Abstrict A vortex flow meter is comprised of a vortex generator provided
in a fluid to be measured and a tube member installed in a direction
intersecting with it at the downstream side. The tube member includes
at least a couple of holes arranged at intervals of predetermined
distances in the direction of the shaft. A pressure variation due
to the Karman vortex created by the vortex generator is applied
to the fluid in the tube member through the above-mentioned holes.
A detector for sensing the pressure variation is installed in the
tube member. The number of Karman vortexes is counted by the pressure
variation detector.
Claims What is claimed is:
1. A vortex flow meter for measuring fluid flow in a conduit comprising
a vortex generator disposed transversely in said conduit, a tube
member in said conduit disposed downstream of said vortex generator
within the stream of vortices, said tube member extending transversely
of said conduit and transversely of said vortex generator, a partition
wall means in said tube member which divides the tube member into
a first tube part and a second tube part, means defining at least
one hole in an intermediate portion of each of said tube parts,
by-pass means external of said conduit and extending between said
first and second tube parts such that the effect of said partition
wall means and said holes provides a fluid flow in said by-pass
means, said by-pass means having a straight line portion which smooths
the flow of fluid through the by-pass means, and measuring means
for measuring the flow of fluid in said straight line portion of
said by-pass means which is indicative of the fluid flow through
said conduit.
2. A vortex flow meter according to claim 1 wherein said measuring
means comprises ultrasonic wave transmitting and receiving devices.
3. A vortex flow meter for measuring fluid flow in a conduit member
comprising a vortex generator disposed in said conduit member so
as to oppose the fluid flow therein, a tube member in said conduit
member disposed downstream of said vortex generator within the stream
of vortices, said tube member extending transversely of said vortex
generator, said conduit member comprising a conduit wall having
wall openings, said tube member passing through said wall openings
in said conduit member, means defining a pair of opened pressure
guiding holes in said tube member for guiding pressure variation
caused by vortices generation, said opened guiding holes opening
up on the downstream side of said tube member, and detecting means
for detecting the variation of fluid flow passing through said tube
member by measuring said pressure variation so that fluid flow in
said conduit member is thereby measured.
4. A vortex flow meter for measuring fluid flow in a conduit comprising
a vortex generator disposed in said conduit, a tube member in said
conduit member disposed downstream of said vortex generator within
the stream of vortices, said tube member extending transversely
of said conduit and having an intermediate part which precludes
communication between a first tube part and a second tube part,
means defining at least one hole in each of said tube parts, by-pass
means extending between said first and second tube parts such that
the effect of the fluid at said holes effects a pressure variation
in said first and second tube parts, said by-pass means comprising
a linear flow path portion, said by-pass means comprising connecting
portions between the longitudinal ends of said tube member and said
linear flow path portion, and valves in said connecting portions,
said valves being operable to adjust the flow of fluid in said by-pass
means, and ultrasonic wave transmitting and receiving devices for
measuring the flow of fluid in said by-pass means which is indicative
of the fluid flow through said conduit, said ultrasonic wave transmitting
and receiving devices being located at the longitudinal ends of
said linear flow path portion, said ultrasonic wave transmitting
and receiving devices detecting the variation of fluid flow flow
in said linear flow path portion.
5. A vortex flow meter for measuring fluid flow in a conduit comprising
a vortex generator disposed in said conduit, a tube member in said
conduit disposed downstream of said vortex generator within the
stream of vortices, said tube member extending transversely of said
conduit and having an intermediate part which precludes communication
between a first tube part and a second tube part, means defining
at least one hole in each of said tube parts, by-pass means extending
between said first and second tube parts such that the effect of
the fluid at said holes effects a pressure variation in said first
and second tube parts, and ultrasonic wave transmitting and receiving
devices for measuring the flow of fluid in said by-pass means which
is indicative of the fluid flow through said conduit, said by-pass
means comprising a linear flow path portion, said ultrasonic wave
transmitting and receiving devices being located at the longitudinal
ends of said linear flow path portion, said ultrasonic wave transmitting
and receiving devices detecting the variation of fluid flow in said
linear flow path portion.
6. A vortex flow meter for measuring fluid flow in a conduit member
comprising a vortex generator disposed in said conduit member, said
conduit member having openings, a tube member in said conduit member
in said conduit member disposed downstream of said vortex generator
within the stream of vortices, said tube member extending transversely
of said conduit and having longitudinal end portions which extend
through said openings, and means defining a plurality of holes in
said tube member disposed such that the effect of the fluid at said
holes effects a pressure variation in said tube member indicative
of the fluid flow through said conduit, said holes being disposed
in said longitudinal end portions.
