Abstrict This invention relates to a target flow meter and method of calibrating
same adapted for use in various configurations of conduit and for
movement from one conduit configuration to another comprising a
housing connected to a conduit; a target means adapted for insertion
into conduits for providing a constant centroid target area for
the fluid relative to the conduit area for any level of fluid in
a conduit; a meter body adapted for connection to the housing and
for movement from one conduit to another; a mounting means for connecting
the target means to the meter body for movement; force transfer
means in relation to the target means for constant proportional
transfer of force from the target centroid to the force transfer
means in response to fluid level and movement in the conduit, and
transducer means connected to the meter body for receiving the force
transferred from said force transfer means and for measuring the
fluid flow as a function of the force on the force transfer means;
and further this invention relates to a method for calibrating a
flow meter having a visually marked point in known relation to the
centroid area of the target comprising attaching a force applying
means to said visual marked point and applying a known force to
the target at the known visual point on the target.
Claims I claim:
1. A flow meter adapted for use in various configurations of conduit
and levels of flow therein comprising
a housing connected to said conduit;
b. a target means adapted for insertion into said conduit area
for providing a constant centroid target area for the fluid relative
to said conduit area for any level of fluid in said conduit;
c. a meter body means adapted for connection to said housing;
d. a mounting means for removably connecting said target means
to said meter body means for movement;
e. a force transfer means in relation to said target means for
limited movement and for constant proportional transfer of force
from said target means to said force means in response to fluid
level and movement in said conduit;
f. transducer means connected to said meter body means for receiving
said force from said force transfer means to measure the fluid flow
as a function of the force on said force transfer means.
2. The flow meter of claim 1 wherein said mounting means for connecting
said target means to said meter body means provide for pivotal movement
of said target means.
3. The flow meter of claim 2 wherein said mounting means is adopted
for connecting said target means along said meter body for receiving
different target means for use in various conduit configurations
and for maintaining a constant proportional mechanical advantage
for the transfer of force from the centroid of said target to said
transducer means.
4. The flow meter of claim 2 wherein said mounting means for removably
connecting said target means to said meter body means for rotational
movement is a pivotal connecting means.
5. The flow meter of claim 4 wherein said force transfer means
is a lever arm connected to said target means in relation to said
centroid area for a predetermined constant proportional mechanical
advantage for the transfer of force from said target to said transducer
means in response to fluid level and movement in said conduit.
6. The flow meter of claim 4 wherein said force transfer means
further comprises a transfer means connected to said meter body
for limited movement and for transferring force to said transducer
means, and
a means connected to said target means for forming a lever arm
means to act against said transfer means.
7. The flow meter of claim 6 wherein the distance from said centroid
on said target to the mounting means and the distance of said lever
arm means from the mounting means to said transfer means are proportional
for a relatively constant mechanical advantage.
8. The flow meter of claim 6 wherein said mechanical transfer means
is a push rod movably mounted for limited movement in said meter
body for force transfer from said lever arm to said transducer means.
9. The flow meter of claim 8 further comprising adjustable fastener
means for removably fastening said housing and meter body means
in said housing and for providing limited vertical adjustment of
said meter body means to compensate for non-uniform flow lines and
target means relative to said conduit configuration for free movement
of said target means in said conduit.
10. The flow meter of claim 9 further comprising variable attachment
means on said meter body for selectively connecting said target
means thereto to provide said constant mechanical relationship between
said centroid target area and said force transfer means when said
centroid target area is changed by changing the size of said target
means.
11. The flow meter of claim 9 wherein the variable attachment means
on said meter body for selectively connecting said target means
to said meter body are further comprising;
a pivotal pin means for removably fastening said target means to
said meter body and a series of aperatures selectively arranged
on said meter body for receiving said pivot pin means for removably
fastening said target means thereto.
12. The flow meter of claim 11 wherein said selected series of
aperatures are arranged for providing a relatively constant mechanical
advantage for various size targets connecting said target to said
meter body at said aperatures to provide a distance from said centroid
on said target to the aperature and the distance of said lever arm
mean from said aperature to said transfer means are the same proportional
distance for various sizes of targets.
