The present invention relates generally to the field of leak detection, and specifically to a system and method for ultrasonic leak detection.
An apparatus in accordance with an embodiment of the disclosure comprises a hand-held ultrasonic leak detector. The leak detector comprises an ultrasound receiver that receives ultrasound signals indicative of leaks in pressurized pipes, for example, defective bearings, and or corona discharge from electrical components.
The present disclosure is best understood by referring to the drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the disclosure.
The leak detection apparatus 100 comprises a front side 120. The front side 120 comprises a display device 101, which can be, for example, a light emitting diode (LED) display device or a liquid crystal display (LCD) device. During operation, the display device 101 displays information relative to operation of the leak detection apparatus 100.
The leak detection apparatus 100 further comprises a plurality of control buttons 102-112. Each of these control buttons 102-112 is described further with reference to the operation of the leak detection apparatus 100.
In this regard, the “On” button 102 and the “Off” button 103 are for activating and deactivating the leak detection apparatus 100. In addition, the leak detection apparatus 100 further comprises the “LED” button 104 for lighting of the display device 101, a “Laser” button 105 and an “Illum” button 106, which are described further with reference to
The leak detection apparatus 100 comprises the “Wide” button 107 and the “Narrow” button 108. As will be described further herein, a signal (not shown) produced by sound detected by the leak detection apparatus 100 is filtered such that it is centered about a particular frequency, e.g., 38.4 kilo Hertz (kHz). In a first stage, the signal is filtered such that some noise components within the signal are filtered out in a first bandwidth. In a second stage, the signal is further filtered such that additional noise components within the signal are filtered out. If the “Wide” button 107 is selected, that signal generated by filtering in the first stage is audibly transmitted to a user (not shown) of the leak detection apparatus 100. If the “Narrow” button 108 is selected, the signal generated by filtering in the second stage is audibly transmitted to the user. Notably, each of these buttons 107, 108 is selected to control the audible signal transmitted for listening by a user (not shown).
In this regard, the “Wide” button 107, when selected, relatively increases the listening area of the leak detection apparatus 100. Whereas, the “Narrow” button 108, when selected, decreases the listening area of the leak detection apparatus 100. Actuating the Wide button 107 causes the apparatus to operate in the normal field of reception and is generally in the 40K hertz spectrum. When the Narrow field button 108 is selected, the apparatus 100 narrows the field of reception which reduces or eliminates competing noise. In this regard, a user (not shown) may use the apparatus 100 with the “Wide” button 107 actuated to narrow in on a potential leak location, and then select the “Narrow” button 108 to narrow the field.
In one embodiment of the apparatus 100, the Narrow mode setting narrows the reception spectrum down to around 38.4 kilohertz, plus or minus 1 kilohertz. In this regard, the apparatus 100 contains an 8-pole filter (not shown), that narrows the spectrum accordingly. When the apparatus 100 is in Wide mode, the 8-pole filter is bypassed so that a receiver 200 in the apparatus 100 receives all of the signals that the transducer (not shown) in the apparatus is capable of receiving. The transducer generally receives signals at 40 kilohertz, plus or minus 2 kilohertz; therefore a wider range of signals is received when the apparatus 100 is in Wide mode.
The leak detection apparatus 100 further comprises a bottom side 121 comprising a plurality of ports 113 and 114. With reference to
With reference to
The leak detection apparatus 100 further comprises a laser 202 and a plurality of lighting devices 203 and 204. During operation, the user can select the “Illum” button 106, which activates the lighting devices 203 and 204. Therefore, when the apparatus 100 is being used in a dimly lit environment, e.g., in an electrical panel when determining corona discharge, the lighting devices 203 and 204 illuminate the field of view.
When the “Laser” button 105 is activated, the laser 202 emits light in a direction in which the top side 122 of the apparatus 100 is being pointed. In this regard, light is emitted from the laser 202 in the same direction in which the top side 122 of the ultrasound receiver 200 is directed. Thus, the beam (not shown) emitted from the laser 202 falls approximately on an object (not shown) in the direction in which the transducer 200 is listening. Therefore, the laser 202 “points” to the object that is being listened to by the transducer 202.
The apparatus further comprises a detector 205. The detector 205 can be used to receive reflected light from the laser 202. Such reflected light can be used to determine, for example, based upon the distanced traveled by light emitted from the laser 202, the distance of an object from the apparatus 100. This distance can be displayed to the display device 101.
In another embodiment, the detector 205 is an infrared sensor. In such an embodiment, the detector 205 may be used to determine the temperature of an object that is being pointed to by the laser 202.
In one embodiment, the input device 208 is a keypad (not shown) that comprises the plurality of buttons 102-112 (
In one embodiment, the listening device 208 is headphones and/or earphones, which connect to the ports 113 and 114 (
The apparatus 100 further comprises a power device 306. The power device 306 may be, for example, a rechargeable battery pack that powers the components of the apparatus 100.
