U.S. patent number RE29,193 [Application Number 05/619,951] was granted by the patent office on 1977-04-26 for fluid metering device.
This patent grant is currently assigned to Economics Laboratory, Inc.. Invention is credited to Lance John Carlyle.
United States Patent |
RE29,193 |
Carlyle |
April 26, 1977 |
Fluid metering device
Abstract
A fluid metering device mixes a predetermined quantity of a
first fluid with a larger quantity of second fluid supplied to the
device at a higher pressure on each cycle. The pressure of the
second fluid provides the force necessary to motivate a first
pumping means which on movement to an `outlet` position within a
housing displaces the mixed fluids on an outlet side of the first
pumping means to their destination. Movement of the first pumping
means actuates a second pumping means which pumps a predetermined
quantity of the first fluid into the housing on each cycle. On the
maximum pumping stroke of the first pumping means being reached at
the `outlet` position, a passage is opened in the first pumping
means which is then restored to an `inlet` position, the second
fluid in the housing passing through the passage during such
restoration and thus being available for dispatch on the next
pumping stroke. When the first pumping means reaches the `inlet`
position the passage closes and a further pumping cycle
commences.
Inventors: |
Carlyle; Lance John (Cambridge,
NZ) |
Assignee: |
Economics Laboratory, Inc. (St.
Paul, MN)
|
Family
ID: |
26649462 |
Appl.
No.: |
05/619,951 |
Filed: |
October 6, 1975 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
294984 |
Oct 4, 1972 |
03818924 |
Jun 25, 1974 |
|
|
Current U.S.
Class: |
137/99; 222/57;
417/375; 137/101.31 |
Current CPC
Class: |
B01F
15/047 (20130101); C02F 1/763 (20130101); Y10T
137/2541 (20150401); Y10T 137/2516 (20150401) |
Current International
Class: |
B01F
15/04 (20060101); C02F 1/76 (20060101); G05D
011/00 () |
Field of
Search: |
;137/98,99,99.5,101.31,88 ;417/375,393 ;222/57 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cline; William R.
Attorney, Agent or Firm: Merchant, Gould, Smith, Edell,
Welter & Schmidt
Claims
What I claim is:
1. A fluid metering device comprising;
a. a housing with a hollow interior
b. first and second fluid inlets into said hollow interior for
first and second fluids respectively
c. a fluid outlet from said hollow interior
d. first pumping means within said hollow interior and displaceable
under fluid pressure between said second fluid inlet and said fluid
outlet from an `inlet` position to an `outlet` position to pump
mixed first and second fluids through said fluid outlet
e. biasing means tending to retain or restore said first pumping
means at or to said `inlet` position in use
f. a passage communicating between said second fluid inlet and said
fluid outlet
g. closure means adapted to close said passage at said `inlet`
position and also during displacement of said first pumping means,
under fluid pressure, from said `inlet` position to said `outlet`
position and to open said passage at said `outlet` position and
also during movement of said first pumping means from said `outlet`
position to said `inlet` position and
h. second pumping means actuated on movement of said first pumping
means to cause a predetermined quantity of said first fluid to
enter said hollow interior through said first fluid inlet on each
cycle of said first pumping means.
2. A fluid metering device as claimed in claim 1 wherein said
closure means comprises a closure member within said hollow
interior and said closure member moves with but is displaceable
relative to said first pumping means; and stop means coacting
between said closure member and said first pumping means and
adapted to limit such relative displacement so that said passage is
closed on maximum relative displacement in one direction and opened
on displacement in the reverse direction.
3. A fluid metering device as claimed in claim 2 wherein engagement
means are provided to alter the relative speed of said closure
member and said first pumping means at said `outlet` position.
4. A fluid metering device as claimed in claim 3 wherein said
closure member has a ratio of thrust surface presented to said
second fluid inlet at said `inlet` position to biasing force
tending in use to retain or restore said closure member at or to
said `inlet` position which exceeds that of said first pumping
means.
5. A fluid metering device as claimed in claim 4 wherein said
engagement means is elastic so that on the point of opening of said
passage and equalisation of the fluid pressure on said closure
member and said first pumping means, the recoil causes a sudden
speed difference to be imparted between said closure member and
said first pumping means.
6. A fluid metering device as claimed in claim 5 wherein said
second pumping means includes a chamber interposed in said first
fluid inlet and first and second one way valve means, said chamber
communicating in use with a supply of first fluid via said first
one way valve means and with said hollow interior via said second
one way valve means, the volume of said chamber being adapted to
fluctuate by a predetermined amount on cycling of said first
pumping means so that said predetermined quantity of said first
fluid is pumped into said hollow interior.
7. A fluid metering device as claimed in claim 5 wherein said
second pumping means includes regulator means adapted to regulate
or adjust the volume fluctuation of said chamber so that the volume
ratio of first to second fluids to be mixed can be altered.
8. A fluid metering device as claimed in claim 7 wherein said
chamber is defined by a barrel and a plunger movable within said
barrel in the line of movement of said first pumping means.
9. A fluid metering device as claimed in claim 8 wherein said
biasing means comprise resilient spring means.
