US3672389A

US3672389A - Liquid proportioning device

Info

Publication number: US3672389A
Authority: US
Inventors: Alexander Mcconnell; Fay D Bickel
Original assignee: Automatic Sprinkler Corp
Current assignee: Automatic Sprinkler Corp; Scott Technologies Inc
Priority date: 1970-09-10
Filing date: 1970-09-10
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

A device for substantially continuously mixing or blending two liquids in predetermined ratios to one another, comprising a first two-way acting piston-cylinder unit connected between a source of a first of the liquids under pressure and an outlet line to a mixing tank through a spool-type rotary reversing valve and reciprocable by the first liquid under the control of the reversing valve to deliver metered volumes of the first liquid to the mixing tank, a second two-way acting piston-cylinder unit connected between a source of the second of the liquids and another outlet line to the mixing tank through one-way flow valve controlled conduits and driven for reciprocating action by the first piston-cylinder unit to deliver metered volumes of the second liquid to the mixing tank through gear means which include a pair of paralleling, slidably mounted racks connected to the piston elements of corresponding of the piston-cylinder units and a rockable or rotatable ring gear mounted between and in meshing relation with the racks. The rock axis of the ring gear is defined by a precision bearing having a worm and screw adjustment and may be infinitely varied through such adjustment to regulate the ''''throw'''' of the ring gear towards the second piston-cylinder unit for purposes of obtaining a desired relationship in the operating strokes of the two units and a consequent desired ratio or proportion in the liquids being delivered thereby into the mixing tank.

Description

United States Patent McConnell etv al.

[451 June 27, 1972 [54] LIQUID PROPORTIONING DEVICE [72] Inventors: Alexander McConnell, Hales Comers; Fay

D. Bickel, New Berlin, both of Wis.

[73] Assignee: "Automatic" Sprinkler Corporation of America, Cleveland, Ohio 22 Filed: Sept. 10, 1970 [21] Appl.No.: 71,071

[52] US. Cl ..l37/99, 74/393, 92/133, 417/398, 417/429 [51] Int. Cl. ..G05d 11/00 [58] Field ofSearch ..92/13.3; 137/98, 99; 417/398, 417/429; 74/393 [56] Relerences Cited UNITED STATES PATENTS 2,887,094 5/1959 Krukemeier ..l37/98X 2,752,989 7/1956 Jenkins 1,012,687 12/1911 Melton 1,964,028 6/1934 Boynton et al... 92/l3.3 X 2,413,029 12/1946 McFarland... 137/99 X 2,438,462 3/1948 Smith 137/99 X 3,116,852 l/1964 Anderson.. .417/429 X 3,148,595 9/1964 Looney ..92/13.3 X

TOE,

Primary Examiner-Alan Cohan Assistant Examiner-David J. Zobkiw Attorney-John K. Crump [57] ABSTRACT A device for substantially continuously mixing or blending two liquids in predetermined ratios to one another, comprising a first two-way acting piston-cylinder unit connected between a source of a first of the liquids under pressure and an outlet line to a mixing tank through a spool-type rotary reversing valve and reciprocable by the first liquid under the control of the reversing valve to deliver metered volumes of the first liquid to the mixing tank, a second two-way acting piston-cylinder unit connected between a source of the second of the liquids and another outlet line to the mixing tank through one-way flow valve controlled conduits and driven for reciprocating action by the first piston-cylinder unit to deliver metered volumes of the second liquid to the mixing tank through gear means which include a pair of paralleling, slidably mounted racks connected to the piston elements of corresponding of the piston-cylinder units and a rockable or rotatable ring gear mounted between and in meshing relation with the racks. The rock axis of the ring gear is defined by a precision bearing having a worm and screw adjustment and may be infinitely varied through such adjustment to regulate the throw of the ring gear towards the second piston-cylinder unit for purposes of obtaining a desired relationship in the operating strokes of the two units and a consequent desired ratio or proportion in the liquids being delivered thereby into the mixing tank.

1 1 Claims, 5 Drawing Figures MIX/1V6 TANK LIQUID PROPORTIONING DEVICE The present invention relates to a device for substantially continuously mixing or blending two liquids in accurately controlled ratios or proportions to one another and is more particularly directed to a proportioner which includes a pair of double acting, positive displacement pumps for handling the separate liquids and which are correlated for pumping action through an interconnecting, variable throw gear mechanism.

There is a particular need in the soft drink industry of an improved apparatus for efiecting the accurate blending or mixing of water with flavored syrup concentrate as a part of the soft drink production process and the present invention, while having application to a wide range of other liquids and to diverse liquid blending or mixing processes, is primarily directed to the fulfillment of such need.

Among other things, apparatus presently utilized in the production of soft drinks by the blending of water and syrup in predetermined ratios or proportions to one another have in some instances had a limited capability of handling syrups of widely differing viscosities consistent with the attainment in the final mix or blend of a desiredor requisite degree of exact ness in the proportions of the syrup to the water. Thus, for example, it is not uncommon to find a proportioner in a soft drink plant which while entirely satisfactory of operation in blending a soft drink utilizing a relatively highly viscous syrup such as that which has a natural sweetening agent is incapable of producing a blend or mix having a syrup to water ratio which is within acceptable tolerances where the syrup is of a relatively low viscosity such as those used in the so-called dietetic type soft drinks and which have an artificial or synthetic sweetener such as cyclamate. Conversely, some designs of proportioners while quite effective in blending liquids having a syrup of relatively low viscosity are for one reason or another not particularly well adapted or suited for use with heavier or thicker syrups and, in the interests of production efficiency, are normally not so employed. This inability of existing designs of proportioners to handle liquids or syrups of widely varying viscosities may and often does constitute a rather serious drawback or shortcoming as many present day soft drink plants entail multi-beverage operations involving, in the typical instance, both dietetic and nondietetic type beverages and/or beverages having syrups of substantially different consistencies or viscosities.

In a somewhat similar vein, certain existing designs of pro portioning mechanisms are satisfactory of operation in certain speed ranges only or in a limited range only of syrup to water proportions or ratios'and when demand for the mix or blend fluctuates sufficiently to require operation at a difiering speed range or when used to produce a beverage having a materially different syrup to water ratio these devices tend to produce erratic and unacceptable results. Here again the trend towards multi-beverage operations in many soft drink plants has given acuteness to this particular problem in existing proportioner designs.

