US2636441A - Lubricant pump - Google Patents

Description

F. C. WOELFER LUBRICANT PUMP April 28, 1953 lll/111111I//llll/ll/lllll,

Filed 001'.. 7, 1949 A Tv'o RNE YS NVENTOR. 0% ulm() du?, #0MM fm G. ||III O 1 f aa w F 0 al//Zm Y B m i M 4 4/ Patented Apr. 28, 1953 TENT OFFICE LUBRICANT PUMP Frank C.v Wcelfer, Cincinnati,

Ohio, assigner .to

Balcrank, Inc., Cincinnati, Ohio, a` corporation 'of Ohio Application October 7, 1949, Serial No. 120,195 15 Claims. (Cl. 10S-48) This invention. relates to lubricant dispensing pumps which are mounted directly upon a lubricantl drum or container, the pump having an elongated cylinder submerged in the lubricant to deliver it under pressure from the drum to the point of use. Such pumps are applied to pres- Sure lubrication generally, and are used most extensively in service stations for chassis lubrication jobs,- the pump unit serving to withdraw the lubricant from its shipping drum for-discharge under pressure into one or more flexible delivery tubes. These tubes are equipped with control nozzles which can be coupled conveniently tothe grease fittings of automobiles, trucks or the like for pressure injection of the lubricant directly into the fittings.

It is essential for ecient operation of a dispensing pump of this nature th-at the delivery chamber of the pump cylinder be lled completely with afresh charge of lubricant upon each Stroke of the pump piston, otherwise the pump operates at reduced capacity. In pumping ordinary liquids, such as oils orlight greases, this is notg'a serious :problem since 'such 4lubricants flow readily into the pump cylinder while back flow can -be controlled by a simple arrangement of check valves. However, in dispensing heavy oils andgreases having limited flowability, .it is difcultfto charge the-cylinder because vofflubricant sluggishness; furthermore, thepumpfcylinder is apt to become'air-bound afterea period-:of service, rendering the `pumppartially or wholly :inoperative until itis-serviced.

- The principal 'objects Vof thepresent .invention have been to overcome -these-iproblems by the provision Vof .an improved lpump structure zcombined with a 'piston-'SWS air motor ywhich I is a1'- rang'ed to force a full charge of lubricant into the cylinder -upon each-stroke in 4spite of lubricant llowresistance, and to provide.. aA combination ofcheck valves'and pistons which eliminate air which may be entrained in thelgrease .by delivering the air through the pump to the rdelivery nozzle in an automatic manner, thus preventing the'pumpy unit from ybecoming air bound. The structure thus provided performs its function in a Indreeiicient and reliable manner than those used inthe past and' is of exceptionallysimple and inexpensive construction.

Brieythe improved pump unit consists ofY an airY motor of the' piston type; operating in conjunction with `an elongated/pump` cylinder assembly which is larrangf-:d to Abe submerged in the lubricant contained in a drum so as to Withdraw the""lubric'z'ant'fromv the drum bysuCtiOn, force it by positive displacement intothe lowerend of the cylinder, then to discharge the lubricant by positive displacement under high pressure from the upper end of the cylinder to the delivery line. In order to provide a full intake charge for each pump stroke, the cylinder is provided with a pair of pistons and cooperating valves, one valve and piston for crowding a full charge of lubricant into the cylinder and the other for simultaneously delivering a charge under high 'pressure through the cylinder to the delivery line. Both pistons operate in tandem, being secured upon a single piston rod which is'connected to the air motor piston for unitaryy reciprocation of the pistons. The lower or charging piston reciprocates in a charging chamber which develops a vacuum or partial vacuum in the charging chamber to admit lubricant into the chamber during the downward stroke of the piston; while `at the same time, `a charge is forced by positive displacement into the cylinder above the delivery piston.A During the upward stroke, the fresh charge which was induced into the charging chamber is now `forced under pressure into the cylinder, while at the same time, the preceding charge which is now above the delivery piston, is forced at high pressure by the delivery piston through the cylinder into the delivery line.

In order-to assure -afulllubricant charge for each delivery stroke of the high pressure delivery piston, the charging chamber is made larger in diameter than the cylinder bore of the delivery piston, whereby the lubricant charge which is forced from thecharging chamber on the upward piston stroke, is greater than the delivery cylinder bore is capable of receiving; consequently, the charge iscrowded into the cylinder under back pressure while the excess is by-passed under resistance. This insures complete filling ofthe cylinder above the delivery piston and forcibly displaces, along with the lubricant, any air which may be entrained -or pocketed in the lubricant charge.

To promote further the efficiency and reliability of the apparatus, it is arranged toydeliver lubricant under pressure during both piston strokes, thereby increasing output` capacity and reducing pressure surges yin the delivery lines'. The pump thus constitutes a double acting pump in the sensey that a major charge of lubricant is delivered under high pressure during the upward or delivery stroke of the piston rod while ,a secondary or minor charge of grease is delivered on the return or downward stroke at substantially 3 the same pressure. The minor discharge is brought about in a very simple manner by providing differential diameters on the piston rod, so that the piston rod itself produces a fractional displacementJ of lubricant from the cylinder during its downward movement.

The air motor piston includes major and minor air pressure areas which are correlated with the major and minor delivery areas of the pump assembly to develop a pumping force consistent with the resistance developed respectively during the upward and downward strokes of the piston rod. The minor piston area is under constant air pressure to force the piston rod downwardly after each upward stroke, serving coincidentally as above noted, to deliver the minor grease charge. The air motor is supplied constantly with compressed air and operates'when the delivery line is open and stalls when the line is blocked; therefore, the lubricant is held under constant pressure vin the delivery line or lines.