13. The flow meter of claim 11 further comprising an attachment
means on said target means in known relation to said centroid of
said target for calibration of said flow meter by applying a known
force on said attachment means on said meter.
14. The flow meter of claim 13 wherein said attachment means is
an aperature on said target.
Description This invention is related to a target flow measuring device which
can measure flow in partially filled conduits and can be moved from
one conduit fluid carrier to another conduit fluid carrier of a
different configuration without making changes or adjustments in
the meter sensing equipment.
It is often desirable to obtain a reading of the flow in a conduit
which is in fact only partially filled and the target meters of
the prior art have generally been unable to read the level of flow
in a partially filled conduit. The reason that the prior art meters
cannot read partially filled conduit is because the targets required
the full pressure of the fluid on the target in order to get an
accurate reading of the flow level of the conduit. For example,
target meters have been unavailable for use in the sanitary sewer
and oil field mud applications because of the problems associated
with partial flow at any given time.
Flow meters such as the flow meter of W. E. Nusbaum, U.S. Pat.
No. 3098384 have been developed for providing a means for reading
flow in partially filled flow lines; but, the prior art such as
Nusbaum has been defective for various reasons. For example, this
prior art has been defective because the target itself is directly
connected to the strain gauge for electrical readout or flow sensing;
and thus the blade or target is deformed in profile to get an electrical
readout of the strain gauge. In such an arrangement the blade or
target itself and the strain gauge are in such close proximity to
the flow in the conduit, that in corrosive environments, such as
sewer lines, the quality of the readout data is effected and the
corrosion can cause failure in the electrical wiring and sensing
head.
Also, the prior art flow meters required a target of a predetermined
size which had been calibrated for the amount of strain force produced
by a particular target and a change in the target required a change
in the sensing heads or the strain gauge in order to provide an
accurate flow measurement. Also, the flow meters of this prior art
could not be transferred from one conduit to another without a complete
change of the meter and targets. Thus multiple meters and targets
are required for setting into various conduits of various sizes
which requires a large inventory of meters and targets.
Also the targets of the prior art are very expensive because they
must be made of a material which can flex and deform without damage
to the target. Usually such material requires special alloys and
heat treating to bring the material up to standard and this raises
its cost.
Also for the prior art type meters to be accurate, the target must
have a relatively constant co-efficient of thermal expansion lest
temperature changes produce strains in the blade which will be read
a false flow.
Further the prior art meters require a special bonding of the strain
gauge to the target so that the strain gauge can accurately reflect
the change in the target. This special bonding drives up the cost
of the meters and provides a weak point for the failure of the meters.
In the prior art type meters, the targets are thin which cause
an increase in the vibrator noise level in the strain gauge signal
and produce errors.
Also the prior art target flow meters must be made of relatively
thin materials which allows flexing of the target to get a reading
of the strain, but thin targets are subject to being broken if hit
by various objects which have been known to flow in sewer lines
and mud lines. If a heavy material is used for the target, then
there is not sufficient deformation of the material to get a good
reading.
It is therefore the principal objects of the present invention
to provide a relatively simple target flow meter which can be adapted
for accurately measuring the flow of various flow conditions in
various sizes of conduit. The flow conditions varying from partially
filled conduit to fully filled conduits. In the flow meter of this
invention, a relatively simple device is provided for use in various
sizes of conduits as well as varying flow conditions in conduits.
In this invention the meter is also adapted for movement from one
conduit size to another conduit size without readjusting the instrument
package of the flow meter. The adjustment which is required in this
invention is a simple mechanical adjustment of the target by putting
on a different target and moving at another location on the meter
such that the target is capable of being inserted into the new conduit
and housing.
It is further the object of this invention to provide a target
which is not directly connected to the strain gauge for electrical
readout or for the sensing of flow. This indirect connection allows
the target to be in the environment of the conduit and the sensing
device to be removed from that environment and thus protected from
corrosive environment.
It is a further object of this invention to provide a flow meter
which is capable of reading storm sewers, sanitary sewers, and oil
field mud lines which have partial flow at some occasions and full
flow at other times.