Other drawbacks and limitations which are prevalent in existing designs of proportioners include such things as the lack of a ready and accurate adjustment to enable rapid changeovers from one beverage to another with a minimum 0 hunting or manipulation to attain the exact syrup to water ratio required in the new beverage, the lack of ready cleanability, having surfaces or operating parts in contact with the liquids which are relatively inaccessible to cleaning fluids or liquids by normal back-flushing procedures or which are accessible for cleaning only by extensive disassembly of the unit, an inability to hold or maintain an accurate ratio between the liquids in the final mix over sustained periods of operation due to normal wear in and between the parts of the unit, and/or, in more recent designs, a complexity of construction and technology which as a practical matter precludes the performance of normal repairs and correction of operation malfunctionings by line personnel and requires, in lieu thereof,

the attention of factory trained technicians.

The present invention is directed to a proportioner of improved overall construction and operation and which substantially overcomes the aforementioned drawbacks and limitations of existing designs of proportioners by an arrangement wherein the liquids are metered through separate double-acting, reciprocatory type pumps, one of which constitutes a driver for the other and is connected thereto through a novel variable throw gear mechanism.

In accordance with a specific embodiment of the invention, the pumps take the form of piston-cylinder units with the one of the units constituting a driver being connected between a source of a first of the liquids under a suitable pressure head and an outlet to a mixing tank through a rotary spool-type reversing valve and being reciprocable by the liquid under the control of the reversing valve to deliver metered volumes of the first liquid to the mixing tank. The other of the pistoncylinder units and which corresponds to the driven element is connected between a source of the second liquid and another outlet line to the mixing tank through a series of conduits having check valves therein for controlling liquid flow between the source and the unit and between the unit and its associated outlet line to the mixing tank.

.The piston-cylinder units are mounted in general parallelism with one another and are connected through a respective one of their piston or cylinder elements to corresponding of a pair of slidable, paralleling rack elements. The rack elements are, in turn, connected to one another and are caused to slide in a synchronized manner with one another as the driver pump is reciprocated to eflect reciprocation of the driven pump unit by a rotatable or rockable ring gear disposed in meshing rela tion between the rack elements in a special, manually adjustable, precision bearing designed to permit the throw of the ring gear towards the driven pump to be adjusted for any given or fixed stroke of the driver pump whereby to permit the attainment of a desired stroke relationship in the two pump units and a corresponding desired relationship or ratio in the liquid volumes being delivered thereby into the mixing tank.

In a preferred construction, the precision bearing adjustment is of the worm-and-screw type and a gear train for actuating the adjustment includes a set of helical gears operable through a relatively large diameter hand wheel, an arrangement providing a substantial step-down or reduction in movement through the gear train in a direction proceeding to the bearing whereby to enable the throw of the ring gear to be finely adjusted for accurate control over the ratio or proportion of the liquids in the final blend or mix.

The present proportioner, among other features, has the capability of metering and proportioning liquids with a degree of accuracy and reliability which is relatively independent or unaffected by such things as the viscosities of the liquids, the relative ratios or proportions desired or required in the liquids in the final blend, and/or the volumetric flow rates of the liquids through the unit. This versatility of operation obtains in a construction which is extremely dynamically stable and operationally eflicient, being formed with few moving parts compactly and conveniently arranged together, and which has, as an additional feature, a precision type adjustment for controlling the liquid ratios or proportions in the final product.

Other objects and advantages of the invention will become readily apparent in the course of the following description of a presently preferred embodiment of the invention, when taken in conjunction with the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a diagrammatic showing of an overall system for efiecting the mixing of two liquids in controlled proportions to one another and which includes the improved proportioning apparatus of the invention;

FIG. 2 is a side view, on an enlarged scale, of the improved proportioning apparatus of the invention, with the side of the apparatus toward the viewer being removed to reveal details of interior construction and with certain parts being broken away and shown in section for further facilitating an illustrative understanding of the invention;

FIG. 3 is a top view of the apparatus of FIG. 2 with portions thereof being broken away and shown in section for purposes of clarity;

FIG. 4 is a view taken along the lines 4-4 of FIG. 3 illustrating the details of the engagement of the ring gear with one of the slidable racks; and

FIG. 5 is a diagrammatic view of the proportioner apparatus and the control valves which are associated therewith.

Referring now to the drawings, a proportioning apparatus formed according to the present invention and indicated generally by the reference numeral 2 is shown applied to a typical blending process and which involves the continuous production of a soft drink of a desired flavor and specific gravity or Baume for supplying an automatic container filling machine by the blending or mixing of predetermined amounts of a flavored syrup concentrate with water. The water which may be derived from any suitable source is desirably substantially free or devoid of dissolved gases, such as air, for example, prior to blending with the syrup and, for this purpose, is passed through a deaerator 4 prior to delivery to the proportioner. The water is also required to be delivered to the proportioner under a rather substantial pressure, 90 psig being a representative value, and to this end the outlet line 6 from the deaerator is shown to have a high pressure pump 8 mounted therein. After passing through the proportioner, the water flows via a line 10 to a mixing tank 12 which in the case of the production of a soft drink will be designed and constructed to carry out simultaneously with the mixing of the water and syrup a cooling and carbonating of the mix or blend. The tank or carbonator-cooler 12 may connect directly to an automatic container filling machine, not shown, which operates in a known or conventional manner to place the production of the tank in suitable containers.

Syrup of a desired flavor and concentration or specific gravity is adapted to be introduced into the proportioner through a line 14 from a supply tank 16, for example, and which is preferably elevated to provide a pressure of say 5 to 10 psig on the syrup at the proportioner. The syrup is withdrawn from the proportioner through a line 18 which leads to the aforesaid tank or carbonator-cooler 12.

Details of valving in the water and syrup lines are not particularly important to an understanding of the invention and it will suffice to note that the lines 6, l4 and 10, 18 normally will include suitable shutofi' and/or flow control valves for regulating the operation and the output of the proportioner in the manner desired.

The proportioner essentially comprises a pair of parallel mounted, double-acting piston-

cylinder units

20 and 22 which function as pumps for the separate liquids and which are associated with a variable throw gear mechanism 24 designed to transmit reciprocatory movement of one of the pumps to the other to provide a coordinated pumping action therebetween. In the illustrated instance, the unit 20 constitutes the water pump and is connected between water outlet line 6 from the deaerator and discharge line 10 to the tank 12 through a 4- way, spool-type rotary reversing valve 26 and through separate conduits 28 and 30 extending between the valve and the opposed ends of the unit, as shown. The valve which is well known per se, see, for example, Machine Design, Sept. 19, 1968 (pages 43 and 44), drives or operates water pump 20 off the pressure or force of the inlet water and includes a conventional spool valve element 32 which is rotatable between two difiercnt or alternate operating positions in the valve housing to provide, in the present application, a controlled reversing of the water inlet and outlet lines 6 and 10 respectively relative to the opposite ends of the pump or piston-cylinder unit 20. Thus, for example, in one operating position of spool element 32, water inlet line 6 may be in communication with line 28 in one end of the unit while at the same time line 30 in the opposite end of the unit is in communication with water discharge line 10 and in the other operating position of the spool valve, water inlet line 6 is in communication with the opposite line to the unit, viz, line 30, while line 28 is in communication with water outlet 10. The spool element 32 of valve 26 has a neutral position intermediate of its operating positions in which liquid flow therethrough is completely blocked so as to prevent inlet water inadvertently by-passing pump 20 and entering the outlet line and to also prevent water discharging from the unit inadvertently passing into the inlet stream of water. By this reversing action of the water inlet and outlet connections relatively of the unit 20 through the spool valve, unit 20 is caused to reciprocate and to discharge in each stroke thereof a metered volume of water into carbonatorcooler unit 12.

