Methods and apparatus for dispensing plural fluids in a precise proportion

A fluid-driven proportioning pump for dispensing precise volumes of at least three different fluids includes a drive cylinder housing a correspondingly formed drive piston which divides the drive cylinder into first and second drive fluid chambers and is propelled in a reciprocating motion by a pressurized drive fluid. Each face of the drive piston is provided with projecting porportioning pistons which extend into proportioning cylinders that open into each drive fluid chamber and being directed toward the drive piston. An over-center mechanis triggered by movement of the drive piston at the extremes of the strokes for its reciprocating motion operates valving which admits the pressurized drive fluid into alternate of the drive fluid chambers. The over-center mechanism is activated by loop springs or preferably by pairs of C-shaped springs, and is housed entirely within the drive cylinder. Selective adjustment of the proportion among the drive fluid and the other constituent fluids is facilitated by configuring each proportioning piston as a disk-like piston head slidably mounted on a turnable shaft that projects from the face of the drive piston with an enlarged head on the side of the disk remote from the drive piston. The head of the turnable shaft is provided with a fitting that is manipulatable from the outside of the pump by a retractable tool.

BACKGROUND OF INVENTION 
1. Field of the Invention 
This invention relates to devices for dispensing a plurality of fluids in a 
precise ratio to each other. More particularly, the invention disclosed 
herein relates to an improved fluid-driven liquid proportioning pump that 
effects the positive displacement of the fluids involved. While adaptable 
to a number of diverse uses, the methods and apparatus of the present 
invention have ready applicability in the field of mixing and dispensing 
carbonated beverages. 
2. Background Art 
Many aspects of industrial processing and consumer merchandising require 
the continuous, precise dispensing and mixing of a plurality of 
constituent fluids into a desired product. This is the case in the 
manufacture of paints, pesticides, fertilizers, and industrial sealants, 
as well as in the preparation of foods and pharmaceutical, such as 
margarine, syrups, medicines, toothpaste, and cosmetic preparations In the 
retial area the dispensing of individual constituent fluids for mixture 
into a final consumable product is prominent in relation to the retailing 
of carbonated and other syrup-based beverages and juices. 
While the methods and apparatus of the present invention finds utility in 
each of the above-named and other fields, an immediate application of the 
present invention resides in meeting the demand in the carbonated beverage 
industry for an improved manner by which the constituent fluids of such 
beverages may be dispensed and mixed into a consumer product having narrow 
specifications that are dictated by desired product taste. 
In the production of carbonated beverages, such as cola-type beverages, 
orange drinks, lemonade drinks, and the like, aromatic flavoring agents in 
liquid form, such as syrups and concentrates, are metered and combined 
with predetermined quantities of carbonated water. Typically, the 
carbonated water is pressurized and mixed with the syrups to form a 
finished beverage that may be dispensed either into reusable or disposable 
containers. 
This process of dispensing and blending into a final mixture the proper 
quantities of each fluid in a manner capable of satisfying the sensitized 
tastes of the consuming public has been rendered moire complicated in 
recent years by two developments. Firstly, the public preference for 
artificially sweetened carbonated beverages has increased dramatically. 
Secondly, the perceived necessity to replace the artificial sweetener 
saccharin with another has resulted in a widespread shift by the foods 
industry to use of the artificial sweetener, aspertaime, commonly marketed 
under the trademark NUTRASWEET.RTM.. Unfortunately, aspertaime has a 
relatively short shelf-life, after which the flavor of the sweetener 
undergoes markedly noticeable alteration. 
This fact about aspertaime has lead to the practice in the soft drink 
industry of separating the sweetening element from the aromatic syrups, so 
that the turnover of sweetener supplies can be accelerated. Accordingly, 
in dispensing and blending the components of a carbonated beverage that is 
to contain aspertaime, it is now necessary to blend, not merely two 
different constituent fluids, but three: carbonated water, an aromatic 
syrup, and sweetener. 
The effort to develop fluid proportioning devices suitable for metering 
more than two constituent fluids only cast in a harsher light the 
drawbacks of the devices previously developed toward the dispensing of two 
constituent fluids. Prior devices were complicated, requiring plural 
conduits, complex valving, and forms of involved linkages for effecting 
coordination between the operation of otherwise independent dispensing 
mechanisms. DEvices which fail to physically integrate the dispensing 
mechanisms necessitated the use of additional mechanical systems for 
coordinating the necessarily separate dispensing functions. This added to 
the complexity of dispensing devices, resulting in a need for require 
increased maintenance. The resort to electrical drive motors to overcome 
the need for motive power only complicated the proportioning pumps by 
adding thereto another system needing its own separate maintenance and 
isolation for safety and operational purposes. 
Many proportioning pumps were reciprocating in nature, but were successful 
in dispensing constituent fluids in one direction of their reciprocating 
motion. This produced uneven flow and irregular ratios of the constituent 
fluids involved in each cycle of operation. 
The actual proportioning aspect of such devices presented several problems. 
Many simply were not accurate, so that a user was faced with unreliability 
in preparing a final product. The proportioning function was frequently 
effected by valving external to the mechanism by which constituent fluids 
were actually advanced through the system. Such external valving itself 
comprised a separate system of mechanical operation requiring its own 
maintenance and coordination. 
In many instances the proportioning ratio of a given device was either 
fixed, or if not fixed, was extremely difficult to alter, requiring in 
most instances disassembly and reassembly in a trial-by-error method. The 
effort to integrate such proportioning mechanisms resulted in some devices 
having the proportioning aspects built into the heads of the pistons that 
are used to advance the constituent fluids. In this location, any 
alteration of the proportioning ratio was at best difficult to achieve 
without suffering the expense of substantial down time. 
A significant problem in prior proportioning pumps was that the plurality 
of fluids involved necessitated the incorporation into the proportioning 
device of a number of dynamic seals. In many cases, of necessity, one or 
more of these seals was exposed on one side to the atmosphere, tending to 
age it rapidly due to drying. The concomitant need for replacement and 
repair of such components is readily predictable. 
Ultimately, prior fluid proportioning pumps were complicated assemblages of 
separate mechanical systems. Each separate component systems required its 
own maintenance. Intervening systems were necessary for effecting 
coordinated operations. In the effort to streamline such devices, 
designers were faced with two conflicting tendencies. Either the 
subsystems ancillary to that used to advance constituent fluids would be 
located external to the advancement system, where they would be relatively 
easily accessible for maintenance and adjustment purposes but relatively 
difficult to coordinate in any simple manner, or such subsystems could be 
integrated into the mechanical structure of the fluid advancement 
subsystem rendered them difficult to access, while possibly more easy to 
coordinate. 
All such drawbacks existed in proportioning pumps used with just two 
constituent fluids. The need for proportioning pumps which could 
effectively dispense more than two fluids exacerbated known problems. 
Additional constituent fluids required additional subsystems for 
coordination and proportioning. Devices grew more complex, rather than 
simpler, as would have been desired. No method or apparatus was available 
which both coped effectively with additional constituent fluids and 
simplified the number of subsystems and components involved. 
BRIEF SUMMARY OF THE INVENTION 
One object of the present invention is to provide methods and apparatus for 
simultaneously dispensing precisely measured quantities of three or more 
different constituent fluids. 
Another object cf the present invention is to provide a fluid proportioning 
apparatus which effects the positive displacement of the constituent 
fluids involved, but which does so with a consistent precision of 
operation acceptable in the industry in which it is applied. 
Yet another object of the present invention is a fluid proportioning 
apparatus and method as described above which is driven exclusively by the 
pressure exerted by one of the constituent fluids being processed. 
An additional object of the invention is a method and apparatus for 
proportioning fluids as described above which utilizes reciprocating 
motion and which is capable of continuously dispensing the constituent 
fluids involved. 
Another object of the invention is an apparatus for proportioning fluids in 
which the dynamic seals thereof avoid exposure to the atmosphere, and 
therefore enjoy effective lifetimes of enhanced duration. 