7. A vortex flow meter according to claim 6 wherein both end portions
of said tube member are opened, said detecting means comprising
an ultrasonic wave transmitting element disposed at one opened end
portion of said tube member and an ultrasonic wave receiving element
installed at the other opened end portion thereof.
8. A vortex flow meter according to claim 6 further comprising
means defining wall parts extending laterally of said conduit, said
longitudinal end portions of said tube member extending into said
wall parts, said longitudinal end portions being spaced from said
wall parts to define a passage space therebetween, and a passageway
providing communication between said passage space and said conduit.
9. A vortex flow meter according to claim 8 further comprising
sound absorbing material in said passageway.
10. A vortex flow meter according to claim 8 further comprising
porous material in said passage space.
11. A vortex flow meter according to claim 8 further comprising
porous material in said passageway.
Description BACKGROUND OF THE INVENTION
The present invention relates to a vortex flow meter utilizing
the Karman vortexes created by a bluff body or a vortex generator
disposed in a fluid.
As is well known, when a pillar-shaped bluff body is placed in
a fluid, the flow of the fluid peels off to both side surfaces of
the bluff body and a regular vortex train, that is, Karman vortexes
occur alternately to the downstream side of the bluff body. The
number of Karman vortex occurrences is proportional to the velocity
or quantity of fluid flowing. The quantity of flow can be measured
by counting the number of Karman vortexes.
However, in the conventional manner, an ultrasonic wave is used
to count the number of Karman vortexes and the frequency modulation
or the phase modulation is detected thereby. The accuracy of this
method is effected by external noises or the like thus resulting
in errors in measurement. Since the ultrasonic wave scatters about,
the power of the signal received is considerably diminished. Furthermore
the flow of the fluid is effected at a place near the vortex so
that the ratio of S/N (signal/noise) is lowered due to the interference
with the turbulence of the vortex. It may be another reason for
inacurracies in measurement. Furthermore, the measurement of the
fluid's flow is badly effected by interference from the reflection
of the wave off the wall. surface opposite the transmitted ultrasonic
wave. Usually, in order to prevent such an effect, a sound absorbing
material like woven cotton or woolen cloth is placed on the inner
wall surface of the tube in such a manner that the measuring of
the fluid's flow can be effectively done in a purified liquid. It
cannot be done effectively in the case of dirty or impure liquid
that is mixed with dust, mist, etc.
It is for the above reasons that the present applicant has proposed
a method in which no sound absorbing material is needed. This method
is one in which another tube is passed through the wall of the fluid-flowing
tube so as to intersect with the vortex generator at the downstream
side. The variation of the flow of the liquid is due to the pressure
variation caused by pressure guiding holes bored at a place near
each of the wall surfaces of the tube member. It is detected by
ultrasonic wave transmitting and receiving apparatuses which are
installed respectively at both ends of the tube.
However, in such a manner as described heretofore, it may be necessary
to provide heat-proof type ultrasonic wave transmitting and receiving
apparatuses in the case of measuring fluids with high temperatures.
It follows then that the cost for manufacturing the device proposed
will be highly increased. Furthermore there will exist the inconvenience
of removing the main body of the flow meter from the connecting
tubes.
SUMMARY OF THE INVENTION
In consequence, the primary object of the present invention is
to provide a vortex flow meter which is not effected by external
noises or the like and which is capable of counting precisely the
number of Karman vortexes.
Another object of the present invention is to provide a vortex
flow meter which is comprised of a bluff body disposed in a fluid
to be measured, a tube member which is placed in a direction intersecting
with said bluff body at a downstream side thereof, and at least
a couple of holes arranged at intervals of predetermined distances
in the direction of a shaft, and finally which detects the pressure
variation of fluid in the tube member.
Still another object of the present invention is to provide a vortex
flow meter for the purpose of precisely measuring the flow of fluid
in which the measurement of the Karman vortexes is performed inside
of a tube that is not effected by external turbulence.
Still another object of the present invention is to provide a vortex
flow meter in which the flow of fluid due to the pressure differences
caused by the vortexes is rectified and in which the scattering
of ultrasonic wave is eliminated, and in which the measurement of
Karman vortexes can be done precisely without being effected by
external turbulence.
