A flow meter mounted in a flow delivery line and having a meter
housing with a fluid opening and an electric counter. A turbine
rotor supported on a turbine shaft is disposed in the fluid opening,
the turbine having plural turbine blades with ferrous slugs embedded
therein, the electric counter responding thereto for fluid delivery
indication. Each turbine blade is tapered from front to rear into
a feathered trailing edge and has a top concave surface along its
length and a bottom convex surface. A pair of shaft supports, having
fluid ports for washing about the turbine shaft, are provided to
support the turbine rotor.
What is claimed is:
1. A flow meter for mounting in a fluid delivery line for dispensing
fluids, the flow meter comprising;
a meter housing having a display cavity disposed in the top thereof
and a fluid opening therethrough, the opposite ends of the housing
adjacent the fluid opening threaded for coupling to the delivery
a turbine having a turbine rotor with a turbine shaft extending
outwardly from the opposite ends of the turbine rotor, the turbine
further having a plurality of turbine blades extending outwardly
from the sides of the turbine rotor, each blade turbine having a
ferrous slug embedded in an enlarged flattened area in the end thereof,
the flattened area adjacent a rounded leading edge with the turbine
blade tapered from front to rear into a feathered trailing edge,
each turbine blade having a top concave surface along its length
for receiving the force of the fluid there against and driving the
turbine and a bottom convex surface along the its length, the turbine
blades when viewed end to end having a hydrofoil type design;
a pair of shaft supports, each of the shaft supports including
a support base with a plurality of support arms extending outwardly
therefrom, the ends of the support arms attached to the sides of
the fluid opening, the support base having fluid ports therein and
communicating with enlarged fluid cavities disposed so that fluid
is washed around and beside the end of the shaft, the end of at
least one of the turbine shafts engaging a thrust bearing mounted
in the support base;
a pickup coil with magnet mounted in the display cavity of the
housing, the magnet disposed adjacent the outer periphery of the
fluid opening for sensing magnetic pulses as the turbine blades
with the ferrous slugs are rotated therepast; and
electric counter means for converting the magnetic pulses to a
readable count, and for displaying the readable count on a digital
counter mounted in the top of the display cavity of the housing.
The invention relates to a fluid flow meter and more particularly,
but not by way of limitation, to a battery operated digital flow
meter used for mounting in a fluid delivery line for dispensing
fluids of various viscosities.
Heretofore, the size and complexity of fluid flow meters precluded
the use of a flow meter which could be used and read at the point
of delivery when the fluid is being dispensed. Further flow meters
with normal turbine blades use a flat profile of machined metal
which is expensive. Also, the high cost of the existing self-contained
battery powered equipment limited this type of equipment for use
by the average consumer. In the past there have been various types
of flow meters with different types of read-out counters. These
types of flow meters are disclosed in the following United States
Patents: U.S. Pat. Nos. 3329021 to Quesinberry et al, 3370465
to Belle, 3774448 to Gass et al, 3823310 to Kalotay et al and
4265127 to Onoda, 128338 to Van Anden, 3084545 to Waugh, 3238776
to Potter, 3757578 to Clinton, 3452593 to Lauter, 3534602
to Boyd, 3623835 to Boyd, 3945253 to Liu et al and 4253341
to Ineda et al. None of the above-mentioned patents specifically
disclose the unique structure and advantages of the subject digital
flow meter as described herein.
SUMMARY OF THE INVENTION
The subject digital flow meter for dispensing fluids is a combination
of a turbine type flow meter with a battery powered digital counter
with a liquid crystal display which meets the user's needs in dispensing
different types of fluids. The flow meter uses pulse sensing which
does not draw current thus allowing extended battery life up to
seven years. Also, the meter has self-shutdown capability to further
conserve the battery's energy. The turbine type design with solid
state electronics allows for compact portable packaging.
A 4-digit, 0.5" high LCD display on the flow meter shows the
volume of fluids that has passed through the turbine since the counter
was reset. The display is capable of receiving a high resolution
signal, i.e. 770 pulses per gallon.
Further, the counter may be reset to zero by simply depressing
a reset switch for three seconds. Also depressing the reset switch
momentarily will display a total cumulative count dispensed which
is lost only when power is lost or removed.
In addition the counter has three methods of calibration which
allow the use of fluids having different viscosities and may be
calibrated in most any unit, i.e. gallons, liters, cubic feet, etc.