Also it is an object of this invention to provide a flow meter
which can resist damage from various objects which are sometimes
carried by the flow of fluid.
It is a further object of this invention to provide a flow meter
which can measure the flow of slurrys, such as coal, sand, pulp,
etc.
It is also an object of this invention to provide a flow meter
which provides for a means of changing targets mechanically by those
relatively unskilled in instrument arts and which does not require
a change in the sensing head or the strain gauge in order to provide
an accurate measurement of flow.
It is a further object of this invention to provide a meter body
which can be used in any size or shape of conduit and only requires
a simple adjustment in the target for the meter to be used in any
size line, thus the meter of this invention does not require multiple
meters for multiple line sizes.
Also an object of this invention is to provide a target which is
relatively inexpensive and can be made of a very common metal or
material.
It is also an object of this invention to provide a target and
meter which is not sensitive to thermal expansion from changing
temperatures in the fluid and/or conduit.
It is also an object of this invention to provide a meter which
is mechanically attached to the meter body and does not require
any special bonding of a strain gauge or sensing equipment to the
target.
It is also an object of this invention to provide a flow meter
which may read flow in a conduit in either direction in the conduit
so that back flow can be measured.
It is a further object of this invention to provide a target which
provides a relatively low level of background noise on the strain
gauge and thus produces a more accurate reading.
Also it is an object of this invention to make the target relatively
thick, which prevents flexing and an inaccurate reading of the flow.
It is yet a further object of this invention to provide a target
of such thickness and rigid material to prevent it from being damaged
by various objects which have been known to flow in sewer and mud
lines and thus prevent breakage of the target.
It is a further object of this invention to provide a flow meter
which can read flow of fluids over a wide range of flow conditions.
Other objects and advantages of this invention will become apparent
from the following description taken in connection with accompanying
drawings, wherein are set forth by way of illustration and example
certain embodiments of this invention.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional view through the flow meter and target
in a side elevation view of the target and conduit.
FIG. 2 is a cross sectional view in front elevation through the
flow meter and conduit on which said flow meter is mounted.
FIG. 3 is the target element in side elevation.
FIG. 4 is the target from the rear elevation.
FIG. 5 is the target as connected to the meter body.
The flow meter of this invention is referred to generally at 10
of FIG. 1. In the flow meter 10 of this invention the functional
parts are generally referred to as an instrumentation 11 meter
body 12 and the target 13. The flow meter 10 in this embodiment
is shown mounted to a conduit 14 at a point on the conduit 14 where
a hole 15 has been made in the conduit 14 for the insertion of the
flow meter 10 of this invention. Attached to the conduit 14 about
the hole 15 is a housing 16 which has been welded to the conduit
14 by a weld bead 17. It should be understood that there may be
other ways of attaching the housing 16 to the conduit 14 but welding
is at least one way in this embodiment of attaching the housing
16 to the conduit 14.
The housing 16 is, at least in this embodiment, provided with a
channel 18 through which the meter 10 of this invention may be inserted
to pass into communication with the inside of the conduit 14. The
channel 18 is machined to provide a good fit of the meter 10 of
this invention into the channel 18 of the housing 16. In this embodiment,
an o-ring seal 19 is provided to form a fluid seal between the inside
of the conduit or a conduit cavity 20 and the ambient environment
outside the conduit 14.
The meter body 12 is the portion of the meter 10 which is in sealed
relationship with the o-rings 19 and channel 18 of the housing 16
to seal the conduit cavity 20 from the ambient environment. Also
as shown in FIG. 2 the meter body 12 is provided with facets 21
for receiving fasteners 22 to hold the meter 10 of this invention
in place in the housing 16. Also these facets 21 are provided to
allow cooperation with the fasteners 22 for limited up and downward
adjustment of the meter body 12 of this invention in the housing
16 and the target 13 in the conduit cavity 20. The facets 21 further
cooperate with the fasteners 22 to prevent rotation of the meter
body 12 in the channel 18 when torquing moments are imparted to
the meter 10 by the flow of fluid in the conduit 14.
