Abstrict A flow meter measures the time rate of mass flow by measuring the
torque or torsion associated with the nutation of the spinning fluid
created by a forced oscillation of the spinning axis of the spinning
fluid flowing through a conical shell wherein the spinning movement
is imposed on the fluid entering through a port disposed at the
diverging extremity of the conical shell by a plurality of spiral
flow guides, which spinning movement becomes accelerated as the
fluid approaches the converging extremity of the conical shell.
An oscillating motion imposed on the converging extremity in a first
direction perpendicular to the spinning axis coinciding with the
central axis of the conical shell produces a precession torque or
torsion creating an oscillating motion in a second direction perpendicular
to the first direction as well as to the spinning axis, wherein
the time rate of mass flow is measured by measuring the oscillating
motion in the second direction.
Claims I claim:
1. A device for measuring flow rate comprising in combination:
(a) a flow passage assembly comprising a conical shell with closed
converging extremity and capped diverging extremity including a
substantially centrally located inlet port disposed through said
capped diverging extremity of said conical shell and extending to
an inlet tube, and an outlet tube coaxially routed and extending
through said inlet port into inside of said conical shell in a substantially
coaxial relationship and terminated near said closed converging
extremity, wherein flow guide means disposed adjacent to said inlet
port for imposing rotating movements on fluid medium entering through
said inlet port and guiding said fluid medium toward the wall of
said conical shell is included;
(b) means for securing said inlet tube;
(c) means for imposing oscillatory movements on said closed converging
extremity of said conical shell in a first direction substantially
perpendicular to the central axis of said conical shell; and
(d) means for measuring vibratory movements of said closed converging
extremity of said conical shell in a second direction substantially
perpendicualr to the central axis of said conical shell and to said
first direction, said vibratory movements being generated by dynamic
interaction between rotating motion of fluid in said conical shell
and said oscillatory movements of said closed converging extremity
of said conical shell.
2. The combination as set forth in claim 1 wherein said combination
includes means for converting output from said means for measuring
vibratory movements to flow rate measurement data indicating flow
rate of the fluid medium flowing through said flow passage assembly.
3. The combination as set forth in claim 2 wherein said combination
includes means for displaying said flow measurement data.
4. The combination as set forth in claim 2 wherein said combination
includes means for transmitting said flow measurement data as an
input to other flow control devices.
5. The combination as set forth in claim 2 wherein said means for
imposing oscillatory movements on said closed converging extremity
of said conical shell operates substantially at a resonance frequency
of said flow passage assembly containing fluid medium flowing through
said flow passage assembly.
6. The combination as set forth in claim 1 wherein a portion of
said inlet tube is constructed in bellows structures intermediate
said capped diverging extremity of said conical shell and said means
for securing said flow passage assembly.
7. The combination as set forth in claim 6 wherein said combination
includes means for converting output from said means for measuring
vibratory movements to flow rate measurement data indicating flow
rate of the fluid medium flowing through said flow passage assembly.
8. The combination as set forth in claim 7 wherein said combination
includes means for displaying said flow measurement data.
9. The combination as set forth in claim 7 wherein said combination
includes means for transmitting said flow measurement data as an
input to other flow control devices.
10. The combination as set forth in claim 7 wherein said means
for imposing oscillatory movements on said closed converging extremity
of said conical shell operates substantially at a resonance frequency
of said flow passage assembly containing fluid medium flowing through
said passage assembly.
11. A device for measuring flow rate comprising in combination:
(a) a flow passage assembly comprising a conical shell with converging
extremity including an outlet port extending to an outlet tube disposed
substantially in line with said conical shell and capped diverging
extremity including a substantially centrally located inlet port
disposed through said capped diverging extremity and extending to
an inlet tube disposed substantially in line with said conical shell,
wherein flow guide means disposed adjacent to said inlet port for
imposing rotating movements on fluid medium entering through said
inlet port and guiding said fluid medium toward the wall of said
conical shell is included;
(b) means for securing said flow passage assembly by securing a
portion of said inlet tube and by securing a portion of said outlet
tube;
(c) means for imposing oscillatory movements on combination of
said converging extremity of said conical shell and a portion of
said outlet tube adjacent to said converging extremity of said conical
shell in a first direction substantially perpendicular to the central
axis of said conical shell; and
(d) means for measuring vibratory movements of combination of said
converging extremity of said conical shell and a portion of said
outlet tube adjacent to said converging extremity of said conical
shell in a second direction substantially perpendicular to the central
axis of said conical shell and to said first direction, said vibratory
movements being generated by dynamic interaction between rotating
movements of fluid within said flow passage assembly and said oscillatory
movements of combination of said converging extremity of said conical
shell and a portion of said outlet tube adjacent to said conical
shell.