It is desirable to have the air motor stall with its major piston area subjected to air pressure so that lubricant is maintained in the lines under pressure by the delivery piston for immediate delivery when required and also to prevent leakage of air when the unit is not operating. This has been accomplished by correlating the air motor piston areas with respect to the grease displacement areas differentially so that the downward stroke presents less resistance than the upward stroke. This causes the pump piston to complete its downward stroke and stall at the beginning of its upward stroke after the discharge nozzle is blocked. The air motor is equipped with a reversing valve which is actuated by movements of the piston to provide sustained reciprocation. This valve is tripped to reverse piston movement at completion of the downward stroke and to seal itself against air leakage when it is positioned to drive the piston upwardly; consequently, air leakage is eliminated after the piston completes its down stroke and starts upwardly.

Further objects and advantages of the invention are more clearly disclosed in the specifcation in conjunction with the accompanying drawings.

In the drawings:

Figure 1 is a vertical sectional view illustrating generally the air motor and pump assembly.

Figure 2 is an enlarged fragmentary view of the lower portion of the pump cylinder illustrating the operation of the pistons and valves during the downward stroke of the piston rod.

Figure 3 is a fragmentary view similar to Figure 2, showing the operation of the parts during the upward or delivery stroke of the piston rod.

Figure 4 is an enlarged sectional view taken from Figure 1 further detailing the packing gland assembly at the outlet end of the pump cylinder.

Figure 5 is a sectional view taken on line 5 5, Figure l, detailing the construction of the shuttle valve.

Figure 6 is a sectional view taken on line 6 6, Figure l, detailing the construction of the lubricant charging inlet means.

Described with particular reference to Figure 1, the pump unit consists essentially of an air motor indicated generally at l having an air operated piston il and reversing valve i2, with an elongated pump cylinder i3 extending downwardly from the air motor. The lower end of the cylinder is provided with a lubricant charging piston i5 secured upon a piston rod i6, which extends through the cylinder with its upper end connected to the air motor piston I l for reciprocation. The air motor embodies a casing generally indicated at Il which is machined to form a cylinder I8, and includes passageways which conduct compressed air from an intake passageway the cylinder under control of the'reversing valve l2. As shown, the air motor casing i1 is mounted upon a lid or cover plate 2l having a central opening 22 for the pump cylinder i3, the plate 2l preferably constituting a cover or lid which may be installed directly upon the original grease container.

Air motor The pump is designed to lift and deliver the lubricant under high pressure during the upward or delivery stroke and also to deliver a small amount of grease during the downward or charging stroke, as more clearly disclosed hereinafter.

For this purpose, the air motor' piston is arranged to actuate the piston rod under maximum effective pressure during the upward or delivery stroke area to force the rod downwardly at less pressure by providing a reduced piston area on the upper side of the piston which is supplied constantly with air pressure. In other words, while the compressed air supplied to the cylinder through port 20 is in constant communication with the upper end of the cylinder to urge the piston downwardly', nevertheless, the effective piston area at the lower end of the piston is a multiple of the reduced area so as to forcel the piston upwardly to deliver lubricant at pres-` sure suiiiciently great for direct application to the bearing iittings.

In FigureA 1, the lower or major piston area is designated at 23 and the minor area is designated at 24. As shown, the piston is approximately at its downward limit of travel, with the reversing valve about to be tripped to reverse the piston travel. The reversing valve l2 is actuated by a stem 25 which is slidably mounted in the motor casing il and connected to the piston Il by an arm 2t slidably cooperating with the stem to elevate the stem toward the upper limit of piston travel and to lower the stem'during the iinal downward movement of the piston, as indicated by the arrows. As shown, the lower portion of stem establishing a connection with a toggle lever 28 which is pivoted as at 29 and spring loaded by the compression spring unit 30 disposed above the pivot point. The toggle lever is arranged to snap the toggle past a dead center position to4 at the limits of pis-` ton travel. In the position shown in Figure 1,`

actuate the valve plunger 3| the valve plunger is in its open position to exhaust the air from the major piston area 23 byl way of passageway 32 through the exhaust ports 33 of the valve. Compressed air is conducted tov the minor piston area 24 by way of the supply' port 20, vertical passageway 34 and lateral open.

ing 35 through the wall of the cylinder. The spring loaded toggle lever 28 is shown near its dead center position so that the valve is aboutto be reversed by continued downward movement l.

of the piston. When the toggle 28 snaps over,

exhaust ports 33 will be blocked by the seat 36. of valve plunger 3l and the tapered seat 31 will?, be opened to admit air from vertical passageway"- 3d, lateral passageway 38, through the valve to` lateral passageway 32 which communicates with" 25 embodies a necked. portion 21y the .-majorfpiston-area 23 to causeupward travel of. .the Apiston land deliveryof grease. .When the pump' is placed infoperation, com'- pressed air is supplied constantly to theair motor so thatthe lubricant supply lines are under pressure atalltimes with the airinotor stalledagainst back pressure unless the line or lines are opened toperrnit the passage of lubricantA and opera.- tion, of the motor. At this point, it is to be noted that by. reason of ,the constanty compressed air supplytothe minor piston area 24, coupled with the fact thatthe piston rod.v moves downwardly with. minimum resistance,.the air motor piston always completes its cycle of piston at its downward vlimit of if the lubricant delivery "line is thapistonis moving in its itrwill follow through autom travel. Thus,

downward stroke, atically until the piston tripsl the valvevat. itsdownward stroke limit. In this position, air is admitted tothe major piston area and the piston is stalled by lubricant back pressures and is ready to deliver lubricant immediately whenv the delivery line again is opened; also, seat 3S of the valve plunger 3l is closed to prevent leakage of air while thel unit is stalled.

