US3834839A

US3834839A - Metering pump

Info

Publication number: US3834839A
Application number: US00175842A
Authority: US
Inventors: F Krebs; F Zimmermann
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-08-30
Filing date: 1971-08-30
Publication date: 1974-09-10
Anticipated expiration: 1991-09-10
Also published as: GB1386085A

Abstract

A precision metering pump of the positive-displacement type in which a variable-stroke drive means including a swivel lever permits adjustment of the volumetric displacement with a high degree of accuracy and constancy between zero and a maximum while the pump is in operation. The pump is self-priming and particularly useful in chemical processing and control operations by reason of construction of the cylinder and piston of highly corrosion-resistant ceramic and plastic materials, and provision of sensitively adjustable magnetic valve means eliminating metallic springs and parts subject to chemical action in a flow line.

Description

United States Patent [191 Krebs et al.

[451 Sept. 10, 1974 METERING PUMP [76] Inventors: Frank Krebs, Glenview; Frederick N. Zimmermann, Deerfield, both of 22 Filed: Aug. 30, 1971 21 Appl.No.: 175,842

52 U.S.Cl 417/505, 92/131,417/0101 51 Int. Cl. F04b 39/08 [58] Field of Search 417/505, 567; 92/13, 13.3, 92/134, 13.41, 13.7,170, 248

[56] References Cited UNITED STATES PATENTS 1,133,778 3/1915 Wrightson, Jr. 92/248 2,043,424 6/1936 Campbell 92/212 X 2,607,342 8/1952 Abel 92/170 X 2,780,404 2/1957 Kuehni 92/137 2,908,288 10/1959 Carr et al 137/540 3,171,287 3/1965 Jesse 92/13.? X

3,306,212 2/1967 Norton 92/137 X 3,326,087 6/1967 Gohlke et a1. 91/275 3,485,441 12/1969 Eaton, .Ir. 417/505 3,489,099 l/l970 I-Iuffsmith, Sr 92/248 FOREIGN PATENTS OR APPLICATIONS 873,057 3/1942 France 1. 92/137 Primary Examiner-William L. Freeh Assistant ExaminerLeonard Smith Attorney, Agent, or FirmCallarc1 Livingston [57] ABSTRACT A A precision metering pump of the positivedisplacement type in which a variable-stroke drive means including a swivel lever permits adjustment of the volumetric displacement with a high degree of accuracy and constancy between zero and a maximum while the pump is in operation. The pump is selfpriming and particularly useful in chemical processing and control operations by reason of construction of the cylinder and piston of highly corrosion-resistant ceramic and plastic materials, and provision of sensitively adjustable magnetic valve means eliminating metallic springs and parts subject to chemical action in a flow line.

PAIENIEDSEPWIW mamas INVENTUBZ Y Fran/Q Xreba X,

METERING PUMP The principal object of the invention is the provision of a self-priming metering pump of the positivedisplacement type having cylinder, piston and valve means constructed from highly corrosion-resistant nonmetallic materials adapting it for use in sensitive chemical processing and control operations and capable of working at relatively high pressure with progressive adjustment over its entire displacement range, rather than by stepped increments, and having such a degree of accuracy and constancy as to make it dependable in critical control applications.

To such ends the invention is characterized by and the disclosures provide a ceramic pumpcylinder and a composition piston formed of non-metallic materials including one or more bearing substances, together with magnetic valve means employing substantially metal-free ceramic magnets acting in polar opposition and capable of sensitive flow adjustment and antisiphoning shut-off, with continuous volumetric adjust ment achieved through a simple variable-stroke drive means comprising an adjustment swivel concentric with a drive shaft and an eccentric .thereon cooperative with lost-motion means to impart adriving stroke of selected amplitude to the piston depending uponthe angular setting of the swivel.