The other of the piston-

cylinder units

20, 22, namely unit 22, constitutes the syrup pump and is connected to the syrup inlet line 14 through a line 34 having

separate branches

36, 38 leading to the opposed ends of the unit and to the syrup outlet line 18 through a line 40 having similar branches 42, 44 leading to the opposed ends of the unit. Each of the

branches

36, 38 and 42, 44 has a check valve 46 mounted therein for permitting syrup flow in the lines in one direction only, the check valves being mounted in

lines

36, 38 to pemiit flow to the unit 22 and in lines 42, 44 to permit flow from the unit.

Unit 22 as will be explained in more detail hereinafter is adapted to be driven or reciprocated by the water unit to deliver metered volumes of the syrup to the mixing tank for each metered volume of water delivered thereto by the pump 20 by the aforesaid gear mechanism 24 and through this means the units are synchronized in operation to produce a blend or mix having a desired proportion or ration of syrup to water.

Adverting now in more detail to the construction of proportioner 2, an outer housing 48 is formed with vertical end walls 50, 52 extending laterally between a side wall 54 along what will be referred to as the front of the proportioner and an intermediate, paralleling wall 56. The piston-cylinder unit 20 is mounted horizontally to the outer, lower end portion of the wall 50 by pairs of horizontally extending mounting rods 58 fixedly attached to wall 50 in any suitable manner and which are fitted through a pair of generally rectangular closure or end plates 60 for the cylinder member 62 of the unit 20. The outer ends of the several mounting rods 58 have nuts threaded thereon to hold plates 60 and cylinder 62 in assembled relation, there being suitable shoulders in the rods to index the unit in a desired axial position on the rods under axial compression supplied thereto by the nuts. Suitable gasketing is provided in the ends of cylinder 62 to provide a sealed fit with the closures 60.

Cylinder 62 receives a slidable piston member 64 having an axially extending piston rod 66 projecting outwardly through a central opening in the closure plate 60 on the end of the cylinder adjacent the mounting wall 50 and through a similar, aligned opening in the latter. The piston is sealed to the cylinder through conventional O-ring means mounted in a circumferential groove in the periphery of the piston body as shown while the piston rod is afforded a sliding seal in the cylinder closure 60 through a suitable packing gland mounted in the central aperture of the closure. The free end of piston rod 66 attaches to a rack assembly 68 located in the base of the housing and which as will be explained hereinafter constitutes a part of the aforesaid variable throw gear mechanism 24 linking the

units

20 and 22 for synchronized operation with one another.

Before proceeding from the water pump, it will be observed that the closure plates 60 are provided with manifolds 70 which connect with the aforesaid flow conduits 28, 30 from the rotary spool valve 26 for water intake and discharge in the unit.

The syrup pump 22 has essentially the same construction as water pump 20, only in this instance the cylinder portion 72 is somewhat smaller in diameter than the water cylinder 62 owing to the requirement in all soft drinks, or at least all those within the present knowledge of the instant applicants, of a smaller proportion of syrup to water on a volume to volume basis. Unit 22 is mounted to the housing end wall portion 50 above and in vertical alignment with the water pump in the manner described for the latter, that is, through additional of the mounting rods 58 extending horizontally, in this instance, through closure plates 74 assembled to the ends of the cylinder 72 and by suitable nuts threaded to the outer ends of the rods. The slidable piston member 76 of the unit 22 carries a piston rod 78 which is related to piston rod 66 of unit in cross-sectional area in identical fashion to the relationship in cross-sectional areas of the respective cylinders 72 and 62 of the

units

22 and 20 and which projects axially of the cylinder through a bore in the cylinder closure plate toward the wall 50 and an aligned bore or opening in the latter. The free end of rod 78 attaches to another or a second rack assembly 80 of gear means 24 located in the upper portion of the housing generally in parallelism with rack assembly 68.

The aforesaid

syrup inlet lines

36, 38 to unit 22 are coupled into the closure plates on the opposite ends of cylinder 72 through suitable fittings 82 and which contain the aforesaid check valves 46 for limiting syrup flow in a direction towards the cylinder or into the unit 22 only. The syrup outlet lines 42, 44 are coupled to the cylinder closures in a similar manner through additional fitments 82, including one at each end for additional check valves 46 arranged to permit syrup flow in an opposite direction only or in a direction relatively from the cylinder or unit 22.

Adverting now to the particulars of the variable throw gear mechanism 24,

rack assemblies

68 and 80 each include a slidable, toothed element or rack 84 and 86 respectively. The racks 84 and 86 are connected to the free ends of piston rods 66 and-78, respectively, and are operatively coupled to one another through a rockable or rotatable ring gear 88 mounted vertically between the rack assemblies through means of a special precision bearing assembly 90 designed to provide for the manual varying and adjustment of the rock axis of the gear for a purpose to appear hereinafter. The rack element 84 of unit 20 is slidably supported in the base of the housing with the teeth of the rack facing upwardly and in meshing relation with the toothed periphery of gear 88 through a pair of horizontal cam rollers 92 supported by a bracket 94 on the base or bottom wall 96 of housing 48 in rotatably engaging relation with the underside of the rack and through a pair of vertical cam rollers 98 mounted to the center of the bracket in straddling relation with the rack. Rack element 86 of the unit 22 is mounted in the upper portion of the housing with periphery through a similar arrangement of horizontal and

vertical cam rollers

92 and 98 on another of the mounting brackets 94 attached to a top cover or plate 100 of the housing, the rollers 92 in this instance being disposed in engagement with the upper or top face of the rack element. The teeth of both rack elements 84 and 86, as particularly noted in FIG. 4 for rack element 84, are cut in a manner which leaves a bearing edge or race 102 to each side of the teeth and which is raised above the tooth pitch line. These edges or races 102 engage against the outer edges of corresponding of a pair of annular plates 104 fixedly mounted in circumferentially extending recesses provided in the opposed faces of the ring gear to each side of its toothed periphery so as to limit the relative projection of the gear teeth of the rack elements into the toothed portion of the ring gear and thereby take up from the various gear teeth the reactive forces between the ring gear and rack elements in the operation of the proportioner, the teeth of the ring gear being complementary to those of the rack elements and the annular plates 104 extending along a line which is generally above the pitch line of the ring gear teeth.