" Pump 'cylinder assembly vThe ,lubricantY cylinder consists of three sections; an upper section 39' which may be designated .as a delivery cylinder, an intermediate or displacementv cylinder .liiand a' lower or charge ing .cylinder 1li', the' respective sections being screwed together asvat {l2-942.. The cylinder is provided 'with a, pair of pistons, 'they charging 0'1" primary, piston l5 whichrecprocatesin cylinderv 4l and a highv pressure ldi'splacenu-:nt or sec; ondary piston l2` which' recprocatesin the'displacement cylinder 4G; and the passage'of lubricant is regulated by a. shuttlevalve 58 anda balll checkpvalve fil., The upper end ,of the de livery cylinder 39 is screwthreaded las at 43 into a fitting M to which is connected va lateral de: livery coupling l5 which preferably .includes 1a check valve. Fitting M formsa partici? alpacking gland indicated generally` at lit, and 1 is clamped Within a boss 47 Aforrned as' an integral part of the air motor casing, I '1. jA clamping nutriti" is screwthreade'd'as atjlil into thefboss, with Vits upper end engagedvagainstashoulder 5D formed in't'ti'ng it. The lateral 'delre'ry tubeA i5 is screwthreaded into the fitting @sat 5i and passes through anopening formed inbOss 4l." The delivery lines andl dispensingflllozzles do''not form a part ci? the present invention, and since they lire well known in the art/they are omitted from this disclosure. Thel delivery line, which consists'usu'allycf av iiexible hose capable o'ffwithstariding high pressure', may be connected directly to the delivery rality of flexible delivery tubes maybe connected to a manifold pipe which is supplied 'froinithe coupling to provide multiple outlets from a sin gle pump unit.

`The upper. end of the piston rod l5 is connected to the air motor piston il by a' coupling nut 52 threaded to the lower end of a thiinbleA 53 formed as an integral part of the air motor piston. The coupling nut includes an internal shoulder Eli and the rod iii includes a nut 55 screwthreaded upon its end and conned between the shoulder 5d` andthe thirnble ,53 to transmit the movements of the piston to the rod. A slight radial clearance is maintained aroundjthe nut and piston rod to permit the -rod to align itself with respect to thepiston H toprevent bindingof the V operation with the blocked ,whilel coupling 45;"01" a plu? 'upper endof the parts: *The i n xbriautv Ychargingy piston s 1151 iis' clamped Vupon'the lower 'encbofthe pistonrod assembly between ea- 4shoulderi and 'afnut' .5T screwthreaded up n a counter-turnedportion o1 therod. f f f 'Thelower portion of charging` cylinder'dl is pr'lnrided withy ports 6l whichy are traversed by piston l5 to'charge the cylinder by suction on the downward piston'strolsei `The vacuum or partial vacuumrorinducing the ow 'of lubricant into' the charging'cylinder land for lpreventingbackoW'from-displacernent cylinder 4D is provided by -a shuttle valve l58-y which is slidably mounted uponthepistorr rodA is and arranged toseat against the upper end ofthe charging cylinder during thedownward stroke ofthefpiston: rod." as shown in'Figure 2; y'Ihe shuttle valve ESV-consiste essentially of asleeve and its upper end` is provided with spaced ears 59 engageable against the shoulder- Gti-of vcylinder 40 to limit upward movementof the valve and-to providev lubricantpassageways. The operationl of the charging pistonand shuttle` valve' `is described with greater detail in a'succeeding section ofA this specification. ,v I f i f 7 hSurrounding theports 6l is a cylindrical perv foratejacket'nor lfilter screen e2, consisting of anA upper ring 63 slidablyrtted upon cylinder 4l and a lower cap screwthreaded as at-upon the lower end of the cylinder. r A line mesh cylindri a1 screen 6G is secured to the ring-63- and cap 64, spaced `frornthe cylinder and enclosing theports 6l to screen'fth'e lubricant whichinay pass into the lower end of cylinderfill. v .Tlitjecfiliy 64 and 'ring 63 are secured together byaplurality o f vertical rods til', having' ytheiry endsl anchored in thecap and' ring toA space them and serving also to reinforcethe screen'agamst collapse."

'From thedisplacement [cylinder 40 `the lubrcant passes' througha ball check Valve generally, indicated at 'H and is'dscliarged under high pressure' by" the vdisp'lace'ment piston indicated generallyatjlZ 'reciprocating in the bore of cylind'erglli). '.*Described in detail, check valve 1Hand pist'v Jg'are interposed in thepiston-rod 'I6 by the' provision' of 'ant insert tube 73 having its oppositeends screwthreade'd as at'i' and 75 upon the adjoining ends ci" the piston 'rod sections'.

uti-esiA and 3) encirclingfthe )tubey I3 and in Sliding Iengagainentr withthe bore yor the displacematerial-having othe necessary resiliency? The the fheadel byflneans lof a spacer co1la`r'83`engaged by awasher811il which', in turn; is clamped against a shoulder of tube "73 by the threaded serves also as Aa `"cage for 'thel placement chamber by way of the lateral ports 90 formed in the lower piston rod section. The ball check normally is maintained in its closed position by the spring 9| which is maintained in compression between the ball and the end of the upper piston rod section. A spur S2 forming an extension of the piston rod, passes downwardly through spring 9| to maintain the spring in alignment with the ball. It will be observed in Figure 3, that the ball check 89 seats against back flow during the upward stroke of the piston rod for positive displacement of the lubricant under high pressure and unseats, las in Figure 2, during the downward stroke to permit lubricant trapped between the piston and shuttle Valve to pass from the displacement cylinder to the delivery cylinder.

The packing gland assembly 46 at the top of the cylinder assembly provides a, double packing, one of which is effective to seal the piston rod with respect to the air motor while the other prevents the escape of lubricant from the cylinder during delivery. The gland includes also a wiper ring interposed between the two packings which is arranged to wipe from the piston rod any lubricant which may adhere to it.