12. The combination as set forth in claim 11 wherein said combination
includes means for converting output from said means for measuring
vibratory movements to flow rate measurement data indicating flow
rate of the fluid medium flowing through said flow passage assembly.
13. The combination as set forth in claim 12 wherein said combination
includes means for displaying said flow measurement data.
14. The combination as set forth in claim 12 wherein said combination
includes means for transmitting said flow measurement data as an
input to other flow control devices.
15. The combination as set forth in claim 12 wherein said means
for imposing oscillatory movements on said closed converging extremity
of said conical shell operates substantially at a resonance frequency
of said flow passage assembly containing fluid medium flowing througn
said flow passage assmebly
16. The combination as set forth in claim 11 wherein portion of
at least one of said inlet tube and said outlet tube is constructed
in bellows structures intermediate said conical shell and said means
for securing said flow passage assembly.
17. The combination as set forth in claim 16 wherein said combination
includes means for converting output from said means for measuring
vibratory movements to flow rate measurement data indicating flow
rate of the fluid medium flowing through said flow passage assembly.
18. The combination as set forth in claim 17 wherein said combination
includes means for displaying said flow measurement data.
19. The combination as set forth in claim 17 wherein said combination
includes means for transmitting said flow measurement data as an
input to other flow control devices.
20. The combination set forth in claim 17 wherein said means for
imposing oscillatory movements on said closed converging extremity
of said conical shell operates substantially at a resonance frequency
of said flow passage assembly containing fluid medium flowing through
said passage assembly.
Description BACKGROUND OF THE INVENTION
In recent times, the type of flow meter known as the coriolis force
flow meter has been successfully developed wherein a U-tube or a
360 degree loop of tube containing moving fluid is oscillated in
a direction perpendicular to the plane including the loop of the
tube or U-tube on the plane of symmetry dividing the U-tube or a
loop of tube into two equal halves and the torque or torsion about
an axis coinciding with the line of intersection between the plane
including the loop of the tube and the plane of symmetry dividing
the loop of the tube into two equal halves is measured to indicate
the time rate of mass flow of the fluid through the loop of the
tube. Although the coriolis force type flow meter is accurate and
reliable when it is used to measure reasonably low rates of flow
of a liquid medium, it has been unsuccessful to measure the flow
rates of gaseous media or fluid flow at a very low rate. The flow
of a gaseous medium does not generate a precession torque large
enough to be detected by a coriolis force flow meter using a vibrating
loop of tube, while the aforementioned type of flow meter is not
suitable to measure the flow rate of fluid at a high flow rate in
terms of difficulties encountered in the construction and operation
thereof.
Although many inventors and engineers pioneering the art of the
coriolis flow meter technology have failed to understand the operating
principles thereof, it is quite clear that a coriolis force flow
meter operates in the same principle as the mechanics of a spinning
top. When the spinning axis of a spinning top deviates from a perfectly
vertical axis, the spinning top nutates about the vertical axis
while it spins about its own spinning axis. A coriolis force flow
meter with a greater sensitivity and broader applicability can be
constructed in structures utilizing the mechanics of the spinning
top.
The primary object of the present invention is to provide a precession
flow meter operating on principles similar to the mechanics of spinning
tops.
Another object is to provide a precession flow meter including
a conical shell with a fluid inlet disposed at the diverging extremity
thereof wherein a plurality of radially disposed spiral flow quides
impose spinning movement on the fluid entering therethrough.
A further object is to provide a precession flow meter including
a fluid outlet disposed at the converging extremity of the conical
shell.
