U.S. patent application number 09/789833 was filed with the patent office on 2001-07-12 for ultrasonic standard.
This patent application is currently assigned to U.E. systems, Inc.. Invention is credited to Chavez, Betty J.R., Goodman, Mark A..
Application Number | 20010007203 09/789833 |
Document ID | / |
Family ID | 23824248 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007203 |
Kind Code |
A1 |
Goodman, Mark A. ; et
al. |
July 12, 2001 |
Ultrasonic standard
Abstract
The invention provides a device that generates predictable and
reproducible sounds. The device according to the invention serves
as a standard to calibrate ultrasonic measuring equipment through
either a gaseous medium or a solid medium. The device according to
the invention is similar in basic shape to an hourglass or venturi
(e.g., a sand-type egg-timer), but instead of using fine particles,
such as sand, the device includes identical media particles (e.g.,
marbles, balls, beads, etc.) which drop from an upper chamber to a
lower one. The media particles are pre-sorted so that those sealed
within the hourglass structure are uniform. An impingement post
(e.g., a bell or sounding plate) is positioned in the path of the
falling media particles so that each will hit the sounding plate,
resulting in a reverberating sound. The impingement post is
cantilevered and supported from a side of a chamber of the hour
glass structure.
Inventors: |
Goodman, Mark A.; (Cortlandt
Manor, NY) ; Chavez, Betty J.R.; (Arvada,
CO) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
U.E. systems, Inc.
|
Family ID: |
23824248 |
Appl. No.: |
09/789833 |
Filed: |
February 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09789833 |
Feb 20, 2001 |
|
|
|
09459307 |
Dec 10, 1999 |
|
|
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Current U.S.
Class: |
73/1.82 |
Current CPC
Class: |
G01N 29/045 20130101;
G01N 29/22 20130101; G01N 2291/02854 20130101; G01N 29/30
20130101 |
Class at
Publication: |
73/1.82 |
International
Class: |
G01M 001/14 |
Claims
I claim:
1. An acoustic calibration device, comprising: a plurality of media
particles; an upper chamber, a lower chamber and a neck disposed
therebetween for connecting said upper and lower chambers, said
media particles being located in at least one of said chambers,
said neck allowing controlled passage of the media particles; and
an impingement post disposed within at least one of said upper
chamber and the lower chamber so as to be contacted by a media
particle pulling through said neck such that a sound results when
one of the media particles makes contact with the impingement
post.
2. The device of claim 1, wherein the media particles are the same
size and weight within a margin of error.
3. The device of claim 1, wherein the impingement post is
cantilevered from a side wall of one of said chambers and is placed
generally horizontally and below the neck.
4. The device of claim 1, whereas the impingement post is comprised
in part one of a bell and sounding plate.
5. The device of claim 1, wherein the device is used in ultrasonic
calibration in one of the group consisting of an airborne mode and
a structure-borne mode ultrasonic probe.
6. The device of claim 1, wherein the device is a hermetically
sealed unit.
7. The device of claim 1, wherein the media particles are selected
from the group of balls, marbles and beads.
8. A method of acoustic calibration, comprising the steps of:
providing an upper chamber and a lower chamber; providing media
particles in the upper chamber; providing an impingement post in
the lower chamber; causing the media particles to fall from the
upper chamber to the lower chamber in a controlled fashion; and
allowing the media particles to contact the impingement post as
they fall from the upper chamber so as to generate repeatable
sounds.
9. The method of claim 8, wherein the method is used for acoustic
calibration in one of the group consisting of an airborne mode and
a structure-borne mode.
10. The method of claim 8, wherein the media particles are the same
size and weight within a margin of error.
11. The method of claim 8, wherein the method is used for acoustic
calibration of a probe for measuring ultrasonic signals from at
least one of mechanical bearings, gear boxes, line blockages, steam
traps, valves, compressors, motors, pipes, flow direction controls,
underground leaks, welds, vacuum leaks, substations, heat
exchangers, seals, pumps, tanks, air brakes, gaskets, pressure
leaks, electric arcs, caulking, air infiltration, wind noise, and
junction boxes.