Another object of the present invention is a fluid proportioning pump as 
described above in which the proportioning aspect thereof is adjustable, 
and further is adjustable without requiring major disassembly of the 
device. 
Yet another object of the present invention is a fluid proportioning pump 
for three or more fluids which is mechanically streamlined in relation to 
prior proportioning pumps so as to be compact, easily assemblable, and 
minimally demanding of maintenance. 
Additional objects and advantages of the invention will be set forth in the 
description which follows, and in part will be obvious from the 
description, or may be learned by the practice of the invention. The 
objects and advantages of the invention may be realized and obtained by 
means of the instruments and combinations particularly pointed out in the 
appended claims. 
To achieve the foregoing objects and in accordance with the invention as 
embodied and broadly described herein, a fluid-driven proportioning pump 
is provided for dispensing in a precise, predetermined ratio quantities of 
an externally pressurized drive fluid and a first and a second constituent 
fluid. In one embodiment of the present invention, such a proportioning 
pump comprises a drive cylinder having closed ends and a drive piston 
disposed therein. The drive piston is propelled by the drive fluid in a 
reciprocating motion comprising successive strokes in opposite directions. 
The drive piston in effect separates the drive cylinder into a first and a 
second drive fluid chamber. 
The inventive proportioning pump further comprises a drive reversal means 
for admitting the pressurized drive fluid alternately into the first and 
the second drive fluid chambers to cause the reciprocating motion in the 
drive piston. In that motion drive fluid is positively displaced from the 
one of the first and second drive fluid chambers into which the 
pressurized drive fluid is not at the time being admitted. 
In a preferred embodiment of the inventive proportioning pump, the drive 
reversal means comprises a pressurized drive fluid passageway and a drive 
fluid exit passageway formed in each of a pair of plate assemblies closing 
the opposite ends of the drive cylinder. First and second valve means are 
provided for placing the first and second drive fluid chambers 
respectively, in communication alternately with the pressurized drive 
fluid passageway and the drive fluid exit passageway in the adjacent plate 
assembly. A linkage means for operating the first and second valve means 
together insures that when one of the drive fluid chambers is in 
communication with a drive fluid passageway, the other is in communication 
with a drive fluid exit passageway. In this manner, the pressure of the 
drive fluid in one of the drive fluid chambers advances the drive piston 
in the direction of the other drive fluid chamber, positively displacing 
drive fluid from the preceding opposite stroke of the reciprocating motion 
of the drive piston. 
An over-center means in turn drives the linkage means between a first 
operative mode, in which the first drive fluid chamber is in communication 
with a pressurized drive fluid passageway, and a second operative mode, in 
which the second drive fluid chamber is in communication with a 
pressurized drive fluid passageway. The over-center means functions in 
this manner responsive to the completion of each successive stroke of the 
reciprocal motion of the drive piston. 
In one embodiment of the present invention, the overcenter means is located 
entirely within the drive cylinder and comprises a pair of resilient 
springs located on opposite sides of the drive piston, each being 
compressed between a linkage bearing surface rigidly attached to the 
linkage means and a drive bearing surface rigidly attached to the drive 
piston. 
The proportioning aspect of the inventive proportioning pump resides in a 
pair of proportioning cylinders for each of the constituent fluids 
involved. One proportioning cylinder for each of the constituent fluids 
opens opposite the drive piston into each of the first and second drive 
fluid chambers. Although other arrangements are conceivable and within the 
scope of the present invention, it is contemplated in the presently 
preferred embodiment of the inventive proportioning pump that the axis of 
each of the proportioning cylinders be parallel to the axis of the drive 
cylinder. To each proportioning cylinder corresponds a single constituent 
fluid passageway through which the constituent fluid corresponding 
therefor is admitted into and positively displaced from the proportioning 
cylinder. 
From each face of the drive piston extend a pair of proportioning pistons 
that are disposed in corresponding individual proportioning cylinders. By 
this arrangement, the reciprocating motion of the drive cylinder 
simultaneously advances and retracts the constituent fluid proportioning 
pistons within their corresponding proportioning cylinders. This in turn 
alternately draws into those cylinders, and on the following reverse 
stroke positive displaces therefrom, precisely measured quantities of 
constituent fluid. Simultaneously, drive fluid is displaced from the drive 
fluid chamber not receiving drive fluid in a pressurized state, and a 
measured displacement of the drive fluid and each of the constituent 
fluids results. 
In one aspect of the present invention, the proportioning pump is provided 
with a ratio adjustment means for selectively varying the quantity of at 
least one of the constituent fluids that is drawn into and displaced from 
one of the proportioning cylinders. Referring to such a proportioning 
cylinder as a meterable proportioning cylinder, this is effected through a 
proportioning piston head in the metering proportioning cylinder in 
combination with and means to permit waste movement of the drive cylinder 
relative to the proportioning piston head in each direction of the 
reciprocating motion of the drive cylinder. 
In one embodiment of the present invention, the means to permit waste 
movement comprises a footing projecting from the drive cylinder toward the 
metering cylinder and a proportioning piston shaft extending from the 
footing. The piston shaft slidably passes through the proportioning piston 
head into the meterable proportioning cylinder. A radially enlarged 
retaining head is provided on the end of proportioning piston shaft within 
the meterable proportioning cylinder. In each stroke of the drive piston, 
waste movement occurs as the proportioning piston slides the length of the 
piston shaft between the retaining head and the footing. 
Means are provided for selectively varying the extent of the waste movement 
involved. Cooperating threading secures the proportioning piston shaft to 
the footing, and an internal adjustment fitting on the retaining head 
permits the retaining head to be rotated to change the distance between 
the retaining head and the footing. This varies the amount of waste 
movement permitted in each stroke of the proportioning pump. An external 
access means cooperates to enable the selective rotating of the internal 
adjustment fitting from the exterior of the proportioning pump. 
In one embodiment of the present invention, the external access means 
comprises an adjustment opening formed through the end of the meterable 
proportioning cylinder opposite the proportioning piston head, and an 
adjusting rod slidably and rotatably mounted in the adjusting opening. The 
end of the adjusting rod interior to the proportioning cylinder includes 
an adjustment transfer tool for mating with the internal adjustment 
fitting. The other end of the adjusting rod is provided with an external 
adjustment fitting by which the adjustment rod may be rotated. by 
selective advancement of the adjusting rod into the proportioning 
cylinder, the adjustment transfer tool can be made to engage the internal 
adjustment fitting. Then rotation of the adjusting rod with the external 
adjustment fitting will also rotate the proportioning piston shaft from 
the exterior of the proportioning cylinder. 
In an alternative characterization, a proportioning pump is provided for 
dispensing in a precise, predetermined ratio quantities of a first and a 
second fluid. The portioning pump comprises reciprocating means for 
continuously dispensing the first fluid. The reciprocating means includes 
a stationary portion enclosing opposed first and second fluid chambers and 
an active portion housed within the stationary portion. The active portion 
is driven in a reciprocating motion comprises successive strokes in 
opposite directions alternately towards the first and towards the second 
fluid chambers. The proportioning pump further comprises first and second 
reservoir means for holding a predetermined quantity of the second fluid. 
These are located individually in said first and second fluid chambers, 
respectively. Fluid advancement means operably connected to the active 
portion of the reciprocating means are provided for continuously 
dispensing the second fluid. The fluid advancement means draws a 
predetermined quantity of the second fluid into one of the reservoir means 
and positively displaces the predetermined quantity of the second fluid 
from the other of the reservoir means in the stroke of the motion of the 
reciprocating means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An overview of the main structural features of an embodiment of a liquid 
proportioning pump incorporating teachings of the present invention can be 
derived by reference to FIG. 1. There, a liquid proportioning pump 10 is 
shown in a disassembled condition as including a drive cylinder 12 having 
first and second ends 14, 16, respectively. In the assembled condition of 
proportioning pump 1-, first end 14 of drive cylinder 12 abuts against an 
inner face 18 of a first plate assembly 20. To assist in effecting a 
secure seal, inner face 18 is provided with an annular recess 22 which 
receives an O-ring not shown in FIG. 1, and first end 14 of drive cylinder 
12. Correspondingly, in the assembled condition of proportioning pump 10, 
a second plate assembly 24 closes drive cylinder 12 by abutment against 
end 16 thereof. This state of assembly is maintained by four elongated 
assembly bolts 26 which pass through eyes 28 in first plate assembly 20 
and thereafter through eyes 30 in second plate assembly 24. Nuts 32 are 
then threaded onto leading ends 34 of assembly bolts 26 to draw first 
plate assembly 20 and second plate assembly 24 against the opposite ends 
of drive cylinder 12. 
