The present invention is directed to an apparatus and method for metering
fluid. More particularly, the present invention is directed to an apparatus to inject
a predetermined amount of a liquid into a fluid stream and methods for its use.
Several devices have been developed for injecting predetermined quantities
of liquid additives into a liquid flow stream for such applications as adding medication
to drinking water with additives such as chlorine or iodine and adding fertilizer
concentrate to irrigation water. An exemplary device which is powered by the liquid
stream to which the additive is being injected is described in U.S. Pat. Nos. 3,937,241
and 4,060,351 as issued to Philippe Cloup. In the apparatus described in the Cloup
patents, the additive or adjuvant is injected into the main fluid stream within
a piston chamber of a hydraulic motor which drives the additive injection pump.
The architecture for this metering pump, however, is disadvantageous
when the additive is a corrosive fluid such as chlorine, fertilizer or other chemically
active substance. Accordingly, it is desirable to be able to inject the additive
into the liquid stream at a point downstream of the motor which is powering the
additive pump to avoid problems associated with the corrosive action of the additive.
To accomplish this objective, a number of fluid pumps have been designed
which inject the additive into the primary fluid stream where the primary fluid
provides the motive fluid for activating the additive injection pump. Such a device
is described for example in applicants' U.S. Patent No.-4,558,715 as issued to Walton.
While overcoming many of the disadvantages of prior fluid injection
system, the apparatus described in the Walton patent involves a number of components
which are subject to wear and subsequent failure. Elastic or elastomeric biasing
components necessary in a piston drive pump are particularly prone to fatigue and
failure. Moreover, the use of a piston and its auxiliary components enhance production
and manufacturing costs.
US-A-3054417 discloses a system for generating a mixture of a first
fluid with a second fluid, such that the second fluid constitutes a predetermined
percentage of the final mixture. The system comprises a flow meter which takes the
form of a hydraulic motor having an inlet and an outlet. Rotatable elements are
positioned between the inlet and the outlet and are rotatable under the action of
the fluid flowing between the inlet and the outlet of the flow meter. The arrangement
further comprises a pump having a rotatable element provided within a housing which
is caused to rotate under the action of the rotatable element of the flow meter
rotating. This causes the pump to pump the second fluid into the flow stream of
the first fluid.
The present invention seeks to address the above and other disadvantages
of prior art metering pumps by providing a system which includes a minimum of moving
components in a robust design to selectively inject a second and/or a third fluid
in a fluid stream, where the second and third fluid constitute a predetermined percentage
of the total mixture.
In one embodiment, the present invention is directed to an apparatus
for generating a mixture of a first fluid and measured quantities of a second fluid,
wherein the second fluid constitutes a predetermined percentage of the ultimate
mixture. In one aspect, the system may include a flow meter which includes an inlet
in fluid communication with the first fluid, a fluid outlet and first and second
gears positioned between the outlet and inlet. The gears of the flow meter are meshed
together and counter rotate relative to each other when the first fluid, e.g. water,
is directed through the inlet to the outlet.
A shaft may be connected coaxially to the first gear and the first
gear of a cavity gear pump. The cavity gear pump includes a first and a second gear
disposed in a housing and includes an inlet and an outlet. Each of the first and
second gears define a transverse cavity or pocket to receive and pump a liquid from
the inlet to the outlet. Because the first gear of the cavity pump is connected
through the shaft to the first gear of the flow meter, a predetermined amount of
the second fluid is pumped through the outlet of the cavity pump when a predetermined
amount of the first fluid is directed through the flow meter.
In another aspect of the invention, a second shaft is coaxially coupled
to the second gear of the flow meter and a first gear of a second cavity gear pump
which also includes an inlet and an outlet where the inlet is coupled to a reservoir
of a third fluid and the outlet is coupled to the fluid stream. In such a fashion,
a third fluid may be selectively metered and introduced into the fluid stream.