Described in detail with reference to Figure 4, the packing gland is enclosed by the boss 41 previously noted, and is clamped in position by the clamping nut 48 which forces the packing gland assembly upwardly against a shoulder 95 at the top of the boss. The air motor seal consists of a closure plate 95 having an internal groove 9'! in which is coniined a resilient sealing ring B formed of synthetic rubber or plastic embracing the piston rod to establish a seal between the air motor cylinder and rod. The plate 96 includes a shoulder |00, and a sealing gasket |0| formed of a material similar to packing ring 98 is maintained under compression between shoulders 9 5, and |00 to establish a seal.

The intermediate wiping ring |02 .is seated against the lower side of closure plate 96 and is tapered in cross section to provide a feathered wiping edge. The wiping ring |02 is conned in a cage |03 which includes an internal bore provided with holes |04 communicating with a lateral passageway |05 to permit the lubricant to drain from the packing assembly through open-A ing v22 back to the drum. The ring |02 is maintained in compression around the piston rod by a spring |06 mounted in compression within cage |03, having its upper end'seated against a pressure ring |31. The pressure ring. |01 includes a cone shaped recess in its upper face which engages the feathered lower end of the wiping ring to force the ring radially into a wiping engagement with the piston rod. Cage |03 is clamped against the closure plate 96 by the fitting 44 previously described.

vThe lower packing ring |08 which provides a lubricant seal around the piston rod, is mounted within the bore ||0 formedin the upper end of tting 44. Ring |08 also is feathered in cross section and is maintained in compression between the bore l0 and the piston rod by a shouldered 'ring seated against the bottom of the bore, with its upper edge in compression against the packing ring. A washer |2 is placed above packing ring |08 in the bore and the assembly is maintained in compression by the clamping nut 48.

Operation In order to assure complete charging of the displacement cylinder 40 upon each stroke of the charging inder 4| is somewhat greater in diameter than displacement cylinder 40. Otherwise expressed, the piston l5 tends to crowd a greater volume of lubricant into the displacement cylinder than it is capable of receiving, by reason of the differential in volumetric displacement between the two. Theoretically, this condition would impede operation of the charging piston I5 or jam it completely, since the lubricant is not compressible; however, a predetermined amount of clearance, indicated at S3, is provided between the diameter of the charging piston l5 and its bore whereby the excess grease is permitted to by-pass while under restricted ow and thus maintain loading pressure upon the lubricant above the piston. By this arrangement, complete charging of the displacement cylinder occurs on each stroke and the output of the pump is kept at maximum.

Lubricant is displaced upwardly through the cylinder assembly in several stages which can best be disclosed by identifying the successive chambers and the function of each. The cham- .ber of charging cylinder 4| is indicated at A,

the chamber of displacement cylinder 40 is indicated at B and the passageway of delivery cylinder 39 is indicated at C. During the downward or charging stroke of the piston rod, as shown in Figure 2, a vacuum or partial vacuum is developed in chamber A to load the chamber when the charging piston passes the ports 6| and, at the same time, lubricant which is trapped in chamber B between shuttle valve 58 and delivery piston 72, passes through the ball check valve into the delivery chamber C, as indicated by the arrows. Primarily, therefore, the downward piston stroke loads chamber A with a fresh charge of lubricant from the drum, and simultaneously transfers the charge in chamber B to chamber C. A given charge of lubricant thus passes through three stages of displacement successively through the chambers A, B and C' during one complete stroke cycle.

Upon execution of the upward or delivery stroke, as shown in Figure 3, the lubricant trapped in chamber A above charging piston i5 is forced into chamber B at a rate in excess of the displacement from chamber B to C by reason of the differential diameters of chambers A and B, as above noted. At the same time, the lubricant above the high pressure delivery piston 12 is forced underhigh pressure through the delivery chamber C to the outlet tube 45, the ball check valve 1| being, of course, closed to prevent back The cylinder assembly has been described up to this point as single yacting in order to render more clearly its primary functions. However, in addition to recharging chamber A by vacuum and recharging chamber C from chamber B during the downward piston stroke, the assembly also discharges a limited quantity of lubricant at full pressure through outlet tube 35 during the down stroke. The cylinder assembly thus may be described as a modied double-acting unit. Otherwise expressed, the major high pressure discharge of lubricant occurs during the discharge or upward stroke (Figure 3) and a minor discharge at substantially the same pressure occurs dur-ing the charging or downward stroke (Figure 2) so that the discharge of lubricant occurs during both strokes of the cycle.

The minor or secondary discharge during the downward charging stroke occurs by reason of piston |5, the bore of the charging cyla difference 'in diameter between the upper and lower sections of the piston rodassembly. As illustrated, the diameter of the" upper rod section, which is indicated at D, is greater than the diameter- 'E of the lower rod section to cause displacement of lubricant equal to the differential :between rod sections D and E.' Thus, during the downwardstroke there is upward displacement of lubricant through the ball check valve -Tl and, at the saine time, rod section D ispassing into chamber C through packing gland' 46 and rod section E is passingou't of chamber B ythrough shuttle valve 58. Since the displacement of rod D which is entering thecylinder isl greater vthan E, which leaving the'cylinder, a quantity'of lubricant equal to the diiferential is discharged from the outlet tube liti.

inthe present disclosure, the differential between sections D and E is suiicient to maintain iull pressure at the deli\ ery nozzle with a. slight vdischarge of lubricant so4 as to eliminate substantially the surges in pressure which otherwise would occur during the pumping cycles.` "This has been found to improve efficiency since the volume displaced is increased and also because constant pressure isappliedto the bearing being lubricated, thus giving the'lubricant an Opportunity to seep into the bearing during the return pump stroke. e

'As previously noted, the major area"23of the air motor piston il is effective during the major deliverystroke of the high pressure delivery pistoni? and the ininor area is effective during the charging orret'urn stroke. The major air piston area 23 is a multiple of lubricant piston area 'l2 and the minor air piston' area 24 is a multiple of the displacementarea provided by the differential rod sections D and E. Under a given set of factors as to input air pressure; grease viscosity and temperature, the pump is capable of delivering lubricant at approximately 6000 lbs. 1:-, s. i. at maximum volume on the upward delivery stroke and to discharge lubricant at substantially the saine pressure but at fractional volume during the return charging stroke.