More particular objects and features of novelty and utility characterizing the invention relate to detailed aspects of the construction and operation of the illustrative embodiments described hereinafter in view of the annexed drawingsin which:

FIG. 1 is a perspective view of the complete pump assembly with enclosing hood and shroud components;

FIG. 2 is an enlarged front elevation of the assembly of FIG. 1 with the pump shroud removed;

FIG. 3 is a side elevation of the unit with both motor hood and pump shroud removed;

FIG. 4 is a horizontal cross section through the valve head looking along lines 4--4 of FIG. 2;

FIG. 5 is an exploded detail of one of the magnetic valves taken to enlarged scale;

FIG. 6 is an end view of one of the magnetic valve plungers;

FIG. 7 is an exploded perspective detail of piston drive components;

FIG. 7A is a side elevation of the adjustment swivel;

FIG. 8 is a front elevational view of the pump with a modified adjustable piston drive means;

FIG. 9 is a fragmentary front detail of the drive means of FIG. 8 with bracket parts broken away;

FIG. 10 is a detail of parts seen in FIG19 but viewed from the side;

FIG. 11 is a perspective detail of the adjusting lever seen in FIG. 8.

A complete pump unit of a type adapted to general use is depicted in FIG. 1 and comprises a base plate 10 on which is footed an upright mounting plate 11 stabilized by brackets 11A with the pump mechanism mounted on the forward side of the plate but normally concealed behind a removable shroud 12, and a driving motor situated on the opposite side of said plate beneath a hood structure 13.

In the view of FIG. 2, the shroud plate has been removed from its mounting block 15 revealing the pump mechanism comprising a cylinder 14 having an upper open end portion sealed within a bore formed in a valve block 16 secured to plate 11 and having outlet and inlet nipples l7 and 18 with appertaining valve means for connection into a flow line. In the drawing the valve head block 16 and parts of the valve structure are shown for illustrative purposes as made from a clear plastic material, but opaque plastics materials such as Penton (TM) are recommended for general chemical usage. Ducts 17B and 18B communicatefrom the nipples to

valve bores

17A, 18A.

Formed in the valve block 16 are

valve bores

17A and 18A interconnected by a flow passage "19 which in turn is intercepted by a cylinder duct 20 communicating into the upper end of the cylinder 14 (FIGS. 2, 3 and 4). Reciprocable in each valve bore is a corresponding valve plunger or poppet 21A or 218 (the valves being identical) which is of the generally tubular cylindrical configuration seen in FIGS. 5 and 6 and having circumferentially spaced apart longitudinally extensive slide ribs or runners 23 on its external surface to reduce the frictional area and wetting drag in the bore.

Each valve plunger 21A or 213 is hollow and open at one end to receive a cylindrical

permanent magnet

24A or 248, while the opposite end is closed with a conical nose2lA' seating in a matching conical valve seat formed in the valve block at a juncture with the flow passage 19, as in FIG. 4. Fine air relief holes 25 penetrate the tubular walls of the valve plungers to relieve compression and-suction .in the zone between the juxtaposed ends of the actuating magnets forming part of each valve unit.

Each of the

valve bores

17A or 18A is partially threaded at its entrance to receive

corresponding screw plugs

26A or 268 which constitute a combination closure and adjusting means (FIGS. 4 and 5), each said plug having the threaded shank portion thereof bored to form a socket for the corresponding actuating magnet 27A or 27B.

Thus, each valve unit has a set of magnets, including a driven magnet, such as 24A, within the appertaining valve plunger or poppet, and a companion driving and control magnet 27A within the corresponding adjustment screw plug 26A, the magnets in each set being coaxially aligned with respect to their magnetic axes and the turning axis of the screw plug. By arranging the two magnets in each set so that their proximate poles are alike, that is to say so that either two south-seeking or two north-seeking poles are juxtaposed, the magnets of each set 24A and 24B, for example, are repulsed by their corresponding driving or actuating

magnets

27A or 278 and thereby forced to seat in the valve-closing condition with a force which can be regulated by turning in the appertaining screw plugs in their respective threaded bores, such adjustment being very sensitive owing to the square-law action of the magnetic forces acting to seat the valve plungers.