Accordingly, the present invention provides apparatus for metering
a predetermined amount of an additive liquid into a fluid stream, the apparatus
having a flow meter with a fluid stream inlet port and a fluid stream outlet port,
a rotatable element that rotates at a selective rate of rotation based on the quantity
of fluid flowing from said inlet port to said outlet port; a metering pump operably
coupled to the rotatable element of the flow meter and having an additive liquid
inlet and an additive liquid outlet; the flow meter outlet and the additive liquid
outlet of the metering pump being in fluid communication, characterised in that:
- the metering pump is provided with a priming means comprising a piston in a
bore disposed in fluid communication with a cavity in the flow meter via an access
bore such that reciprocation of the piston in the bore allows fluid to pass through
the bore to prime the metering pump.
Preferably, the metering pump is coupled to the rotatable element
of the flow meter by a shaft.
Advantageously, the rotatable element comprises first and second gears
mounted in comeshing relationship.
Conveniently, the gears are of a double helical configuration.
The present invention offers a number of advantages over prior art
metering pumps. One such advantage is a robust design which requires a minimum of
moving components. In such a fashion, the apparatus is relatively inexpensive to
manufacture and maintain.
Another advantage of the present invention is its lack of dependence
on elastic biasing components to accomplish the metering process.
Another advantage is the ability to avoid contamination of the fresh
water supply by introducing the metered additive concurrently with the metered water
into the treatment pool. In such a fashion, inadvertent backflow will not result
in a contamination of the water supply.
Yet other advantages include quiet operation, a compact size when
compared to competitive devices and a low pressure loss across the inlet and outlet
of the pump.
So that the present invention may be more readily understood and so
that further features thereof may be appreciated, embodiments will now be described,
by way of example, with reference to the accompanying drawings, in which :-
- Figure 1 illustrates a perspective, partially phantom view of one embodiment
of the present invention operative for the injection of a metered, second fluid.
- Figure 1A illustrates a detail, perspective view of the embodiment illustrated
in Figure 1;
- Figure 2 illustrates a side, cross sectional view of the embodiment illustrated
in Figure 1;
- Figure 3 illustrates a perspective view of a second embodiment of the present
invention operative for the injection of a second fluid;
- Figure 4 illustrates a top view of the embodiment illustrated in Figure 3;
- Figure 5 illustrates a side, cross sectional view of a third embodiment of the
- Figure 6 illustrates a side, cross sectional view of a helical gear pump;
- Figure 7 illustrates an exploded view of the helical pump illustrated in Figure
- Figure 8 illustrates a perspective, assembly.view of a fourth embodiment of
the invention utilizing an impeller;
- Figure 9 illustrates a cross section of an impeller as it may be used with the
embodiment of Figure 8; and
- Figure 10 illustrates yet another embodiment of the invention.
One embodiment of the pumping system of the present invention may
be seen reference to Figures 1 and 1A.
As illustrated, the pumping system 2 includes a flow meter 4 to which
is mounted a metering pump 40 where flow meter 4 includes a housing 13, a fluid
inlet port 18 and a fluid outlet 17. As intended by the present invention, flow
meter broadly means a device which has at least one movable element, and the movable
element can be moved when fluid is directed through the device. In the embodiment
shown in Figures 1 - 1A, the flow meter 4 is a gear-type flow meter, as more fully
In the illustrated embodiment, the fluid inlet port 18 of the flow
meter 4 is connected to a fluid conduit 20. More specifically, in one presently
preferred embodiment, conduit 20 includes an angular threaded connector 18 which
can rotate relative to said conduit, and the connector can be engaged with threads
that are formed on inlet port 18. In turn, conduit 20 is situated in fluid communication
with a water supply or other source of fluid 19. It is to be understood that conduit
20 can be connected to a water supply by any suitable means known in the art, e.g.,
by connecting conduit 20 to a fitting or nozzle that is in turn in fluid communication
with a water supply.
The housing 13 of flow meter 4 comprises a top wall 7, a bottom wall
11 and a side wall 14 where each of the aforereferenced elements are adapted to
be combined to form a substantially fluid tight unit. Typically, housing 13 includes
some sort of access means, e.g. an access plate (not shown), to allow for inspection,
repair and replacement of the internal components of flow meter 4.
In accordance with the present invention, flow meter 4 includes one
or more rotational elements which, in the embodiment shown in Figures 1 - 2, include
a first gear 24 and a second gear 25 which rotate when the pressurized first fluid
passes from the inlet 18 port to the outlet port 17.