Formed in first and second plate assemblies 20, 24, respectively, but not 
visible in FIG. 1, are a plurality of passageways for the constituent 
fluids to be dispensed by proportioning pump 10. These fluids enter the 
passageways referred to through openings identified generally in FIG. 1 by 
reference character 36. Typically, openings 36 are provided with fittings 
by which to connect to proportioning pump 10 tubes bringing the 
constituent fluids to proportioning pump 10 from reservoirs or container 
thereof, as well as tubes conveying away metered quantities of the same. 
For the benefit of simplicity, such fittings and tubing have been omitted 
from FIG. 1 and all subsequent figures of this disclosure, as it is 
readily within the capacity of those skilled in the art to effect the 
required fluid connections for proportioning pump 10. 
Aside from the tubes and constituent fluid sources discussed above, all 
other operating components of proportioning pump 10 are located interior 
to first and second plate assemblies 20, 24, respectively, or within drive 
cylinder 12. Such additional components will be identified briefly by 
reference to FIG. 1, but discussed subsequently in more detail and 
interrelated with the other components of proportionate pump 10. 
A drive piston 40 is disposed in drive cylinder 12 and propelled in a 
reciprocating motion of successive strokes in opposite directions by the 
pressurized drive fluid. The details of the structure of a preferred 
embodiment of a drive piston, such as drive piston 40, for use in 
proportioning pump 10 will be discussed subsequently in relation to FIG. 
4. Nevertheless, alternative forms of such a drive piston could easily be 
accommodated within the limitation and teachings of the present invention. 
It is important to note that while the cross-section of drive cylinder 12 
as shown in FIG. 1 is circular and while the cross-section of drive piston 
40 corresponds thereto, it would be equally workable, although not 
presently preferable, to employ a drive cylinder in proportioning pump 10 
that has virtually any workable prismatic cross-section. Thus, a drive 
cylinder such as drive cylinder 12, could be elliptical, rectangular, or 
of any other workable cross-section, provided that the size and shape of 
the drive piston to function therewith is modified accordingly from that 
shown for drive piston 40 in FIG. 1. 
Other structural elements of proportioning pump 10 which in the assembled 
state thereof are contained within drive cylinder 12 include a pair of 
proportioning cylinders 42, 44 projecting into drive cylinder 12 from 
inner face 18 of first plate assembly 20. Similarly, but less clearly 
shown in FIG. 1, proportioning cylinders 46, 48 project from second plate 
assembly 24, also into drive cylinder 12. The ends of proportioning 
cylinders 42, 44, 46, 48 oriented toward drive piston 40 are open. 
Generally, the longitudinal axis of the proportioning cylinders are 
parallel to the longitudinal axis of drive cylinder 12, although this need 
not absolutely be the case within the scope of the present invention. One 
of the two proportioning cylinders on each of first plate assembly 20 and 
second plate assembly 24 corresponds to the first of the constituent 
fluids, other than the drive fluid, that is to be dispensed in a 
predetermined quantity by proportioning pump 10. The other proportioning 
cylinder on each of first and second plate assemblies 20, 24, 
respectively, corresponds to the second of the constituent fluids. The 
constituent fluid for each proportioning cylinder enters and exits through 
passageways in the respective plate assembly from which each proportioning 
cylinder projects. These passageways terminate in openings on the exterior 
of the plate assemblies, such as openings 36. 
Constituent fluid is drawn into each proportioning cylinder and positively 
displaced therefrom by a proportioning piston which projects from the face 
of drive piston 40 opposite thereto. The proportioning pistons move 
backwards and forwards in each respective proportioning cylinder with 
drive piston 40 in the reciprocating motion in which it is propelled by 
the drive fluid. Specifically, when proportioning pump 1- is assembled, a 
proportioning piston 50 extending from the face of drive piston 40 not 
visible in FIG. 1 is received in proportioning cylinder 42, whereby 
reciprocating motion of drive piston 40 alternately advances and retracts 
proportioning piston 50 within proportioning cylinder 42 to 
correspondingly draw thereinto and to positively displace therefrom 
precisely measured quantities of the constituent fluid corresponding 
thereto. In a similar manner, a proportioning piston 52 and a 
proportioning piston 54 projecting from the side 56 of drive piston 40 
visible in FIG. 1 extend into proportioning cylinders 46, 48, 
respectively, when proportioning pump 10 is assembled. The operation of 
proportioning pistons 52, 54 within their respective proportioning 
cylinders is reversed with respect to that of proportioning piston 50 
described above. Thus, when a stroke if drive piston 40 is advancing 
proportioning piston 50 into proportioning cylinder 42 to positively 
displace the constituent fluid therefrom, proportioning pistons 52, 54 are 
simultaneously being retracted within proportioning cylinders 46, 48, 
respectively, to draw thereinto the constituent fluid. A fourth 
proportioning piston not visible in FIG. 1 but appearing hereafter in 
various figures of this disclosure will be identified by the reference 
character 58. This proportioning piston extends from the side of drive 
piston 40 not visible in FIG. 1 into proportioning cylinder 44 when 
proportioning pump 10 is assembled. 
In its reciprocating motion within drive cylinder 12, drive piston 40 is 
stabilized by means of a guide shaft 60 which slidably passes through 
drive piston 40 and has each end thereof secured in one of first plate 
assembly 20 and second plate assembly 24. Drive piston 40 is also guided 
by a shaft 62 which also slidably passes through drive piton 40 and is 
secured from lateral, although not longitudinal, motion at its opposite 
ends in first plate assembly 20 and second plate assembly 24. Shaft 62 
plays an integral role in the valving of the pressurized drive fluid into 
drive cylinder 12 alternately on opposite sides of drive piston 40 so as 
to induce a reciprocating motion therein. This role will be explored in 
close detail presently. 
Before leaving FIG. 1, it will be useful to point out further structural 
components of proportioning pump 10 which are housed within drive cylinder 
12 when proportioning pump 10 is assembled. These additional elements 
include first and second valve blocks 64, 66, respectively, which in the 
assembled state of proportioning pump 10 are rigidly secured to valving 
shaft 62 near the remote ends thereof. Between the inner surface 67 of 
drive cylinder 12 and each of first and second valve blocks 64, 66, 
respectively, is interposed a roller bearing 71 that facilitates the free 
lateral movement of valving shaft 62 with first valving block 64 and 
second valving block 66, attached thereto. 
This lateral movement partially effected as a result of a first and a 
second spring 68, 70, respectively, which can satisfactorily take many 
forms. As shown in FIG. 1 for illustrative purposes, first and second 
springs 68, 70, respectively, comprise resilient loops, which may be 
discontinuous at one point in the circumferences thereof having free ends 
that facilitate the resiliency desired. First spring 68 is held in 
compression between first valve block 64 and a first spring shoe 72 which 
in the assembled condition of proportioning pump 22 is slidably mounted on 
guide shaft 60 and rigidly attached to the side of drive piston 40 not 
visible in FIG. 1. Correspondingly, second spring 70 is held in 
compression between second valve block 66 and a second spring shoe 74 
which similarly is slidably mounted on guide shaft 60 and rigidly secured 
to side 56 of drive piston 40. Guide shaft 60 passes through a bore 75 
formed in spring shoe 74. The free ends of the loops of first and second 
springs 68, 70, respectively, are covered and clamped to first and second 
spring shoes 72, 74, respectively, and covered by spring clamp plates 69. 