10. A fluid metering device as claimed in claim 9 wherein said
first pumping means includes a resilient diaphragm, the perimeter
of which is sealingly engaged with said housing.
11. A fluid metering device as claimed in claim 8 wherein said
first pumping means comprises a piston, the perimeter of which is
in sealing engagement with said housing.
12. A fluid metering device comprising;
a. a housing with a hollow interior
b. first and second fluid inlets into said hollow interior for
first and second fluids respectively
c. a fluid outlet from said hollow interior
d. first pumping means within said hollow interior comprising a
piston in continuous sealing engagement with said housing and
displaceable under fluid pressure between said second fluid inlet
and said fluid outlet from an `inlet` position to an `outlet`
position to cause mixed first and second fluids to be expelled
through said fluid outlet
e. biasing means tending to retain or restore said first pumping
means at or to said `inlet` position in use
f. a passage through said piston communicating between said second
fluid inlet and said fluid outlet
g. closure means adapted to close said passage at said `inlet`
position and also during displacement of said first pumping means
under fluid pressure from said `inlet` position to said `outlet`
position and to open said passage at said `outlet` position and
also during movement of said first pumping means from said `outlet`
position to said `inlet` position comprising a closure member
within said hollow interior adapted to open and close said passage,
said closure member moving with, but being displaceable relative
to, said piston, stop means coacting between said closure member
and said piston and adapted to limit such relative displacement so
that said passage is closed on maximum relative displacement in one
direction and opened on displacement in the reverse direction,
engagement means adapted to alter the relative speed of said
closure member and said piston at said `outlet` position, said
closure member having a ratio of thrust surface presented to said
second fluid inlet at said `inlet` position to biasing force
tending in use to retain or restore said closure member at or to
said `inlet` position which exceeds that of said first pumping
means and
h. second pumping means actuated on movement of said first pumping
means to cause a predetermined quantity of said first fluid to
enter said hollow interior through said first fluid inlet on each
cycle of said first pumping means, said second pumping means
including a chamber interposed in said first fluid inlet and first
and second one way valve means, said chamber communicating in use
with a supply of first fluid via said first one way valve means and
with said hollow interior via said second one way valve means, the
volume of said chamber being adapted to fluctuate by a
predetermined amount on cycling of said piston so that said
predetermined quantity of said first fluid is pumped into said
hollow interior.
13. A fluid metering device as claimed in claim 12 wherein said
closure member has a ratio of thrust surface presented to said
second fluid inlet at said `inlet` position to weight which exceeds
that of said piston and said `inlet` position is adapted to be
lower than said `outlet` position in use so that said piston
travels in a substantially vertical direction and the density of
said piston is adapted to exceed that of said second fluid.
14. A fluid metering device as claimed in claim 13 wherein said
engagement means are elastic so that at the point of opening of
said passage and equalisation of the fluid pressure acting on said
closure member, the unbalanced recoil force of said engagement
means provides an initial acceleration to said closure member,
displacing it relative to said piston to open said passage
quickly.
15. A fluid metering device as claimed in claim 14 wherein said
chamber is defined by a barrel and a plunger movable within said
barrel in the line of movement of said first pumping means.
16. A fluid metering device comprising;
a. a housing with a hollow interior
b. first and second fluid inlets into said hollow interior for
first and second fluids respectively
c. a fluid outlet from said hollow interior
d. first pumping means within said hollow interior slidable under
fluid pressure between said second fluid inlet and said fluid
outlet from an `inlet` position to an `outlet` position to cause
mixed first and second fluids to be expelled through said fluid
outlet
e. biasing means tending to retain or restore said first pumping
means at or to said `inlet` position in use
f. a passage between said first pumping means and said housing
communicating between said second fluid inlet and said fluid
outlet
g. closure means adapted to close said passage at said `inlet`
position and also during displacement of said first pumping means
under fluid pressure from said `inlet` position to said `outlet`
position and to open said passage at said `outlet` position and
also during movement of said first pumping means from said `outlet`
position to said `inlet` position, said closure means comprising a
resilient skirt on the inlet side of said first pumping means
adapted to open said passage except when the circumference is
forced into contact with said housing and a difference in fluid
pressure is applied between its sides with a higher fluid pressure
on the second fluid inlet side, said fluid outlet being positioned
so that said skirt uncovers said fluid outlet at said `outlet`
position, thereby equalising the pressure and opening said passage
and
h. second pumping means actuated on movement of said first pumping
means to cause a predetermined quantity of said first fluid to
enter said hollow interior through said first fluid inlet on each
cycle of said first pumping means.
17. A fluid metering device as claimed in claim 16 wherein said
biasing means coacts with an inwardly coned or curved portion of
said housing to spread the circumference of said skirt into sealing
contact with said housing at said `inlet` position. .Iadd. 18. A
fluid metering device having a housing with a hollow interior and
inlet and outlet openings respectively into and out of said hollow
interior, first pumping means within said hollow interior and
displaceable under fluid pressure between said inlet and outlet
openings from an `inlet` position to an `outlet` position to pump
fluid through said fluid outlet opening, biasing means tending to
retain or restore said first pumping means to said `inlet` position
in use, and said first pumping means defining a passage
communicating between said fluid inlet and outlet openings;
characterized by: closure means adapted to close said passage at
said `inlet` position and also during displacement of said first
pumping means, under fluid pressure, from said `inlet` position to
said `outlet` position and to open said passage at said `outlet`
position and also during movement of said first pumping means from
said `outlet` position to said `inlet` position; and second pumping
means actuated on movement of said first pumping means to meter a
predetermined quantity of other fluid into said first mentioned
fluid on each cycle of said first pumping means. .Iaddend..Iadd.
