A fluid flow meter comprising a shallow rectangular block with
first and second faces parallel to each other, a circular opening
of selected radius through the block, perpendicular to the faces,
an impeller with multiple radial vanes inserted into the central
opening, an entrance conduit longitudinally drilled through the
block approximately midway between the first and second faces which
intersects the circular opening approximately tangentially, a portion
of the first face adjacent the circular opening depressed a selected
small depth forming a first channel for outflow of fluid. Second
conduit means connected to the first channel, and means to cover
the first and second faces of the block to seal all openings.
What is claimed is:
1. A fluid flow meter, comprising;
(a) a shallow block with first and second faces parallel to each
other and separated by a thickness T, with a circular opening of
selected radius R through said block; with axis perpendicular to
(b) a first entrance conduit longitudinally through said block
approximately midway between said first and second faces, intersecting
said circular opening approximately tangentially;
(c) a portion of said first face adjacent said circular opening
depressed a depth D, forming a first channel of approximate width
W, where W is slightly less than 2R, and depth D;
(d) second exit conduit means connected to said first channel;
(e) circular impeller means of radius slightly less than R in said
circular opening, said impeller having a plurality of spaced substantially
radial vanes, and having a first axial boss of length D extending
from a first face, and a second axial boss extending from the second
face of said impeller, the total thickness of impeller plus first
and second bosses equal approximately to T, with said first face
of said impeller approximately coplanar with said first channel;
(f) means on said first and second faces to at least cover and
seal all openings on said first and second surfaces.
2. The flow meter as in claim 1 and including means to sense the
rotation of said impeller.
3. The flow meter as in claim 2 and including means to count the
revolutions of said impeller.
4. The flow meter as in claim 1 and including a second channel
in said second surface of said block, approximately the size and
position of said first channel; said second exit conduit intersecting
both said first and second channels.
5. The flow meter as in claim 2 in which said sensor means is electromagnetic.
6. The flow meter as in claim 1 in which the sides of said vanes
of said impeller are straight.
7. The flow meter as in claim 1 in which the sides of said vanes
of said impeller are curved.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention lies in the field of apparatus for measuring the
flow rate and total flow of a selected fluid.
2. Description of the Prior Art
There are many examples of fluid flow meters from the conventional
home gas meter, that measures the flow of natural gas to the home,
or the water meter that measures the total flow of water delivered
to a home. There are many different types and sizes of flow meters
for specialized purposes, in connection with other devices such
as chemical mixers and the like. One important application of this
flow meter would be with apparatus for monitoring the total flow
of fluid through a purifier or other similar device, where a chemical
action takes place and the chemical is consumed in the operation.
It becomes important to know when the chemical is consumed and needs
replacement and a simple small convenient and inexpensive flow meter
such as that of this invention would be extremely useful.
SUMMARY OF THE INVENTION
It is a primary object of this invention to provide a simple, small,
convenient and inexpensive type of flow meter for many commercial
These and other objects are realized and the limitations of the
prior art are overcome in this invention by utilizing a slab of
suitable material which can be metal or plastic, and can be machined,
cast or molded, for example. It comprises a body which conveniently
can be a rectangular slab or a selected thickness T. A circular
opening of selected radius R is drilled through the body from the
first face to the second face, and an impeller is positioned inside
that cylindrical cavity, with sufficient clearance that it can turn
freely within the circumferential wall.
A plurality of radial vanes are formed on the outer portions of
the impeller equally spaced and similarly shaped. A cylindrical
boss of selected diameter and length is formed on one face of the
impeller, and a corresponding boss of equal or lesser axial dimension
on the other face of the impeller. The total dimension of the impeller
plus the two bosses are substantially equal to the thickness T of
the block. Two thin plates of suitable material are attached and
sealed to the two faces of the body. With those in place, the rotor
is enclosed and is free to turn when fluid flows through the device.
An inlet tube or passage is drilled longitudinally into the block
approximately midway between the two faces so as to intersect the
cylindrical cavity approximately tangentially.
A portion of the top face of the block adjacent the circular cavity
and in a selected relation to the point of tangency of the inlet
conduit, is depressed a selected depth D forming a shallow channel
through which the fluid that enters through the inlet conduit can
flow longitudinally through the slots of the impeller, to the channel
and from the channel to an outlet conduit.
The rotation of the impeller or rotor is sensed by placing a small
diameter short permanent magnet within one of the vanes of the impeller
and positioning a suitable coil close to the rotating impeller so
that as a magnet moves across the coil, an electrical voltage will
be generated which can be amplified. This can be sent to a binary
counter which will count the pulses, one for each rotation of the
impeller. The total count will, of course, be equal to the total
number of revolutions, and will be a function of the total flow
through the meter. This total flow can be converted from binary
to decimal notation and can be displayed as a decimal number, or
can be recorded. The electrical circuitry is quite simple. It can
also have a clock which will count to a selected period of time
and will determine the total number of revolutions within the period
of that time. Such a number will be the flow rate of fluid through
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of this invention and a
better understanding of the principles and details of the invention
will be evident from the following description taken in conjunction
with the appended drawings in which:
FIG. 1 represents schematically a plan view of the flow meter of
this invention with the top plate removed.
FIG. 2 is a cross-section taken along the plane 2--2 of FIG. 1.
FIG. 3 is a cross-section taken along the plane 3--3 of FIG. 1.
