test, the method allows the results of tests performed at different times to be reliably compared. Furthermore, the automatic storing and retrieving of data saves time and money over the prior art approach of manually recording test results.
In accordance with a preferred method of the present invention, an improved method of diagnosing mechanical defects or leaks producing ultrasonic sound is provided. A set of instructions for performing the series of measurements is stored and an operator is directed along a route of measurement points. The set of instructions are provided to the operator at appropriate times. Thus, the operator is provided information concerning the type of measurements to be taken and the manner in which the measurements should be taken. The operator is then prompted to perform the series of me
Johnson William S.
Piety Kenneth R.
CSI Technology, Inc.
Luedeka Neely & Graham P.C.
Miller Rose M.
Williams Hezron
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