The pump cylinder 14 is formed of a substantially chemically inert material such as procelain or the like having minimal silica content and high resistance to caustic and aciduous agents, and the associated piston 40 is likewise made of an equally inert materials but having, in addition, desirable bearing qualities, for which purpose it has been found that a mixture of a fluorocarbon material such as teflon with a filler of Molybdenum and graphite is suitable.

The magnets in the valve units are of the so-called ceramic type formed of barium ferrite and having minimal or no free iron or metal content likely to be attacked by, or to contaminate, the pumped liquid, by reason of which these valves eliminate conventional metallic valve springs which are highly vulnerable to corrosion in many chemical processing operations.

As viewed in FIG. 7, the piston 40 will normally be provided at its upper end with sealing means such as a pair of acid-resistant piston rings 41 seated in circumferential grooves to render the pump effective even in relatively high-pressure applications, for example, up to 160 psi. At its lower end the cylinder is provided with a lengthwise slot 42 communicating through the side wall into a short axial bore formed thereat to receive one end of an offset or dog-leg drive link 43 pivotally connecting with the piston by pin means 44, through slot 39.

The opposite end of the offset piston link 43 is fitted with a bearing means 45 adapted to engage one end of a coupling pin 46 fixed at one of the ends of a connecting rod or crank 47 (FIGS. 2, 3 and 7), while the remaining end of said link is provided with another bearing 48 engaging a tapped eccentric crank pin 49 with which it is pivotally secured by screw means 49.

The eccentric is fast by means of a set screw on the power shaft 50 rotated by motor means 51 and the associated reduction gear means 52, FIG. 3. The pivotal connection 46 between the crank rod 47 and the dogleg driving link 43 is constrained to follow a guided arcuate stroke-regulating path by reason of its projection into an arcuate guideway 55 formed in an adjustment swivel member 56 having a wide central bore surrounded on its rearward side by an outwardlyprojecting collar 57, FIG. 7A, which fits rotatively into the seating hole in the upright plate 11 (FIG. 2) which also serves as a bearing for the adjustment motion of the swivel concentrically about the axis of the power shaft 50 and the eccentric 49, such swivel motion being for the purpose of changing the angular attitude of the stroke-regulating lost-motion guideway and consequently the permitted magnitude of the throw of the piston link 43. The more nearly horizontal the attitude of the arcuate guideway 55 relative to the axis of the power shaft, the shorter will be the driving stroke of the link 43 and therefore the smaller will be the resultant displacement of the piston. Conversely, the greater the downward inclination of the arcuate guideway 55 (below the almost horizontal minimal-stroke setting shown in FIG. 2) the longer will be the driving stroke of link 43 and the greater will be the piston displacement.

The permitted angular range of adjustment for the swivel member is determined by another arcuate slot 58 formed as a part thereof (FIG. 2) and the clamp screw 60 projecting therethrough as a limiting stop in both directions of movement. Adjustment of the swivel control lever is faciltated by provision of a finger tab 59 projecting well beyond the edge of the upright mounting plate 11; and suitable scalar graduations 61 may be displayed adjacent thereto on said plate to indicate the settings in desired terms of volumetric, percentile or other scalar values of displacement per stroke or per minute, etc.

The selection of settings afforded by the disclosed variable-stroke linkage means is continuous in very minute increments or decrements between the angular limits of travel of the swivel lever to cover a range from zero to maximum displacement with consistent accuracy and reproducibility even in the case of pumps manufactured to ordinary production tolerances, while pumps machined to close tolerances exhibit high performance accuracy within 1 per cent and better.