19. A fluid metering device comprising:
a. a housing with a hollow interior;
b. said housing having inlet and outlet openings respectively into
and out of said hollow interior;
c. first pumping means within said hollow interior and displaceable
under fluid pressure between said inlet and outlet openings from an
`inlet` position to an `outlet` position to pump fluid through said
fluid outlet opening;
d. biasing means tending to retain or restore said first pumping
means at or to said `inlet` position in use;
e. said first pumping means defining a passage communicating
between said inlet and outlet openings;
f. closure means adapted to close said passage at said `inlet`
position and also during displacement of said first pumping means,
under fluid pressure, from said `inlet` position to said `outlet`
position and to open said passage at said `outlet` position and
also during movement of said first pumping means from said `outlet`
position to said `inlet` position;
g. and at least one second pumping means actuated on movement of
said first pumping means to meter a predetermined quantity of other
fluid into said first mentioned fluid on each cycle of said first
pumping means.
Description
BACKGROUND OF THE INVENTION
It is frequently desired to mix fluids, particularly liquids such
as water, with some chemical in metered quantities. Where the exact
ratio of the two fluids to be mixed is not important and the two
fluids are available at the same pressure, it is possible to mingle
the two pressure streams directly through suitable valves governing
the relative proportions. However, if one of the fluids must be
metered accurately and is available at a lower pressure than the
other, there is no satisfactory existing metering apparatus.
One particular application of this invention is to inject a bloat
control chemical into the drinking water fed to cow troughs to
control bloat in cows. In dry weather cows drink 12 - 22 gallons of
water per day. In wet weather they drink less, but since cows are
habit forming creatures, a cow which has bloat in wet weather will
from past experience know that drinking water helps relieve the
discomfort. It is, of course, under wet weather conditions when the
farmer is least likely to inspect his stock for signs of bloat. In
a preferred arrangement of this invention, the quantity of bloat
control fluid injected into the water supply varies with the rate
of flow of water through the device. Thus on a fine day when a
large amount of water is consumed, the concentration of bloat
control fluid in the water is lower than on a wet day when a lesser
amount of water will be consumed. Thus a cow which will naturally
drink a lesser amount of water on a wet day will still get the
requisite amount of chemical needed to control any bloat
condition.
The control of bloat in cows is only one possible application of
this invention. It can be applied to mix oil and petrol for
2-stroke fuel, in fertiliser and weed control systems and where
gases are required to be mixed, to name just a few.
SUMMARY OF THE INVENTION
The present invention consists in a fluid metering device
comprising;
A. a housing with a hollow interior
B. first and second fluid inlets into said hollow interior for
first and second fluids respectively
C. a fluid outlet from said hollow interior
D. first pumping means within said hollow interior and displaceable
under fluid pressure between said second fluid inlet and said fluid
outlet from an `inlet` position to an `outlet` position to cause
mixed first and second fluids to be expelled through said fluid
outlet
e. biasing means tending to retain or restore said first pumping
means at or to said `inlet` position in use
f. a passage communicating between said second fluid inlet and said
fluid outlet
g. closure means adapted to close said passage at said `inlet`
position and also during displacement of said first pumping means,
under fluid pressure, from said `inlet` position to said `outlet`
position and to open said passage at said `outlet` position and
also during movement of said first pumping means from said `outlet`
position to said `inlet` position and
h. second pumping means actuated on movement of said first pumping
means to cause a predetermined quantity of said first fluid to
enter said hollow interior through said first fluid inlet on each
cycle of said first pumping means.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred forms of the present invention will be described with
reference to the accompanying drawings in which:
FIG. 1 shows a side elevation of one embodiment of the
invention,
FIG. 2 shows plan view II -- II,
FIG. 3 shows plan view III -- III,
FIG. 4 shows a side elevation of first pumping means, closure means
and part of second pumping means removed from the housing,
FIG. 5 shows plan view V -- V,
FIG. 6 shows plan view VI -- VI,
FIG. 7 shows a side elevation of part of a closure means removed
from the first pumping means,
FIG. 8 shows a central longitudinal cross section through first
fluid inlet means and part of second pumping means,
FIG. 9 show a cross section IX -- IX through part of second pumping
means,
FIG. 10 shows a cross section through a different embodiment of the
invention,
FIG. 11 shows a schematic partial cross section through a still
further embodiment of the invention having some resemblances to
that of FIG. 10,
FIG. 12 shows a cross section through a different embodiment of the
second pumping means,
FIG. 13 shows a cross section through yet another embodiment of the
second pumping means,
FIG. 14 shows a schematic perspective view of a further embodiment
of first pumping means and closure means,
FIG. 15 is a graph showing a typical variation of volume of water
passing through the preferred device of FIG. 1 per cycle, at
different flow rates,
FIG. 16 shows a graph of cycle duration of the device of FIG. 1 at
different flow rates,
FIG. 17 shows a further embodiment of the present invention and
shows a cross section through the upper part of a housing, first
pumping means and closure means, FIG. 18 shows a still further
embodiment of the present invention and shows a cross section
through the upper part of a housing, first pumping means and
closure means,
FIG. 19 shows yet another embodiment of the present invention and
shows a cross section through the lower part of a housing, first
pumping means, closure means and second pumping means, and
FIG. 20 shows the last embodiment of the present invention and
shows a partial cross section through the lower part of a housing,
first pumping means, closure means and second pumping means.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first of all to the embodiment illustrated in FIGS. 1 -
9, the fluid metering device comprises a housing 1 having a hollow
interior. The housing is provided by means of a 3 inches internal
diameter clear perspex tube 2 provided with plastic end caps 3 and
4 clamped on the tube by means of a wire frame 5 fitted with
mounting brackets 6 and clamping screw 7. A sturdy frame is
necessary to hold the end caps on to the tube 2 since there may be
quite large internal forces acting against the end caps tending to
blow them off the tube. End cap 4 which is arranged to be lower
than end cap 3 in use, since the tube 2 must be arranged to be
vertical or near vertical, is provided with first and second fluid
inlets 9 and 10 through it and into the hollow interior of the
housing 1. End cap 3 is provided with a fluid outlet 11.