Yet another object is to provide a precession flow meter including
means disposed at the converging extremity of the conical shell
for imposing oscillatory movements of the converging extremity relative
to the diverging extremity thereof on a first plane including the
central axis of the conical shell.
Yet a further object is to provide a precession flow meter including
means for measuring the amplitude of the vibratory movements of
the converging end of the conical shell taking place on a second
plane including the central axis of the conical shell and perpendicular
to the first plane on which the oscillatory movement is imposed.
Still another object is to provide a precession flow meter including
means for converting the amplitude of the vibratory movement of
the converging extremity of the conical shell on the second plane
to the mass flow rate of the fluid passing through the conical shell.
Still a further object is to provide a precession flow meter wherein
the converging extremity of the conical shell is oscillated at a
resonance frequency of the vibrating system including the conical
shell and the fluid moving therethrough.
These and other objects of the present invention will become clear
as the description thereof proceeds.
BRIEF DESCRIPTION OF THE FIGURES
The present invention may be described with a great clarity and
specificity by referring to the following figures:
FIG. 1 illustrate a cross section of an embodiment of the precession
flow meter constructed in accordance with the principles of the
present invention
FIG. 2 illustrates another cross section of the embodiment shown
in FIG. 1.
FIG. 3 illustrates a further cross section of the embodiment shown
in
FIG. 4 illustrates a cross section of another embodiment of the
precession flow meter.
FIG. 5 illustrates a cross section of a further embodiment of the
precession flow meter.
FIG. 6 illustrates another cross section of the precession flow
meter shown in FIG. 5.
FIG. 7 illustrates a cross section of yet another embodiment of
the precession flow meter.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
In FIG. 1 there is illustrated a cross section of an embodiment
of the precession flow meter constructed in accordance with the
principles of the present invention, which cross section is taken
along a plane including the central axis of the flow meter. The
precession flow meter includes a conical shell 1 with a closed converging
extremity 2 and a capped diverging extremity 3. The capped diverging
extremity 3 of the conical shell includes a centrally disposed fluid
inlet 4 connected to an inlet tube 5 that is rigidly anchored to
a supporting structure 6. An outlet tube 7 coaxially disposed within
the inlet tube 5 extends into the inside of the conical shell 1
through the fluid inlet 4 and is terminated near the converging
extremity 2 of the conical shell where it provides a fluid outlet.
A plurality of spiral flow guides 9 are disposed in an axisymmetric
radial pattern intermediate the capped diverging extremity 3 of
the conical shell 1 and a flow deflector disc 10 disposed adjacent
and parallel thereto. Means for imposing oscillatory movements to
the converging extremity 2 of the conical shell 1 on a first plane
including the central axis of the conical shell includes one or
more electromagnets 11 and 12 and a magnetically reacting member
13 rigidly affixed to the diverging end of the conical shell 1.
Means for sensing the magnitude of the vibratory movements of the
converging extremity 2 of the conical shell 1 on a second plane
including the central axis of the conical shell 1 and perpendicular
to said first plane includes a signaling means 14 and sensing means
15 which will be further described in conjunction with FIG. 3.
In FIG. 2 there is illustrated another cross section of the embodiment
shown in FIG. 1 taken along a plane 2-2 as shown in FIG. 1. The
plurality of spiral flow guides 9 disposed in an axisymmetric radial
pattern with respect to the central axis of the conical shell 1
may be affixed to the flow deflector disc 10 or the capped end 3
of the conical shell 1 or to both elements. It should be mentioned
that a desirable construction should be employed in arranging the
outlet tube 7 spiral flow guides 9 and the flow deflector disc
10 in order to satisfy the design requirement that makes the combination
of the aforementioned elements 7 9 and 10 mechanically linked to
or isolated from the oscillatory movements of the combination including
the conical shell 1 and the portion of the inlet tube 5 intermediate
the diverging extremity 3 of the conical shell 1 and the anchoring
structure 6.