Description
FIELD OF THE INVENTION
[0001] The invention relates to the field of acoustic measurement
and calibration and, more particularly to a standard and device
useful in testing and calibrating ultrasonic equipment and
generating predictable and reproducible sounds.
BACKGROUND OF THE INVENTION
[0002] A convenient way to test the performance of acoustic
equipment is to compare its acoustic emission response to an
acoustic source emitting uniformly repeatable sound waves. The
comparison is dependent on the acoustic source being able to
reproduce sounds reliably and accurately. The acoustic source then
serves as an acoustic measurement or calibration standard against
which comparisons are made. Repeatable acoustic sounds are
generated according to a method known in the art, by carefully
breaking a Hsu pencil lead against a test block. The use of a Hsu
pencil in generating repeatable sound waves is described in ASTM
E976-94, "Standard Guide for Determining the Reproducibility of
Acoustic Emission Sensor Response," pp. 388-390, which is
incorporated by reference herein. When the lead of the Hsu pencil
breaks, there is a sudden release of the stress on the surface of
the test block where the lead is touching. The stress release
generates an acoustic wave. In generating reproducible, uniform
sound waves, care is taken to always break the same length of the
same type of lead, and to break the lead at the same spot on the
test block with the same angle and orientation of the Hsu
pencil.
[0003] There are disadvantages inherent in the conventional method
using a Hsu pencil for generating repeatable sounds. Great care and
effort must be expended to ensure uniformity in the breaking of the
Hsu pencil in order to reliably produce repeatable sounds.
Additional devices, such as a Nielsen shoe (as shown in ASTM
E976-94 "Standard Guide for Determining the Reproducibility of
Acoustic Emission Sensor Response", p. 390), are required to
achieve that uniformity. Furthermore, once a Hsu pencil is broken
to produce a sound, it is no longer reusable.
[0004] Calibration standards, and devices therefor, are useful in
calibrating ultrasonic instruments used in locating and estimating
measurements of gas leakage. Exemplary methods in the art for
measuring gas leakage using airborne ultrasonic techniques are
described in ASTM E 1002-96, "Standard Test Method for Leaks Using
Ultrasonics," pp. 422-424, which is also incorporated by reference
herein.
[0005] FIG. 1 is a block diagram illustrating a prior art
ultrasonic airborne calibration standard for gas leakage. Airborne
ultrasound is a pressure wave or longitudinal wave that travels
through air. It is produced by either turbulent flow or a vibrating
surface. Referring to FIG. 1, there is shown a nitrogen gas supply
11 and a regulator 13 for regulating the gas flow from the nitrogen
gas supply 11. The nitrogen gas supply 11 is a pressurized gas
source that creates the equivalent of a nitrogen gas leak through
an orifice 15. A sound absorbing barrier 17 is selectively placed
in front of the orifice 15 to intercept the pressure wave and stop
it or removed to allow a uniform wave to be received by air probe
19. Since the wave is uniform because of the regulator, the
apparatus forms a standard for gas leakage, which can be used to
calibrate probe 19.
[0006] FIG. 2 is a flow diagram illustrating the operation of a
prior art ultrasonic calibration method for measuring gas leakage
using the equipment shown in FIG. 1. Referring to FIG. 2 (in
conjunction with FIG. 1), the regulator 13 regulates the gas flow
from nitrogen gas supply 11 to a leak standard, e.g.,
4.9.times.10.sup.-5 mol/s (1.1 std. cm.sup.3/s at 0.degree. C.)
.+-.5% (step 21). The size of the orifice 15 of the nitrogen gas
supply 11 is approximately 0.2 mm (0.008 inches). Since the
calibration is conducted in the airborne mode for ultrasound
received in a gaseous medium, the air probe 19 is positioned at a
distance D1 of 10 meters (.+-.0.1 m) from the orifice 15 (step 23).