First pumping means 12 are slidable within the hollow interior and
separate the first and second fluid inlets 9 and 10 from the fluid
outlet 11 since the first pumping means which largely comprises a
brass cylinder 13 is in sealing engagement with the internal walls
of the housing 1 by means of a resilient sealing ring 14. The
weight of the first pumping means 12 provides biasing means tending
to retain or restore the pumping means at or to an `inlet` position
which is the lowermost position it can assume within the housing 1.
For the weight to provide a biasing means it is necessary that the
average density of the first pumping means exceed that of the fluid
or mixed fluids which are to pass through the device; otherwise the
pumping means would float and alternative biasing means would be
needed. The first pumping means 12 also has a passage 15 which
communicates between the first and second fluid inlets 9 and 10 and
the fluid outlet 11. However, the passage is adapted to be closed
at the `inlet` position and also during displacement of the first
pumping means 12 under the pressure of the second fluid (that
entering via the second fluid inlet 10) when it travels up the tube
2 to an `outlet` position which is defined as being the position
when the passage is first opened. Closure means 19 are adapted to
close the passage 15 at the `inlet` position and also during
displacement of the first pumping means 12 from the `inlet`
position to the `outlet` position and are adapted to open the
passage at the `outlet` position and also during movement of the
first pumping means from the `outlet` position to the `inlet`
position. The forces causing such movements will be described
later.
In the preferred embodiment, the closure means is provided with a
closure member 20 in the form of a disc of brass surmounted by a
heavy brass stem 21. The closure member 20 is displaceable relative
to the first pumping means 12 and in order to limit the
displacement, stop means are provided by the diameter of the
closure member disc 20 being larger than the diameter of passage 15
and by means of a cage 22 bolted onto the bottom of the cylinder
13. A circular neoprene sealing ring 23, embedded in a groove in
the cylinder 13, is provided between the closure member 20 and the
cylinder 13 so that the passage 15 may be effectively sealed.
In order that the closure means opens the passage when required, it
is necessary in this embodiment for the closure member 20 to have a
ratio of thrust surface (which is basically the area contained
within the diameter of the sealing ring 23) presented to the second
fluid inlet 10 at the `inlet` position to the biasing force (which
in this case is weight) tending in use to retain or restore the
closure member to the `inlet` position which exceeds the same ratio
of the pumping means 12 (where the thrust surface is the internal
area of the housing tube 2 minus the thrust area of closure member
20). The weight of the closure means 19 is the total weight of the
cylinder 13, the cage 22 and the associated plunger 24 of second
pumping means 26, the operation of which will be described later
on. This requirement is necessary so that under a given second
fluid pressure, when the first pumping means and closure means are
at the `inlet` position with the passage closed, the closure means
19 is more floatable than the first pumping means 12, i.e., it
experiences a greater resultant up-thrust and thus tends to carry
the first pumping means up the tube so that the seal is maintained
until the `outlet` position is reached.
In order to open the passage at the `outlet` position, engagement
means 25 are provided adapted to restrain or stop the movement of
the closure member 20 as the first pumping means 12 approaches or
attains the `outlet` position. In the embodiment shown, the
engagement means 25 are provided by the stem 21 surmounted by
spiral spring 29 which at the `outlet` position bears against the
end cap 3.