The air rnoto'r is arranged to complete its downward stroke before stopping by reason of the constant piston return air pressure supplied to the minor piston area 2e, Ias noted previously. Since air pressure is supplied constantly to .air motor l and gre-ase delivery is controlled at `the nozzle by stalling the motor against. grease back pressure, the charge of lubricant .in the pump must be discharged into the blocked delivery line in order that the pump In'ay complete its downward stroke. It is found that the ilexible delivery hose will expand sufficiently to receive the balance of the discharge since the discharge volume is very slight in proportion to the hose area. `This permits the piston to complete its downward discharge stroke and .trip the valve toggle'lever to vdeliver compressed air to the major piston area which will cause the piston Il to begin its upward stroke, then stall against lubricant back pressure.

In' order to cause the piston'to complete its downward stroke -in spite of the minor grease delivery resistance, the diiferentialv piston rod sections Dand E are proportioned to require. less piston rod foice'than the delivery piston l2, bearing in mind that the volume discharged isa' small fraction of the major delivery volume; in other words, by correlating the major air piston area 23 to the delivery piston 'i2 to produce agiven lubricant output pressure, `and-correlating the and .thisstreamy 10 minor piston area 2li with the diierentialrod displacement areas D and E to produce slightly greater .output pressure, resistance on they down stroke is less than on the up stroke. This differ` ence-in resistance Ycauses piston Il to complete :its down stroke before stalling, the effect being to unbalancefpiston pressure in thedown direction.

It has-been found, by virtue ofv the arrangement of positive displacement chambers A, B and C,V incombination with the shuttle and check valves, that the improved pump assembly dischargesfthrough the control lnozzle any aix` which may be trapped in the grease. This `eliminates the-need of manually bleeding air, which inthe past, frequently became trapped-in-grease pumps of this nature, rendering-the pumpj inoperative. tjis believed that air w'hichmay be drawnhinto thefcharging cylinder fli'with, the lubricant,v is displaced readily into chamber B by reason of low resistance and ample Ipassageways through the shuttle valve 58. It is to be noted -atthis point that, by virtue of the lslidable, engagement of the shuttle valve with the piston rod, the valve is urged mechanically in itsopening and/closing movements by the piston rod itself instead of by the fluid pressure passing through, it.v Inother words, since the valve is vnot springloaded, ilow resistance is reduced and the puinpoperates ymore efficiently. Afterpassinginto chamber B, the .air is forced lthrough ball check Il byupositive displacement since v,it is trapped between piston ,12 and shuttle valve'ell; It Iis Afound that ify the pump is lifted out ofthe grease drum while running, then Vplunged back linto the drum,y the -air that has been sucked into thepurnp is forced out ahead of the grease instead of causingthel pumpf'to become air bound. A, v y f It is found in practice, that the screen ,unit 62 surrounding the intake ports aids 'in' charging lubricant into` the charging chamber, causing the chamber to force a lfull charge into the Vdis placement cylinderupon each kupward strokaand causingthe-cylinder inturn, to deliver lubricant atv maximum volume upon each upward stroke of thehigh pressure delivery piston. The screen is of relatively fine mesh tohlter/out veryv line solid particles-and naturally'resistspto alcertain extent, the free passage of'viscous lubricant. lhev piston moves more rapidly `upon they downward or charging stroke than upon the upward or delivery stroke,consequently giving the lubricant a'greater opportunity'. to flow inwardly through the lscreen thany outwardly. Moreover, during the downward stroke of the charging piston, the piston has-a displacement effect with respect to the. lubricantl within the `strainer jacket which surrounds the lower-portion of the cylinder. The impedance to the liow of 'lubricant through the meshes of the strainer, causes the strainer, in conjunction withthe cylinder which it surrounds,-to actas an annular ytrap .withv respect to the lubricant. The downwardly moving vpiston thus provides a laterally flowingstreamof-lubricant ,under the localized pressure of the .piston is; deflectedbythe jacket. up wardly-,about thepiston toward the open `portion of 'the intake ports; above the piston. Thus, `the partialyacuuin y.drawn by theY piston islsatised by-directing streams of additional lubricant towardy theports by the sustained displacement effect of the piston during the remainder ofthe downward stroke. Maintaining flowing. streams of lubricant internally `or the strainer jacket toward the intakegports forthe durationof the downward stroke is of particular advantage with respect to stiif lubricants because it provides a time interval during which the slow moving lubricant may ll in any void which may exist in the charging chamber after the ports open. Tests have indicated that the output of the pump per stroke is measurably greater with the strainer installed on the charging chamber as shown, due to the baflie action of the strainer with respect to the lubricant, partially resisting the outward flow of lubricant under the displacement of the charging piston. i

Ordinarily, the pump unit will operate satisfactorily without a check valve in the delivery coupling 45 since the piston stalls in the delivery stroke direction against back pressure. However, when several delivery lines are connected to a single pump, there is a tendency for the delivery piston to be forced downwardly by back pressure in the lines after stalling and for this reason the unit performs more satisfactorily with a check valve interposed in the line. As shown, the coupling 45 consists of a cage H5 loosely conning a ball l I6 and provided with cooperating seat I I1. The ball is maintained in the cage by a retainer IIB which is secured in position by a fitting H9 screwthreaded into the cage. When excessive back pressure prevails, the ball seats and prevents it from being imposed upon the pump piston.