A built-in calibration allows for low viscosity liquids, i.e. gasoline,
diesel fuel, water, with an error of plus or minus 11/2. A two point
calibration allows the meter to be used for high viscosity liquids
including viscous fluids such as oils and herbicides with an error
within plus or minus 1%.
An additional advantage of the digital flow meter is that it may
be mounted at the nozzle in the end of the delivery hose where it
may be easily read by the operator. By placing the flow meter at
the delivery end of the hose, the volume of fluid which ordinarily
would be in the hose if the flow meter were mounted at the supply
end of the hose is eliminated.
The simple calibration procedures as mentioned above allow the
invention to be used with a wide range of different types of fluids
and at operating temperatures from -14 degrees F. to +140 degrees
F. and stored at -22 degrees F. to +150 degrees F. Further the flow
meter utilizes solid state CMOS electronic circuitry for low power
consumption and reliability and a weatherproof enclosure.
The flow meter has a low pressure drop to minimize load on the
pump and accommodates flow rates from 3 to 30 gallons per minute.
Also the meter is adaptable for handling less than three gallons
or greater than 30 gallons per minute. It is highly accurate and
repeatable. The blades of the turbine have been designed for optimum
performance based on a "K" factor (number of pulses per
unit measure) over the meter's flow range. The turbine and blades
are molded of plastic or other similar materials to greatly reduce
the cost of the flow meter.
The shaft support of the turbine allows for flushing of the shaft
and bearing areas to prevent accumulation of chemical residue which
results in shaft "freeze-up".
The digital flow meter for mounting in a fluid delivery line for
dispensing fluids of various viscosities includes a meter housing
having a fluid opening therethrough. The opposite ends of the housing
adjacent the opening are threaded for coupling to the delivery line.
A turbine having turbine blades is mounted inside the opening. The
turbine blades include ferrous slugs mounted therein. The turbine
further includes a turbine shaft received in shaft supports which
are attached to the sides of the opening. A pickup coil with magnet
is mounted in a display cavity in the top of the housing. The magnet
counts the magnetic pulses as the turbine blade rotates thereby.
An electronic counter with digital display is connected to the pickup
coil for converting the magnetic pulses to a readable count display
on the digital counter.
The advantages and objects of the invention will become evident
from the following detailed description of the drawings when read
in connection with the accompanying drawings which illustrate preferred
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a top view of the digital flow meter housing.
FIG. 2 is a side sectional view of the flow meter taken along lines
2--2 shown in FIG. 1.
FIG. 3 is an end sectional view of the meter housing taken along
lines 3--3 shown in FIG. 1.
FIG. 4 is an end sectional view of the meter housing taken along
lines 4--4 shown in FIG. 1.
FIG. 5 illustrates the turbine mounted on a pair of stationary
FIGS. 6 and 7 illustrate a front and rear view of one of the stationary
FIG. 8 illustrates a plot of a "K" factor (pulses per
unit measure) and flow rate (i.e. gpm).
FIG. 9 illustrates an enlarged view of the turbine blade profile.
DETAILED DESCRIPTION OF THE DRAWINGS
In FIG. 1 the digital flow meter is designated by general reference
numeral 10. The digital flow meter includes a meter housing 12 having
a display area 14 mounted in the top of the housing 12. In the display
area 14 is a liquid crystal display 16 with a digital counter 18
displaying, for example, 20.75 gallons of fluid dispensed. Also
shown in the top of the display area 14 is a display button 20 and
a calibration button 22 connected to the digital counter 18.
In FIG. 2 a side sectional view of the housing 12 is shown taken
along line 2--2 shown in FIG. 1. In this Fig. the housing 12 can
be seen having a display cavity 24 for receiving the electronic
counter controls therein. The meter housing 12 further includes
a fluid opening 26 therethrough with opposite ends 28 and 30 threaded
for coupling a delivery line. The direction of fluid flow is indicated
by arrows 29.
A turbine designated by general reference numeral 32 is disposed
inside the opening 26. The turbine 32 includes a turbine rotor 34
with a plurality of turbine blades 36 equally spaced around the
turbine rotor 34 and extending outwardly therefrom. Mounted in the
ends of the blades 36 are ferrous slugs 38. The turbine 32 further
includes turbine shaft 40. The shaft 40 can be seen in FIG. 5. The
turbine shaft 40 is mounted on support bearings 42 received in a
pair of support bases 44. Each base 44 is part of a shaft support
46. The two shaft supports 46 include a plurality of support arms
48 extending outwardly from the support base 44 with the ends of
the arms 48 attached to the sides of the opening 26.