To describe the operation of the parts of the device so far
described, assume that a cycle commences with the first pumping
means and closure means at the `inlet` position with the space in
the tube 2 above these filled with fluid. The fluid referred to as
the "second" fluid is introduced under a suitably high pressure
through the second fluid inlet 10. The first pumping means 12 and
closure means 19 form a slidable barrier across the interior of the
tube 2 and are therefore acted upon by the fluid pressure and
caused to rise displacing as they do so fluid through the fluid
outlet 11 if the outlet pressure is sufficiently lower than the
second fluid pressure. Eventually the spring 29 meets the cap 3 and
is compressed on further upward movement of the stem 21 until
either the stem strikes the cap 3, or the force developed within
the spring, if it is sufficiently stiff, is such as to provide a
greater downward force on the closure member 20 than the up-thrust
it experiences because of the pressure differential on the inlet
side. When either happens, the passage is opened. Immediately the
pressure differential disappears and the spring 29 recoils
providing an initial acceleration to the closure member 20
displacing it relative to the first pumping means 12 which will
continue moving upwards a little from the point of opening until
its kinetic energy is dissipated so that the passage is opened very
quickly and cleanly. Immediately the closure means 19 begins to
sink and the closure member 20 would usually come to rest on the
bottom of the cage 22 and the combination of first pumping means
and closure means would descend down the tube to the `inlet`
position. There the legs 30 extending below the closure member disc
20 and through holes 27 in the cage hold the closure member at a
suitable height so that it supports the weight of the first pumping
means 12 at the `inlet` position. However, immediately the first
pumping means 12 descends on the closure member disc 20 to close
the passage, the cycle recommences.
Since the device will often be operated with outlets fitted with
shut-off valves such as ballcocks on troughs, it should be
appreciated that the cycling of the first pumping means will stop
when the outlet back pressure builds up to such an extent that
there is an insufficient force on the inlet side of the first
pumping means to move it against the force provided by the combined
weights of closure means and first pumping means and the fluid
pressure on the outlet side. This means that occasionally on
movement from the `inlet` position to the `outlet` position such a
balance between the forces is encountered and the first piston
means and closure means simply remain stationary with the passage
closed until such time as the outlet back pressure is reduced when
the cycle can continue.
The second pumping means 26 provided by the plunger 24 extending
from the bottom of the cage 22 and the barrel 31 provided centrally
within a hexagonal plug 32 threaded at 33. The plug forms part of
the first fluid inlet means 9 and is able to be screwed into the
end cap 4. The combination of plunger 24 and barrel 31 serve to
define a chamber 34 interposed in the first fluid inlet and as will
be described, the volume of this chamber is caused to fluctuate by
a predetermined amount on cycling of the first pumping means so
that a predetermined quantity of the "first" fluid to be admitted
into the hollow interior through the first fluid inlet 9 is pumped
in by the second pumping means once per cycle. To facilitate this
pumping action, first and second one way valve means 35 and 39 are
provided. The first one way valve means 35 is preferably in the
form of a flap valve with a circular neoprene disc 40 being held in
the barrel 31 by means of a circlip or pin 37. The second one way
valve means 39 is provided in a bore 41 through plunger 24 and may
comprise a flap valve substantially the same as the first one way
valve means 35 or alternatively, and as shown, may comprise a
phosphor bronze ball 42 held in place by pin or circlip 43.
The arrangement of plunger and barrel is such that at the inlet
position, the plunger extends into the barrel 31 a certain amount.
When the pumping cycle commences from the `inlet` position, the
plunger 24 rises with the cage 22 and cylinder 13. A resilient seal
44 ensures that there is a suction created below the plunger in the
barrel which causes the first one way means 35 to open (the second
one way valve means 39 being shut) and draws the first fluid,
usually from an open container attached by means of a flexible tube
to the nipples 45, into the chamber 34.
In the embodiment shown, a point is eventually reached where the
plunger 24 leaves the barrel 31 and at that juncture the first one
way valve means 35 shuts. There may be some mixing of the first
fluid contained within the barrel with the second fluid in the
housing but the degree of mixing is unimportant for on the descent
of the first pumping means, the plunger 24 enters the barrel and
the second one way valve means 39 opens to relieve the pressure
which would otherwise be created (since the first one way valve
means 35 is shut). Any first fluid remaining in the barrel is
expelled through the bore 41 of the plunger and thus into the
hollow interior where it mixes with the second fluid. In order to
ensure turbulent flow and good fluid mixing, lugs 47 are provided
on stem 21.
It is possible to adapt the seal 44 to form a one way valve in the
manner of the normal tyre pump so that the bore 41 may be dispensed
with. Also it is possible, as is shown in FIG. 13 where like parts
have been given like references where possible, for the second one
way valve means 39' to be provided in the plug 32' communicating
with the chamber 34' via a passage 36 a little above the first one
way valve means 35'. The reverse form of arrangement where the
plunger 24" is provided as part of the first fluid inlet 9" and the
barrel is provided depending from the cage 22" is shown in FIG. 12,
where again like parts have been given the same references.
In the preferred embodiment described so far, the cylinder 13 is
not constrained against rotation in the tube 2 and therefore the
plunger 24 is provided concentric with the axis of the cylinder so
that it will always mate with the barrel 31, which is provided
centrally in the end cap 4, when the cylinder 13 descends. In order
to regulate the volume fluctuation of the chamber 34, regulator
means comprising the threads 33 and mating threads in the end cap 4
are provided so that the relative position of the chamber along the
direction of movement of the first pumping means 12 may be varied,
i.e. the depth of entry of the plunger 24 into the barrel 31 is
adjustable.