The apparatus 100 further comprises control logic 214. The control logic 214 can be software, hardware, or a combination thereof. In the exemplary apparatus 100, the control logic 214 is shown as software stored in memory 302. The memory 302 may be of any suitable type of computer memory known in the art, such as RAM, ROM, flash-type, and the like.
As noted herein, the control logic 214 is shown in
The processing unit 304 may be a digital processor or other type of circuitry configured to run the control logic 214 by processing and executing the instructions of the control logic 214. The processing unit 304 communicates to and drives the other elements within the apparatus 100 via the local interface 306, which can include one or more buses.
During operation, the user activates the apparatus 100 via the input device 208, which can be comprised of one of the plurality of buttons 102-112 (
When the user activates the “Wide” button 107 (
When the user activates the “Sound Byte” button 109 (
The control logic 214 may further store historical data 225 identifying particular tests that have been performed on an identified object. For example, the data 225 may indicate that a test has been performed on a pipe identified as “Pipe 1.” The historical data 225 can store the identifier Pipe 1 associated with an ultrasound reading taken from the transducer 200 and data indicative of how far away the reading was taken. Thereafter, the user can return to the same Pipe 1 and, based upon the previously generated data, take another reading at the same distance to determine if a detected leak has increased or changed.
As another example, the apparatus 100 may be used to capture sound and temperature data (not shown) related to a particular bearing. In this regard, the user may obtain data indicative of a sound reading from the transducer 200 and a temperature reading from the detector 205. This data may be stored as historical data 225. In the future, the user can recall the historical data 225 and compare it with a new sound reading and temperature reading to determine if the bearing has degenerated.
The control logic 214 further initiates and controls the calibration of the apparatus 100. In operation, the apparatus 100 calibrates itself based information obtained from internal electronics. In this regard, when the apparatus 100 first powers on, the calibration routine goes through each of four gain ranges and bypasses the transducer and collects information about the DC offset in each gain range. In this process, the “noise floor” in each gain range is obtained and recorded with no signal being received by the transducer 200. After the calibration sequence is complete, the transducer 200 is put back online and the noise floor values are subtracted for each range. This process is described further with reference to
The highest gain range employs the use of a high gain circuit that amplifies the input signal 40,000 times. Signals received on the low end of the spectrum are as small as 0.3 micro volts and thus require high amplification in order to be able to translate the signal into the audible range. When this type of gain is used in circuits, the circuits tend to drift with temperature and time and the like. When the gain is very high, even small deviations in temperature, for example, can result in a large offset in the circuitry. Signals may be varied by as much as a million to one on the high end, and this much gain would saturate all of the electronics. Therefore, the signal is attenuated automatically based upon the size of the signal coming in. For example, if the incoming signal is too big for a gain range, the signal is automatically attenuated until the signal is just large enough so that it is in a linear range. If it is too small, gain is added automatically and the signal is raised up as far as possible without over-ranging.
In this regard, control logic 214 directs a signal through the appropriate amplifiers based upon the size of the signal. The signal is maintained into a linear range of the amplifiers to avoid introducing harmonics into the signal.
Upon activation, the transducer 200 (
The detector 205 (
Based upon data displayed to the display device 101 (
The receiver head 500a comprises a threaded end 501a, a gripper portion 502a, a shaft 503a, and a receiving end 504a. In this embodiment, the threaded end 501a comprises male threads that mate with the female threaded cylindrical structure 201 (
The shaft 503a is a generally cylindrical extender with a hollow, generally cylindrical bore and is integrally formed with the threaded end 501a, the gripper portion 502a, and the receiving end 504a. In one embodiment, the shaft 503a is one and one-half (1-½) inches long with a hollow bore. In other embodiments, other dimensions can be used. The shaft 503a may be fabricated from stainless steel or other rigid materials. In one embodiment the shaft 503a is fabricated from a non-conductive material such as Delrin so as to avoid arcing when testing for corona discharge of electrical circuits or in electrical panels.
In another embodiment, the shaft 503a and/or the receiving end 504a is fabricated from a magnetic material. A magnetic receiving end 504a may be desirable when testing certain components, such as bearings, because the end 504a is attracted to and may temporarily affix to the jacket of the bearing. While the end 504a is temporarily affixed to the component under test, the sound quality may be greater and the incidence of undesirable sounds being received may be decreased.
The receiving end 504a is open-ended for pointing at and receiving ultrasonic signals. The receiving end 504a is a generally straight cylindrical end. As discussed below with respect to the receiving end 504b, other embodiments have tapered ends.
The receiver head 500b comprises a shaft 503b that is longer than the shaft 503a of the receiver head 500a. A longer shaft may be desirable, for example, when testing for leaks among a plurality of pipes in a small area. In this regard, the elongated shaft 503b may fit in amongst multiple pipes to test around joints and seals. In one embodiment, the shaft 503b is five inches in length, though other lengths could be used.