The manner in which the structures just described interact mechanically 
with valving shaft 62 to effect a valving function will appear presently. 
An additional fact about the relative positioning of the components of 
proportioning pump 10 is best appreciated by reference to FIG. 1 and 
deserves mention at this time. First and second springs 68, 70, 
respectively, are so configured and so positioned by the locations of the 
valve block and shoe spring between which each is constrained that when 
first and second plate assemblies 20, 24, respectively, are in place 
against drive cylinder 12, first spring 68 encircles proportioning 
cylinders 42 and 44 together in the space between those proportioning 
cylinders and inner surface 67 of drive cylinder 12. Similarly, second 
spring 70 encircles proportioning cylinders 46 and 48 together in the 
space between those proportioning cylinders and inner surface 67 of drive 
cylinder 12. 
In the operation of proportioning pump 10, a pressurized drive fluid is 
valved into drive cylinder 12 alternately on opposite sides of drive 
piston 40 in a manner yet to be fully disclosed. This valving of the 
pressurized drive fluid sets drive piston 40 into a reciprocating motion 
in which drive fluid on the side of drive piston 40 that is no longer 
pressurized is vented, and the drive motion of drive piston 40 positively 
displaced that non-pressurized drive fluid therefrom. On the return 
stroke, the previously vented side of drive piston 40 is made to 
communicate with the drive fluid in a pressurized state, while the drive 
fluid on the opposite side of drive piston 50, which was previously 
pressurized, is vented and begins to be positively displaced from drive 
cylinder 12 by the reversed movement by drive piston 40. 
In the process described, proportioning pistons 50, 52, 54, and 58 (the 
latter not shown in FIG. 1) alternately advance and retract within their 
corresponding proportioning cylinders due to their attachment to drive 
piston 40. The pair of proportioning pistons oriented in the direction of 
each stroke of drive piston 40 move into the proportioning cylinders 
corresponding thereto, positively displacing a predetermined volume of 
constituent fluid from each. The pair of proportioning pistons oriented 
counter to the motion on the opposite side of drive piston 40, are 
retracted within their corresponding proportioning piston on the same 
stroke. This draws constituent fluid thereinto. When the motion of drive 
piston 40 is reversed, the proportioning pistons reverse their functions 
as well. 
In each stroke of drive piston 40, predetermined quantities of drive fluid 
and a first and a second constituent fluid are positively displaced for 
mixing outside of proportioning pump 10 to form a desired final product. 
In general the extent of travel both of drive piston 40 and of the 
proportioning pistons attached thereto are equal, the ratio of the fluids 
displaced thereby corresponds approximately to the ratio of the areas of 
each of the piston heads involved. Thus, the sizes of drive cylinder 12 in 
relation to each of the proportioning cylinders utilized will in a 
relatively permanent sense determine the ratio with which drive fluid and 
each of the constituent fluids is displaced. 
Thus, in one manner of characterizing the present invention, an apparatus 
is provided for dispensing in a precise, predetermined ratio quantities of 
a first and a second fluid. The apparatus includes reciprocating means for 
continuously dispensing the first fluid. As shown by way of example in 
FIG. 1 the reciprocating means comprises a stationary portion, including 
drive cylinder 12, first plate assembly 20, and second plate assembly 24, 
and an active portion housed therewithin. The active portion includes 
drive piston 40 and valving shaft 62 is driven in a reciprocating motion 
comprising successive strokes in opposite directions alternately toward 
first end plate 20 and second end plate 24. 
Alternative forms of a reciprocating means, such as a suitably configured 
diaphragm pump, are workable and contemplated as within the scope of the 
present invention. While it is presently preferable that the active 
portion of the reciprocating means be fluid driven, the use of alternative 
motive sources, such as motors and engines, while foregoing some 
advantages of the present invention, is still contemplated as being within 
the scope thereof. 
Also provided in the inventive apparatus are first and second reservoir 
means for holding a predetermined quantity of the second fluid. Each is 
located individually within drive cylinder 12 on opposite sides of drive 
piston 40. As shown by way of example in FIG. 1, proportioning cylinders 
42, 44 project into drive cylinder 12 from first plate assembly 20, while 
proportioning cylinders 46, 48 project from second plate assembly 24 into 
drive cylinder 12. 
Finally, the apparatus of the present invention according to this manner of 
characterization includes a fluid advancement means that is operably 
connected to drive piston 40 for continuously dispensing the second fluid. 
As shown in FIG. 1 by way of example and not limitation, proportioning 
pistons 52, 54 project from side 56 of drive piston 40 and extend into 
proportioning cylinders 46, 48, respectively. Correspondingly, 
proportioning piston 50 and proportioning piston 58, not shown in FIG. 1, 
project from the opposite side cf drive piston 40 into proportioning 
cylinders 42, 44, respectively. Accordingly, during each stroke of the 
reciprocating motion of piston 40 the reciprocating means thus disclosed 
draws a predetermined quantity of the second fluid into the proportioning 
cylinders on one side of drive piston 40 while displacing a predetermined 
quantity of the second fluid from the proportioning cylinders ont the 
opposite side of drive piston 40. 
As used herein, and in the claims hereafter, the use of the term 
"continuously" in relation to the advancement of any fluid by 
reciprocating components of the present invention refers both to a 
discharge of fluid which occurs at each moment during operation, as well 
as the discharge of at least some of the fluid during each successive 
stroke of the reciprocating motion. Thus, if either of proportioning 
pistons 50, 52 displaces at least some of the second fluid during each 
stroke of drive piston 40 toward second plate assembly 24 and either of 
proportioning pistons 50, 58 displaces at least some of the same second 
fluid in each stroke of drive piston 40 in the opposite direction toward 
first plate assembly 20, then the fluid advancement means which comprises 
the recited proportioning pistons is to be considered to continuously 
dispense the second fluid. This will be the case even where the second 
fluid is not dispensed during the entire line of travel of each stroke of 
drive piston 40. 
In one aspect of the present invention, however, ratio adjustment means are 
provided for selectively varying the quantify of at least one of the 
constituent fluids drawn into and displaced from the proportioning 
cylinders corresponding thereto. While in all likelihood it is preferable 
that all proportioning cylinders in a proportioning pump according to the 
present invention be provided with such a ratio adjustment means, any 
proportioning cylinder so provided will herein, and particularly int he 
claims hereafter, be referred to as a meterable proportioning cylinder to 
enhance descriptive clarity. 
A typical structure corresponding to such a ratio adjustment means is 
disclosed in the cross-section shown in FIG. 2, wherein the structures 
already discussed in relation to FIG. 1 are labeled consistently 
therewith. The view provided in FIG. 2 reveals firstly that each of first 
and second plate assemblies 20, 24, respectively, comprise a drive 
cylinder end plate 80 which actually effects closure of the ends of the 
drive cylinder 12 by engaging first and second ends 14, 16 thereof and a 
valve plate 82 on the outside of each drive cylinder end plate 80. 
In each valve plate 82 are formed a plurality of constituent fluid 
passageways 84, one of which communicates with each of proportioning 
cylinders 42, 44, 46, 48. Each constituent fluid passageway 84 
communicates through an intake passageway 86 to one of the openings 36 
shown in FIG. 1 on the exterior of each plate assembly. Within each intake 
passageway 86 is a check valve 88 oriented to permit one-way flow of 
constituent fluid into each proportioning cylinder. Constituent fluid 
enters each of the proportioning cylinders by the route of check valve 88, 
intake passageway 86, and constituent fluid passageway 84. 
In addition, constituent fluid passageway 84 is connected through a venting 
passageway 90 to other of openings 36. Within each venting passageway 90 
is a check valve 92 oriented to permit one-way flow of constituent fluid 
out of each proportioning cylinder. Constituent fluid is displaced from 
each proportioning cylinder through constituent fluid passageway 84, 
venting passageway 90, and check valve 92. 