A modified form of variable-stroke metering pump drive is depicted in FIGS. 8 to 11 wherein substantially the same assembly of pump elements is employed in respect to the use of an identical base and

upright plate structure

10X, 11X, as well as cylinder, valve and piston means 14X, 16X, 26AX, 26BX and 40X, which are the same as described for the embodiment of FIGS. 1 to 7, the modification, however, employing a different piston drive means, as in FIG. 8, wherein the lower end of the stem of the piston is fitted with a frusto-conical collar at the underside of which are trunnions 71 journalling a cam roller 72 adapted to engage a driving cam 80 rotated by motor shaft 50X (FIG. 9).

A stroke-adjusting swivel lever 75 is pivoted on pin means 79 supported between the upright plate and a bracket member 78 affixed to the base plate. As depicted in FIG. 11, this swivel lever is a unitary structure preferably molded from a synthetic plastic material such as Nylon to include a finger tab 73, an arcuate clamp screw slot 74 for clamp screw 74X, a pivot hub 76, and a bifurcated end formation providing spaced pawl 77 which underlie the piston collar 70 and straddle the cam roller 72.

A compression spring 69 is fitted loosely about the piston cylinder to expand between the valve head 16X and the collar 70 to urge the piston in the direction of retraction to a lowered position determined by the setting of the swivel lever and consequent elevation of the pawls 77, from which position the rotating drive cam 80 acting on the roller means 72 will drive the piston upwardly in its pressure stroke a distance depending upon the relative starting position determined by the setting of the pawls, it being possible to depress the lever 75 to its lower limit and thereby elevate the piston toward its upper limit an amount sufficient to cause the roller 72 to stand wholly clear of the driving periphery of the cam 80 with a consequent zero movement of the piston as the cam rotates; and conversely, by swinging the lever 75 to its upper limit of travel the pawls 77 will be lowered to the maximum so that the cam roller can engage the driving cam throughout its cycle and produce the maximum driving stroke for the piston.

Both forms of piston drive afford the advantage of permitting adjustment of the piston stroke between maximum and minimum volumetric displacement limits while the pump is in operation, although the action of each is different in the respect that the driving force acting on the cam roller in the embodiment of FIG. 8 is momentarily discontinuous in all settings except that for maximum piston stroke, there being in the other settings a brief interval in each cycle of the cam during which the roller 72 is held beyond driving engagement therewith because the setting of the swivel lever in such cases does not permit the piston to descend far enough to follow the cam completely throughout its 360 travel, whereas in the variable stroke linkage embodiment of FIG. 2 there is no similar discontinuity and the driving action is in effect continual but for an instant of zero motion as the travel reverses.

Where the high corrosion resistance and sensitivity of the novel magnetic repulsion valve means is not required, other forms of valve may be substituted; for example, plastic-ball or similar poppets and conventional seating springs (not illustrated) may be used in substantially the same valve bores and seats in replacement of the magnet-carrying valve elements and their respective repulsion magnets, in either embodiment.

The motor drive means for the embodiment of FIG. 8 (not seen) is identical to that shown in FIG. 3 except that the drive shaft 50X is extended outwardly farther for full engagement with the cam 80, and is accordingly given extra support in a Nylon bushing block 81 affixed as at 82 to bracket 78.

We claim:

1. In a pump for metering chemical solutions of caustic and acidic character, a cylinder, a piston reciprocable in said cylinder, drive means including a shaft rotatable about a first axis extending in a direction at one side of and at right angles to a second axis relative to which the piston reciprocates, and variablestroke mechanism drivingly interconnecting said shaft and piston and comprising a crank rod having opposite end regions one of which has pivotal eccentric driving connection with said shaft; a driving link having opposite end regions one of which has pivotal driving connection with said piston on a locus lying along the second axis; and guided pivot means pivotally interconnecting the respective remaining end regions of said crank rod and link, together with pivot-guiding means adjustable to selectable fixed positions cooperative with said guided pivot means to constrain the motion of the latter in said positions along an arcuate path extending along an arc of circle which intercepts the center of said first axis in all of said fixed positions and is effective responsive to rotation of said shaft to cause reciprocation of the piston with full or lost-motion in a stroke the magnitude of which lies between zero and predetermined maximum limits depending upon the selected fixed angular disposition of said path relative to said second axis, at least.