Having described my invention, I claim:

1. A dispensing pump for viscous liquids comprising; a cylinder having a charging chamber at one end thereof and a delivery passageway at its opposite end, a primary and secondary piston slidable in said chamber and cylinder respectively, valve means operable to charge the cylinder and chamber upon movement of the pistons in the charging direction and to advance both charges upon movement of the pistons in the delivery direction whereby the charge in the charging chamber is forced under pressure into the cylinder and the charge in the cylinder is forced under greater pressure toward the said delivery passageway, and an air motor having a piston connected to the primary and secondary pistons for reciprocating the same, the air motor piston having a major area operable to thrust the pistons under high pressure during the delivery stroke of the pistons and a minor area for thrusting the pistons at low pressure during the charging stroke of the pistons, the minor piston areav being under constant air pressure and the major area being supplied intermittently with air pressure to provide reciprocation.

2. A dispensing pump for viscous liquids comprising; a cylinder having respective charging and displacement chambers at one end thereof and a delivery 'passageway at its opposite end, respective pump pistons slidable in said chambers, valve means operable to charge both of said chambers with liquid upon movement of the pistons in one direction and to advance both charges under pressure upon movement of the pistons in the opposite direction, the said charging chamber having a greater displacement capacity than the displacement chamber to force the charge under pressure into the displacement chamber, and an air motor having a piston connected to the pump pistons for reciprocating the same, the air motor piston having a major area under intermittent air pressure operable to thrust the pump pistons at high pressure during the advancing stroke and having a minor area under constant air pressure operable to thrust the pistons at low pressure during the charging stroke.

3. A lubricant dispensing pump comprising; an elongated cylinder having respective charging and displacement chambers at one end adapted to be submerged in the lubricant and a delivery passageway at its opposite end, respective pump pistons slidable in said charging and displacement chambers, valve means associated with the respective chambers operable to pass a charge of lubricant simultaneously from the charging chamber to the displacement chamber and from the displacement chamber toward the said delivery passageway during a delivery stroke of the said pistons and to block the back flow of lubricant during a charging stroke of the pistons, the said charging chamber having an intake port arranged to be traversed by the piston to induce a charge of lubricant into the chamber by vacuum upon the charging stroke of the piston, and an air motor having a piston connected to the pump pistons, the motor piston having a major area which is supplied intermittently with air pressure to thrust the pistons in their delivery stroke and having a minor area which is under constant air pressure to thrust the pistons in their charging stroke and develop the vacuum in the charging chamber.

4. A lubricant dispensing pump comprising; an elcngated cylinder having respective charging and displacement chambers and a delivery passageway, respective pump pistons slidable in said respective charging and displacement chambers, valve means associated with the respective chambers operable to pass a charge of lubricant simultaneously through the charging and displacement chambers during a delivery stroke of the pistons and to block back flow of lubricant during a charging stroke of the pistons, the said charging chamber having an intake port which is traversed by the charging piston and arranged to induce 9, charge of lubricant into the chamber under vacuum developed in the chamber during the charging stroke, and a fluid pressure motor having a piston connected to the said pump pistons for actuating the same, the motor piston having a minor piston area which is under constant fluid pressure to drive the pump pistons in their charging stroke and having a major pigtcn area under intermittent fluid pressure operable to drive the pump pistons in their displacement stroke against the constant force applied by the minor piston area.

5. A lubricant pump comprising; an elongated cylinder having respective charging and displacement chambers at one end thereof and a delivery passageway at its opposite end, respective charging and delivery pistons slidable in said charging and displacement chambers, a piston rod connected to said pistons and extending through the cylinder for reciprocating the pistons in unison in charging and delivering strokes, power means for reciprocating the piston rod, a valve seat interposed between the charging and displacement chambers, a movable check valve sleeve cooperating with said seat and slidably engaged upon the piston rod, the check valve sleeve being adapted to engage said seat and thereby block lubricant back flow during the -charging stroke of the pistons and to develop a vacuum in the charging chamber during the charging stroke, the chamber having an intake port which is traversed by the charging piston to admit lubricant when the port is uncovered by the `charging piston, a second check .valve aswell operable to pass lubricant from the displacement "chamber- 'to .theopposite side of the 'delivery piston during the charging stroke and "to block lubricant'baoknow during the delivery stroke, .the said piston rod having a'major diameter slidably sealed'with respect to theendof -the cylinder. and' al minor diameter slidably sealed with respect to .the movable check valvezsleeve and adapted to displace a minoricharge of lubricant fromthe cylinder duringtheeharging stroke of the piston rod, whereby lubricantis discharged through. the. delivery' passageway both during the .charging and delivery strokes.