Check valves 88 and 92 can be of any type of check valve known in the art 
capable of insuring an appropriate one-way flow. Umbrella, duck bill, or 
ball-and-spring check valves are thus suitable in this regard. 
FIG. 2 further reveals that drive piston 40 is comprised of a pair of 
substantially identical drive piston plates 100, shown to better advantage 
in the perspective view of FIG. 4. Drive piston plates 100 are mated in a 
back-to-back relationship to form therebetween a circumferential retaining 
slot 102 in which is disposed a sealing ring 104. Sealing ring 104 engages 
inner surface 67 of drive cylinder 12 to enable reciprocal sliding of 
drive piston 40 therewithin. Sealing ring 104 isolates drive cylinder 12 
into a first drive fluid chamber 106 on the side of drive piston 40 that 
contains proportioning cylinders 42, 44, and a second drive fluid chamber 
108 on the side of drive piston 40 opposite therefrom that contains 
proportioning cylinders 46, 48. 
As seen in FIG. 2, drive piston 40 has reached the full extent of its 
movement leftwardly in the direction shown by arrow A, a movement that is 
induced by placing first drive fluid chamber 106 in oommunication with a 
drive fluid under pressure. In the process of movement in the direction of 
arrow A, drive fluid was positively displaced from second drive fluid 
chamber 108 due to the advancement of drive piston 40. 
Although the cross-section of the proportioning cylinders and pistons shown 
in FIG. 2 are constant, the inventive proportioning pump disclosed herein 
includes a ratio adjustment means for selectively varying the quantify of 
at least one of the constituent fluids drawn into and displaced from one 
of said proportioning cylinders. Any proportioning cylinder provided with 
this feature will herein, and particularly in eh claims hereafter, be 
referred to as a meterable proportioning cylinder. Each of the 
proportioning cylinders 42, 44, 46, and 48 shown in FIG. 2 are meterable 
in this sense, but for illustrative purposes only one, namely 
proportioning cylinder 44 with the proportioning piston 58 corresponding 
thereto, will be discussed and labeled incomplete detail. 
Proportioning piston 58 comprises three main elements. First, a footing 110 
projects from first drive piston place 100 opposite proportioning cylinder 
44. The end of footing 100 remote from drive piston 40 is formed into a 
flat bearing surface 112 from which a proportioning piston shaft 114 
further projects toward proportioning cylinder 44. Proportioning piston 
shaft 114 is threaded into a bore 115 longitudinally formed at the center 
of footing 110. The end of proportioning piston shaft 114 remote from 
footing 110 slidably and rotatably passes through a disc-shaped 
proportioning piston head 116 to terminate in a radially enlarged 
retaining head 118. 
Proportioning piston head 116 has a front surface 120 oriented toward the 
interior of proportioning cylinder 44 and a read surface 122 oriented 
toward drive cylinder 40 and bearing surface 112. The fixed cross-section 
of proportioning cylinder 44 would, under normal circumstances, determine 
in a fixed manner the ratio of the constituent fluid positively displaced 
therefrom in relation to the quantify of drive fluid positively displaced 
from first drive fluid chamber 106. Nevertheless, the ratio adjustment 
means of the present invention, which includes proportioning piston head 
116, is in turn provided with means to permit waste movement or drive 
cylinder 40 relative to proportioning piston head 116 in each direction of 
the reciprocating motion of drive cylinder 40. Footing 110, proportioning 
piston shaft 114, and retaining head 118 comprise such a means to permit 
waste movement. In embodiments of the present invention provided with this 
feature, the rule thus does not apply that the ratio of fluids displaced 
in each pumping stroke is equal to the ratio of the areas of the piston 
heads involved. 
As drive piston 40 moves in the direction indicated in FIG. 2 by arrow A, 
proportioning shaft 114 of proportioning piston 58 is also drawn in the 
direction of arrow A with drive piston 40. Initially, proportioning shaft 
114 slides through the corresponding proportioning piston head 116 until 
retaining head 118 encounter front surface 120 thereof. Thereafter, 
continued movement of drive piston 40 in the direction of arrow A causes 
retaining head 118 to pull proportioning piston head 116 in the direction 
of arrow A thereafter. This draws constituent fluid into proportioning 
cylinder 44. 
When the direction of movement of drive piston 40 is reversed relative to 
arrow A, proportioning piston shaft 114 of proportioning piston 58 slides 
through the corresponding proportioning piston head 116 until bearing 
surface 112 of proportioning piston 58 engages rear surface 122 of 
corresponding proportioning piston head 116. Thereafter, continued 
movement of drive piston 40 in the direction opposite that shown by Arrow 
A will advance proportioning piston head 116 into proportioning cylinder 
44. The sliding of proportioning piston shaft 114 relative to 
proportioning piston head 116 thus results in waste movement of drive 
piston 40 relative to proportioning piston head 116 on each stroke of the 
reciprocating movement of drive piston 40. In relation to proportioning 
piston 58, this waste movement is in an amount illustrated in FIG. 2 by a 
distance D extending between bearing surface 112 and rear surface 122 of 
proportioning piston head 116 when retaining head 118 is engaging front 
surface 120 thereof. The grater the amount of such waste movement, the 
less constituent fluid will be displaced through proportioning cylinder 44 
during each stroke of drive piston 40. 
In accordance with another aspect of the present invention, adjustment 
means are provided to selectively vary the extent of the waste movement 
undertaken by drive piston 40 in relation to each of the meterable 
proportioning cylinder of proportioning pump 10. As shown by way of 
illustration and not limitation, the adjustment means of the present 
invention comprises threadings 124 on one end of proportioning piston 
shaft 114. Threadings 124 engage cooperating threadings in bore 115 in 
footing 110 and secure proportioning piston shaft 114 thereto. In order to 
effect the required fluid seals, proportioning pistons 52, 54 are shown in 
FIG. 2 as including O-rings 126 encircling proportioning piston heads 116 
and O-rings 127 encircling proportioning piston shafts 114. In addition, 
retaining head 118 is provided with an internal adjustment fitting 128 by 
which proportioning piston shaft 114 may be rotated. By way of threadings 
124 this varies the distance D, and correspondingly the amount of waste 
movement, associated with each stroke of drive piston 40. 
Rotation of proportioning piston shaft 114 fully into bore 115 will bring 
rear surface 122 of proportioning piston head 116 into abutment with 
bearing surface 112. Such a situation is shown in relation to 
proportioning piston 50 in proportioning cylinder 42. Under such 
conditions, no waste movement of drive cylinder 40 occurs relative to 
proportioning piston head 116 of proportioning piston 50, and a maximum 
predetermined quantity of constituent fluid is displaced from 
proportioning cylinder 42 on each stroke of drive piston 40. 
As shown in relation to proportioning pistons 52, 54 and corresponding 
proportioning cylinders 46, 48, movement of drive piston 40 in the 
direction of arrow A has initially advanced proportioning piston shafts 
114 through proportioning piston heads 116 of proportioning pistons 52, 54 
into the proportioning cylinders corresponding thereto. This continues 
until such point as bearing surfaces 112 on foots 110 engages rear 
surfaces 122 of proportioning piston heads 116 in each proportioning 
piston. During such waste movement no displacement occurs of the second 
constituent fluid from the proportioning cylinders involved. Thereafter, 
proportioning piston heads 116 of proportioning pistons 52, 54 are 
advanced into their respective proportioning cylinders by the movement of 
drive piston 40. This displaces constituent fluid from the proportioning 
cylinders 46, 48 at a fixed rate for the balance of the full stroke of 
drive piston 40. Where this process occurs ont he reverse stroke of drive 
piston 40 in proportioning cylinders ont eh opposite side of drive piston 
40, the displacement of the second constituent fluid is nevertheless 
herein referred to as being continuous despite any interruptions in the 
displacement due to waste movement of proportioning piston heads. 