2. Mechanism according to claim 1 wherein said pivot guiding means is itself concentrically rotatable into said selectable positions about the shaft axis to orient said arcuate path in changed angular relation to said second axis with resultant change in the magnitude of the piston stroke between the limits aforesaid.

3. Pump mechanism comprising, in combination with a cylinder and a piston reciprocable therein, drive means including a driving eccentric rotatable about an axis extending in a direction laterally of the axis of the cylinder and piston travel and situated adjacent a particular end of the cylinder at which a driving connection with the piston is effected; crank means driven by said eccentric; link means drivingly interconnecting with said piston to provide the driving connection aforesaid; and pivot means drivingly interconnecting said link means with said crank means; guide means mounted to turn concentrically about said eccentric axis into selectedpositions and affording an arcuate guideway extending in a generally lateral sense relative to said eccentric and piston axes in a region adjacent said particular end region of the cylinder; and guided means having a coaxial relationship with said pivot means and guided relationship with said guideway such that rotation of the eccentric imparts reciprocatory drive to said link means and piston in a magnitude ranging between zero and a maximum depending upon the angular attitude of said guide means relative to said piston axis in the selected positions aforesaid.

4. Mechanism according to claim 3 further characterized in that said guide means is rotatively adjustable about said eccentric to change said angular attitude of the guide means whereby the magnitude of displacement of the piston can be progressively changed throughout said range.

5. In metering pumps and the like having a cylinder, a piston reciprocable therein, and rotary shaft means for reciprocating said piston, stroke-adjusting drive means interconnecting said shaft and piston and com prising: an eccentric rotated by said shaft; an adjust ment member and means mounting the same to turn into selected angular adjustment positions concentrically about the axis of said shaft and eccentric; arcuately extending guide means forming a fixed integrally conformed part of said adjustment member with the arc thereof containing the locus of a point which intercepts said shaft axis in all angular positions of said adjustment member; crank means having one end region pivotally connecting with said eccentric and a further end region which is adapted to follow the arc of said guide means in rotation of the eccentric; link means having one end region pivotally connecting with an end region of said piston and having a further end region which is also adapted to follow the arc of said guide means in interconnection with said crank means; means pivotally interconnecting the respective said further end regions of the crank means and link means; and guided means movable with and concentric with said interconnecting means and constrained by said guide means to oscillate along the arc thereof responsive to rotation of said eccentric in displacements of variable magnitude depending upon the angular setting of said adjustment member, whereby the stroke of said piston may be varied between zero and a predetermined maximum displacement; together with means operative to secure the adjustment member in any selected adjustment position.

6. Apparatus acording to claim 5 wherein said link means is a dog-leg lever characterized in that said further end region thereof is offset angularly from the first mentioned end region thereof for pivotal connection with the piston as aforesaid; and said shaft axis is situ ated to extend at right angles to the axis of piston travel and along a locus at one side of said piston axis.

7. Pump apparatus according to claim 5 wherein said adjustment member is a disc-like molded plastic member having a central opening fitting freely about said eccentric means concentrically of the axis aforesaid, and said guide means is an arcuate channel conformed with said member in position to extend relative to the axis and eccentric in the manner aforesaid, and said guided means includes a part guidedly constrained to travel in said channel.

8. Apparatus according to claim 7 wherein said plastic member is further provided with an integrally conformed annular collar protuberant from one side thereof concentrically with said central opening therein and seating rotatively in support means disposing the same concentrically relative to said axis and eccentric in the manner aforesaid.

UNITED STATES PATENT OFFICE 7 ERTIFICATE OF CORRECTION Patent No. 3,834,839 Dated September 10, 1974 u; InventorQsM Frank Krebs and Frederick N. Zimmermann It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the first page of the patent before 22] Filedj Aug. 30, 1971" insert [73] Assignee: March Manufacturing Company, Glenview,

Hlinois"; column 2, line 68, for "materials read --material--.