In FIG. 3 there is illustrated a further cross section of the embodiment
shown in FIG. 1 taken along a plane 3-3 as shown in FIG. 1. The
one or more electromagnets 11 and 12 powered by an alternating electric
current vibrates the magnetically reacting element 13. The signaling
means 14 affixed to the magnetically reacting element 13 or to the
converging end of the conical shell 1 may be a permanent magnet
bar and the sensing means 15 and 16 may be one or more induction
coils that generate electromotive force as the magnetic bar 14 moves
in and out of the core of the induction coils. It should be understood
that there are many different methods and means available for measuring
the magnitude and/or frequency of the vibratory movements of the
converging end of the conical shell 1 which is a matter of design
to be elected by the professional designers designing the precession
flow meter taught by the present invention. The combination of the
permanent magnet and the induction coils shown in the illustrated
embodiment is an example of such matter of design. Consequently,
the practice of the present invention is not limited to such an
illustrated example. Means for measuring the amplitude and/or frequency
of the vibratory movements of the converging end of the conical
shell 1 may include a device measuring the electromotive force or
electric current generated by the induction coils 15 and/or 16
which measurement is then converted to flow rate data by a data
processing means. The black box 17 represents the combination of
the aforementioned means, which may include data display means 18
and data transmission means 19.
The precession flow meter shown in FIGS. 1 2 and 3 operates in
the following principles : The fluid medium flowing into the conical
shell 1 through the inlet tube 5 is imposed with a spinning movement
about the central axis of the conical shell 1 by the plurality of
the spiral flow guides 9. As the fluid medium with an angular momentum
approaches the converging end 2 of the conical shell 1 the spinning
movement of the fluid medium rapidly gains intensity in accordance
with the law of the conservation of angular momentum. The fluid
medium under a high intensity spinning movement leaves the conical
shell through the outlet tube 7 coaxially disposed within the combination
of the conical shell 1 and the inlet tube 5. The fluid under a high
spin as it flows through the conical shell 1 is lietrally a fluid
top that behaves much like a spinning top. When the angular momentum
vector of the spinning fluid in the conical shell 1 that is parallel
to the central axis of the conical shell 1 is imposed upon by an
additional angular momentum vector perpendicular to the central
axis of the conical shell 1 that is generated by the oscillatory
movements of the converging end of the conical shell 1 created by
the electromagnets of alternating currents, there results a precession
torque vector with direction perpendicular to the angular momentum
vector representing the spinning movement of the fluid in the conical
shell and perpendicular to the imposed angular momentum associated
with the oscillatory movements of the converging end of the conical
shell 1 relative to the diverging end thereof, of which magnitude
is proportional to the angular momentum vector of the spinning fluid
in the conical shell 1 that is, in turn, proportional to the mass
flow rate of the fluid medium flowing through the conical shell,
multiplied by the product of the amplitude and frequency of the
oscillatory movement imposed on the converging end of the conical
shell by the electromagnets. Consequently, for given value of the
amplitude and frequency of the oscillatory movements of the converging
end of the conical shell created by the electromagnets, the magnitude
of the precession torque is porportional to the mass flow rate of
the fluid flowing through the conical shell 1 which precession
torque creates vibratory movements of the converging end of the
conical shell in a direction prependicular to the oscillatory movements
thereof created by the electromagnets, wherein the magnitude of
the vibratory movements is porportional to the mass flow rate of
the fluid medium. Therefore, the measurements of the magnitude of
the aforementioned vibratory movements enables it to measure the
mass flow rate of the fluid medium flowing through the flow meter
comprising the elements shown in FIGS. 1 2 and 3.
It should be understood that the means for imposing the oscillation
and the means for measuring the magnitude of the vibration of the
converging end of the conical shell may include arrangements different
from those shown in the illustrated embodiments. It should be also
understood that the cap covering the diverging end of the conical
shell may be a conical cap instead of a flat cap. It is also evident
that the roles of the converging and diverging end of the conical
shell can be reversed in such a way that the inlet and outlet tubes
are connected to the converging end of the conical shell and the
means for imposing and measuring vibratory movements are installed
at the diverging ends of the conical shell. It should be mentioned
that the oscillatory movements of the converging or diverging end
in either arrangement may be imposed at a resonance frequency of
the mechanical system including the conical shell assembly and the
fluid therein, for such vibrations at a resonance frequency generates
the precession torque alternating at the resonance frequency that
creates the resulting vibration of the conical shell taking place
at the resonance frequency, which enables one to measure a very
low flow rate of a gaseous medium.
