Abstrict The invention concerns a Karman's vortex flow meter including dampening
members for absorbing vibrations. A stopper is provided to permit
limited movement between an amplifier casing and a supporting stand
containing a flow detector. The stopper is coupled to one of the
supporting stand and the casing and extends into a hole in the other
of the supporting stand and the casing. The flow meter includes
an elastic member positioned in the hole between the stopper and
the other of the supporting stand and the casing so that the stopper
and the other of the supporting stand and the casing are out of
direct contact. The elastic member absorbs vibrations and prevents
direct contact of the components to ensure accurate flow measurement.
Claims What is claimed is:
1. A Karman's vortex flow meter comprising:
a supporting stand mounted on a pipe line, said supporting stand
including a hollow cylinder having a flow meter detecting section
therein;
first vibration damping elements fitted in annular grooves formed
on an outer surface of said hollow cylinder of said supporting stand;
a casing fitted on said hollow cylinder of said supporting stand
with said first vibration damping elements positioned therebetween,
said casing having a flow meter amplifier disposed therein;
a stopper provided between said supporting stand and said casing,
said stopper permitting limited axial movement of said casing with
respect to said hollow cylinder of said supporting stand and being
inserted into a recess formed on an outer surface of said hollow
cylinder of said supporting stand so that a gap is formed between
said stopper and said hollow cylinder; and
a second vibration damping element disposed in said gap between
said recess of said supporting stand and said stopper.
2. A Karman's vortex flow meter according to claim 1 wherein said
second vibration damping element includes a thin hollow cylindrical
elastic member fitted on an end portion of said stopper.
3. A Karman's vortex flow meter according to claim 1 wherein said
second vibration damping element includes an O-ring received in
an annular groove formed on an end portion of said stopper.
4. A Karman's vortex flow meter according to claim 1 wherein said
second vibration damping element includes an O-ring received in
an annular groove formed on a peripheral surface of said recess
of said supporting stand.
5. A Karman's vortex flow meter comprising:
a supporting stand mounted on a pipe line, said supporting stand
including a hollow cylinder having a flow meter detecting section
therein;
a casing for containing therein an amplifier to amplify a signal
from said detecting section;
elastic means for floatingly mounting said casing onto said hollow
cylinder of said supporting stand with said casing out of direct
contact with said hollow cylinder; and
displacement limiting means for permitting limited displacement
of said casing relative to said hollow cylinder, said displacement
limiting means including:
a stopper coupled to one of said casing and said hollow cylinder
of said supporting stand, and
an elastic member interposed between said stopper and the other
of said casing and said hollow cylinder of said supporting stand.
6. A Karman's vortex flow meter according to claim 5 wherein said
displacement limiting means further includes
a blind hole formed in said hollow cylinder, said blind hole having
an inner diameter larger than an outer diameter of said stopper,
said stopper being coupled to said casing and extending into said
blind hole, and
said elastic member being interposed between an inner peripheral
surface of said blind hole and an outer peripheral surface of said
stopper.
7. A Karman's vortex flow meter according to claim 5 wherein
said displacement limiting means further includes a through-hole
formed in said casing, said through-hole having an inner diameter
larger than an outer diameter of said stopper,
said stopper extending through said through-hole and being coupled
to said hollow cylinder of said supporting stand, and
said elastic member being interposed between an inner peripheral
surface of said through-hole and an outer peripheral surface of
said stopper.
8. A flow meter comprising:
a supporting stand for mounting on a pipeline, said supporting
stand including a hollow cylinder having at least a portion of a
flow detector therein;
a casing for containing an amplifier to amplify signals from the
flow detector, the casing being mounted on the hollow cylinder;
a stopper for permitting limited movement between the casing and
the supporting stand, the stopper being coupled to one of the supporting
stand and the casing and extending into a hole in the other of the
supporting stand and the casing; and
an elastic member positioned in the hole between the stopper and
the other of the supporting stand and the casing so that the stopper
and the other of the supporting stand and the casing are out of
direct contact.
9. The flow meter of claim 8 wherein the stopper is coupled to
the casing and the hole is a blind hole formed in the supporting
stand.
10. The flow meter of claim 9 wherein the elastic member is a
thin cylinder fitted on the stopper.
11. The flow meter of claim 9 wherein the elastic member is an
O-ring received in a groove formed on the stopper.
12. The flow meter of claim 9 wherein the elastic member is an
O-ring received in a groove formed in a portion of the supporting
stand surrounding the hole.
13. The flow meter of claim 9 further comprising dampeners between
the hollow cylinder of the supporting stand and the casing so that
the supporting stand casing are out of direct contact.
14. The flow meter of claim 9 wherein the stopper is coupled to
the supporting stand and the hole is a through hole in the casing.