In step 25, the air probe 19 and the orifice 15 are aligned to
obtain peak acoustic response. The flow rate of the gas emitted
from the nitrogen gas supply 11 is scaled back 50% of the fall
scale (.+-.5%). The sound absorbing barrier 17 is placed in front
of the orifice 15 blocking out the calibrated gas leak (step 27).
The meter reading of the flow rate of the gas being emitted from
the nitrogen gas supply 11 is checked to see if it is equal to
zero, that is, no audible signal detected (step 29). This
calibration process is repeated for each level used in detecting
and measuring gas leakage (step 28).
[0007] Application of the methodology described in FIGS. 1 and 2
has become impractical today since many industrial environments do
not have the space for such a great testing distance (e.g., D1=10
m) with no competing ultrasound. Further, the long testing distance
results in low acoustic sensitivity, which has a negative impact on
the accuracy of the ultrasonic calibration. Also, in general
calibration devices in the art can perform ultrasonic calibration
in the airborne mode only, but not in the structure-borne mode for
ultrasound received through a solid medium.
[0008] A reliable, easy-to-use methodology and device therefor are
thus needed for ultrasonic calibration which overcome the problems
in the prior art. There is a further need in the art for an
ultrasonic calibration method and device for both the airborne mode
and the structure-borne mode.
SUMMARY OF THE INVENTION
[0009] The present invention relates to a device that generates
predictable and reproducible sounds. The device according to the
invention serves as a standard to calibrate ultrasonic measuring
equipment through either a gaseous medium or a solid medium.
[0010] In an exemplary embodiment, the acoustic calibration device
according to the invention is similar in basic shape to an
hourglass or venturi (e.g., a sand-type egg-timer), but instead of
using fine particles, such as sand, the device includes uniform
media particles (e.g., marbles, balls, beads, etc.) which drop from
an upper chamber to a lower one. The upper chamber is connected to
the lower chamber, with a neck disposed therebetween. The media
particles are pre-sorted so that those sealed within the hourglass
structure are of uniform size. An impingement post (e.g., a bell or
sounding plate) is positioned in the path of the falling media
particles so that each will hit the sounding plate, resulting in a
reverberating sound. The neck allows the passage of only a
controlled number of the media particles per unit of time. The
impingement post is cantilevered and supported through a connection
to the hour glass structure.
[0011] The device according to the invention is advantageous over
the prior art because it is easy to use and carry, and reliably
provides a uniform acoustic output of repeatable sounds without the
need for an external energy source. The device according to the
invention does not require a large testing space nor additional
devices aiding the ultrasonic calibration process. The invention is
further advantageous over the prior art in that the device
according to the invention can be used for ultrasonic calibration
in both the airborne mode and the structure-borne mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other features, aspects, and advantages of the
invention will become readily apparent with reference to the
following detailed description of a presently preferred, but
nonetheless illustrative embodiment, when read in conjunction with
the accompanying drawings, in which like reference designations
represent like features throughout the enumerated Figures. The
drawings referred to herein will be understood as not being drawn
to scale, except if specifically noted, the emphasis instead being
placed upon illustrating the principles of the invention. In the
accompanying drawings:
[0013] FIG. 1 is a diagram generally illustrating the equipment for
a prior art calibration method for devices that detect gas leakage
in the airborne mode;
[0014] FIG. 2 is a flow diagram illustrating the operation of the
calibration equipment shown in FIG. 1;
[0015] FIG. 3 is a diagram illustrating an embodiment of the
acoustic calibration device according to the invention;
[0016] FIG. 4A is side elevation of another embodiment of the
acoustic calibration device according to the invention;
[0017] FIG. 4B is a cross sectional view of the device 24 FIG. 4A
along line 4-4 thereof;
[0018] FIGS. 5A and 5B are respective views illustrating the