By reference to Figure 2, gears 24 and 25 are disposed within an internal
cavity 23 defined by housing 13. In some embodiments, gears 24 and 25 may be provided
with magnetic inserts (not shown). The introduction of fluid through inlet 18 rotates
gears 24 and 25, thereby moving inserts past a point on the housing 13, which contains
means to detect the rotation of said insert. The frequency of this rotation may
then be monitored to determine a flow rate.
In the embodiment illustrated in Figures 1 - 2, metering pump 40 includes
a housing 41 defining an internal cavity 49 in which are disposed a pair of intermeshing,
counter rotating rotors 44 and 46. Housing 41 includes a sidewall 43, a bottom wall
45 and a top wall 47, the combination adapted to be sealed to form a fluid tight
compartment defining an inlet 50 and an outlet 52, where inlet 50 is disposed in
fluid communication with a reservoir 51 of a second fluid via conduit 55.
In some embodiments, the bottom wall 45 of pump 40 may comprise the
top wall 7 of flow meter 4. In such a fashion, economy of construction may be observed.
By reference to Figures 1A, 6 and 7, it is desired that rotors 44
and 46 define a tooth pattern which promotes a maximum amount of fluid flow from
inlet 50 to outlet 52. It may be desirable to utilize a helical tooth pattern such
as that disclosed in U.S. Patent No. 5,415,041, the disclosure of which is herein
incorporated by reference. For example, it may also be desirable to adopt a herringbone
or straight tooth pattern to advance the objects of the invention.
By reference to Figures 6 and 7, rotors 44 and 46 are preferably provided
with a system of bearings to enhance smoother and low drag operation. Top wall 47
preferably comprises a cover to close the cavity 49 by fitting on a machined face
of said housing 41 which is bolted in place with bolts 42 which extend through openings
63 of cover 48 into aligned receivers 65 in.housing 41.
The buildup of deposits, e.g., calcium and precipitants from the additive
solution, is a major cause for premature failure of cavity gear pumping systems.
In some applications therefore, it may be desirable to utilize a metering pump housing
which defines a close tolerance between rotors 44 and 46 and the pump outlet 52,
the walls defining cavity 49 and the pump inlet 50. In such a fashion, any deposits
collecting about the inlet 50 or outlet 52 are continuously sheered off by rotors
44 and 46 during the operation of pump 40.
In the embodiment illustrated in Figures 1 and 2, a connecting element
30, e.g., a spline, is coupled to first rotor 25 of flow meter 4 and extends through
flow meter housing 13 into operative engagement with the rotor 44 of pump 40. In
such a fashion, the rotation of gear 24 as induced by the flow of the first fluid
from the inlet 18 to outlet 17 rotates the first rotor 44 and hence second rotor
46. The counter rotation of rotors 44 and 46 create a partial vacuum in housing
41, thereby inducing fluid flow of the second fluid from reservoir 51 through conduit
55 into inlet 50 and ultimately through outlet 52.
The coupling of rotor 25 to rotor 44 of pump 40 allows for the metered
input of the additive second fluid based on the flow valve of the fluid as dictated
by the rotation of rotors 24 and 25. The proportions of the additive fluid may be
varied based upon the ratio of the size of rotors 24 and 25 vis-a- vis rotors
44 and 46. Alternatively, spline 30 may be formed to include a manually adjustable
gear down assembly (not shown) to allow the ratio of the additive fluid to be altered.
By reference to Figures 1A and 2, in one aspect of the invention,
pump 40 may be provided with priming means which comprises a piston 86 slidably
situated in a bore 89 which is disposed in fluid communication with cavity 23 of
flow meter 4 via access bore 95. Reciprocation of piston 86 in bore 89 allows the
first fluid, e.g. water, to pass through bore 89 into cavity 49, thereby priming
It is contemplated that it may be desirable in some situations to
introduce the additive fluid downstream of flow meter 4. In other applications,
however, the pump outlet 52 may be disposed upstream of meter 4 or concomitant with
flow meter outlet 17.