The bottom 23 of the meter body 12 is inserted into the channel
18 and is exposed to the conduit cavity 20. Connected to the bottom
23 of the meter body 12 are paired ridged member 24 as best shown
in FIG. 5 which extends downward from the bottom 23 of the meter
body 12 into the conduit cavity 20. The paired ridged members 24
have a series of apertures 25 in a line along the paired ridged
members 24. Also along the bottom 23 of the meter body 12 is provided
an opening 26 which extends through the meter body 12. This opening
26 is provided for the insertion of a push rod 27 which is movable
from top to bottom in the opening 26. The push rod 27 has, at least
in this embodiment, o-rings seals 28 and 29 to form a sealed sliding
surface between the conduit cavity 20 and the instrumentation 11
thus the push rod 27 may freely move in the opening 26 while sealing
the conduit cavity 20 from the instrumentation 11.
The meter body 12 has a top surface 30 which is provided with a
flange 31. The flange 31 has bolt holes 32 drilled therethrough
for the attachment of the instrumentation 11 of the flow meter 10
of this invention. Along the top surface 30 of the meter body 12
is provided a seal 33 to seal the instrumentation 11 from the ambient
air. Forming a part of the seal is the instrumentation housing 34
which has a flanged surface 35 in sealing engagement with the top
surface 27 of the meter body 12 and the seal 33. Through the flanged
surface 35 of the instrumentation housing 34 are provided bolt holes
36 which are aligned with the bolt holes 32 of the meter body 12
for the insertion of bolts 37 to fasten the instrumentation 11 and
the meter body 12 together. Within the instrument housing 34 is
provided a standard strain gauge 38 which converts strain into an
electrical signal which is functionally related to the amount of
strain induced. The strain induced in at least one embodiment of
this invention is through the push rod 27 which is connected to
the strain gauge 38 on one end 41 of the push rod 27. The other
end 42 of the push rod 27 is positioned adjacent the target 13 to
transmit force from the target 13 through the push rod 27 to the
strain gauge 38. Also in some embodiments of this invention, the
push rod 27 may be connected to the target 13 at one end 42 for
reading a back flow or movement of the target in another direction
in response to flow.
In some embodiments an adjustable stop 43 is provided to prevent
the push rod 27 from over straining the strain gauge 38 and damaging
it. The strain gauge 38 can be of any standard type which will transduce
force strain into an electrical signal. The electrical signal produced
in the strain gauge is then converted to a readout system 39 which
gives a visual gauge read on a meter 40 as shown in FIG. 2.
Movably attached to the bottom 23 of the meter body 12 is the target
13 which extends down from the bottom 23 of the meter body 12 into
the conduit cavity 20 for receiving the flow pressure of the fluid
in the conduit 14. As shown by comparing the target 13 position
in FIG. 1 and FIG. 2 the target 13 has a target pressure surface
44 which is set at right angles to the flow of the fluid in the
conduit cavity 20.
The target pressure surface 44 in this embodiment has a surface
area configuration which provides a centroid area 43 having a constant
effective length of the target 13 over which that fluid force acts
no matter what the flow conditions in the conduit. This effective
length on the target 13 is from the centroid area 45 to a point
of attachment 46 of the target 13 to the meter body 12.
In a relatively round conduit cavity 20 as shown in FIG. 2 the
target pressure surface 44 is shaped to provide a constant centroid
area 45 to the flow of fluid in the conduit cavity 20 whether there
is little flow or a completely filled cavity. The centroid area
45 is maintained by the configuration of the target pressure surface
44 which provides a relatively long lever arm and smaller surface
area when the flow is low or less than a full conduit cavity 20.
But when the conduit cavity 20 is full, the force exerted by the
fluid is of course greater but the length of the target pressure
surface 44 exposed to the flow of fluid at the point of attachment
46 of the target 13 to the meter body 12 provides a short lever
arm, thus an averaging of forces occurs at the centroid area 45
of the target 13. The portional adjustment of the target area configuration
to conduit cavity area thus provides a target pressure surface 44
which has the effect of averaging the pressure exerted on it over
the target 13 in relation to the conduit cavity area whether low
flow or completely filled. The centroid area 45 thus creates a constant
lever arm no matter what the flow condition because the centroid
45 remains constant over any given flow condition in the conduit
14.