In FIGS. 3 and 4 sectional end views of the meter housing 12 can
be seen. As the turbine blades 36 rotate on the turbine shafts 40
in the opening 26 the ferrous slugs 38 move adjacent the outer
periphery of the opening 26 and past a pickup coil 50 having a magnet
52 mounted in the end thereof. The pickup coil 50 converts the magnetic
pulses received by the magnet 52 and converts the magnetic pulses
to a readable count sent to a microprocessor which is part of the
liquid crystal display 16. The above-mentioned electrical controls
are powered by a pair of batteries 54 received in the display cavity
24 and secured therein by battery supports 56.
Referring now to FIG. 5 the shaft supports 46 can be seen with
the support base 44 cut-away to expose fluid ports 57 therethrough.
These ports 57 can be seen in a front view of the shaft support
46 seen in FIG. 6 and a rear view of the shaft support 46 seen in
FIG. 7. The fluid ports 57 open into enlarged fluid cavities 58
at the rear of the support base 44 as the fluid is transmitted past
the turbine 32. The fluid acts as a washing agent for washing around
and beside the turbine shaft 40 a thrust bearing 43 and the moving
parts of the turbine 32. Further when various types of corrosive
fluids are used, a light viscosity washing fluid such as gasoline
can be used later for cleaning the insides of the turbine 32 so
the fluid meter 10 will be clean for future use in dispensing different
types of fluids.
In the past, normal turbine blades have had a flat profile which
is typically of machined metal construction. This type of construction
is expensive. The subject turbine 32 has been molded using plastic
material and the like with the normal flat profile of the turbine
blades 36 modified to provide room for the metal slug 38 and improved
FIG. 8 illustrates how the unique shape and design of the turbine
blades 36 influence the performance and accuracy of the amount of
fluid delivered by the flow meter 10. It has been found that the
shape of the blades 36 directly influence the "K" factor
(pulses per unit measure) over a certain flow range. The vertical
line in FIG. 8 shows flow rate from 0 to 40 gals. per minute. Ideally
the "k" factor should be a vertical line when ploting
the "k" factor vs. flow rate. But on a practical basis,
the "k" factor curve shown as line 60 is not a vertical
line and has some slope to it and at the low end the line 60 has
a "knee" shape.
In FIG. 8 it can be appreciated that once the flow meter 10 has
begun delivering fluid and at a volume greater than 2 gals. per
minute, the pulses per unit measured are plus and minus 1.5% accurate
within this example the pulses being approximately 770 per unit
delivered. The straight line constant of the "k" factor
helps insure accuracy in the amount of fluid delivered into a storage
tank and the like.
As mentioned above the "k" factor is directly influenced
by the design of the turbine blades 36. The shape of the blades
as shown in FIG. 9 is not a true "turbine" which is commonly
found with a flat profile. The subject turbine 32 is molded of plastic
and similar materials with the blade 36 having an enlarged flatten
area 62 in an end 64 of each blade for receiving the ferrous slug
38 therein. This structure can also be seen clearly in FIG. 5.
Each blade 36 includes a rounded leading edge 66 with the blade
tapered from front to rear upwardly in the range of 40 degrees from
the horizontal into a feathered trailing edge 68. A top 70 of the
blade 36 has a concave surface 72 along the length of the blade.
The concave surface 72 receives the force of the fluid thereagainst
for driving the turbine 32 in a clockwise direction as shown in
FIG. 5. A bottom 74 of the blade 36 has a convex surface 76 along
the blades length. The blades 36 when viewed end to end have a hydrofoil
In operation, the flow meter 10 incorporates a volumetric flow
transducer which displays a digital output on the counter 18 directly
proportional to the flow volume. Each digital pulse on the counter
18 represents a discrete volume which is scaled to a desired display
When the battery power is first applied the unit is set by grounding
an internal test point. An internal RAM and ROM check is performed
and registers are initialized. If all checks are positive, the counter
18 shows 18.104.22.168. to verify all LCD segments. This display remains
until the unit is RESET or until five minutes have elapsed since
the last activity. At this time, the display counter 18 is cleared.