Still another object of the present invention is to provide a vortex
flow meter which is not effected by external turbulence and which
has a hole for guiding the fluid pressure variation caused by Karman
vortexes. The hole thereof may not be clogged by dust mixed into
the fluid to be measured.
Further stil, another object of the present invention is to provide
a vortex flow meter which is comprised of a bluff body placed in
opposition to the flow of fluid in a tube member and another tube
member which passes through its wall in a direction intersecting
with the bluff body at its downstream side, and in which the variation
of pressure caused by the bluff body outside of the tube member
is guided into the other tube member and the pressure variation
is detected inside of it.
Still another object of the present invention is to provide a vortex
flow meter in which the fluid pressure variation, due to a Karman
vortex is guided into a tube member, the internal, middle portion
of the tube member is closed, the pressure variation guided into
a tube member is further guided into a bypass fluid passage, and
the flow of the fluid is detected in the bypass fluid passage by
use of ultrasonic wave-transmitting and receiving apparatuses.
According to the present invention, a device for measuring the
flow of fluid can be manufactured at a lower cost; the maintenance
or monitoring work can be simplified considerably; and the new device
can be safer than a conventional one.
The above-mentioned objects, characteristics, and merits of the
present invention will be clearly explained in a detailed description
of the invention together with accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view for explaining the construction
of a vortex flow meter's main portion according to the present invention.
In FIG. 1 FIG. 1 (A) is a cross-sectional view taken on line A--A
of FIG. 1 (B), and FIG. 1 (B) is a cross-sectional view taken on
line B--B of FIG. 1 (A).
FIGS. 2 (A) through (F) are cross-sectional views showing modifications
of the hollow members that can be used in the present invention.
FIG. 3 is an enlarged cross-sectional view showing the construction
of a vortex flow meter's main portion according to the present invention.
FIG. 4 is a cross-sectional view for explaining another embodiment
of the vortex flow meter according to the present invention.
FIG. 5 is a cross-sectional view taken on line V--V of FIG. 4.
FIGS. 6 and 7 are views showing the construction of other embodiments
of the present invention.
FIG. 8 is a cross-sectional view showing the construction of another
embodiment of the vortex flow meter taken along a plane running
through the bluff body or Karman vortex generator and being perpendicular
to the fluid-flowing passage.
FIG. 9 is a cross-sectional view taken on line IX--IX of FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a cross-sectional view for showing the construction of
a vortex flow meter's main portion that is the embodiment of the
present invention.
FIG. 1 (A) is a cross-sectional view taken on line A--A of FIG.
1 (B), and FIG. 1 (B) is a cross-sectional view taken on line B--B
of FIG. 1 (A).
In FIG. 1 1 is a fluid-flowing tube; 2 a well known bluff body
or vortex generator; 3a and 3b, Karman vortexes created by the bluff
body 2; and 4 a tube member established according to the present
invention. The tube member 4 is established at the downstream side
of the bluff body 2 in the direction intersecting perpendicularly
to the bluff body 2 and has at least a couple of holes 4a and 4b,
arranged at intervals of predetermined distances in the direction
of the shaft.
However, as is well known, the pressure at the side of hole 4a
decreases when the Karman vortex 3a is generated, and the pressure
at the side of hole 4b decreases also when the Karman vortex 3b
is generated. The pressure variation effects the fluid in the tube
member 4 through holes 4a and 4b resulting in alternating pressure
differences .DELTA.P in tube member 4 as shown by an arrow.
Consequently, if the movement of the fluid, the pressure difference
thereof, or the like is measured by use of optional desired means,
for instance, an ultrasonic wave, a laser beam, a pressure-sensitive
element, etc., then the number of Karman vortex occurrences can
be measured thereby.
FIGS. 2 (A) through (F) are cross-sectional views showing modifications
of the afore-mentioned tube member. FIG. 2 (A) shows an example
of arranging the holes 4a and 4b at the downstream side of the tube
member 4. FIG. 2 (B) shows another example of forming the downstream
side of the tube member 4 in a streamline manner and for preventing
it from generating a Karman vortex. The Karman vortexes generated
by the tube member 4 might probably effect the fluid in it through
holes 4a and 4b which are placed in it. FIG. 2 (C) shows another
example of arranging the holes 4a and 4b in a streamline at the
downstream side of the tube member 4. FIG. 2 (D) shows another example
of installing a partition plate 5 parallel with the tube member
4 at the downstream side of the cylinder-shaped tube member 4 and
of preventing it from generating a Karman vortex. FIG. 2 (E) shows
another example of arranging the holes 4a and 4b at the downstream
side of the tube member 4 in which a partition plate is installed.