A second embodiment of the present invention may been seen by reference
to Figures 3 - 4 in which is illustrated a flow meter 100 of the general configuration
as described above in relation to the embodiment of Figures 1 and 2, where such
flow meter 100 includes a first 102 and second 104 rotational element rotatingly
disposed within an internal cavity 106 defined within a housing 105 which also includes
an inlet 108 and an outlet 110. Inlet 108 is disposed in fluid communication with
a first source of fluid, e.g., water, through a conventional conduit 113 or other
similar fluid flow member. Outlet 110 is likewise coupled to a conduit 115, as illustrated.
A first metering pump 140 and a second metering pump 160 are joined
to flow meter 100 in a similar manner to that described in relation to the embodiment
of Figures 1 and 2. In this connection, one or both of first 140 and second pumps
160 may share a common wall with flow meter 100. Alternatively, either or both of
first and second pumps may be formed integrally with the flow meter in a common
housing with means provided for the separation of fluid flow. Still alternatively,
first or second pumps may be raised or separated from flow meter 100 as long as
means are provided for the translation of the rotation of the rotational element(s)
of flow meter 100 to said first and second pumps. This later arrangement may be
helpful, for example, where it is desirable to remove one or more metering pumps
from exposure from the heat of the primary fluid passing through flow meter 100.
Such an arrangement, may also be helpful when there exists space and design concerns.
This design also provides an air gap to separate the source of drive water and the
chemical being pumped.
Each of metering pumps 140 and 160 include, in the example of the
first pump 140, a housing 122 defining an internal cavity 123 and an inlet 125 and
an outlet 126, where said inlet 125 is coupled to a second source of fluid 137 by
a conduit 129. In this embodiment, at least one rotational element 131 is rotatably
disposed in cavity 123 such that the rotation of said element 131 induces fluid
flow through inlet 125 and outlet 126.
A connecting element 120, e.g., a spline, is coupled to one or both
of rotational elements 102 and 104 and to at least one of the rotor elements disposed
in both first and second pumps 140 and 160, respectively. In such a fashion, the
flow of fluid from inlet 108 to outlet 110 of flow meter 100 rotates first and second
rotational elements 102 and 104 and at least one of the rotors disposed in each
of first and second pumps 140 and 160. As described above in relation to prior embodiments,
the rotation of rotors in pumps 140 and 160 induces fluid flow from each of reservoirs
137 and 143 through respective fluid inlets 148 and 129 and through outlets 126
and 132 and ultimately through valve 91 and common flow passage 80. In the embodiment
illustrated in Figure 4, additive second and third fluids are introduced to the
fluid stream through housing 105. Alternatively, one or more of the additive fluids
may be introduced in the outflow conduit 115 as illustrated in Figure 3.
In some applications, it may be desirable to include means to divert
at least a portion of an additive fluid back to the fluid reservoir. Such reticulation
may be important, for example, when the additive fluid is prone to settling. By
reference to Figure 4, a valve 91 may be disposed in outlet conduit 80 such that
upon partial opening of valve 91 a portion of the additive fluid is diverted back
to the fluid reservoir.
Yet another embodiment of the present invention may be seen by reference
to Figure 5 in which is illustrated a flow meter 150, a first pump 170 and a second
pump 190. Flow meter 150 is configured in much the same fashion as described above
in relation to other embodiments and may adopt a variety of configurations. It is
desired, however, that meter 150 include a fluid tight housing defining an inlet
and an outlet, where at least one rotor element 155 is disposed therebetween. Similarly,
pumps 170 and 190 may also adopt a number of configurations involving the use of
at least rotational element which is coupled to element 155. In this connection,
it is contemplated that one or both of pumps 170 and 190 may incorporate counter
rotating helical gears of the type illustrated in Figures 6 and 7 or may alternatively
utilize a single rotor formed in a cavity disposed in a housing. In each case, however,
it is desirable that the rotor element of pumps 170 and 190 be rotationally coupled
to at least one of the rotational elements of the flow meter 150.
In the illustrated embodiment, pumps 170 and 190 are arranged in a
vertical or "stacked" relationship with respect to one another as to share a common
interconnecting element or spline 175. In such a fashion, the rotation of the rotational
element of flow meter 150 results in the rotation of rotors in each of pumps 170
and 190 to include the metered flow of second or third fluids as described above.