Through the aforesaid arrangement of earns 92 and 98 and of the ring gear 88, the separate rack elements 84, 86 are confined for sliding or lineal movement in fixed horizontal travel paths and at the same time are locked or geared positively to one another such that any slide movement in rack element 84 of the water pump 20 responsive to the latter being reciprocated through the action of the aforesaid reversing spool valve 26 in the water inlet and discharge lines of the proportioner will be translated through the ring gear into linear sliding movement of the rack element 86 of syrup pump 22 and, in turn, into reciprocatory movement of the latter, it being observed that the rack elements as well as the pumps will slide or reciprocate in 180 out-of-phase relation with one another. The limits of linear travel of rack element 84 manifestly are directly dependent upon and determined by the efiective operating stroke afforded piston 64 in the cylinder 62 of the unit 20 and, in any given proportion, these limits are finite and constant as the water pump has a fixed stroke and is provided a consistent or uniform motion by the water and spool valve co-action. It is to be appreciated, however, that the linear stroke of rack element 86 in any given construction while indeed dependent on the stroke of rack element 84 is directly further afiected by and dependent upon the locus of the rotational axis of the ring gear and that by varying the locus of such axis the stroke of rack element 86 and, in turn, of syrup pump 22 may be correspondingly varied. It is to this end and to the resultant attainment of a ready and convenient adjustment of and control over the relative volumes of syrup and water being delivered into the carbonator-cooler by the

separate pumps

20 and 22 and, in turn, of the syrup to water ratio being produced in the final liquid blend or mix that the special precision bearing assembly 90, now to be described, has been incorporated into the gear mechanism.

With particular reference to FIGS. 2 and 3 of the drawings, the ring gear bearing shown to be carried principally in a vertically extending slot 106 provided in the center of the ring gear essentially is generally in the nature of a worm-and-screw mechanism, the worm of which is in the form of a stud-like element 108 having a bored, spirally threaded center ferrulelike portion 110 which threadably receives the screw element, of the mechanism, indicated by the reference numeral 112. The worm 108 and screw 112 are carried as an assembly in the ring gear slot 106 with the worm ends disposed horizontally through pairs of bearing plates 114 and pivotable support arms 116 arranged on either side of the ring gear in a manner which as will now be explained efiectively provides the ring gear with a movable bearing whose axis is coincident with that of the stud-like worm 108. Bearing plates 114 are of a generally rectangular construction and are provided for assembly purposes to the opposite ends of the worm with center, through bores 118 confonning closely to the outside diameter of the stud portions of worm 108. The longitudinal edges of the inner face of each of plates 114 are provided with chamfers 120 and these edges engage or fit against complementary beveled edge portions 122 of slot 106 so that the plates while displaceable lengthwise or axially of the slot as a unit with the worm 108 are effectively constrained with the worm against movement laterally of the slot. The pivotable support arms 1 16 are connected into a number of flange-like extensions 124 formed vertically in the housing end wall 52 by a pivot pin 126 inserted horizontally through suitable apertures in the outer ends of the arms and project inwardly over and in straddling relation to the ring gear 88 for assembly to the opposed ends of the won-n 108, suitable apertures being provided in the inner ends of the arms for receipt of the worm extremities. Conventional bearing assemblies 128 are provided in the apertures in the opposite ends of each of arms 116 to provide precise joumaled fits therein for pivot pin 126 and the ends of worm 108 whereby to prevent any looseness or play in, and/or between these members in the planes of the support arms. Suitable washers 130 are shown to be interposed between the inner ends of the support arms 116 and corresponding of the bearing plates 114 for spacing purposes. Another of the washers 130 is received on the ends of worm 108 axially outwardly of the ends of the arms 116 together with a lock nut 132 for holding the arms captive to the worm. With the nuts tightened in place, bearing pressure will be transmitted from the support arms equally to the opposed faces of the ring gear by the bearing plates 114 and the ring gear will thus be securedly held between the arms in a constant relative position to the worm element. At the same time, the ring gear is free to rotate or rock as a unit with the bearing plates 1 14 on the axis of worm 108.

The screw element 112 of the bearing assembly 90 extends lengthwise of slot 106 or vertically and, for turning purposes, has mounted to its lower end a helical gear 134 of an adjustment assembly 136, the ring gear slot 106 being extended to receive the gear along with a suitable bearing 138 for the lower extremity of the screw element. A second helical gear 140 of the adjustment assembly 136 is received in a further cut-out or slotted portion of the ring gear in 90 meshing relation with gear 134 and, with one or the other of the lock nuts 132 in a backed-off or loosened condition relatively of the worm 108 is adapted to be rotated to rotate the gear 134 and screw member 112 of the ring gear bearing assembly 90 by a relatively large diameter hand wheel 142 carried on the outer or forward end of a horizontal shaft 144 connected to the gear 140. A ready means is thus provided for actuating the wormand-screw combination of the ring gear bearing 90 and for effecting corresponding movement and/or adjustments in the relative position in the ring gear slot 106 of the rotational or rock axis of the ring gear. The particular arrangement described herein for effecting this shifting or adjustment of the ring gear rotational axis is highly advantageous in that the hand wheel which may be considered as the driving element of a gear train to worm element 108 has a diameter which is appreciably larger than that of the elements which it drives and, hence, a considerable mechanical distance reduction or stepdown is effected through the gear train. As a result, a full turn, for example, of hand wheel 142, will effect only a slight axial shifting of the worm 108 on the screw 112 and a corresponding slight displacement only in the rock axis of the ring gear proper and it is thus possible to efi'ect a fine setting of the ring gear axis along the screw and to attain thereby a precise adjustment or setting of the lineal movement which the ring gear will impart to the rack element of the syrup pump with any given lineal displacement in the rack element of the water pump. This, in turn, leads to or results in an extremely close control over the syrup to water ratio which will be provided in the final mix or blend and makes the device highly useful in blending liquids in any desired ratio to or within industry accepted tolerances.

To facilitate calibration of the proportioner and to permit ready reproducibility of results in blending any particular soft drinks or beverages, the particular one of the bearing plates 1 14 which is to the front side of the housing is provided with a pointer or indicator 146 and the ring gear is provided along one edge of the slot 106 with a linear-type scale 148 having a series of regularly spaced markings or lines adapted to provide with the pointer, in direct readable form, an exact indication of the position of the ring gear rotational axis at any particular moment relative of any arbitrary reference point or position. The scale may preferably be of a vernier type with a series of primary markings, spaced by the distance which the rotational axis moves in say ten full turns of the hand wheel, being provided, together with a series of secondary markings between the primary markings and which have one-tenth the spacing of the latter or a spacing corresponding to the displacement of the ring gear axis effected by one full turn of the hand wheel.