f6.; A .lubricant pump comprising; an Velongated cylinder. having lrespective @charging 'anddisplacement chambers .at one end thereof and a .delivery passageway at its oppositev end, a respectivecharging and delivery piston 'slidablef in Isaid charging and displacement chambers, as piston rod" .connected to said pistonsfand 'extending .through-the cylinder. for reciprocating the pistonsincharging and delivery strokes, a sealrfor saidrod at the end of the cylinder opposite to the charging and. displacement chambers, a'valve seat'fnterposed. between the. charging and displacement chambers, a. movable valveelement cooperating with said seat and slidablyl engaged uponthex piston rod, vthe movable Vvalve"element bengadapted to block the iiowof lubricant dur the 'charging stroke .of theipistonsythe said pistonrod -having diderential diameters: passing .through said seal and valve element adapted to provide a. minor displacement v.oi lubricant during the` charging strokeof the rod and a major displacement during the delivery'v stroke, and an air. motor having a piston connectedto the said piston rod for actuating the samathe air' mo- .torvv piston having diierential areas for reciprocating the piston rod atfhigh pressure during the delivery stroke of. the piston. rod and' vat low pres surenduring the charging strokezlof.A 'the piston md. Y 7.. A lubricant pump comprising; an elongated cylinder having respective. charging and` dis placement chambers at onefend thereof' and a delivery passageway' at itsv opposite end, respec tives charging. and' delivery pistons slidabief in said charging` and displacement chambers; .a piston rod .connected to. said pistons and Yextending .through the. cylinder for reciprocating the'pis- .tons inunisonpower meansior vreciprocating the piston rod in charging and deliveryl strokes,` the said power means .being adapted to reciprocate the piston rod; at. a rapid rate 'during the chargin'gstroke and at. a slow rate'v during the delivery- ,strokaavalve seat interposed between the charg-f ing; and displacement chambers, a movable valve element ccoperating..withy said seat and. slidably engagedupon the piston rod to block. lubricant backlovv from the displacement chamber to the charging chamber during the charging strokel ofi thepistons and to develop a vacuum in the charging; chamber during the charging stroke, thechargingV chamber having intake ports which are traversed bythe. charging piston, val-vev means operable to. pass. lubricant from the 'displacement chamber during the. charging. stroke, 'and a screen, disposed in. spaced.. relationship upon the charging chamber surrounding the intakefpmxtsV lto lter solid particles from the lubricant and. to provide resistance to theflovv of lubricant Wherebylubricant. pressure is developed. with-in. the. screen by displacement of the charging piston at said rapid rate during the charging stroke'to supplementthe: charging of.. lubricant-(through rminor area is eiective the intake ports under K'vacuum Ywhen. the-ports are`uncovered-- f' '.8'. Ina lubricant dispensing pump, having a delivery passageway, ber :at one endrof the cylinder having an intake port, primary and secondary pump pistons-ldisposed Tin the charging chamber and cylinder respectively', respective valves for developing 'negative pressurein the charging chamber forcharg ingthe same and. -for displacing lubricant through the cylinder during the strokes ofv the pistonsfan air motor for reciprocating the .pump pistons consisting A`of 4a cylinder having 'anrair piston connected `to thepump' pistons, thecair piston having-a major areaion one sidetandra minorareafon its .opposite side, means for admitting' air pressure to the major pistoniareain termittently and.` for maintaining-constantfair pressure upon thel 'minor area to cause reciprocation of the air and pump pistons whereby.v :the for developing the i said negative* pressure in the charging chamber and thef-major area is Veiiectivez for delivering the lubricant .at high pressure fromtthelpump cylinder. f- .y 9. In a lubricant pump, a cylinder having-lubricant intake and 'delivery passageways,.ipistcn andval've means for displacing 'lubricant under pressure through the cylinder, a pistons'rodfcon.- nected tothe.` piston means havingdifferential diameters passing Ithrough the oppositelendsl-:of the cylinder and arranged vto .provide a :minor displacement of lubricant from thecylinder'during the charging stroke of the piston. anair motor for reciprocating the pump piston-consisting of a cylinder having an'K air piston connected to the said piston rod, the air. piston having a Aand a. minor areaonI `its a cylinder a `charging chammaintaining air pressure constantly upon.the minor area to. cause reciprocation of thev piston', the said major area being eilcectivetodrivel'th'e pump piston its discharge vstroke todeliver a major lubricant charge at a given pressure fand the minor area being correlated to the differential piston rod displacement` diameters to `dis placca minor lubricantcharge during the1charging stroke for delivery at .greater pressurefthan the nl'ajcuf'd-ischargf-.

'Yf-i l i 10'. In a; lubricant: dispensing pump, a oylinderhalving lubricant .intake and. delivery'. paslmotor motor being. supplied constantly withcompressed air land arranged. to deliver lubricant automatically and to stall at predetermined --lubricant' back A.p1-essure and 'having' a piston connected to the said piston rod, the air motor piston havingV afmaj'or and. minor area. arranged to provide a dinerenmov-ement in the charging stroke than in the discharge stroke causing the -ai-r motorv piston to complete its charging stroke and actuate the said air valve means to supply air pressure to the major piston area prior to stalling under .lubricant back pressure. Y

11. In a lubricant pump, a cylinder having intake and delivery passageways and piston and valve means for discharging lubricant, an air motor for driving the pump having a motor` cylinder,. a piston slidable within the cylinder and having a major and minor area at opposite sides thereof, means for maintaining constant air pressure against the minor piston area, piston actuated valve means for admitting air pressure to the major piston area and exhausting the same intermittently in response to piston movements to reciprocate the piston against the constant pressure exerted by the minor area, a pump piston rod connected to the ai-r motor piston, a major delivery,v pump piston secured upon the said piston rod related to the major area of the motor piston, the piston rod having differential lubricant displacement diameters related to the minor area of the motor piston, the said major area being so proportioned to the minor area to develop a differential thrust sufficient to displace the air maintained against the minor area concurrently with the pressure delivery of the major lubricant charge by the pump piston, the i' piston rod being reciprocated in one direction by the said minor piston area to deliver a minor lubricant charge by piston rod displacement at a given pressure and being reciprocated in the opposite direction to deliver a major lubricant charge by pump piston displacement at substantially the same pressure by air pressure eifective against the major piston area.

