US2943578A - Pumps of the air displacement type - Google Patents

Description

y 1960 F. w. MCCOMBIE 2,943,578

PUMPS OF THE AIR DISPLACEMENT TYPE Filed Dec. 10, 195'? 2 Sheets-Sheet 1 3 F I G. 1

Inventor @wE /cw 4/ M (2/15 1 I At r e July 1950 F. w. MGCOMBIE 2,943,578

PUMPS OF-THE AIR DISPLACEMENT TYPE Filed Dec. 10, 1957 2 Sheets-Sheet 2 Inventor FreevEp/cw M da/v 1;

Atto ey in the chamber by means of floats.

United States: Patent PUMPS or THE AIR DISPLACEMENT TYPE Frederick Walter McCombie, London, England, asslgnor to Megator Pumps and Compressors Limited, London, England Filed Dec. 10, 1957, Ser. No. 701,768

Claims priority, application Great Britain Dec. 13,1956

2 Claims. (Cl. 103-242) This invention relates to pumps of the air-displacement type, ie to pumps wherein the liquid, often a liquid which is diflicult to handle with ordinary pumps, is displaced by air or other gaseous medium hereinafter referred to as air for convenience of description.

Such pumps include a chamber having inlet and outlet valves near the bottom and a connection at the top through which air can be evacuated to draw the liquid into the chamber and admitted under pressure to force the liquid out of the chamber. u

It is present practice to control the evacuation and admission of air in accordance with the level of the liquid Such floats are generally unreliable in operation as they are subject to sticking, corrosion and incrustation.

The chief object of this invention is to evolve a generally improved construction of air-displacement type pump which does not rely on such floats for its successful operation.

A pump of the air-displacement type is characterized in accordance with present invention in that the chamber is movable in a vertical direction in accordance with the weight of the contained liquid, thereby actuating the valve controlling the evacuation and admission of air to the chamber directly or indirectly.

The weight of the empty chamber is balanced by a counterweight or spring so'that the chamber rises as it empties and falls as it fills.

Consequently, the terminal movement of the chamber in an upward direction may be arranged to open the air valve controlling evacuation of the chamber and thus allow the chamber to fill with liquid and commence to fall, the terminal movement of the chamber in a downward direction being used to open the valve admitting air under pressure to expel the liquid.

it will be appreciated that the air valves may be actuated by the movement of the chamber through mechanical means, or indirectly through limit switches or pilot valves.

The air connection tothe chamber may be made by a further tube or pipe which again may be of a flexible character, or may be otherwise arranged to allow unrestricted movement of the chamber in a vertical direction.

Referring to the drawings:

Figures 1 and 2 are diagrammatic views illustrating the construction of an air-displacement type pump in accordance with the invention; and

Figures 3 and 4 are fragmentary views illustrating two modifications.

Referring in the first case to Figures 1 and 2, the pump comprises afixed casing 1 having inlet andoutlet connections 2 and 3 at its opposite ends and a further connection 4 at an intermediate point. The flow of liquid through the fixed casing is under the control of inlet and outletnon-return valves 5 and 6, these valves normally maintaining a closed position under the action of gravity.

2,943,578 Patented July 5, 1960 Aflexible pipe 7 is connected with outlet connection 4, thispipe 7 leading to achamber 8 which is pivotally connected at 9 to asteelyard 10 having afulcrum point 11 and carrying anadjustable weight 12 which wholly or partly balances the weight ofchamber 8. A spring may be used instead of or in addition toweight 12.

The free end of thesteelyard 10 is pivotally connected at 13 to alink 14 which in turn is pivotally connected at 15 to alever 16 associated with a three-way valve mounted in avalve casing 17.

Thelever 16 has associated with it anupstanding lever 18 carrying aweight 19.

Apipe connection 20 is taken from thevalve casing 17 to aconnection 21 on the upper end of thechamber 8, thepipe 20 terminating in aflexible pipe 22 which is itself connected with thepart 21.

Thevalve casing 17 has aconnection 23 for the entry of air under pressure and afurther connection 24 to atmosphere or vacuum.

In the construction shown in Figures 1 and 2, liquid can enter thefixed casing 1 via theinlet connection 2 anddisplace valve 5 into the position shown, the connection 4,flexible pipe 7 andchamber 8 then filling with liquid, the air being displaced fromchamber 8 as a result ofpipe 20 being connected to atmosphere or vacuum through the medium of the three-way valve. When a sufiieient weight of liquid has enteredchamber 8,chamber 8 will move downwardly under the weight of. the contained liquid and against the action of theweight 12, and consequently lever 18 together with itsweight 19 will be moved over a dead centre position into the position shown in Figure 2. Thepipe 20 and the interior ofchamber 8 will then be connected with a source of compressed air supply through the medium of the three-way valve which has moved through an angle of and consequently the liquid contained inchamber 8 and its associatedflexible pipe 7 and connection 4 will be displaced downwardly, causingvalve 5 to close and valve 6 to open, and will so be discharged from the outlet connection 3. Owing to the reduction of weight resulting from the discharge of the liquid fromchamber 8 andpipe 7, the chamber will now rise and operate the three-' way valve, so that thepipe 20 is again connected to the atmosphere or vacuum and the cycle repeated.

Although a rotating three-way valve is shown by way of example, any suitable kind of valve may be used.