FIG. 2 (F) shows another example of installing a dust-proof plate
6 at the upstream side of the tube member 4 preventing the holes
4a and 4b from being clogged up by dust or the like, and for further
preventing dust from entering therein through the holes 4a and 4b.
The dust-proof plate 6 can be installed only at the upstream side
of the tube member 4.
Moreover, the vortex flow meter according to the present invention
is applicable to either liquid or gas. In the case of measuring
the flow of gas, especially high temperature vapor, etc., as shown
in FIG. 1 (A), it may be preferable to provide a drainage hole 7
in tube member 4 and to drain the water vapor that has accumulated
through drainage hole 7. The example of arranging a couple of holes
4a and 4b in the tube member 4 is explained heretofore. However,
it be may easily understood that the holes are not limited to a
couple only and do not always have to be in pairs.
FIG. 3 is an enlarged cross-sectional view showing the main portion
of another embodiment according to the present invention. In the
embodiment shown in FIG. 3 dust-proof plates 6a and 6b covering
holes 4a and 4b of tube member 4 are unitarily provided. In such
a manner, dirt, dust, etc. do not enter into tube member 4 through
holes 4a and 4b when they are directed to either the upstream side
or the downstream side of it. On that occasion, the opening portion
of the dust-proof plates 6a and 6b is situated at the vortex side
as shown in FIG. 3 so as to effectively guide the pressure variation
due to the vortex into tube member 4.
As is apparent from the foregoing description, according to the
present invention, the measurement of the fluid flow can be performed
precisely since the number of Karman vortexes occurring in the tube
member are not effected by external turbulence.
FIG. 4 is a cross-sectional view for explaining the main portion
of another embodiment of the vortex flow meter according to the
present invention. FIG. 5 is a cross-sectional view taken on line
V--V of FIG. 4. In FIGS. 4 and 5 11 is a fluid-flowing tube in
which the fluid to be measured flows; 12 is a well known vortex
generator or bluff body; 13a and 13b are Karman vortexes created
by the bluff body; and 14 is a tube member. Tube member 14 is a
hollow member installed at the downstream side of the bluff body
12 and intersecting with it. Then in the embodiment of the present
invention, the tube member 14 is installed in a space passing through
the hole A bored in the wall of the fluid-flowing tube 11 and the
hole B is bored at the external portion of the fluid-flowing tube
11. The tube member 14 extends into a wall part 11a.
Consequently, according to the embodiment of the present invention,
the pressure variation of the fluid to be measured due to the Karman
vortex created by the bluff body 12 is guided into the tube member
14 through the holes A and B, and then the pressure variation in
the tube member 14 or the fluid flow variation due to the pressure
variation is detected by sensing apparatuses for instance, an ultrasonic
wave transmitter 15 and an ultrasonic wave receiver 16. By such
means, the measurement of the velocity or quantity of the fluid
is performed.
As mentioned heretofore, according to the embodiment, a hole A
guiding a fluid pressure variation due to the Karman vortexes is
bored into the wall of the fluid-flowing tube forming a passage
for carrying the fluid to be measured, and another hole B, guiding
fluid pressure variation due to Karman vortexes, is bored in the
tube member 14 at the external side of the tube wall. Therefore,
the measurement of the fluid flow is hardly effected by the noise
generated in the fluid-flowing tube 11. Furthermore since the fluid
flow due to the fluid pressure variation caused by Karman vortexes
is rectified, the quality of the detected wave form is largely improved.
Also the hole B guiding fluid pressure variation caused by Karman
vortexes can be enlarged so that the measurement of the fluid flow
is hardly effected by dust or the like in the fluid-flowing tube
11. As a result, the pressure variation due to Karman vortexes can
be effectively detected. Since the pressure guiding hole B can be
bored perpendicularly to the fluid-flowing tube 11 as shown in FIG.
5 the measuring may be effectively performed in the presence of
water (or moisture), dirt, dust, or the like. Moreover, hole A is
perpendicular to hole B so that the measuring may be effectively
performed without being effected by external ultrasonic waves. The
above features represent the merits of the flow meter according
to the present invention.