In FIG. 4 there is illustrated a cross section of another embodiment
of the precession flow meter of the present invention constructed
essentially in the same way as the embodiment shown in FIGS. 1
2 and 3 with two exceptions, which are, firstly, the portion of
the inlet tube 20 intermediate the conical shell and the anchoring
structure comprises a bellows construction that facili- tates the
oscillatory movements of the converging end of the conical shell
at a particular resonance frequency and, secondly, the flow deflector
21 comprises a conical guide that guides the spinning fluid following
the wall of the conical shell. In this embodiment, it is also possible
to reverse the role of the converging and diverging ends of the
conical shell as described in conjunction with the embodiments shown
in FIGS. 1 2 and 3.
In FIG. 5 there is illustrated a cross section of a further embodiment
of the precession flow meter constructed in accordance with the
principles of the present invention, which is constructed in a way
similar to those devices shown in FIGS. 1 and 4 with a few exceptions
and operates in the same principles as those described in conjunction
with FIGS. 1 2 and 3. The conical shell 22 including a conical
flow deflector-guide 23 and a plurality of spiral flow guides 24
has a fluid inlet tube 25 extending from the center of the capped
diverging end 26 of the conical shell 22 wherein the inlet tube
25 is anchored to a first supporting structure 27. The fluid outlet
tube 28 extending from the converging end 29 of the conical shell
22 is anchored to a second supporting structure 30. Means for imposing
oscillatory movements on the converging extremity of the conical
shell such as one or more electromagnets 31 and 32 and means for
measuring the precession torque or torsion such as the induction
coil 33 are disposed adjacent to one extremity of the fluid outlet
tube 28 connected to the converging end of the conical shell 22.
In FIG. 6 there is illustrated another cross section of the embodiment
shown in FIG. 5 taken along plane 6--6 as shown in FIG. 6 which
cross section further illustrates the arrangements of the means
for imposing the oscillatory movements on the converging extremity
of the conical shell 22 and the means for measuring the precession
torque or torsion. In this illustrative embodiment presented as
an example of arranging the aforementioned means, one or more electromagnets
31 and 32 energized by alternating electric currents imposing oscillatory
forces on a pair of magnetically reacting plates 34 and 35 affixed
to the wall of the fluid outlet tube 28 constitutes the means for
imposing oscillatory movements in a first direction perpendicular
to the central axis of the combination including the inlet tube-conical
shell-outlet tube arranged in line. The pair of permanent magnets
36 and 37 respectively extending from the magnetically reacting
plates 34 and 35 and slidably engaging the core of the pair of induction
coils 38 and 39 respectively, constitutes the means for measuring
the precession torque or the vibratory movements of the converging
extremity of the conical shell in a second direction perpendicular
to said first direction and perpendicular to the central axis of
the precession flow meter assembly. It should be understood that
the means for imposing the oscillatory movements may comprise one
electromagnet and one or more biasing mechanical springs instead
of two electromagnets, which alternate arrangement may be also applied
to the precession flow meters shown in FIGS. 1 4 and 7. The means
for measuring precession torque or vibratory movements of the converging
end of the conical shell may comprise one induction coil instead
of two or other devices designed to measure the position or velocity
or acceleration of the target employed in place of the permanent
magnet 36 or 37.
In FIG. 7 there is illustrated a cross section of yet another embodiment
of the precession flow meter that is constructed essentially in
the same way as the embodiment shown in FIG. 5 with two exceptions
being that, firstly, the flow deflector disc 40 with round edge
41 is employed in place of the coni cal flow the deflector-guide
employed in FIG. 5 and, secondly, the portions of inlet tube 42
and outlet tube 43 intermediate the respective supporting structures
44 45 and the conical shell are constructed in bellowing structures
46 and 47 respectively. It should be understood that only one of
two tubes may be provided with the bellows construction.
While the principles of the present invention have now been made
clear by the illustrative embodiments, it will be immediately obvious
to those skilled in the art many modifications in the structures,
arrangements, proportion, elements and materials which are particularly
adapted to the specific working environments and operating conditions
in the practice of the invention without departing from those principles. |