In the present mechanism wherein the rack element 84 of water pump has a fixed stroke and is confined along with the rack element 86 of syrup pump 22 for operation in a fixed horizontal plane, the stroke of rack element 86 and syrup pump 22 will vary geometrically to that of rack element 84 and pump 20 with movement of the rotational axis of the ring gear, changing in increments which are initially rather gradual with the ring gear axis in a centered or nearly centered position between the two racks and being moved in a given direction relatively toward one rack or the other and which increase rather sharply with continued movement of the axis in the given direction. Because of this, a limited range of movement only need be provided the rotational axis of the ring gear to cover a fairly wide range of syrup to water proportions, making possible in a proportioner capable of producing beverages of widely varying syrup a compact and dynamically stable construction.

It is preferred for reasons of practicality that the stroke of the syrup unit be maintained within a range which at no time exceeds the stroke of the water pump and, to this end, the special bearing assembly normally will be restricted for movement in the slot 106 between the geometric center of the ring gear and a point or position which is removed from the centerline in a direction towards rack element 86 of syrup pump 22. Also, in the usual instance, the pump units will be constructed such that the relation of their volumetric capacities to one another at full or equal strokes corresponds generally to the syrup to water ratio at the lower extreme (the ratio which is richest in syrup) in the range of ratios desired to be produced in the proportioner such that as the stroke of the syrup pump is decreased from a value which equals the stroke of the water pump the leaner syrup to water ratios in the desired range will be produced. Thus, for example, assuming the proportioner is to be used for blending soft drinks having a range in syrup to water ratio of say 1:2.5 to 1:7, expressed in tenns of volume, the piston-cylinder unit 20 would then be constructed with a volumetric capacity at full stroke approximately 2 to 2% times that of piston-cylinder unit 22 at its full and equal stroke. The ring gear and precision adjustable mounting assembly 90 would then, in such instance, be constructed and arranged to permit a range of settings of the rock or rotational axis of the ring gear which would, with such relationship between the volumetric capacities of the

units

20, 22, permit the bearing 90 to move from a point approximately coincident with the actual center of the ring gear relatively toward the rack element 86 of syrup pump 22 a distance which would, at the minimum, result in a syrup to water ratio at the higher limit of the range desired or, in this case, a 1:7 ratio.

For synchronizing the switching or reversing of the water flow relatively between the ends of the water pump 20 with the reciprocatory movement of the latter, a pneumatic-type control circuit, schematically illustrated in FIG. 5, is provided the reversing valve 26 and which has as its basic elements a 4- way air valve of the pilot operated type, and an air cylinder 152 operatively coupled with the movable valve element 32 of the reversing valve. The 4-way valve 150 herein shown to be attached to the medial housing wall 56 through means including a pair of spacer blocks 154 includes a valve housing 156 within which is a slidable spool element 158 configured to direct air from a supply line, shown at 160, selectively to one or the other of a pair of

outlet ports

162, 164 to a port 166 leading to atmosphere. The port 162 is connected via a conduit 168 to one end of the air cylinder 152, the head end in the illustrated instance, while port 164 is connected via a conduit 170 to the opposite or piston end of air cylinder 152 such that depending upon the slide position of spool 158 in housing 156 air is free to flow into one or the other of the ends of the air cylinder from supply line 160 simultaneously while exhausting from the other end of the cylinder through port 166. The air cylinder 152 which may be mounted also to the housing wall 56 adjacent the 4-way valve 150 is connected by a suitable linkage 172 to rotary spool element 32 of the reversing valve 26 and when actuated by the 4-way valve operates to reverse the position of the spool element 32 in the valve 26 whereby to efi'ect a reversal of the water connections to pump 20.

The spool 158 has cored or ported end portions for permitting air to pass into the ends of the housing from supply line 160 to operate the spool for slide movement in the valve 150 in a known or conventional manner. The ends of housing 156 are in communication through restricted ports 174 and corresponding of the

lines

176 and 178 in such ports with respective of a pair of

poppet valves

180 and 182 associated with the mounting bracket 92 of rack 84 of the water pump, and which include an air chamber adapted to be ported to atmosphere through a normally closed, spring loaded actuator button 184 engageable by a striker plate 186 on the rack as the latter is reciprocated by water pump 20. The poppet valves act simply to cause through an air bleed off action in the valve 150 an imbalance in air pressure in the opposed ends of valve housing 156 at the proper time in the operating stroke of the water pump to cause a reversal in the slide position of the spool 158 in the housing and a corresponding reversal in the air inlet and exhaust connections to the air cylinder 152. This, in turn, will actuate the air cylinder and thereby switch the rotary spool 32 of the reversing valve 26 to its alternate operating position and thereby reverse the flow of inlet and discharge water relatively of the water pump to institute an operating stroke thereof. The

poppets

180, 182 are mounted such that their respective actuators 184 will be engaged by the striker plate 186 as rack element 84 approaches either limit of slide movement. Thus, for example, taking the instance where the water pump is undergoing reciprocatoryaction in a retracting direction of movement, striker plate 186 will be moved by rack 84 ultimately to a position of engagement with actuator 184 of the right-hand poppet valve 182, causing air to bleed from the poppet and from, in this instance, the right-hand end of the 4- way valve through line 178 and housing end port 174. The spool 158 of 4-way valve 150 in the present example will initially be in a left-hand slide position in valve housing 158 and, as air starts to bleed from the right end of the housing, a force imbalance is created on the ends of the spool, the efiect of which will be to cause the latter to move to a right-hand slide position in the housing. When this occurs, air from supply line 160 will be directed into air cylinder 152 through line 168 concomitantly as line 170 opens to exhaust port 166. The air cylinder which may be assumed to have initially been in a retracted position will thereby be caused to move to an extended condition and thereby switch the rotary valve element of the reversing valve to an opposite operating condition. This, in turn, results in the water inlet connection being switched through the valve 26 to the cylinder or head end of the water pump simultaneously as the opposite or piston end of the pump unit is switched to the water discharge line to institute another operating and, in this instance, an extension, stroke in the pump unit. The action of the other spool valve is exactly the same only of course in this case all valve movements are exactly reverse to that described and are instituted by the full or substantially full extension of the pump unit 20. This switching of the rotary type spool reversing valve through the control circuit described may be timed to occur at the instant the pump completes a full stroke in either direction of movement so as to maintain both

pumps

20 and 22 in substantially continuous operation.