15. The flow meter of claim 9 further comprising an auxiliary
stopper coupled to the one of the supporting stand and the casing
and extending into an auxiliary hole in the other of the supporting
stand and the casing, and
an auxiliary elastic member positioned in the auxiliary hole between
the auxiliary stopper and the other of the supporting stand and
the casing so that the auxiliary stopper and the other of the supporting
stand and the casing are out of direct contact.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow meter including structure
for limiting axial movement between a casing and supporting stand.
More particularly, the present invention relates to a Karman's vortex
flow meter having a vibration dampener for improving flow measurement
accuracy.
2. Description of Related Art
FIG. 7 illustrates the structure of a conventional Karman's vortex
flow meter. As shown in this figure, the Karman's vortex flow meter
includes a vortex generator 2 extending diametrically across the
interior of a pipeline 1 for flowing fluid. The vortex generator
2 has a columnar member provided at its upstream side (facing the
left side of FIG. 7) and another columnar member provided at its
downstream side (facing the right side of FIG. 7). To seal fluid
in the pipeline 1 and prevent vibration at the junction between
the vortex generator 2 and the pipeline 1 O-rings 5 and 6 are fit
between the vortex generator 2 and pipeline 1 adjacent to opposite
ends of the vortex generator 2.
The Karman's vortex flow meter also includes a detecting bar 3
having a disk-shaped diaphragm 3a, a lower bar portion 3b, and an
upper bar portion 3c. The diaphragm 3a contacts an O-ring 24 positioned
on an upper portion of the vortex generator 2. The lower bar portion
3b has a diameter smaller than that of the remainder of the detecting
bar 3 and extends from the diaphragm 3a, through a vibration reducing
and sealing O-ring 4 and into a cavity formed in the downstream
columnar member of the vortex generator 2. The upper bar portion
3c extends from the diaphragm 3b and includes exterior threads (not
shown).
A piezo-electric element 7 insulating plate 8 and disk spring
9 are mounted successively on the threads of the upper bar portion
3c of the detecting bar 3. A balance weight 10 coupled to the upper
bar portion 3c secures the piezo-electric element 7 insulating
plate 8 and disk spring 9 in place. In addition, the balance weight
10 reduces the effects of external vibrations, such as vibrations
of the pipeline 1.
As shown in FIG. 7 the Karman's vortex flow meter also includes
a supporting stand 22 having a flange 22a and a hollow cylinder
22b extending from the flange 22a. The hollow cylinder 22b houses
a detecting section of the Karman's flow meter including the diaphragm
3a and piezo-electric element 7. Bolts 11 fixedly mount the flange
22a and hollow cylinder 22b to the pipeline 1 so that the flange
22a secures the vortex generator 2 in the pipeline 1.
In use, fluid flowing in the pipeline 1 displaces the lower bar
portion 3b and this displacement is transmitted to the diaphragm
3a of the detecting bar 3. The piezo-electric element 7 then outputs
an electrical signal when it detects even a slight displacement
of the diaphragm 3a.
The conventional Karman's vortex flow meter also includes an amplifier
casing assembly having a casing 13 and two covers 14 threadably
secured to the casing 13 and sealed with O-rings 16. The amplifier
casing assembly contains a signal amplifier 18 including a printed
circuit board and other elements, for determining fluid flow rate
in pipeline 1 based on the electrical signal output from the piezo-electric
element 7. An O-ring 15 seals a lower end portion of the casing
13 and an upper end portion of the hollow cylinder 22b of the supporting
stand 22 and bolts 19 threaded in the casing 13 and hollow cylinder
22b secure the casing 13 to the hollow cylinder 22b. The O-ring
15 sealingly isolates the detecting section and detecting circuitry
from the exterior of the flow meter.
One disadvantage of the above-described conventional Karman's vortex
flow meter is that it is affected by external vibrations caused
by noise transmitted through the pipeline 1 or impacts with the
amplifier casing 13. For example, when an external vibration resonates
the amplifier casing 13 this vibration is transmitted by the supporting
stand 22 to the detecting section including the piezo-electric element
7 thus affecting the output of the element 7. If the pipeline 1
or amplifier casing 13 vibrate enough to oscillate the Karman's
vortex flow meter when the flow rate is low, accuracy of flow rate
measurement can be significantly reduced.
In light of the foregoing, there is a need in the art for a flow
meter capable of dampening vibrations.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a flow meter
capable of reducing the drawbacks associated with the conventional
Karman's vortex flow meter. More specifically, an object of the
invention is to provide a stable output signal by reducing the likelihood
that vibrations, external noises, and impacts will adversely affect
flow measurement.
An additional object of the invention is to isolate a stopper from
a hollow cylinder of a supporting stand or from a casing.