Activity in the meter 10 is defined as pulse counts greater than
5 pulses per second.
During normal operation, 5 minutes after the last activity of the
meter 10 the counter 18 clears and the units store the total cumulative
volume since power was applied and the most recent volume since
RESET of memory. The unit ignores and does not count or accumulate
counts less than 5 pulses per second.
A count ratio, N, in pulses per gallon or any other desired volume
measurement is computed for each fluid being transferred based on
a calibration sequence performed by the operator. The count ratio
is stored and used to compensate for varying flow rates by updating
the display based on a linear relationship between frequency and
flow rate. A count value N=770 PPG is utilized for the internal
In calibrating the meter 10 three methods of calibration are provided.
The first method of calibration allows the operator to calibrate
the meter 10 to an internal standard which will have an error not
to exceed + or -11/2%. First the calibration button 22 is pressed
and the display counter 18 shows CAL blinking. Then the calibration
button 22 is pressed a second time within five minutes after the
first calibration input. The unit will display 00.00. This procedure
initializes the count ratio to N=770 PPG. This count ratio is then
used to convert pulses to gallons for all operations until the next
The second method of calibration is a single point calibration
and is used when working with low viscosity fluids such as gasoline,
diesel fuel and the like. The following calibration sequence may
be used to reduce the error to within + or -1/2%. First the calibration
button 22 is pressed to display "CAL" blinking. Then the
fluid is dispensed into a container capable of holding 5 units of
measure having a total volume of no less than 0.8 gallons. 5 units
are then dispensed. As soon as pulses greater than 5 pulses per
second are detected, the blinking CAL will stop blinking indicating
the calibration mode is in process. When this is completed the operator
waits 10 seconds but not more than 5 minutes. The CAL display will
blink to indicate that 10 seconds have elapsed.
After this time, the CAL buttom 22 is pressed a second time after
the display begins to blink. The display now indicates 00.00. The
unit stores the count value and intializes to the count ratio, N,
of the measured fluid and measures the count ratio to convert pulses
to units for all operations until the next calibration sequence.
The last calibration method is a two point calibration used when
working with high viscosity fluids such as oils, herbicides, molasses
and the like with the following calibration sequence used to ensure
an error within + or -1%. First the calibration button 22 is pressed
and the display will show "CAL" blinking. Five units of
fluid are dispensed into a container capable of indicating 5 units
accurately. The CAL display will stop blinking as soon as fluid
transfer starts. The operator then waits 10 seconds but not more
than 5 minutes. The CAL display starts to blink to indicate that
10 seconds have passed. The operator then dispenses another 5 units
of fluid at a different flow rate into a container capable of again
indicating 5 units accurately. The CAL display will stop blinking
as soon as the fluid transfer starts.
Ten seconds are then allowed to elapse but not more than 5 minutes.
The CAL display will blink to indicate that 10 seconds have elapsed.
The operator then presses the calibration button 22 a second time.
The display counter 18 now indicates 00.00.
The meter 10 stores the count ratios N1 and N2 and initializes
a linear calibration line between the two count ratios. The value
of N varies with pulse rate and is updated once during each second
during the pumping operation. The computed linear calibration line
is then used to convert pulses to units for all operations until
the next calibration sequence.
During normal pumping operations, the counter 18 shows the current
volume of fluid pumped in units. Counts greater than 5 pulses per
second are accumulated with the calibration count ratio applied
and the display is updated twice per second. The decimal point shifts
right to accomodate more significant digits to the left of the decimal
up to a maximum reading of 9999.
The display counter 18 shows the most recent volume in units for
five minutes after the last operation. After five minutes, without
input and counts, the display goes blank, the final volume is stored
and the unit goes into a standby mode to conserve the life of the
batteries. The operator may return the unit to operational mode
by momentarily, less than three seconds, pressing the display button
20. The counter 18 then shows the accumulative volume dispensed
since power up from the first three seconds, then it shows the volume
pumped since the last display zero reset. When the operator presses
the display button 20 for longer than 3 seconds, the counter 18
shows the total accumulative volume pumped since power up during
the first three seconds, then resets the counter 18 to 0 and a display
of 00.00. Subsequent transfer of fluids results in new counts to
the flow meter 10.
Changes may be made in the construction and arrangement of the
parts or elements of the embodiments as described herein without
departing from the spirit or scope of the invention defined in the