In another aspect of the present invention, external access means are 
provided for selectively rotating internal adjustment fitting 128 from the 
exterior of proportioning pump 10. As shown by way of example and not 
limitation, in FIG. 2 in relation to proportioning cylinder 48, an 
adjustment opening 130 is formed through second plate assembly 24 opposite 
proportioning cylinder 48. Adjustment opening 130 is in axial alignment 
with constituent fluid passageway 84. Slidably and rotatably mounted in 
adjustment opening 130 is an adjustment rod 132 which is provided at the 
end thereof internal to proportioning pump 10 with an adjustment transfer 
tool 134 by which to engage internal adjustment fitting 128. Adjustment 
rod 132 may be selectively advanced into proportioning cylinder 48 to 
engage internal adjustment filling 128 on proportioning piston shaft 114 
therein. The end of adjustment rod 132 opposite from transfer tool 134 is 
equipped with an external adjustment fitting 136 by which adjustment rod 
132 may be rotated by a common tool, such as a screw driver or wrench. 
When external adjustment fitting 136 is thus rotated, this motion is 
transferred by transfer tool 134 to proportioning piston shaft 114. 
As discussed earlier, rotation of proportioning piston shaft 114 varies the 
distance D representing waste motion between drive piston 40 and the 
proportioning piston involved. This in turn affects the quantity of 
constituent fluid displaced from the corresponding proportioning cylinder 
on each of the strokes of drive piston 40. In FIG. 2 adjustment rod 132 
associated with proportioning piston 54 is shown thusly advanced into the 
proportioning cylinder 48, and is engaging internal adjustment fitting 128 
on retaining head 118 with transfer tool 134. Adjustment rod 132 is 
sealingly retained in adjustment opening 130 by an O-ring 138. 
Proportioning pump 10 accordingly is not only capable of dispensing a drive 
fluid and at least two constituent fluids in a predetermined proportion, 
but of permitting the selective adjustment of the predetermined proportion 
from exterior proportioning pump 10 without the inconvenience of any 
disassembly whatsoever. 
The manner in which the direction of movement of drive piston 40 is 
reversed will now be disclosed in relation to the sequence of FIGS. 3A, 
3B, 3C, and 3C. First, however, the structures illustrated in these 
figures will be explained in some detail by reference to FIG. 3A. There, 
drive piston 40 can be seen to be positioned within drive cylinder 12 
separating first drive fluid chamber 106 from second drive fluid chamber 
108. Drive piston 40 engages in reciprocating motion stabilized by guide 
shaft 60 and valving shaft 62 the ends of both of which are constrained 
from lateral movement by first and second plate assemblies 20, 24, 
respectively. Drive piston 40 slides freely upon both guide shaft 60 and 
valving shaft 62. While guide shaft 60 is also constrained from movement 
in its longitudinal direction, valving shaft 62 is longitudinally slidable 
back and forth in first plate assembly 20 and second plate assembly 24. 
In order to admit pressurized drive fluid alternately into first drive 
fluid chamber 106 and second drive fluid chamber 108, the proportioning 
pump disclosed herein includes a drive reversal means. As shown by way of 
example and not limitation, a pressurized drive fluid passageway 140 is 
formed in each drive cylinder end plate 80, and a drive fluid exit 
passageway 142 is formed in each valve plate 82. Neither pressurized drive 
fluid passageway 140, nor drive fluid exit passageway 142, communicate 
directly with the interior of drive cylinder 12. 
Further, a first valve means is provided for placing pressurized drive 
fluid passageway 140 and drive fluid exit passageway 142 in first plate 
assembly 20 alternately in communication with first drive fluid chamber 
106. By way of example and not limitation, this first valve means 
comprises a first valve bore 144 extending from first drive fluid chamber 
106 into first plate assembly 20 and communicating with both pressurized 
drive fluid passageway 140 and drive fluid exit passageway 142 therein. 
A valve stem 146 formed on the end of valving shaft 62 is slidably mounted 
in valve bore 144 in first plate assembly 20. Longitudinally formed in 
valve stem 146 is a valving passageway 148. Valving passageway 148 opens 
at one other end thereof through an aperture 150 into either of 
pressurized drive fluid passageway 140 or drive fluid exit passageway 142, 
depending upon the longitudinal position of first valve stem 146 in first 
valve bore 144. As shown in FIG. 3A, the position of first valve stem 146 
is such that aperture 150 is within drive fluid exit passageway 142, 
whereby first drive fluid passageway 106 is vented through valving 
passageway 148 to permit the positive displacement of drive fluid from 
first drive fluid chamber 106. 
Correspondingly, a second valve means is provided for placing pressurized 
drive fluid passageway 140 and drive fluid exit passageway 142 in second 
plate assembly 24 alternately in communication with second drive fluid 
chamber 108. By way of example and not limitation, this second valve means 
comprises a second valve stem 152 at the end of valving shaft 52 remote 
from first valve stem 146 and a second valve bore 154 in which second 
valve stem 152 is slidably mounted. Second valve bore 154 extends from 
second drive fluid chamber 108 into second plate assembly 24 and 
communicates with both pressurized drive fluid passageway 140 and drive 
fluid exit passageway 142 formed therein. Formed longitudinally in second 
valve stem 152 is a valving passageway 148 which opens at one end thereof 
into second drive fluid chamber 108. The other end of valving passageway 
148 in second valve stem 152 opens through an aperture 150 into either 
pressurized drive fluid passageway 140 or drive fluid exit passageway 142 
in second plate assembly 24, depending on the longitudinal position of 
second valve stem 152 in second valve bore 154. 
As shown in FIG. 3D, each of first and second valve bores 144, 154 is 
provided with a seal assembly 76. The elements of each seal assembly 76 
are shown in greater detail in FIG. 3E, wherein valving shaft 62 has been 
eliminated from the foreground to enhance clarity. Seal assemblies 76 
include a pair of square-D seals 77 that encircle valving shaft 62 and 
open toward each other in an opposed relationship. Compressed between each 
pair of square-D seals 77 is a rigid cylindrical sleeve that also 
encircles valving shaft 62. Sleeve 78 has formed therethrough a plurality 
of perforations 79 which permit drive fluid in pressurized drive fluid 
passageway 140 to flow into proximity with the sides of valving shaft 62 
and to enter aperture 150 when the position of valving shaft 62 locates 
aperture 150 within seal assembly 76. 
The operation of first and second valve stems 146, 152, respectively, is 
coordinated by a linkage means comprising valving shaft 62. Valving shaft 
62 serves to operate first and second valve stems 146, 152, respectively, 
in either a first or a second operative mode. In the first operative mode, 
first drive fluid chamber 106 is placed in communication with pressurized 
drive fluid passageway 140 formed in first plate assembly 20, while second 
drive fluid chamber 108 is placed in communication with drive fluid exit 
passageway 142 formed in second plate assembly 24. In the first operative 
mode, drive piston 40 is urged in the direction of second drive fluid 
chamber 108 from which non-pressurized drive fluid is thereby positively 
displaced. The first operative mode is illustrated in FIGS. 3A-3C. 
In the second operative mode of first and second valve stems 146, 152, 
respectively, first drive fluid chamber 106 is placed in communication 
with drive fluid exit passageway 142 formed in first plate assembly 20, 
while second drive fluid chamber 108 communicates with pressurized drive 
fluid passageway 140 formed in second plate assembly 24. In the second 
operative mode, drive piston 40 is urged in the direction of first drive 
fluid chamber 106, accordingly displacing therefrom non-pressurized drive 
fluid. The second operative mode is illustrated in FIG. 3D and will be 
more readily understood following a short discussion of the manner in 
which valving shaft 62 is driven alternately into the first and the second 
operative mode. 