embodiment of the invention as shown in FIGS. 4A and 4B with
exemplary media particles, with FIG. 5B being a cross-sectional
view along line 5-5 of the elevation view of FIG. 5A;
[0019] FIG. 6 is a diagram illustrating the operation of an
acoustic calibration device according to the invention in the
airborne mode;
[0020] FIG. 7 is a diagram illustrating the operation of an
acoustic calibration device according to the invention in the
structure-borne mode; and
[0021] FIG. 8 is a diagram illustrating the operation of an
acoustic calibration device according to the invention with an
exemplary probe in the structure-borne mode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] FIG. 3 is a diagram that illustrates an acoustic calibration
device according to the invention. Referring to FIG. 3, the
acoustic calibration device 1 includes an upper chamber 31
connected to a lower chamber 33 by means of a neck 35 disposed
therebetween. Media particles 37 (e.g., marbles, balls, beads,
etc.) are stored in the upper chamber 31 and can flow through the
neck 35 to the lower chamber 33 in a controlled fashion. The neck
35 also allows the passage of the media particles 37 from the lower
chamber 31 to the upper chamber 33 if the device 1 is placed upside
down. An impingement post 39, such as a sounding plate or a bell,
is cantilevered in the lower chamber 33 by connecting one end of
the impingement post 39 to the sidewall of the lower chamber 33.
The impingement post 39 is placed generally horizontally and
directly below the neck 35 in the lower chamber 33. The impingement
post 39 can also be positioned in the upper chamber 31, or in both
chambers 31 and 33 in other embodiments according to the invention
which are further described below.
[0023] The acoustic calibration device 1 generates reproducible and
repeatable sounds by allowing media particles 37 to fall through
the neck 35 from the upper chamber 31 to the lower chamber 33 and
onto the impingement post 39. A reverberating sound is generated
when one of the media particles 37 contacts the impingement post
39. The media particles 37 are pre-sorted or control manufactured
to have identical weight and sizes (within a margin of error) so
that the sounds generated by the device 1 are consistently uniform
for calibration purposes because the distance from neck 35 to post
39 is fixed. The device 1 can be used for ultrasonic calibration in
both the airborne mode (ultrasound received in a gaseous medium)
and the structure-borne mode (ultrasound received in a solid
medium).
[0024] The device 1 according to the invention is a hermetically
sealed unit, so that moisture will not enter into the upper and
lower chambers 31 and 33, which could cause a non-uniform
distribution of the media particles 37. The device 1 is generally
in a hollow, tubular form, having any suitable length. The outer
surface of device 1 may have any cross sectional shape, such as
circular, as well as various polygonal shapes, including
triangular, square, pentagonal, hexagonal, octagonal, etc. In the
present embodiment of the invention, the device 1 is made by
injection molding, so that unit-to-unit uniformity is
maintained.
[0025] FIGS. 4A and 4B are diagrams that illustrate a further
embodiment of the acoustic calibration according to the invention.
FIG. 4B is a cross sectional view taken along line 4-4 of the
elevation view of the acoustic calibration device shown in FIG. 4A.
Referring to FIGS. 4A and 4B, the acoustic calibration device
includes an upper chamber 41 connected to a lower chamber 43 by an
orifice 45 disposed therebetween. The orifice 45 permits the
controlled passage of single media particles (not shown) from the
upper chamber 41 to the lower chamber 43. When the acoustic
calibration device is placed upside down, the orifice 45 similarly
permits, due to gravity, the passage of media particles from the
lower chamber 43 to the upper chamber 41 one at a time. The
impingement posts 48 and 49 are respectively placed generally
horizontally in the upper and lower chambers 41 and 43. The
impingement posts 48 and 49, e.g., a bell post or a sounding plate,
are respectively fastened to the acoustic calibration device at
indent 48A and 49A.
[0026] FIGS. 5A and 5B are diagrams that illustrate the embodiment
of the invention (as shown in FIGS. 4A and 4B) with exemplary media
particles. FIG. 5B is a cross-sectional view of the elevation view
of the acoustic calibration device along line 5-5 and shown in FIG.