In order to prevent water hammer in the water inlet lines due to too abrupt switching of the rotary spool valve, each of the

air lines

168, 170 preferably includes a flow control valve 188 of a known or conventional design and which includes a needle valve controlled flow passage for air passing in one direction through the valve and, in the present case, towards air cylinder 152 and a check valve controlled by-pass for air moving in an opposite direction in the valve or in this case in a direction from the air cylinder 152. The valves 188 have a suitable externally exposed adjustment screw for varying the setting of the needle valve in the flow passage and hence the effective rate of air flow into air cylinder 152 and, in operation of the proportioner, the rate of air flow into air cylinder may thus be readily set to a value which prevents any objectionable water hammer action in the switching of the water connections to the pump 20 through the rotary spool valve 26.

The operating circuit of the reversing valve 26 which has been described herein has been found reliable and quite eflective in producing a desired phased operation of the rotary spool valve with the pump 20 but it is to be particularly noted that various other controls and combinations of controls could be used with equally satisfactory results and no claim of novelty is based on the control arrangement as such, and rather it should be realized that any control which will phase the switching of the spool-valve properly with the stroking of the pump unit 20 will suffice.

Although the operation of the proportioner is believed evident from the foregoing description, a brief description is set forth herein of a typical procedure which may be followed in the production of a soft drink of a predetermined syrup to water ratio. Assuming water and syrup to be present within the deaerator 4 and supply tank 16 respectively and that the rotational axis of the ring gear is initially set at a position which from previous operating experience is believed to be correct for the particular syrup to water ratio desired, the proportioner is started in operation by opening all the valves in the syrup and water inlet and outlet lines and by starting of the pump 8. The water under the control of the spool reversing valve 26 and the air valve 150 and air cylinder 152 flows first into one end of the unit 20 and then the other to cause a reciprocatory pumping action in the unit with water flowing into the outlet line 10 to the mixing tank or carbonator-cooler l2 alternately from one end and then the other of the unit 20. As the water pump is reciprocated, the syrup pump is correspondingly reciprocated through the gear mechanism previously described to pump metered volumes of syrup into the carbonator-cooler simultaneously with the water. As this occurs, a sample of the blend or mix is removed from the tank and a reading is taken of its specific gravity to determine whether the mix has the desired proportion of syrup to water. Normally at this point the syrup to water proportion in the blend or mix will be within an acceptable tolerance range and no adjustment of the ring gear will be necessary. If corrective action is needed, however, say for example to reduce the amount of syrup in the blend, one of the nuts 132 on the worm-like element 108 of the bearing assembly is initially loosened and the hand wheel 142 of the adjusting mechanism is then turned manually in a direction to cause the rotational axis of the ring gear to move relatively further away from the center of ring gear 88 and toward rack assembly 86 of the syrup pump 22. The amount of turn movement required of the hand wheel will of course depend upon the syrup variance initially present but in any event after the rotational axis of the ring gear has been adjusted and the nut re-tightened a further check is made of the blend with further adjustments, should they be needed, again being made by appropriate turning of the hand wheel. In the event that the water content in the blend is initially too high, the hand wheel would of course be initially turned in an opposite direction to cause the axis of the ring gear to be adjusted or moved relatively toward the center of the ring gear or in a direction relatively away from the rack assembly 86 of the syrup pump 22 so as to increase the lineal displacement of rack element 86 and the stroke of syrup pump 22 relatively of the lineal displacement of the rack element 84 and the stroke of water pump 20.

The proportioner which has been described herein features a simplified arrangement of ruggedly constructed, precision parts and components, arranged compactly and conveniently with one another to provide a highly dynamically stable and operationally efficient unit. The separate pump units are locked for operation together through gear means which are positively indexed to one another through relatively large bearing surfaces at the gear interfaces to insure the maintenance of a desired stroke relationship in the pump units and a constant proportion of the liquids in the final blend or mix over prolonged and sustained periods of operation. Problems of drift from industry prescribed or accepted tolerances in the proportions of the liquids in the final mix or blend due to normal wear in the unit are thereby greatly alleviated. The above advantages obtain in a unit which includes a highly convenient, precision adjustment for changing the relative strokes of the pumps and the relative proportions of the liquids being delivered thereby to a mixing zone and which is featured by its capability of efi'ecting widely differing proportions or ratios in the liquids. The constructional and operational simplicity of the present proportioner makes the latter readily susceptible of running by line personnel and, to the extent required, repairs, ordinary maintenance, adjustments and other servicing of the proportioner normally may be performed without the need for special technicians, tools, parts and the like. A

further advantage of the proportioner resides in its ready cleanability and which is attributable to the fact that the liquids are confined wholly to the inlet and outlet lines, the valving therein and the separate piston-cylinder units, all of which are susceptible of being thoroughly cleansed by the expedient of cycling wash water through the unit and the system as a whole.

The present proportioner unit is capable of providing consistently highly accurate operation over a substantial range of different liquid handling fiow rates and mix production rates, in blending liquids having widely varying viscosities, and in producing blends or mixes having widely difi'ering ratios or proportions in the constituent liquids thereof. Thus, while described in conjunction with the forming of a soft drink through the blending of predetermined amounts of syrup and water with one another, the present proportioner may generally be applied to any liquid which is susceptible of being handled in a positive displacement type pump, including for example such diverse liquids as juices, acids, petroleum oils, liquid detergents, milk, chemicals such as anti-freeze, acid, etc. and to a variety of blending processes entailing or requiring widely varying proportions or ratios of one liquid or material to the other, varying degrees of exactness in the resultant proportions or ratios of the liquids or materials being blended or mixed, varying fiow rates and production requirements.

While the piston-cylinder or pump unit which constitutes the driver element for the other pump has been shown and described herein as powered or reciprocated by the energy of one of the liquids being proportioned through the reversing action of the 4-way spool valve in the liquid inlet and outlet lines of such pump, it is to be pointed out that means other than this could be employed to power the driver pump without departing from the concept of the invention. Thus, for example, the pump constituting the driver could be connected say through the rack element with which it is associated with an air cylinder or other similar mechanism controlled for reciprocating action through a suitable pneumatic or electropneumatic operating circuit to provide continuous or sustained back and forth movement in the driver unit and, in turn, in the driven unit through the interconnecting gear structure described. In such an event, a gravity feed would be provided the liquid and, the spool valve 26 and conduit arrange ment previously described for the water pump 20, would be replaced by a series of check valve controlled inlet and outlet conduits similar to that described herein for the driven or syrup pump 22.

Various modes of carrying out the present invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subjectmatter regarded as the nature of the invention.