12. A lubricant pump suitable to transfer lu bricant from a lubricant supply to the intake end of a high pressure grease dispensing pump, said lubricant pump comprising a cylinder adapted to be mounted upon the intake end of the grease dispensing pump in a vertical position submerged in the lubricant supply, a nonsealing piston in the cylinder, a piston rod extended upwa-rdly from the piston, a cylinder head on the lower end of the cylinder, the cylinder having intake ports in its lower side wall extending upwardly above the cylinder head part way to the top of the cylinder, whereby the piston when on the level of the top of the intake ports subdivides the cylinder into an upper and a lower compartment the volumes of which are unequal, the

volume of the lower compartment being. greater than that of the upper, a check valve in the upper end of the cylinder providing one-way passage of lubricant upwardly from the cylinder into the intake end `of the grease dispensing pump during the upward stroke of the piston, means connected to the upper end of said piston rod for reciprocating the piston over substantially the full extent of the cylinder whereby the downward stroke of the piston tends to create a void above the piston and a localized positive lubricant pressure below the piston, and a pervious jacket surrounding the ports in outwardly spaced relation to the piston with its upper and lower ends joined to the cylinder above and below the intake ports, the jacket providing an annular trap about the cylinder which is effective to impede the lateral ilcw of lubricant produced by the downward stroke of the piston, whereby a localized flow of lubricant passes upwardly about the piston to equalize the lesser pressure above it.

13. A lubricant pump suitable to transfer'lubricant from a lubricant supply to the intake end of a high pressure grease dispensing pump, said lubricant pump comprising a cylinder adapted to be mounted upon the intake end of the grease dispensing pump in a vertical position submerged in the lubricant supply, a non-sealing piston in the cylinder, a piston rod extended upwardly from the piston, a cylinder head on the lower end of the cylinder, the cylinder having an intake port in its lower side wall extending upwardly above the cylinder head part way to the top of the cylinder, whereby the piston when on the level of the top of the intake port subdivides the cylinder into an upper and a lower compartment the volumes of which are unequal, the Volume of the lower compartment being greater than that of the upper, a check valve in the upper end of the cylinder providing one-way passage of lubricant upwardly from the cylinder into the intake end of the grease dispensing pump during the upward stroke o the piston, means connected to the upper end of said piston rod for reciprocating the piston over substantially the full extent of the cylinder whereby the downward stroke of the piston tends to create a void above the piston and a localized positive lubricant pressure below the piston, and a pervious jacket surrounding the port in outwardly spaced relation to the piston, the pervious jacket providing a trap eiective to impede the lateral now of lubricant produced by the downward stroke of the piston whereby a localized flow or lubricant passes upwardly about the piston to equalize the lesser pressure above it.

14. A lubricant pump suitable to transfer lubricant from a lubricant supply to the intake end of a high pressure grease dispensing pump, said lubricant pump comprising a cylinder adapted to be mounted upon the intake end of the grease dispensing pump in a Vertical position submerged in the lubricant supply, a piston in the cylinder, a piston rod extended upwardly from the piston, a cylinder head on the lower end of the cylinder, the cylinder having intake ports in its lower side wall extending upwardly above the cylinder head part way to the top of the cylinder, whereby the piston when on the level of the top of the intake port subdivides the cylinder into an upper and lower compartment, the volumes of which are unequal, the volume of the lower compartment being greater than the volume of the upper, a check valve in the upper end of the cylinder providing one-way passage of lubricant upwardly from the cylinder into the intake end of the grease dispensing pump during the upward stroke of the piston, means connected to the upper end of said. piston rod for reciprocating the piston over substantially the full extent of the cylinder whereby the downward stroke of the piston tends to create a void above the piston and a localized positive lubricant pressure below the piston, and a pervious jacket surrounding the ports in outwardly spaced relation to the piston with its upper and lower` ends joined to the cylinder above and below the intake ports, the jacket providing an annular trap about the cylinder which is effective to impede the lateral ow of lubricant produced by the downward stroke of the piston whereby a localized flow of lubricant passes upwardly about the piston to equalize the lesser pressure above it, the piston during upward movement being eiective to trap lubricant in the portion of the cylinder above the intake ports for transfer upwardly through the check valve to the grease dispensing pump, the piston having clearance with respect to its cylinder to provide restricted downward passage of lubricant in excess of the intake capacity of the grease dispensing pump.

15. A lubricant pump adapted to extend Vertically into a lubricant container to dispense lubricant under high pressure from the container, said lubricant pump comprising an elongated delivery cylinder having a lubricant outlet at its upper end, a delivery piston, an upper piston rod connected to the piston and passing siidably in sealed engagement through the upper end of the cylinder, a motor connected to the upper end of the piston rod for reciprocating the piston rod and piston, an intake check valve sleeve providing one-way passage of lubricant upwardly into the lower end of the cylinder during upward movement of the piston, a check valve associated with the piston providing passage of lubricant upwardly through the piston during downward movement thereof, a charging cylinder mounted upon the lower end of the delivery cylinder, a charging piston in the charging cylinder, a second piston rod extending from the delivery piston downwardly to the charging piston adapted to reciprocate the charging piston in unison with the delivery piston, the second piston rod passing in sealed slidable engagement through the intake sleeve valve and having a diameter which is smaller than the upper piston rod, the upper and v18 lower piston rods by their sealed engagement at the upper and lower ends of the delivery cylinder and their dierential diameters being adapted to displace lubricant from the cylinder during the downward stroke, the charging cylinder having elongated intake ports in its lower extent, the charging piston adapted to draw a partial vacuum in the charging cylinder during the initial portion of the downward stroke and to traverse the intake ports during the remainder of the downward stroke, and a pervious jacket surrounding the cylinder at said intake ports, the jacket providing an annular trap about the cylinder effective to impede the flow of lubricant outwardly whereby a iiowing stream of lubricant is deflected by the jacket upwardly about the piston to satisfy the partial vacuum above it during said downward piston stroke.

FRANK C. WOELFER.

References iited in the file of this patent UNITED STATES PATENTS Number Name Date 2,922,232 Davis Nov. 26, 1935 2,357,029 Smith Aug. 29, 1944 2,357,030 Smith Aug. 29, 1944 2,399,172 Davis Apr. 30, 1946 2.409,962 Shearman Oct. 22, 1946

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