To achieve these and other advantages and in accordance with the
purpose of the invention, as embodied and broadly described herein,
the invention includes a Karman's vortex flow meter comprising a
supporting stand mounted on a pipe line, said supporting stand including
a hollow cylinder having a flow meter detecting section therein,
first vibration damping elements fitted in annular grooves formed
on an outer surface of said hollow cylinder of said supporting stand,
a casing fitted on said hollow cylinder of said supporting stand
with said first vibration damping elements positioned therebetween,
said casing having a flow meter amplifier disposed therein, a stopper
provided between said supporting stand and said casing, said stopper
permitting limited axial movement of said casing with respect to
said hollow cylinder of said supporting stand and being inserted
into a recess formed on an outer surface of said hollow cylinder
of said supporting stand so that a gap is formed between said stopper
and said hollow cylinder, and a second vibration damping element
disposed in said gap between said recess of said supporting stand
and said stopper.
In another aspect, the invention includes elastic means for floatingly
mounting a casing onto a hollow cylinder of a supporting stand with
said casing out of direct contact with said hollow cylinder, and
displacement limiting means for permitting limited displacement
of said casing relative to said hollow cylinder, said displacement
limiting means including a stopper fixed to one of said casing and
said hollow cylinder of said supporting stand, and an elastic member
interposed between said stopper and the other of said casing and
said hollow cylinder of said supporting stand.
In a further aspect, the invention includes a flow meter having
a stopper for permitting limited axial movement between a casing
and a supporting stand, the stopper being coupled to one of the
supporting stand and the casing and extending into a hole in the
other of the supporting stand and the casing, and an elastic member
positioned in the hole between the stopper and the other of the
supporting stand and the casing so that the stopper and the other
of the supporting stand and the casing are out of direct contact.
It is to be understood that both the foregoing general description
and the following detailed description are exemplary, and are intended
to provide further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a further understanding
of the invention and are incorporated in and constitute a part of
this specification. The drawings illustrate embodiments of the invention
and, together with the description, serve to explain the principles
of the invention. In the drawings,
FIG. 1 is a cross-sectional side view of a first embodiment of
the Karman's flow meter of the invention;
FIG. 2 is a cross-sectional view taken along line 2--2 of FIG.
1;
FIG. 3 is a cross-sectional side view similar to FIG. 1 of a second
embodiment of the Karman's flow meter of the invention;
FIG. 4 is a cross-sectional side view similar to FIG. 1 of a third
embodiment of the Karman's flow meter of the invention;
FIG. 5 is a cross-sectional side view similar to FIG. 1 of a fourth
embodiment of the Karman's flow meter of the invention;
FIG. 6 is a cross-sectional view taken along line 6--6 of FIG.
5; and
FIG. 7 is a sectional side view of a conventional Karman's vortex
flow meter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the present preferred embodiments
of the invention, examples of which are illustrated in the accompanying
drawings. In the drawings, like reference numeral are used to identify
like or identical elements.
FIGS. 1 and 2 show a first embodiment of the Karman's vortex flow
meter. As shown in FIG. 1 the first embodiment includes a supporting
stand 12 having a flange 12a and a hollow cylinder 12b extending
from the flange 12a. A detecting section including a piezo-electric
element 7 is positioned in the hollow cylinder 12b. O-rings 15'
are fit in two annular grooves formed in an outer surface of the
hollow cylinder 12b, and a pair of opposed blind holes or recesses
12c are formed in the outer surface of the hollow cylinder 12b between
the O-rings 15'.
The O-rings 15' frictionally fit a lower cylindrical shaped end
of an amplifier casing 13' on the hollow cylinder 12b of the supporting
stand 12. As shown in FIGS. 1 and 2 the O-rings 15' form an annular
clearance between the lower end of the casing 13' and the hollow
cylinder 12b so that the casing 13' and the supporting stand 12
do not contact one another. The O-rings 15' dampen and absorb vibrations
occurring, for example, when the casing 13' of the amplifier resonates.
Because the vibrations are dampened and absorbed rather than being
transmitted directly to a detecting section in the hollow cylinder
12b, flow rate measurement is very accurate.
Axial movement of the casing 13' with respect to the supporting
stand 12 is limited by stoppers 17. As shown in FIGS. 1 and 2 the
stoppers 17 are shaped like bolts and have an external thread portion
threaded in holes in the lower end portion of the casing 13'. The
stoppers 17 have heads seated against an outer surface of the casing
13' and end portions extending into the blind holes 12c formed in
the hollow cylinder 12b. Because the portions of the stoppers 17
extending into the blind holes 12c are smaller and shorter than
the blind holes 12c, a gap forms between each corresponding stopper
17 and blind hole 12c.
As shown in FIGS. 1 and 2 elastic vibration dampening members
or elements 50 are positioned in the blind holes 12c in the gaps
formed between the stoppers 17 and the blind holes 12c. In this
embodiment, the elastic elements 50 are thin, hollow, cylindrically
shaped, and frictionally fitted on the end portions of the stoppers
17. The elastic elements 50 are slightly deformable to allow for
limited movement of the stoppers 17 within the blind holes 12c and
corresponding limited movement of the casing 13' with respect to
the supporting stand 12.