FIG. 6 is a cross-sectional view showing the main portion of the
other embodiment of the present invention. In the embodiment, the
pressure variation guiding hole A and the through-hole of the tube
member 14 are bored separately. It may be easily understood that
the embodiment shown in FIG. 6 may perform its functions as well
as that shown in FIGS. 4 and 5.
FIG. 7 is a cross-sectional view showing the main portion of still
another embodiment of the present invention. In this embodiment,
a sound-absorbing material 17 is mounted on the surface of the member
situated at a place near the pressure-guiding hole B. It follows
that the measurement of the signal to be detected will not be greatly
effected by external turbulence which is caused by an ultrasonic
wave entering the tube member.
Furthermore, in each of the afore-mentioned embodiments, a filter
can be installed in the place near the fluid pressure-guiding hole
A. The filter is comprised of a porous material, for example porous
metal. In the case of installing a filter therein, it may be possible
thereby to prevent dust from entering into the tube member and from
mixing with the fluid to be measured.
As is apparent from the foregoing description, the vortex flow
meter which is not effected by external turbulence can be provided
according to the afore-mentioned embodiments of the present invention.
Furthermore, in the vortex flow meter, the fluid pressure-guiding
hole will probably not be clogged by dust mixed into the fluid to
be measured.
FIGS. 8 and 9 are cross-sectional views for explaining another
embodiment of the present invention. FIG. 8 is a cross-sectional
view including the bluff body or vortex generation 22 of the vortex
flow meter according to the present invention and being shown on
a plane that is perpendicular to the fluid-flowing passage 21. FIG.
9 is a cross-sectional view shown on line (shaft of the tube) IX--IX
of the tube member 23 shown in FIG. 8. The line IX--IX intersects
with the vortex generator 22 at the downstream side thereof and
runs through the wall of the fluid-flowing passage 21.
Each of the pressure guiding holes 24 and 25 is bored at a place
near the wall surface of the tube member 23. A partition wall 26
installed at the central portion thereof prevents the movement of
the fluid between the pressure guiding holes 24 and 25. The partition
wall 26 does not have to be perfectly air-tight. It is sufficient
that the fluid flow, due to pressure variation, be stably displaced
in the bypass, flowing passage to be mentioned hereinafter.
As already mentioned, the partition wall 26 does not always need
to be completely at the central position of the fluid-flowing tube.
The bypass flowing passage comprises of tubes 29 31 and 33. The
bypass tube 31 forms a straight flowing passage. An ultrasonic wave
transmitter 34 and an ultrasonic wave receiver 35 are installed,
respectively, at both end portions of the straight bypass flowing
passage. An ultrasonic wave emitted from the ultrasonic wave transmitter
34 driven by an ultrasonic wave oscillator now shown in the figure
is received by the ultrasonic wave receiver 35. The modulation of
the ultrasonic wave due to fluid displacement between both ends
of the straight flowing passage is applied to the detecting circuit
and the amplifying circuit not shown in the figure. The amplifying
circuit generates a vortex signal. The valves 30 and 32 are employed
for adjusting or intercepting the fluid displacement in the straight
flowing passage. Those valves are used mainly for the purpose of
adjusting the bypass fluid flow so as to optimize the vortex signal
and for intercepting the fluid flow at the time of checking the
ultrasonic wave transmitter and receiver. The reference numeral
36 represents the joint or coupling for connecting the tubes with
each other.
According to the afore-mentioned embodiment, even in the case of
a fluid with a high temperature to be measured, the temperature
is lowered at a place near the straight-flowing passage 31. Since
the lowered value of the temperature increases in accordance with
the length of the bypass flowing passage, a low-priced material
like PTZ, etc. can be used as a material for the ultrasonic wave
transmitter and receiver instead of a high-priced material such
as niobic acid lithium having a characteristic of a high Curie point.
Furthermore, it may be possible to adjust the vortex signal so as
to detect the optimized signal by opening and closing the valves.
Moreover, at the time of checking the vortex flow meter, the ultrasonic
wave transmitter and receiver can be easily exchanged for another
by shutting off the valves without removing the vortex flow meter
from the fluid-flowing tubes. As is apparent from the foregoing
description, the vortex flow meter according to the present invention
has so many merits that it functions much more effectively when
compared with the conventional one. |