In order to give a better appreciation of the workings of the
preferred embodiment illustrated in FIGS. 1 - 9, a few dimensions
will be given. The overall length of the tube 2, which has an
internal diameter of 3 inches, is 251/2 inches. The weight in air
of the cylinder 13 with cage 22 and plunger 24 is 6 lbs. The weight
of the closure means 19 is 2 lbs. Most of those parts are
constructed of solid brass. The diameter of the circular seal 23 is
1.875 inches so that the ratio of up-thrust area of the closure
means 19 when at the `inlet` position to weight is approximately
twice that of the first pumping means. This ensures that the
passage 15 is properly closed when the combination moves from the
`inlet` to the `outlet` position. At high draw-off rates through
the fluid outlet 11, the cycle time is fairly short, as shown in
FIG. 16. This means that the first pumping means 12 is moving with
a relatively high velocity when the closure means is restrained
from further movement by contact with the end cap 3 and under these
conditions the resilient spring 29 is not really necessary since
the first pumping means has a relatively large amount of kinetic
energy when the passage is opened and it moves an appreciable
distance further up the tube 2 before this is wholly converted to
potential energy and the velocity falls to zero. By that time, if
not before, the closure means 19 has probably descended to rest on
the cage 22. At low draw-off rates, however, the velocity of the
first pumping means at the outlet position may be fairly slow so
that there is only a short lag after the passage is opened before
the cylinder 13 begins to descend. Under those circumstances the
initial impetus provided to the closure means 19 via the spring 29
is useful to ensure that the passage is opened quickly and
completely at the `outlet` position; otherwise there is a
possibility if certain other undesirable characteristics are
present that the passage may not open cleanly and in fact the
passage can even shut after a short descent of the first pumping
means, if certain criteria are not met and a cycle can then
commence without the necessary influx of first fluid.
There are various other ways in which it can be ensured that the
closure means 19 descends to the `inlet` position before the first
pumping means 12. FIG. 14 shows one method useful where the fluid
is relatively viscous. There, instead of one large central passage
15, the cylinder 49 with embedded circular sealing ring 50 is
provided with a large number of small passages or tubules 51 as
well as a central passage 52 of a diameter just sufficient to
loosely receive a small diameter engagement means stem 53 fastened
to a closure member disc 54 of a diameter slightly larger than that
of the sealing ring 50. The closure means in such a case suffers
far less fluid frictional retardation when descending than does the
cylinder 49 where the relatively small diameter passages 51 and 52
impede the rate of flow of fluid through it and thus slow its
descent. It is also possible to arrange that the mechanical
friction of the resilient sealing ring 14 surrounding the cylinder
13 is quite high, which again retards the rate of descent of the
first pumping means. Also, since the first pumping means and the
closure means are at the `outlet` position and on descent suspended
in a fluid, then the forces acting on the first pumping means and
the closure means, ignoring mechanical friction forces, are in each
case its weight acting downwards, the Archimedes up-thrust acting
upwards and the viscous resistance acting upwards. Where the first
pumping means and the closure means are each made of an identical
material, the Archimedes up-thrust equal to the weight of fluid
displaced will in each case bear the same proportion to the total
weight of the first pumping means or the closure means
respectively. However, by varying the relative densities, such as
by including air voids or making them of dissimilar materials, the
resultant downward forces acting on each can be made unequal, thus
resulting in different accelerations, thus keeping the passage open
during the descent with a suitable choice of parameters.
In the application of the preferred embodiment of FIGS. 1 - 9 to
bloat control, typical flow rates may be 5-500 gallons per hour and
typical water inlet pressures may be 2-175 pounds per square inch.
Throughout this specification "gallons" means Imperial or United
Kingdom gallons. The first fluid is simply located in a vessel open
to atmospheric pressure and is sucked into the first fluid inlet
through a 3/16 inch internal diameter plastic tube. With the
dimensions of the preferred embodiment mentioned, when one cycle of
the first pumping means causes the volume of bloat control fluid
contained in a 3 inches length of the 3/16 inch plastic tube to be
displaced into the hollow interior of the housing then this
corresponds to a desired 15 ounces of bloat control fluid per 100
gallons of water when the flow rate is 100 gallons per hour. The
hexagonal plug 32 is screwed in or out to achieve this. If the flow
rate is only 50 gallons per hour, 25 ounces of bloat control fluid
are injected per 100 gallons of water but at rates higher than 100
gallons per hour, a lesser amount than 15 ounces per 100 gallons is
injected. This is because at higher flow rates a greater amount of
water will pass through the passage on descent of the first pumping
means during the relatively fixed time it takes to descend in
water. This is because on the descent part of the cycle, the device
presents an open valve between second fluid inlet and outlet. The
effect is shown in FIG. 15. Thus while the volume of second fluid
is variable per cycle, the volume of first fluid remains constant
and thus the concentration rate alters with draw-off rate.