This is accomplished using the same source of power as causes movement in 
drive piston 40, namely the pressurized drive fluid. Toward this end, the 
inventive proportioning pump comprises an over-center means for driving 
valving shaft 62 to operate first valve stem 146 and second valve stem 152 
between the first and second operative modes in response to the completion 
of each of the successive strokes of the reciprocal motion of drive piston 
40. As shown in FIG. 3A by way of example and not limitation, the 
overcenter means of the present invention comprises a linkage bearing 
surface and a drive bearing surface on either side of drive piston 40 and 
a resilient spring compressed therebetween. Each linkage bearing surface 
is fixed to valving shaft 62, while each drive bearing surface is fixed to 
drive piston 40. 
On the side of drive piston 40 facing first drive fluid chamber 106, the 
linkage bearing surface and drive bearing surface take the form, 
respectively, of a slot 156 formed in first valve block 64 and a slot 158 
formed in first spring shoe 72. As first spring shoe 72 is slidable upon 
guide shaft 60, slot 158 is moveable in each successive stroke of the 
reciprocating motion of drive piston 40 into a center position relative 
slot 156 in which slots 156 and 158 are maximally proximate. First spring 
68 mounted in compression between slots 156 and 158 urges slot 156 in 
first valve block 64 and valving shaft 62 attached thereto into the first 
operative mode when slot 158 is on the side of the center position thereof 
adjacent to drive piston 40. When slot 158 is on the side of the center 
position thereof remote from drive piston 40, first spring 68 urges slot 
156 in first valve block 64 and valving shaft 62 into the second operative 
mode. Slots 156 and 158 can be seen in the center position of slot 158 in 
FIG. 3C. 
On the side of drive piston 40 adjacent to second drive fluid chamber 108 
are a second linkage bearing surface and a second drive bearing surface 
taking the form, respectively, of a slot 160 formed in second valve block 
66 and a slot 162 formed in second spring shoe 74. As second spring shoe 
74 is slidable upon guide shaft 60, slot 162 is moveable in each 
successive stroke of drive piston 40 into a center position relative to 
slot 160 in which slots 162 and 160 are maximally proximate. Second spring 
70 mounted in compression between slots 160, 162, urges slot 160 in second 
valve block 66 and valving shaft 62 attached thereto into the first 
operative mode when slot 162 is on the side of the center position thereof 
remote from drive piston 40. When slot 162 is on the side of the center 
position thereof adjacent to drive piston 40, second spring 70 urges slot 
160 in second valve block 66 and valving shaft 62 attached thereto into 
the second operative mode. Slots 160 and 162 can be seen in the center 
position of slot 162 in FIG. 3B. 
The operation of the drive reversal means of the present invention will now 
be explained by reference to the sequence of FIGS. 3A-3D. In FIG. 3A, 
first and second valve stems 146, 152, respectively, are in the second 
operative mode. First drive fluid chamber 106 is in communication through 
first valve stem 146 with drive fluid exit passageway 42 formed in first 
plate assembly 20, while second drive fluid chamber 108 is in 
communication through second valve stem 152 with pressurized drive fluid 
passageway 140 formed in second plate assembly 24. Under these conditions, 
the pressure of drive fluid in second drive fluid chamber 108 impels drive 
piston 40 to the right as shown in FIG. 3A by arrow B. In the process, 
drive fluid is positively displaced from first drive fluid chamber 106 
through valving passageway 148 in first valve stem 146 and drive fluid 
exit passageway 142 formed in first plate assembly 20. Simultaneously, one 
of the constituent fluids is also positively displaced from proportioning 
cylinder 44, while the same or a different constituent fluid is drawn into 
proportioning cylinder 48 on the opposite side of drive piston 40. 
Movement of drive piston 40 in the direction of arrow B with first and 
second spring shoes 72, 74, respectively, attached thereto initially tends 
to bring both slot 158 and slot 162 closer to the center positions of 
each. 
In FIG. 3B, movement of drive piston 40 in the direction shown by arrow B 
is seen to have brought slot 162 into the center position thereof, 
maximally proximate to slot 160. This results in the placement of second 
spring 70 in maximum compression. In FIG. 3B first and second valve stems 
146, 152, respectively, are still in the second operative mode with first 
drive fluid chamber 106 being vented through first valve stem 146 into 
drive fluid exit passageway 142 formed in first plate assembly 20 and 
second drive fluid chamber 108 being pressurized through second valve stem 
152 from pressurized drive fluid passageway 140 formed in second plate 
assembly 24. Under such conditions, movement of drive piston 40 in the 
direction of arrow B continues, as pressurized drive fluid fills second 
drive fluid chamber 108, moving drive piston 40 in the direction of arrow 
B and positively displacing drive fluid from first drive fluid chamber 
106. Concomitantly, constituent fluid continues to be displaced from 
proportioning cylinder 44, while the same or another of the constituent 
fluids is drawn into proportioning cylinder 48. 
Continued movement of drive piston 40 in the direction of arrow B 
eventually brings slot 162 to the side of the center position thereof 
adjacent to drive piston 40, whereby spring 70 will commence to urge 
second valve block 66 and valving shaft 62 attached thereto out of the 
second operative mode. Nevertheless, the urging of first spring 68 in the 
opposite direction precludes any shift of position of valving shaft 62 for 
a period of continued movement of drive piston 40 in the direction of 
arrow B. 
That continued movement of drive piston 40 in the direction shown by arrow 
B in FIG. 3B brings the components of proportioning pump 10 into the 
relationship shown in FIG. 3C. There, slot 158 has reached the center 
position thereof relative to slot 156. Accordingly, first spring 68 is in 
the maximum state of compression thereof, and any further movement of 
drive piston 40 in the direction shown by arrow B will take slot 158 to 
the side of the center position thereof remote from drive piston 40, 
causing first spring 68 to also urge first valve block 64 and valving 
shaft 62 attached thereto out of the second operative mode. The 
positioning of slot 162 on the side of the center position thereof 
adjacent to drive piston 40 instead tends to urge valving shaft 62 and 
second valve block 66 out of the second operative mode, so that the 
over-center means of the disclosed invention, as shown in FIG. 3C, is 
about to drive the valving means thereof into a new operative mode and 
reverse the driven direction of drive piston 40. Nevertheless, prior to 
that reversal, first and second valve stems 146, 152, respectively, remain 
in the second operative mode with pressurized drive fluid entering second 
drive fluid chamber 108 through second valve stem 152 and pressurized 
drive fluid passageway 140 in second plate assembly 24. Fluid in first 
drive fluid chamber 106 is positively displaced therefrom through second 
valve stem 152 and drive fluid exit passageway 142 formed in first plate 
assembly 20. 
FIG. 3D shows the relationship of the components of proportioning pump 10 
after movement of drive piston 40 in the direction of arrow B past the 
position shown in FIG. 3C. Such movement displaces slot 158 to the side of 
the center position thereof remote from drive piston 40, resulting in the 
biasing force of both first spring 68 and second spring 70 urging both 
first and second valve block 64, 66, respectively, and valving shaft 62 
attached thereto out of the second operative mode. Facilitated by rollers 
71, first and second valve blocks 64, 66, respectively, and valving shaft 
62 attached thereto snap leftwardly as seen in FIG. 3D in the direction 
indicated by arrow C. 
In FIG. 3D this has occurred. As a result, aperture 150 in first valve stem 
146 no longer communicates with drive fluid exit passageway 142 in first 
plate assembly 20, but rather opens onto pressurized drive fluid 
passageway 140 formed therein. At the opposite end of valving shaft 62, 
second valve stem 152 has shifted position so that aperture 50 therein no 
longer communicates with pressurized drive fluid passageway 140 in second 
plate assembly 24, but instead vents second drive fluid chamber 108 into 
drive fluid exit passageway 142 formed in second plate assembly 24. This 
is the second operative position for first and second valve stems 146, 
152, respectively. 
Under such conditions, pressurized drive fluid enters first drive fluid 
chamber 106 and begins to impel drive piston 40 leftwardly as seen in FIG. 