FIG. 4 illustrates a variation of the design of FIG. 2.
FIG. 5 illustrates an alternative construction of the impeller
FIG. 6 illustrates schematically the electronic circuitry for displaying
the total flow through the flow meter and the flow rate of fluid
through the flow meter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings and in particular to FIGS. 1 2 and
3 there are shown in three views one embodiment of this invention.
The flow meter of this invention is indicated generally by the
numeral 10. It comprises for example, a rectangular body, slab or
plate 12 of thickness T with parallel faces. A circular opening
18 is machined through the block, with axis perpendicular to the
faces, having a radius R. A cylindrical impeller 20 having an outer
diameter slightly less than 2R, is adapted to be positioned inside
this cylindrical cavity. It has a first axial boss 24 of length
D on one side and a second axial boss 30 on the other side. The
second boss can be as thick as the first boss or axial thinner.
It serves to maintain a selected dimension of clearance 22 between
the bottom surface of the impeller and the bottom cover plate 16.
The impeller has a plurality of spaced similar radial vanes 26
with corresponding spaces 28 between the vanes. These can be straightsided
as will be shown in FIG. 5 or curved, as shown in FIG. 1. An inlet
conduit 34 is drilled through the block and intersects the circular
cavity approximately tangentially, as shown in FIG. 1. Means 32
and 52 are provided for the attachment of suitable conduits into
and out of the flow meter.
A portion of the top face of the body 12 adjacent half of the circular
cavity is depressed a selected depth D and has a width W, which
is slightly less than the diameter of the cylindrical cavity. This
volume 38 between the depressed surface 36 and the cover plate 14
on the top, forms a channel for the outflow of fluid from the spaces
between the vanes as the impeller, having one face substantially
coplanar with the channel 36 rotates and leads to a channel 46
and to an outlet conduit 50 with corresponding fixture 52.
To sum what has been said, there is a central body 12 which is
a slab of uniform thickness T with plane parallel faces and has
a cylindrical cavity cut from the top or the first face to the bottom
face, part of the face 36 is cut away to form a channel for outlet
flow of fluid from the impeller in accordance with arrows 54 through
the channel 38 and to conduit 46 to the outlet conduit 50. Inflow
of fluid is through the entrance conduit 34 which intersects the
cylindrical cavity approximately tangentially. Two cover plates
14 and 16 are provided to be positioned over and sealed to two faces
of the body, which completely enclose the impeller.
In FIG. 1 a volume 40 is cut out of the body from top to bottom
for the purpose of positioning therein batteries and electronics
for counting the revolutions of the impeller. A small diameter magnet
60 is inserted into a drilled hole into one of the vanes, and as
shown in FIG. 6 a suitable coil 64 (not shown in FIG. 1) is mounted
in the space 38 for example, or on the outside of the top cover,
with suitable electronic means to count the pulses generated each
time the rotor impeller makes one complete revolution. This signal
is generated in the coil 64 and amplified by a preamplifier 66.
The voltage is generated when the magnet 60 moves laterally in direction
62 with respect to the coil 64. The output of the amplifier goes
to a digital counter 68 which continuously updates a binary number
representing the total counts of rotation of the impeller. This
binary number formed in 70 goes to a binary coded decimal coder
and to a decoder 72 and to a decimal display 74. Thus, a decimal
number is continually displayed in the display 74 which represents
total rotations of the impeller.
By use of a conventional digital clock 76 well known in the art,
and a counter divider 78 which can be set or programmed, the block
will count to a selected number of time units, and will then reset
itself and reset the digital-to-binary coded decimal in box 70.
This will reset the display to zero which will then count up from
zero each time it is reset by the clock. The number that the display
shows just before it is reset is then a number corresponding to
the flow rate. That is, the total number of rotations of the impeller
in a selected number of time units.
I have found that the operation and the precision of operation
of this fluid flow meter does not greatly depend upon the shape
of the impeller which can vary from a rounded contour as shown in
FIG. 1 to a straight sided contour as shown in FIG. 5; where the
vanes 26 are substantially parallel sided, and the space between
28 is substantially tapering. The magnet 60 would be positioned
in one of the vanes such as 26.
Referring now to FIG. 4 there is shown a second embodiment, which
is a variation of FIG. 2. What has been done here, has been to make
a second depressed surface 36A a distance D below the bottom surface
of the block, as a mirror image of the depressed surface 36 on the
first side of the block. The rotor would be similar except that
the two bosses 24 and 30A would be of equal dimension. The inlet
conduit 34 would be positioned substantially in the midpoint between
the two surfaces of the impeller so the flow of fluid would be symmetrically
up and below the impeller through the two channels 38 and 38A, to
a transverse opening through the body 48A and to an outlet conduit
Since there is clearance on all surfaces of the impeller, with
respect to the cover plates 14 and 16 and the wall of the circular
cavity, the flow of fluid will be around, over and under the impeller,
which will "float" in the surrounding fluid. No axis is
required to hold the impeller in position. The floating action does
While the invention has been described with a certain degree of
particularity, it is manifest that many changes may be made in the
details of construction and the arrangement of components without
departing from the spirit and scope of this disclosure. It is understood
that the invention is not limited to the exemplified embodiments
set forth herein, but is to be limited only by the scope of the
attached claim or claims, including the full range of equivalency
to which each element thereof is entitled.