The weight of the first pumping means and closure means is such
that with second inlet pressures within the above range, no
difficulty is caused by jetting of the water through the second
fluid inlet. The jetting forces are insufficient to prevent a seal
being made on descent of the first pumping member on to the closure
means. To avoid back syphoning through the fluid outlet 11 in the
event of a possible malfunction, a one way valve 46 (FIG. 2) admits
air into the housing in the event of the pressure within the
housing dropping below atmospheric.
An alternative embodiment of the invention is shown in FIG. 10.
There, instead of relying on gravity to provide the biasing
acceleration on the masses and thus a force tending to retain or
restore the first pumping means at or to the `inlet` position, a
spiral compression spring 55 is utilised. The spiral compression
spring 55 acts between the housing (indicated generally as 58) and
the first pumping means 59. A weaker compression spring 60 acts
between the closure means 61 and a bridge 62 forming part of the
first pumping means 59. Resilient blocks 63 of rubber or other
elastic material surmount the bridge 62 for the same purpose as the
spiral compression spring 29 of FIG. 1. The arrangement is such
that at the `inlet` position, as illustrated, second fluid entering
the second fluid inlet 64 is met with a situation where the closure
member 61 is more floatable (against spring pressure) than the
first pumping means 59 so that the passage 65 is closed until the
`outlet` position is reached. Then on opening of the passage and
equalisation of the fluid pressure around the closure member 61 the
initial displacement of the closure member 61 from the first
pumping means 59 given by recoil of the elastic blocks 63 is
maintained or increased by means of the spring 60 as the first
pumping means descends until the closure means, which includes (but
is not limited to) the compression spring 60, closure member 61 and
resilient block 63, seats on the bottom of the housing when spring
55 causes the first pumping means to continue moving until the
passage is closed. It will be apparent that the biasing force need
not be provided by a spiral spring but could be provided by any
resilient material. Furthermore it would be possible to make an
embodiment utilising elastic materials placed in tension and by
means of suitable valving to construct an embodiment of this
invention where the biasing means is provided by fluid
pressure.
The second pumping means 69 (FIG. 10) is virtually identical to
that described with reference to FIGS. 8 and 9 except that it may
be noted that the bore 70 of the plunger 71 communicates on the
outlet side of the first pumping means 59, not the inlet side. This
illustrates that the position of the first fluid inlet is not of
vital importance to this invention since adequate mixing will
probably occur in most circumstances regardless of whether it is
situated on the inlet or outlet side of the first pumping means. It
should also be noted that although the plunger 71 probably would
leave the barrel 66 in the embodiment illustrated in FIG. 10, this
is by no means necessary. In fact the chamber 75 could be provided
by some flexible diaphragm, diaphragm pair or concertina like
arrangement provided with the first and second one way valve means
which would be equivalent to the form of second pumping means
illustrated. There are, however, many other types of second pumping
means which could be used in this invention and they need not be
situated on the inlet side, nor need they be provided with one way
valves since an arrangement of simple shut-off valves could be used
to achieve a similar pumping effect.
A further embodiment illustrated in FIG. 11 has resemblances, as
far as the first pumping means 72 and closure means 76 are
concerned, to FIG. 10. However, the first pumping means 72 instead
of being slidable within the housing 73, incorporates a flexible
diaphragm 74 secured to the housing around its circumference. The
use of a diaphragm obviates the possibility of leaks between the
first pumping means and the housing which may be very desirable in
certain applications where considerable metering accuracy is
necessary. Also the short length of travel which is possessed by
the embodiment illustrated in both FIGS. 10 and 11 tend to limit
the variation in volume of second fluid passing through the device
at different draw-off rates which may be desirable in certain
applications.
Although in the embodiments described above the closure member has
been unattached to the first pumping means, it will be evident that
the closure member could comprise a flap hinged to the first
pumping means and such a device would function in an obviously
equivalent manner. Also, although in the embodiment described above
the closure means has been more "floatable" than the first pumping
means, it is not essential that that should be so. In FIG. 17, the
housing 79 has an end cap 80 including three downwardly depending
engagement means 81 (only two of which are shown) equipped with
spiral compression springs 82. The first pumping means 83 in this
embodiment comprises a cylindrical piston with a central passage 84
through it and an outer sealing ring 85. It is surmounted by the
closure means 89 which comprises a closure member 90 in the form of
a disc having a downwardly dependent plunger 91 forming part of
second pumping means. A resilient sealing ring 92 is contained in a
groove in the first pumping means 83. The arrangement is such that
the thrust area of the closure means 89 presented to the second
fluid inlet (not shown), being that area contained within the
diameter of the sealing ring 92, to the biasing means (which in
this case is its weight) tending to retain or restore the closure
means at or to the `inlet` position is less than that of the first
pumping means 83 so that the first pumping means is relatively more
floatable and on movement from the `inlet` position to the `outlet`
position tends to carry the closure means 89 upwardly so that the
passage 84 is closed. At the `outlet` position it is not the
closure means 89 which is restrained from further movement but the
first pumping means by means of the engagement means 81.
The embodiment of FIG. 17 has the disadvantage that mechanical
friction forces at the seal 85 could, in certain circumstances such
as where grit might enter through the second fluid, slow down the
rate of descent of the first pumping means so that the closure
means 89 caught up to it and closed the passage 84 before the
plunger 91 had fully re-entered its barrel. For this reason the
diaphragm and spring equivalent may be preferred over the sliding
piston type illustrated.