Similar to the O-rings 15', the elastic elements 50 absorb vibrations
to ensure that flow measurement will be accurate. In addition, the
elastic elements 50 prevent or significantly limit direct contact
between the stoppers 17 and the hollow cylinder 12b to reduce vibrational
transmission. This vibrational absorption and reduction of vibration
transmission maintains the accuracy of the Karman' vortex flow meter
even when the casing 13' or another structural element vibrates.
FIG. 3 shows another embodiment of the Karman's vortex flow meter
of the present invention. This embodiment includes stoppers 17',
similar to the stoppers 17 described in connection with FIG. 1.
As shown in FIG. 3 the stoppers 17' include annular grooves 17a
in an end portion of the stoppers 17'. An elastic O-ring 51 is fit
in each of the annular grooves 17a. The elastic O-rings 51 function
like elastic elements 50 described in connection with FIG. 1 to
limit movement, absorb vibrations, and reduce vibrational transmission.
In FIG. 4 another embodiment of the Karman's vortex flow meter
is shown. This embodiment includes a supporting stand 12' having
a hollow cylinder 12b' and blind holes 12c', similar to the supporting
stand 12 hollow cylinder 12b, and blind holes 12c described in
connection with the embodiment of FIG. 1.
As shown in FIG. 4 annular grooves 12d are formed in the portions
of the hollow cylinder 12b' forming the blind holes 12c'. An elastic
O-ring 52 is fit in each of the grooves 12d. The elastic O-rings
52 also function like the elastic elements 50 shown in FIGS. 1 and
2 to limit movement, absorb vibrations, and reduce vibrational transmissions.
FIGS. 5 and 6 show another embodiment of the Karman's vortex flow
meter. As shown in FIG. 5 a lower cylindrical shaped end of an
amplifier casing 13" is positioned on a hollow cylinder 21b
of a supporting stand 21. Stoppers 17" extend through holes
13a passing through the casing 13" and are threaded into the
hollow cylinder 21b.
As shown in FIGS. 5 and 6 annular dampening members 26 made of
elastic rubber are arranged on inner and outer surfaces of the lower
cylindrical end of the casing 13" so that openings in the dampening
members 26 are aligned with the holes 1 3a. The dampening members
26 are positioned between the hollow cylinder 21b and the casing
13" and between heads of the stoppers 17" and the casing
13". The dampening members 26 place the hollow cylinder 21b
and casing 13" out of direct contact with one another to reduce
the likelihood of vibrational transfer to a detecting section in
the hollow cylinder 21b. In addition, the dampening members 26 absorb
and dampen vibrations.
The holes 13a in casing 13" have an inner diameter larger
the outer diameter of the portion of the stoppers 17" passing
through the holes 13a. This causes a gap to form in the holes 13a
between the stoppers 17" and the casing 13". To limit
movement of the casing 13" with respect to the supporting stand
21 and to absorb vibrations, elastic members 53 such as elastic
cylinders or O-rings, are positioned in holes 13a in the gaps formed
between the stoppers 17" and casing 13".
The combination of both the dampening members 26 and the elastic
members 53 dampen vibrations to ensure accurate fluid flow measurement.
The elastic members 53 are preferably deformable to allow for limited
movement of the stoppers 17" in the holes 13a and corresponding
limited movement of the casing 13" with respect to the hollow
cylinder 21b.
As shown in the embodiments of FIGS. 1-6 longitudinal axes of
the stoppers 17 17', 17" are preferably in the same plane
as the path of fluid flow in the pipeline 1. This arrangement allows
the casing 13', 13" to pivot slightly about the stoppers 17
17', 17" or move with respect to the casing 13', 13" when
an object traveling perpendicular to the flow path contacts the
casing 13', 13". However, other arrangements are possible.
For example, the above-mentioned embodiments of the invention have
particular advantages when the casing 13', 13" is mounted on
the supporting stand 12 12', 21 so that longitudinal axes of the
stoppers 17 17', 17" are in a plane perpendicular to the path
of fluid flow in the pipeline 1. The elastic members 50-53 allow
for this type of mounting because they ensure that the stoppers
17 17', 17" will not contact the hollow cylinder 12b, 12b',
21b or casing 13', 13" when an object hits the casing 13',
13".
It will be apparent to those skilled in the art that various modifications
and variations can be made to the structure of the present invention
without departing from the scope or spirit of the invention. For
example, the invention could be practiced with various other types
of flow meters other than a Karman's vortex flow meter. In view
of the foregoing, it is intended that the present invention cover
modifications and variations of this invention provided they fall
within the scope of the following claims and their equivalents.
|