The target 13 in this embodiment has a ridged reinforcing member
47 connected along the target 13 on the opposite side of the target
pressure surface 44 to reinforce the target 13 against being bent
or damaged by any debris which might be in the fluid flow in the
conduit 14. A portion of the ridged reinforcing member 47 extends
from the point of attachment 46 of the target 13 along the bottom
23 of the meter body 12 to form a lever arm 48. The lever arm 48
is positioned as can best be seen in FIG. 1 where the target 13
is attached to the meter body 12 at the attachment point 46 and
the lever arm 48 is shown acting against the push rod 27 in response
to the force exerted on the target pressure surface 44 by the fluid
in the conduit 14. The effective length of lever arm 48 is determined
by the distance of the lever arm 48 as measured from the point of
attachment 46 to the point at which the lever arm 48 acts on the
push rod 27. Thus in this invention the forces exerted by the flowing
fluid act on the target 13 over an effective constant distance as
determined by the distance from the centroid area 45 to the point
of attachment 46 of the target 13 and that force is then transmitted
to the predetermined length of lever arm 48 for a the proportional
transfer of the fluid force through the target 13 to the push rod
27. Thus the force acting on the target pressure surface 44 is transmitted
to the push rod 27 over a known mechanical advantage or relationship
from which a computation of the force transmitted to the strain
gauge 38 can be made for determining the flow in the conduit 14.
In at least one embodiment as shown in FIG. 5 the point of attachment
46 of the target 13 to the meter body 12 is formed by providing
an aperture 49 through a portion of target 13 adjacent the point
of attachment 46. The aperture 49 of target 13 is then inserted
between the paired ridged members 24. The apertures 25 of the paired
ridged members 24 are aligned with the aperture 49 of the target
13 and a pin 30 is inserted through the aligned apertures 25 and
49 for pivotally attaching the meter body 12 to the target 13. The
pin 50 is held in place by lock rings 51 and 52 respectively.
It should be noticed in FIG. 1 that the paired ridged members 24
have a series of apertures 25 there along for pivotally mounting
targets 13 of various sizes to the meter body 12 at different apertures
25. Thus the series of apertures 25 provide a means to adjust the
length of the lever arm 48 for different sized targets having different
centroids, by pulling pin 50 and reinserting it at another aperture
25 which may make the distance between the point of attachment 46
and the point on the lever arm 48 which acts on the push rod 27
longer or shorter depending on which way the point of attachment
46 is moved. If it is moved toward the push rod 27 the lever arm
48 is shortened, but if it is moved away from the push rod 27 then
the lever arm 48 is lengthened. In this embodiment of this invention
the ratio of lengths of the centroid area 45 to the point of attachment
46 of the target 13 and the lever arm 48 of target 13 must, remain
constant for any given precalibrated strain gauge to provide interchangably
of the targets and meters from one size conduit to another by changing
the target 13 without recalibrating the instrumentation 11. This
interchangability is accomplished by selecting the proper point
of attachment 46 for the particular target size to maintain the
same mechanical ratio of lever arm lengths which transmit the forces
to the push rod 27.
By allowing easy mechanical adjustment of the targets to fit any
size conduit without recalibrating the instrumentation 11 relatively
unskilled people may move the flow meter from one size conduit to
another. Also the only inventory required for multiple size conduit
uses is an inventory of targets because the meter body 12 and instrumentation
11 may be used on any size line without recalibration if the proper
point of attachment 46 is used for a given target 13.
Also by using a visual point 53 on the target 13 in a known relation
to the centroid area 45 and by applying a known force thereto, a
method is provided for the easy calibration of the flow meter of
this invention. The method of this invention may be accomplished
in several ways. In one embodiment a force line is attached to the
visual point 53 and then a known force is applied to the force line.
By comparing the known force applied to the visual point 53 on the
target and the reading of the flow meter 40 an accurate calibration
of the meter may be made.
The foregoing disclosure and description of the invention is illustrative
and explanatory thereof, and various changes in the size, shape
and materials as well as in the details of the illustrated construction
may be made within the scope of the appended claims without departing
from the spirit of the invention. |