It will also be apparent from the above description that where the
second pumping means are provided by a plunger and barrel or some
equivalent instead of regulating the position of the barrel 31 of
FIG. 8 or the plunger 24" of FIG. 12 with respect to the housing,
it would be possible to regulate the position of the plunger 24 of
FIG. 9 or barrel 31" of FIG. 12 at the inlet position with respect
to the housing. Incidentally, the reason why the second pumping
means preferably forms part of the first pumping means (where that
is less "floatable" than the closure means) is that if it were part
of the closure means, there would be a danger that the descent of
the closure means would be slowed up on re-entry of the plunger
into the barrel and that a seal would be made closing the passage
before the plunger had fully entered the barrel. This would mean
that a cycle would commence in such circumstances with a lesser
amount of first fluid being pumped into the housing.
It will also be apparent that the engagement means, although it has
been described primarily as a stem extending up through the passage
from the closure member, could equally well comprise a stem or
similar protruding from the inside of the housing, such as FIG. 17
illustrates.
In the embodiment shown in FIG. 18, the closure member 93 is a flap
pivotted at 94 within the hollow head region 95 above a tube 96.
These parts are situated within a housing 99 within which there is
a piston 100 comprising part of first pumping means and by means of
seals 101 and 102 making sealing engagement with the cylindrical
wall 103 of the housing and with the tube 96. The closure member 93
is by means of gravity or the pressure of a light spring 104, or
both, caused to cover a port 105 in the head. There are also one or
more ports 109 near the base of the tube 96. On the upper surface
of the piston 100 there is a striker pin 110 forming part of
engagement means. The fluid outlet is indicated at 111.
The operation of this device is as follows. Assume a cycle
commences with the piston 100 approximately in the position shown
and with the closure member 93 shut against the port 105. The
pressure of the second fluid on the inlet side 112 of the piston
100 causes it to rise up the housing. If the port 109 is not
already uncovered, it becomes uncovered so that the pressure on the
inlet side also exists within the tube 96 and the head 95. Seeing
there must be a lesser pressure on the outlet side 113 of the
piston 100 for it to move, the closure member 93 will remain shut.
However, eventually the piston 100 comes to a position where the
striker pin 110 displaces the closure member 90 from the port 105.
The thrust area of the piston is chosen to be large enough to
achieve this. At that point the second fluid is able to flow
through the tube 96 and out through the port 105 on its journey to
the outlet 111 and the piston 100 sinks seeing that the pressure
around it is equalised. Eventually it will restrict the flow of
fluid through the port 109 so that the flow which previously held
the closure member 93 open against the force of its weight and the
pressure of spring 104 is insufficient to hold the closure member
open and the port 105 is sealed. Immediately the second fluid
pressure causes the piston 100 to rise once more, thus commencing
another cycle. As will be appreciated, second pumping means of some
form are actuated by cycling of the piston 100 to meter in the
desired amount of first fluid. The notable difference of this
embodiment is that the closure means does not cycle with the first
pumping means. Also the tube 96 can be C shaped so that the passage
through it passes around and not through the piston 100.
In FIG. 19 an embodiment is shown which uses a still different
approach. There the first pumping means 114 is not in continuous
sealing engagement with the housing 115 but comprises a piston 119
which is loosely fitting within the housing, having depending from
it a plunger 120 forming part of second pumping means 121. The
piston 119 is in sealing engagement with the housing 115 only via a
resilient rubber somewhat cone shaped device 122 secured to the
under surface of the piston. A second fluid inlet is shown at 123
and the fluid outlet at 124. The `inlet` position is as
illustrated.
In operation the second fluid causes the first pumping means 114 to
rise in the housing until the outlet 124 is uncovered. The second
pumping means 121 is actuated as usual. When the outlet 124 is
uncovered, the natural resilience of the cone device 122 causes the
outer circumference 125 to contract. This leaves a passage around
the first pumping means through which the second fluid may flow as
the first pumping means descends. When the cone strikes the end cap
126, however, it is spread outwardly by the weight of the piston
119 so that the circumference 125 re-establishes sealing contact
with the housing 115. The cycle then commences once more.
In a similar construction the portions 127 of the coned device 122
can be omitted and the base end cap 126 can be pronouncedly coned
upwardly to assist in the spreading and sealing operation when the
device 122 decends on the end cap. Such a device is shown in FIG.
20 where the same references are used where possible. The sealing
means 130 is in the form of a skirt formed with an inner groove to
receive a loop tension spring 131 so that in its normal position
the circumference 125' does not make sealing contact with the
housing 115'. However, when the first pumping means reaches the
`inlet` position on descent the pronounced cone shape of end cap
126' assists spreading of the seating means 130 to form a seal
against the housing 115' which is retained by the pressure of the
second fluid on ascent of the first pumping means.
In FIGS. 19 and 20 it will be appreciated that biasing means other
than weight could be used, e.g., a compression spring and that the
passage communicating between the second fluid inlet and the fluid
outlet passes around the first pumping means.
* * * * *