As shown in Figures 1 and 2, thechamber 8 is of cylindrical form and is connected with the fixed casing through the medium of aflexible pipe 7. It may be desirable in'some cases to avoid the use of thiscylindrical chamber 8, in which case the necessary weight of liquid can be entirely contained in a long pipe bent or folded back on itself or Wound in a coil or helix as shown in Figure 3. Thehelical pipe 25 is closed at its upper end by aclosure member 26 which in turn is pivotally connected at 9 with the steelyard '10. It will be seen that the lower end of thepipe 25 is connected directly with connection '4 associated with the fixed casing.

Such an arrangement is simple to make and easy to flush out for cleaning and has the advantage that thepipe 25 ban be comparatively long, thus giving great flexibility and also enabling a considerable volume of liquid to be contained in its convolutions.

Thesteelyard 10 again carries aWeight 12 by means of which the weight of the helical pipe is partly balanced, the free end of the steelyard being connected with the three-way valve through the medium of alink 14 as in the previously described arrangement.

It will be seen from Figures 1, 2 and 3 that thepipe 7 or 25, where it joins connection '4, lies substantially horizontally, thus avoiding any material vertical re- 3 action :on the pipe arising-.:.fromthe pressure of tl'ie'liquid whichwwould make .the .workingof the, mechanism vary. with every variation of pressure or vacuum, instead of being controlled entirely by the weight of liquid in the pipe: 1 The pipepreferablyhas, however, :23.sligh'tslope 5 downwards towards: the:,:connection '4 to facilitate) drainage.

It will be appreciatedathatiin the-.previouslywdescribed, 1 construction illustratediby Figuressl andt2, thezpipe Jis necessarilyiof a flexiblel'charactenas in order to operatezlfl the valve direct, ;the :chambenr8 must-ahave asubstantial movement in a vertical;;direction.;..:

The .carrangernent; shownF-in Figure-s4 has,ztherefore,:1, been designed to permit of satisfactory operation WithLfiL, pipe ,7. composedof a more;.rigid:material;such-,asmetal 15 or glass. Such a pipe composed of amorerigiimaterialti will;,;-if correctly .designed,1-be incapable :of .a small degree of longitudinal flexure which will be :sufficienhto initiate; the operation .of a .suitablesvalve. 1

In such a case, the steelyardlO again .carries;al balancet.;20

weight-.12 and is also.-.conne.cted.-with a fixed.;p.oint,.by

means ,of a coilsspringr27landgan adjusting 'device'28,'1;i whereby the balance of the chamber, 2 can-.i-be-accuratelyn-t determined.

In ,this constructiomhowever, :instead of operating 1116 :26

valve dire'ct,.theivalve is electrically actuatedqandacomal prises-a solenoid operated three-way valve29,;theiwind1 ingslof the solenoid,being.:com1ected:by leads 30 witha pairnof micro switches'31 and 32,,arrangedon'opposite.:. SldBSzOf the steelyard. Atleastoneof the micro switches..z 31 and :32 maylbe'adjustable, verticallyhbyimeansuof a. finger-actuated.adjusting nut-=33 ;associated:with 'a. fixed..-:

paruof the apparatus:

With; this ::arrangement,:,.by suitable; adjustment of .the,.-..: adjusting-devices '28 and 33,;the .valve 29v canbeoperatede3 with only-a minimum of upward-:and .downwardmover ment-cof :thei'chamberx 8 and.1ongitudinal:.flexure;;of

It will benotedthatthe .weightsi-12andh19 and them springx27 which balance the .weightyofthe chamber. andr liquid are adjustableso as to compensatefor the. 1ifI'e1' v ing-specificr gravities of different :liquids .that. maybe pumped. These adjustments'may alsoflbe used, in cases .-1 where .it is desired '10 cleanse. the:pump completelyv after,-.. usegbypumpinga eleansingliquid through it, sothat;1 the :cleansingliquidis made ,to rise :slightlyhigherzin then:

chamber: than .thepumped liquid,

'lhe'pipe' 7 or 25 -may be'composed of metal; glass, rubben or othensuitablematerial .andimayv with advantage be partly or wholly transparent, thus enabling the level of liquid within the pipe to be observed. For example,pipes 7 and 25 may be composed of a transparent or substantially transparent thermo=plastic material such as, for example, polyethylene, methyl methacrylate, polyvinylch1oride,i'nylon:or tether: suitable material;

I claim:

1. A pump'of .the'f 'airdisplacement type'icomprising ahelical tithedefinir'rg a chamber, the lower end of .said tube being fixed, said tube being flexible with the'upper end thereof being' movable in aceordancewithrthe weight of a liquid containedewithin the, coils thereof, a pipe in communication" with theupper'end of said tubefor evacuating air therefromj-iand'iadmittingzair thereinto, a valve connected to said pipe and controlling the evacuation and admission of air to the chamber, means operativelyzxonnectechiwith lthe'zuppen zend-zof ;said,.;tube .for

controlling saidwalve-to evacuate; airswhenisaidiend is in the-.rupperspositionrandn-admittainwhendt is in a lower e position; and: liquidsconnectiommeans: :in communication.

with the lower 'z-endmf :saidi'etubene,

2. The'rpumpzof rclairm'zl whereintsaid'.;tube..1is constructedteof a thermoplastic imaterial,:;said:.;valve. con-.7 trolling:means,including'eounterbalaneingmeans:attached to the; 'upper: endzof saiditube fonraising itzupon removalv of the liquid therefrom.

References: (lit'ed'rin the .file .of this patent UNITED -.STAIESI PATENTS I

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