We claim:

1. In a mechanism for blending a first liquid with a predetermined ratio of a second liquid on a substantially continuous basis and which includes a pair of two-way acting, positive displacement pump units through which the separate liquids are metered and means in association with a first of the pump units for reciprocating the same on a substantially continuous basis, means connecting the second of the pump units for reciprocating motion with the first of the pump units, comprising a first slidable rack element connected to said first pump unit and movable linearly by said first pump unit during reciprocation thereof, a second slidable rack element connected to said second pump unit and movable linearly to reciprocate said second pump unit, said first and second rack elements disposed in paralleling relation with one another and having toothed edges facing toward one another, ring gear means mounted between said first and second rack elements for transmitting by arcuate travel lineal movement of said first rack element to lineal movement of said second rack element to effect reciprocating motion of said second pump unit with reciprocating motion of said first pump unit, and means mounting said ring gear means for rotational movement on an axis whose locus is infinitely variable within fixed limits between the rack elements to enable varying of the lineal displacement of the second pump unit for any given lineal displacement of said first rack element and operating stroke of said first pump unit to obtain a desired ratio in the volumes of the first and second liquids being metered through said pump units as said first pump unit is operated.

2. The construction of claim 1 wherein said ring gear means is provided with an elongate center slot extending generally perpendicularly of said rack elements and wherein the means mounting said ring gear means for rotational movement on an axis whose locus is infinitely variable within fixed limits between the racks is the nature of a worm and screw mechanism and comprises a worm having stud-like end portions and an annular, interiorily, helically threaded center portion, an elongate screw threadably received in the center portion of said worm, said worm and screw fitting within the slot of said ring gear means with the stud-like end portions of the worm extending transversely outwardly from the opposite faces of said ring gear means to define a rotational axis of said ring gear means and the screw disposed longitudinally in the slot of said ring gear means, and bearing means on the studlike end portions of said worm for coupling said worm to said ring gear means and for releasably, fixedly holding said worm against longitudinal movement relatively of the slot of said ring gear means, said screw adapted to be rotated in said worm to efiect worm displacement longitudinally of the slot of said ring gear means and corresponding displacement relatively of said ring gear means of the rotational axis defined therefor by said worm.

3. The construction of claim 2 wherein said bearing means comprises a pair of bearing plates carried one each on the stud-like end portions of said worm in bearing relation with the opposed faces of said ring gear means, a pair of pivotable support arms disposed in straddling relation to said ring gear means and having free end portions joumaled to the opposed stud-like end portions of said worm axially outwardly of said bearing plates, and means for releasably retaining said support arms to said worm and for releasably clampingly holding said bearing plates to said ring gear means.

4. The construction of claim 2 including means for rotating said screw relatively of said worm and including a first helical gear mounted to one end of said screw, a second helical gear mounted in said ring gear means in meshing relation with said first helical gear, and hand wheel means connected to said second helical gear for turning the same and the first helical gear on said screw.

5. In a mechanism for blending a first liquid with a second liquid in predetermined volumetric proportions to another and having a paralleling arrangement of 2-way acting pistoncylinder type pump units through which the liquids are metered and means associated with a first of the pump units for reciprocating the same on a substantially continuous basis to meter a constant volume of a first of the liquids therethrough in each operating stroke of such pump unit, adjustable gear means connecting the second of the pump units for reciprocating movement with the first of said pump units to meter with each volume of the first liquid being metered through said first pump unit a given volume of the second liquid, comprising a pair of rack elements connected to corresponding of the pump units, means supporting said rack elements for slide movement in a fixed common plane with one another, rotatable ring gear means mounted between said rack elements and in the common plane thereof for transmitting slide movement of the rack element connected to said first pump unit to the rack element connected to the second pump unit to cause the two pump units to reciprocate in correlated fashion to one another, and means for varying the rotational axis of said ring gear means to provide with a given operating stroke of the first pump unit and a corresponding given slide movement of the rack element associated therewith a lineal movement in the rack element associated with said second pump unit and an operating stroke in the latter as will provide 13 the desired volumetric relation in the liquids being metered through the pump units.

6. The construction of claim wherein the ring gear means is provided with an elongate slot extending generally perpendicularly of the rack elements and wherein said means for varying the rotational axis of said ring gear means is in the nature of a worm and screw mechanism which comprises, a studlike worm element disposed transversely in the slot of said ring gear means and formed with a center, interiorly threaded, annular worm portion, an elongate screw element threadably received in the center worm portion of said worm element and extending longitudinally of the slot of said ring gear means, a pair of rectangular bearing plates located in bearing relation on-the opposed faces of said ring gear means and in co-axial relation with the opposed end portions of said worm element, a pair of support arms disposed in straddling relation with. said ring gear means and having fixedly pivotally mounted outer end portions and free inner end portions having a joumaled connection to the opposed end portions of said worm element axially outwardly of said bearing plates and means on the opposed end portions of said worm element for retaining the inner end portions of said support arms to said worm element and for releasably clampingly maintaining said bearing plates in bearing relationship with the opposed faces of said ring gear means and with the inner end portions of said support arms so as to confine the ring gear means for rotational movement on an axis coincident with that of said worm element.

7. The construction of claim 6 including a first helical gear mounted to one end of said screw element, a second helical gear rotatably mounted in said ring gear means in 90 meshing relation with said first helical gear, and a manually operable turn wheel connected with said second helical gear for effecting rotation of the screw element relatively of the worm element for effecting adjustment of the locus of the rotational axis of said ring gear means in said slot and corresponding adjustments in the volumetric proportions between the liquids being metered through the pump units.

8. In a mechanism for mixing two liquids in a selected one of a range of different volumetric proportions to one another and having a pair of two-way acting, positive displacement pump units for pumping metered volumes of respective ones of the two liquids into a mixing tank, a first of said pump units connected to a high pressure source of one of the two liquids and said mixing tank through a reversing valve designed to automatically reverse liquid flow into and from the ends of said first pump unit responsive to each operating stroke of the first pump unit and a second of the pump units connected to a source of the other of the two liquids and to said mixing tank through check valve controlled inlet and outlet lines, gear means coupling said second unit for reciprocating movement with said first pump unit, comprising a pair of opposed and facing, linearly movable rack elements connected one to the first pump unit and one to the second unit, ring gear means rotatably mounted between said rack elements for transmitting linear movement of the rack element connected to said first pump unit to the rack element connected to said second pump unit to reciprocate said second pump unit as said first pump unit is reciprocated, and means for varying the rotational axis of said ring gear means between said rack elements to obtain the relationship between the strokes of the two pump units and the resultant liquid volumes being delivered thereby into said mixing tank as will provide the selected one of the volumetric proportions desired between the liquids in the mixing tank.