As set forth above, the ratio of the injection of the second and first fluids may
be determined as a function of the ratio of the respective gear size between each
of pumps 170 and 190 to flow meter 150. Alternatively, a compound spline 175 may
be employed which allows for the selective adjustment of the rotation of one or
both of pumps 170 and 190 vis-a-vis metering pump 150.
The immediately aforedescribed embodiment may be desirable due to
space constraints or design limitations.
Yet another embodiment of the invention may be seen by reference to
Figs. 8 and 9 in which is illustrated a flow meter 200 which includes a housing
202, a fluid inlet port 204 and a fluid outlet 206, as described previously in relation
to other embodiments. Housing 202 itself comprises a top wall 211, a bottom wall
209 and a side wall 202. Consistent with prior embodiments, flow meter 200 includes
one or more rotational elements 214 (as shown in phantom) which rotate about shafts
and include an extended spline 215 which extends outside housing 202. In the illustrated
embodiment, spline 215 includes a flat 216 to aid in engaging pump 230, as will
be described below.
By reference to Figures 8-9, pump 230 includes a housing 232 which
is generally circular in configuration and which defines a substantially circular
bore 239, a fluid inlet 240 and an outlet 242. Bore 239 is receivable to an impeller
234 which is adapted to rotate about a hub 238. It is contemplated that hub 238
includes a fixed shaft engageable with spline 215 so as to transfer the rotation
of spline to impeller 234 so as to pull fluid from inlet 240 through outlet 242.
As illustrated, impeller 234 is eccentrically disposed in bore 239,
which eccentricity is adjustable depending on desired flow rates. Housing 232 includes
an adjustment flange 260 which includes a pivot aperture 262 about which housing
232 may be pivoted in a plane coplanar with the plane described by housing top 211.
The pivot of housing 232 serves to distort the shape of impeller 234 so as to increase
or decrease the quantity of fluid moved through said pump 230. In this connection,
impeller 234 is preferably made from a pliable compound,e.g. rubber, which allows
resilient deformation. Impeller 234 itself defines a number of fins which will be
familiar to those skilled in the art.
It is contemplated that the aforedescribed adjustment to impeller
234 may be made manually and gauged about gradations scored on top 207. Alternately,
a flow gauge (not shown) may be situated in the outflow line (not shown) and manual
adjustments made from this flow gauge. Still alternately, pump 230 may be remotely
adjusted, e.g. by a stepper motor, to achieve a desired and preprogrammed flow rate.
In the instance of manual adjustment, pump housing 232 may be secured to meter housing
202 about a particular orientation by a screw 250, as illustrated.
Fluid metered through pwnp 230 need not be necessarily introduced
into flow meter 200, to outlet 206 or outlet line 213 immediately downstream from
outlet 206. Instead, the metered additive may be carried in a separate line 243
which may parallel water outlet line 209, where lines 209 and 243 coterminate at
a given point, e.g., the mixing pool. In such a fashion, inadvertent backflow will
not result in a contamination of the water supply.
Still another embodiment of the invention may be seen by reference
to Figure 10 in which is illustrated a flow meter 300 defining a housing 302 and
at least one interior metering element which is rotated about the introduction of
fluid through meter 300 in a manner consistent with that described above. In the
illustrated embodiment, at least one of the rotatable elements includes a spline
304 which extends beyond housing 302 and is coupled to a cam wheel 307 which in
turn is coupled to a crank 309 in a manner familiar to those skilled in the art.
Crank 309 is in turn coupled to a metering pump 312 of a design generally disclosed
and claimed in U.S. Patent No. 4,558,715.
In such a fashion, the introduction of water into meter 300 turns
at least one rotatable element which in turn acts upon crank 309 and pump 312 to
induce a metered flow of fluid, e.g. medication or chemicals. The amount of fluid
introduced through pump 312 may be adjusted in a conventional fashion as disclosed
in Applicant's prior patents, Patent Nos. 4,809,731 and 4,558,715.
Although particular detailed embodiments of the apparatus and method
have been described herein, it should be understood that the invention is not restricted
to the details of the preferred embodiment.