Signed and sealed this 18th day of February 1975.

(SEAL) Attest:

a C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks USCOMM-DC 6O376-P69 u.sv GOVERNMENT PRINTING OFFICE: mu o-Jes-aal,

F ORM PO-1050 (10-69)

Claims

1. In a pump for metering chemical solutions of caustic and acidic character, a cylinder, a piston reciprocable in said cylinder, drive means including a shaft rotatable about a first axis extending in a direction at one side of and at right angles to a second axis relative to which the piston reciprocates, and variable-stroke mechanism drivingly interconnecting said shaft anD piston and comprising a crank rod having opposite end regions one of which has pivotal eccentric driving connection with said shaft; a driving link having opposite end regions one of which has pivotal driving connection with said piston on a locus lying along the second axis; and guided pivot means pivotally interconnecting the respective remaining end regions of said crank rod and link, together with pivot-guiding means adjustable to selectable fixed positions cooperative with said guided pivot means to constrain the motion of the latter in said positions along an arcuate path extending along an arc of circle which intercepts the center of said first axis in all of said fixed positions and is effective responsive to rotation of said shaft to cause reciprocation of the piston with full or lost-motion in a stroke the magnitude of which lies between zero and predetermined maximum limits depending upon the selected fixed angular disposition of said path relative to said second axis, at least.

3. Pump mechanism comprising, in combination with a cylinder and a piston reciprocable therein, drive means including a driving eccentric rotatable about an axis extending in a direction laterally of the axis of the cylinder and piston travel and situated adjacent a particular end of the cylinder at which a driving connection with the piston is effected; crank means driven by said eccentric; link means drivingly interconnecting with said piston to provide the driving connection aforesaid; and pivot means drivingly interconnecting said link means with said crank means; guide means mounted to turn concentrically about said eccentric axis into selected positions and affording an arcuate guideway extending in a generally lateral sense relative to said eccentric and piston axes in a region adjacent said particular end region of the cylinder; and guided means having a coaxial relationship with said pivot means and guided relationship with said guideway such that rotation of the eccentric imparts reciprocatory drive to said link means and piston in a magnitude ranging between zero and a maximum depending upon the angular attitude of said guide means relative to said piston axis in the selected positions aforesaid.

5. In metering pumps and the like having a cylinder, a piston reciprocable therein, and rotary shaft means for reciprocating said piston, stroke-adjusting drive means interconnecting said shaft and piston and comprising: an eccentric rotated by said shaft; an adjustment member and means mounting the same to turn into selected angular adjustment positions concentrically about the axis of said shaft and eccentric; arcuately extending guide means forming a fixed integrally conformed part of said adjustment member with the arc thereof containing the locus of a point which intercepts said shaft axis in all angular positions of said adjustment member; crank means having one end region pivotally connecting with said eccentric and a further end region which is adapted to follow the arc of said guide means in rotation of the eccentric; link means having one end region pivotally connecting with an end region of said piston and having a further end region which is also adapted to follow the arc of said guide means in interconnection with said crank means; means pivotally interconnecting the respective said further end regions of the crank means and link means; and guided means movable with and concenTric with said interconnecting means and constrained by said guide means to oscillate along the arc thereof responsive to rotation of said eccentric in displacements of variable magnitude depending upon the angular setting of said adjustment member, whereby the stroke of said piston may be varied between zero and a predetermined maximum displacement; together with means operative to secure the adjustment member in any selected adjustment position.

6. Apparatus acording to claim 5 wherein said link means is a dog-leg lever characterized in that said further end region thereof is offset angularly from the first mentioned end region thereof for pivotal connection with the piston as aforesaid; and said shaft axis is situated to extend at right angles to the axis of piston travel and along a locus at one side of said piston axis.