9. In a mechanism for blending two liquids in predetemrined ratios to one another and which includes a pair of 2-way acting positive displacement pump units through which the separate liquids are pumped in metered volumes and means associated with a first such pump unit for driving the same for reciprocatory movement, means connecting the second of the pump units for reciprocatory movement with the first pump unit, comprising a pair of generally parallel extending, linearly movable rack elements having toothed portions in facing-relatron to one another and connected one to each of the pump units, said elements movable linearly in direct proportion to the displacement of its respective pump unit, rockable means intermediate said pair of rack elements and operatively coupled thereto for transmitting linear movement of the rack element connected to said first pump unit to the rack element connected to said second pump unit, said rockable means including a ring gear mounted between and in meshing engagement with said rack elements, and means mounting said rockable means for rocking motion on an axis, the locus of which is infinitely variable within fixed limits between the rack elements to permit the linear movement of the rack element connected to said second pump unit to be varied relatively of the linear movement of the rack element connected to said first pump unit for obtaining a desired relationship in the operating strokes of the two units and a corresponding desired ratio in the volumes of the liquids being metered through the units as the first of the pump units is reciprocated.

10. The construction of claim 9 wherein the ring gear is provided with an elongate, center slot and wherein the means mounting said rockable means for rocking movement on an axis whose locus is infinitely variable within fixed limits comprises a worm element fixedly, rotationally mounted in the slot of said ring gear and a screw element rotatably mounted in said worm element.

11. The construction of claim 10 including means for manually rotating said screw element and comprising a pair of meshing bevel gears, one of which is carried on the screw element and the other of which is carried in the ring gear on a shaft to which is mounted a large diameter turn wheel.

* i i l

Claims

2. The construction of claim 1 wherein said ring gear means is provided with an elongate center slot extending generally perpendicularly of said rack elements and wherein the means mounting said ring gear means for rotational movement on an axis whose locus is infinitely variable within fixed limits between the racks is the nature of a worm and screw mechanism and comprises a worm having stud-like end portions and an annular, interiorily, helically threaded center portion, an elongate screw threadably received in the center portion of said worm, said worm and screw fitting within the slot of said ring gear means with the stud-like end portions of the worm extending transversely outwardly from the opposite faces of said ring gear means to define a rotational axis of said ring gear means and the screw disposed longitudinally in the slot of said ring gear means, and bearing means on the stud-like end portions of said worm for coupling said worm to said ring gear means and for releasably, fixedly holding said worm against longitudinal movement relatively of the slot of said ring gear means, said screw adapted to be rotated in said worm to effect worm displacement longitudinally of the slot of said ring gear means and corresponding displacement relatively of said ring gear means of the rotational axis defined therefor by said worm.

3. The construction of claim 2 wherein said bearing means comprises a pair of bearing plates carried one each on the stud-like end portions of said worm in bearing relation with the opposed faces of said ring gear means, a pair of pivotable support arms disposed in straddling relation to said ring gear means and having free end portions journaled to the opposed stud-like end portions of said worm axially outwardly of said bearing plates, and means for releasably retaiNing said support arms to said worm and for releasably clampingly holding said bearing plates to said ring gear means.

4. The construction of claim 2 including means for rotating said screw relatively of said worm and including a first helical gear mounted to one end of said screw, a second helical gear mounted in said ring gear means in 90* meshing relation with said first helical gear, and hand wheel means connected to said second helical gear for turning the same and the first helical gear on said screw.

5. In a mechanism for blending a first liquid with a second liquid in predetermined volumetric proportions to another and having a paralleling arrangement of 2-way acting piston-cylinder type pump units through which the liquids are metered and means associated with a first of the pump units for reciprocating the same on a substantially continuous basis to meter a constant volume of a first of the liquids therethrough in each operating stroke of such pump unit, adjustable gear means connecting the second of the pump units for reciprocating movement with the first of said pump units to meter with each volume of the first liquid being metered through said first pump unit a given volume of the second liquid, comprising a pair of rack elements connected to corresponding of the pump units, means supporting said rack elements for slide movement in a fixed common plane with one another, rotatable ring gear means mounted between said rack elements and in the common plane thereof for transmitting slide movement of the rack element connected to said first pump unit to the rack element connected to the second pump unit to cause the two pump units to reciprocate in correlated fashion to one another, and means for varying the rotational axis of said ring gear means to provide with a given operating stroke of the first pump unit and a corresponding given slide movement of the rack element associated therewith a lineal movement in the rack element associated with said second pump unit and an operating stroke in the latter as will provide the desired volumetric relation in the liquids being metered through the pump units.

6. The construction of claim 5 wherein the ring gear means is provided with an elongate slot extending generally perpendicularly of the rack elements and wherein said means for varying the rotational axis of said ring gear means is in the nature of a worm and screw mechanism which comprises, a stud-like worm element disposed transversely in the slot of said ring gear means and formed with a center, interiorly threaded, annular worm portion, an elongate screw element threadably received in the center worm portion of said worm element and extending longitudinally of the slot of said ring gear means, a pair of rectangular bearing plates located in bearing relation on the opposed faces of said ring gear means and in co-axial relation with the opposed end portions of said worm element, a pair of support arms disposed in straddling relation with said ring gear means and having fixedly pivotally mounted outer end portions and free inner end portions having a journaled connection to the opposed end portions of said worm element axially outwardly of said bearing plates and means on the opposed end portions of said worm element for retaining the inner end portions of said support arms to said worm element and for releasably clampingly maintaining said bearing plates in bearing relationship with the opposed faces of said ring gear means and with the inner end portions of said support arms so as to confine the ring gear means for rotational movement on an axis coincident with that of said worm element.

7. The construction of claim 6 including a first helical gear mounted to one end of said screw element, a second helical gear rotatably mounted in said ring gear means in 90* meshing relation with said first helical gear, and a manually operable turn wheel connected with said second helical gear for effecting rotation of the screw element relatively oF the worm element for effecting adjustment of the locus of the rotational axis of said ring gear means in said slot and corresponding adjustments in the volumetric proportions between the liquids being metered through the pump units.

9. In a mechanism for blending two liquids in predetermined ratios to one another and which includes a pair of 2-way acting positive displacement pump units through which the separate liquids are pumped in metered volumes and means associated with a first such pump unit for driving the same for reciprocatory movement, means connecting the second of the pump units for reciprocatory movement with the first pump unit, comprising a pair of generally parallel extending, linearly movable rack elements having toothed portions in facing relation to one another and connected one to each of the pump units, said elements movable linearly in direct proportion to the displacement of its respective pump unit, rockable means intermediate said pair of rack elements and operatively coupled thereto for transmitting linear movement of the rack element connected to said first pump unit to the rack element connected to said second pump unit, said rockable means including a ring gear mounted between and in meshing engagement with said rack elements, and means mounting said rockable means for rocking motion on an axis, the locus of which is infinitely variable within fixed limits between the rack elements to permit the linear movement of the rack element connected to said second pump unit to be varied relatively of the linear movement of the rack element connected to said first pump unit for obtaining a desired relationship in the operating strokes of the two units and a corresponding desired ratio in the volumes of the liquids being metered through the units as the first of the pump units is reciprocated.