3D in the direction shown by arrow A. Correspondingly, drive fluid in 
second drive fluid chamber 108 begins to be positively displaced therefrom 
through drive fluid exit passageway 142 formed in second plate assembly 
24. The action upon the constituent fluid or fluids in proportioning 
cylinders 44, 48 is also reversed. Constituent fluid begins to be 
displaced from proportioning cylinder 48 and drawn into proportioning 
cylinder 44. Movement in the direction of arrow A will continue, bringing 
first slot 158 into the center position thereof and thereafter slot 162 
into its center position. Further movement will then trigger the 
over-center means of the inventive proportioning pump, altering the 
valving of pressurized drive fluid and reversing the direction of drive 
piston 40 as the relative relationships shown in FIG. 3A are reassumed. As 
a general rule the trailing slot in terms of the direction of travel of 
drive piston 40 is, in the embodiment disclosed, the first to reach its 
center position. 
The prompt reversal of drive fluid valving through operation of the 
over-center means of the inventive proportioning pump is facilitated by 
the contrasting manner in which valve blocks 64, 66 and spring shoes 72, 
74 bear against inner surface 67 of drive cylinder 12. In both instances, 
a sliding interaction must be achieved, but it is preferable that the 
sliding motion effected between valve blocks 64, 66 and inner surface 67 
be substantially freer of resistance than the sliding relationship 
structured between shoe springs 72, 74 and inner surface 67. 
As illustrated n each of FIGS. 3A-3D first spring shoe 72 and second spring 
shoe 74 are provided with curved bearing surfaces 164, 166, respectively, 
which slide upon inner surface 67 during the reciprocating motion of drive 
piston 40. By contrast, neither first valve block 64 nor second valve 
block 66 bears directly against inner surface 67. Instead, in each 
instance roller 71 is interposed therebetween in order to substantially 
decrease the frictional resistance to movement of valve blocks 64, 66 and 
valving shaft 62 when the components of the over-center means of the 
inventive proportioning pump reach a position that necessitates the 
reversal of the valving of the drive fluid. Due to the relatively 
substantial friction between bearing surfaces 164, 166 and inner surface 
67 of cylinder 12, first spring shoe 72 and second spring shoe 74 can 
serve as a stable fulcrum about which valve block 64, 66 can pivot in 
effecting movement of valve shaft 62 back and forth between the first and 
second operative modes thereof. 
Proportioning pump 10 is thus reliably driven in a reciprocating motion 
without the aid of any auxiliary power source other than a pressurized 
drive fluid. In the process, the pressurized drive fluid and at least a 
first and a second constituent fluid are dispensed in a predetermined 
precise ratio one to the other. Operation within the industry standard of 
.+-. 3 percent accuracy is easily attained in the inventive proportioning 
pump. In many cases a range of .+-. 1 percent accuracy has been 
consistently achieved. 
All moving parts required to effect this functioning are compactly housed 
interior to drive cylinder 12, and a continuous flow is effected due to 
the positive displacement developed in both directions of the 
reciprocating motion of the pump. The simplicity of the disclosed design 
renders proportioning pump 10 easy to assembly and rarely in need of 
maintenance Adjustment rods 132 discussed in relation to FIG. 2 permit the 
discharge proportion among the plurality of fluids being processed to be 
selectively varied without incurring any down time. 
An additional advantage of the design disclosed resides in the fact that 
all dynamic seals incorporated thereinto are fully lubricated on both 
sides thereof by the fluids being dispensed. Thus, sealing ring 104, 
O-rings 174, and seal assemblies 76 are lubricated on both sides thereof 
by the drive fluid. By reference to FIG. 2 it will be appreciated that 
O-rings 126 and O-rings 127 are lubricated on one side by the drive fluid 
and on the other side by one of the constituent fluids being dispensed by 
the inventive proportioning pump. The wetting of these movable seals on 
both sides thereof contributes substantially to the enhanced effective 
lifetime thereof. Only in relation to O-rings 138 encircling adjustment 
rod 132 is this not the case 0-rings 138 are lubricated on one side by a 
constituent fluid and are on the other side exposed to the atmosphere. 
This 0-ring is static except during infrequent and short duration 
adjustments. 
Of further interest, FIG. 4 shows a disassembled perspective view of the 
components of drive piston 40. These include identical first and second 
drive piston plates 100, 101, respectively, mated in a back-to-back 
relationship at surfaces 168. In each of the drive piston plates is formed 
a pair of openings 169 through which pass guide shaft 60 and valving shaft 
62 when proportioning pump 10 is assembled. Each drive piston plate is 
provided at one of openings 169 with a sleeve 170 projecting from surface 
168. AT the other opening 169 a recess 172 is formed in surface 168. In 
the back-to-back relationship of drive piston plates 100, 101, projecting 
sleeve 170 of each is received into recess 172 of the other. In the 
assembly of first and second drive piston plates 101, 102, respectively, 
an O-ring 174 is disposed in recess 172. As seen in FIGS. 3A-3D, O-ring 
174 forms a seal with guide shaft 60 and valving shaft 62 slidably 
disposed in openings 169. 
FIG. 5 illustrates an alternative, and in the present case 
preferred,embodiment of the valve blocks, spring shoes, and springs of the 
over-center means of the present invention. In contrast to first or second 
springs 68, 70 shown in FIG. 1, FIG. 5 shows a pair of resilient, C-shaped 
springs 180, which when assembled are compressed between a valve block 182 
and a spring shoe 184. In order to optimize the motive power for the 
over-center means of the present invention, it has been found advantageous 
to configure C-shaped springs 180 with an ambit between the free ends 
thereof that is slightly greater than 180.degree.. Each end of C-shaped 
spring 180 is provided with a mounting ball 186 that is snappingly 
receivable into corresponding sockets 188 formed in face 190 of valve 
block 182 and opposing face 192 of spring shoe 184. Sockets 188 function 
as spring receiving slots and are thus the sites off drive bearing 
surfaces and linkage bearing surfaces between which C-shaped springs 180 
are actually compressed. In other respects, valve block 182 may be similar 
in structure to valve blocks 64, while spring shoe 184 corresponds in 
structure to that of spring shoes 72. 
The use of two springs, such as C-shaped springs 180, has been found to 
result in several advantages over the use of single unitary springs, such 
as springs 68, 70 shown in FIG. 1. The pair of C-shaped springs 180 
exhibit less fatigue and therefore enjoy longer effective lifetimes than 
single-piece springs. In addition, the stresses of compression between the 
valve blocks and shoe springs is more evenly distributed to each side 
thereof using the two-spring configuration. Providing C-shaped springs 180 
with an ambit greater than 180.degree. results in a more even distribution 
of stresses along the length of the springs than if these were merely 
semicircular. 
The subject invention also embodies methods for proportioning a plurality 
of at least three fluids in a precise, predetermined ratio. The methods 
comprise the steps of providing a pressurized drive fluid alternately to 
opposite sides of a drive piston in a drive cylinder, while venting the 
side of the piston not provided with the drive fluid. This causes 
reciprocating motion in the drive piston and the positive displacement of 
drive fluid from the leading side thereof. Further, the methods comprise 
the step of securing within the drive cylinder on each side of the drive 
piston a pair of proportioning pistons. These extend from the drive piston 
parallel to the axis of the drive cylinder into corresponding 
proportioning cylinders that face the drive piston within each end of the 
drive cylinder. The proportioning pistons advance into the recede within 
corresponding proportioning pistons with the reciprocating motion of said 
drive piston. Constituent fluid is supplied to the proportioning cylinders 
when the pistons therein recede therein, and is vented from the 
proportioning cylinders when the pistons therein advance thereinto. The 
disclosed methods require reversing the valving of the drive fluid when 
each stroke of the reciprocating motion of the drive piston nears its 
extremes. 
The present invention may be embodiment in other specific forms without 
departing from its spirit or essential characteristics. The described 
embodiments are to be considered in all respects only as illustrative and 
not restrictive. The scope of the invention is, therefore, indicated by 
the appended claims rather than by the foregoing description. All changes 
which come within the meaning and range of equivalency of the claims are 
to be embraced within their scope.