The receiver head 500b further comprises a tapered receiving end 504b. The tapering of the receiving end 504b serves the purpose of narrowing the end to enable it to squeeze into tighter spaces. The tapering further serves to funnel the ultrasonic signals into the receiver 200 and also reflects undesirable signals away from the receiver head 500b. The receiver head 500c also comprises a tapered receiving end 504c.
The display device 101 further comprises a saturation level indicator 606 that indicates the saturation level of the electronics. The display device 101 further comprises a mode indicator 605 that indicates that the apparatus 100 is in “Manual Gain” mode.
The transducer 701 detects sound present in the area of the transducer 701, i.e., the transducer 701 listens for sound. When the leak detection apparatus 100 is initially powered on, the circuit 700 enters calibration mode. In calibration mode, the transducer 701 is disconnected from the circuit 700. In this regard, when the circuit 700 is powered on, the micro-controller 709 transmits a signal to the electronic switch 702, and the electronic switch 702 disconnects the transducer 701 from the circuit 700.
During calibration, the micro-controller 709 grounds the electronic components within the gain/active filter 703. The micro-controller 709 then measures a plurality of direct current (DC) offset values and an inherent noise floor value for the circuit 700. The offset values and the noise floor values are eventually subtracted out of any signal received through the transducer 701.
In one embodiment, the gain/active filter 703 is configured and constructed as shown in
During calibration mode, the micro-controller 709 (
Referring to
During operation, the transducer 701 detects sound and outputs the analog signal 714 indicative of the sound received to the gain/active filter 703. Based upon the analog signal 714 received, the gain/active filter 703 generates four signals 710-713 filtered at or around 38.4 kHz, each signal exhibiting a differing gain. With reference to
The analog signal 714 (
Referring to
The micro-controller 709 selects which analog signal 804-807 is output as the multiplexer's output 808. Such output may be referred to as the “Wide” range output signal. When the circuit 700 is powered up and calibration is complete, the analog signal 808 output from the multiplexer 704 is the analog signal 807, which is the signal exhibiting the largest amount of applied gain through the amplifiers 800-803.
The output signal 808 is transmitted to audio logic 705, which is described further herein, and the output analog signal 808 is also passed through an 8-pole active filter 706 to further eliminate extraneous noise components that may be in the signal 808. The 8-pole active filter 706 filters the signal 808 at or around 38.4 kHz and outputs another analog signal 809, which may be referred to as the “Narrow” range output analog signal.
The Narrow range output analog signal 809 is transmitted to the audio logic 705, which is described further herein, and the Narrow range output analog signal 809 is also transmitted to the root mean square (RMS) to DC converter 707. The RMS to DC converter 707 rectifies the analog signal 809, so there are no longer negative components in the signal 809. The RMS to DC converter 707 further smoothes the signal 809 to an approximate steady constant signal.
The rectified smoothed signal is output 810 that is then sampled by the A/D converter 708. Such sampling indicates the maximum voltage amplitude of the output signal 810. If the signal 810 reaches a threshold value, which is described further herein, then the micro-controller 709 transmits a signal to the multiplexer 704 to select one of the other signals 710-712 as the output 808 of the multiplexer 704. Thus, the micro-controller 709 compares the digital values obtained from the A/D converter 708 to a threshold value to determine whether the signal 808 output from the multiplexer should be switched to one of the other signals 710-712. Notably, as indicated hereinabove, initially signal 714 is output as signal 808.
In one embodiment, the threshold value is 3 Volts. Thus, if the digital value indicative of the signal 810 is substantially close to 3 Volts, e.g., if the signal is at 99% or 2.97 Volts, then the micro-controller 709 transmits a signal to the multiplexer 704, and the multiplexer 704 transmits as its output the next analog signal 712 having a smaller gain than the signal 713. This process continues throughout operation.
Note that the Wide range output signal 808 is output from the multiplexer 704, and the Wide range output signal 808 exhibits a particular gain applied by the gain/active filter 703. The output signal 808 is indicative of the input signal 714 having some noise components removed. Further note that the Narrow range output signal 809 is also indicative of the input signal 714; however, additional noise components are removed by the 80pole active bandpass filter 706 above that which was removed by the gain/active filter 703.
During operation, a user (not shown) can select the “Wide” button 107 (
Note that the output signals 710-713 may be represented by G1, G2, G3, and G4, respectively. Thus, with reference to
Step 902 is detecting the analog signal indicative of the sound detected by the transducer 701. Step 903 is displaying to the display device 101 (
This application claims the benefit of U.S. Provisional Application No. 61/089,248 filed on Aug. 15, 2008, the entire contents of which are herein incorporated by reference.
Number | Date | Country | |
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61089248 | Aug 2008 | US |