5A. The calibration device shown in FIGS. 5A and 5B have similar
structural components as that of FIGS. 4A and 4B. Media particles
57 are found in the upper and lower chambers 51 and 53. The
acoustic calibration device according to the invention generates
reproducible and repeatable sounds since the orifice 55 only allows
the media particles 57 to fall through the orifice 55 in a
controlled fashion from the upper chamber 51 to the lower chamber
53 at a uniform rate. A reverberating sound is generated upon one
of the media particles 37 contacting the impingement post 59.
[0027] The consistent, repeatable sounds generated by the acoustic
calibration device according to the invention can be used as the
standard for ultrasonic calibration in both the airborne mode and
the structure-borne mode. FIGS. 6 and 7 are diagrams illustrating
the operation of an acoustic calibration device according to the
invention in the airborne mode and the structure-borne mode,
respectively. Referring to FIG. 6, a probe 63 is placed at a short
distance D6 (e.g., D6=5 cm) away from an acoustic calibration
device 61 according to the invention. In contrast to conventional
acoustic calibration devices, e.g., the calibration equipment shown
in FIG. 1, the acoustic calibration device according to the
invention advantageously occupies little space and is simple to
use, without requiring cumbersome equipment and complex operating
procedures. The probe 63 can be any acoustic or detection probe
available in the art, e.g., ULTRAPROBE.RTM. 9000, ULTRAPROBE.RTM.
2000, ULTRAPROBE.RTM. 550, or ULTRAPROBE.RTM. 100, all of which are
available from UE Systems, Inc., the assignee of the invention. The
consistent, repeatable sounds generated by the device 61 according
to the principles of the invention described herein provide the
standard for acoustically calibrating and testing the detection
consistency of the probe 63.
[0028] Referring to FIG. 7, the acoustic calibration device 71
according to the invention can also be used for calibration in the
structure-borne mode. The device 71 is fastened on the tip or spout
75 of the probe 73, which can be any acoustic or detection probe in
the art, e.g., the ULTRAPROBE.RTM. series available from the
assignee of the invention, as described herein. Probe 73 is used to
detect ultrasonic vibrating or acoustic activity in the
structure-borne mode, e.g., by contacting the detection tip or
spout 75 of probe 73 with the solid medium to be tested. The
consistent, repeatable sounds generated by device 71 according to
the invention serve as the standard for acoustically calibrating
the probe 73. An illustration of such an operation of the device 71
in acoustically calibrating a probe in the structure-borne mode is
shown in FIG. 8. Structure-borne ultrasounds are microscopic
oscillations or transverse waves in a structure that produce sound.
Referring to FIG. 8, the acoustic calibration device 81 generates
repeatable sounds which serve as the standard for acoustically
calibrating and testing the detection consistency of an acoustic or
detection probe 83.
[0029] The acoustic calibration device according to the invention
can be used in acoustically calibrating and testing the detection
consistency of acoustic or detection probes in many applications in
the structure-borne mode and airborne modes. Structure-borne
applications of the invention include, e.g., acoustic or vibration
detection in mechanical bearings, gear boxes, line blockage, steam
traps, valves, compressors, motors, pipes, flow direction,
underground leaks, etc. Airborne applications of the invention
include, e.g., vacuum leaks, as well as leaks in welds,
substations, heat exchangers, seals, pumps, tanks, air brakes,
gaskets and pressure leaks of all types, electric arc, caulking,
air infiltration, wind noise, junction boxes, etc.
[0030] Thus, while there have been shown, described, and pointed
out fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions, substitutions, and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit and
scope of the invention. For example, it is expressly intended that
all combinations of those elements and/or steps which perform
substantially the same function, in substantially the same way, to
achieve substantially the same results are within the scope of the
invention. Substitutions of elements from one described embodiment
to another are also fully intended and contemplated. It is also to
be understood that the drawings are not necessarily drawn to scale,
but that they are merely conceptual in nature. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
* * * * *