US2612846A - Venting and draining means for pumps - Google Patents

Description

F. w. MCCOMBIE VENTING AND DRAINING MEANS FOR PUMPS Filed July 50,1947

Fla v Oct. 7, 1952 Patented Oct. 7, 195 2 Frederick Walter McCombie, London, England,

ass'ignorto Megator Pumps & Compressors Limited, Feltham,

England Application July so, 1941, Serial No. 764,827 I In Great Britain September 11, 1946 This invention relates to pumps for delivering liquids and other than of the centrifugal type, an example of such a pump being that'disclosed by the specification and drawings of British Patent No. 592,432.

In order to retain liquidin pumps of the noncentrifugal type for lubrication and sealing of the working parts,v it is,known' .practicefior the inletand outlet branches to be'situated at or near the top of the pump so that air orvapour drawn into the pump may be readily expelled and so that the liquid in the pump will not drain out when the pump isstationary. A' di'sadvanta'ge of this arrangement is that the'liquid resting in the lower portion of the pump may remain relatively stagnant while the pumplswo'rking and that solid matter carried in suspension in the liquid may be deposited in the lower portion of the pump instead of being'carried away by the flow of liquid. The object of theinv'ention is to provide means by which stagnation and deposition of solids in thebottom part of 'a pump of the non-centrifugal type may be avoided whilst still arranging the inlet and outlet at or near the top of the A pump of the non-centrifugal type is characterized, according to the invention, .byuthe provision of a passage leading'fromthe lower part of the pump to the outlet, the upper part of the pump being also connected with said outlet,either directly or through the medium of said passage, so as to permit the escape of air or vapour from the upper part of the pump casin'g' lout of the pump outlet and the upward flow of at least a part of the liquid and any solid matter which might otherwise accumulate in the lower part of the pump, along the passage 'and out of the pump outlet. Owing to, the' greater fluidity of air or vapour as compared with that of liquids, the opening from the upper part of the-pump to the outlet may be of smaller cross sectional area than the passage leading from the lower portion, thereby causing the greater part of the liquid to pass to the outlet through the lower part of the pump casing and up the passage to the outlet while still providing ample area to pass the maximum volume of air or vapour that is liable to enter the pump. v I

The aforesaid passage may be an external pipe or may be formed integrally with the pump, casing or with the aid of a separate deflector or baf fie located in position withinthepump casing.

In order that the invention may be clearly understood and readily carried into effect the invention is hereinafter described with referenceto the accompanying drawings-in which:

Figure 1 is a sectional view of a pump modified in accordance with the present invention;

Figures 2 and 3 are further sectional views ilpump for the reasons already stated.

6 Claims. (01. 103-203) lustrating diagrammatically two alternative constructions. I I V Figure 1 illustrates by way of example the invention applied to the type of pump disclosed by the specification. and drawings of British Patent No. 592,432,. the pump, comprising av casing l forming a pressure chamber fitted with a cover 2 the interior of which constitutes the suction chamber, a partition wall 3 being interposed between the two chambers. The pressure branch which is indicated by reference numeral 4 is connected directly with the pressure chamber l, the suction branch (not shown) being connected with the interior'of' the cover 2. The rotor comprises a shaft 5 carrying eccentrics 6 and 6a angularly offset to give uniform delivery, each eccentric being arranged in a displacement chamber I of a width and depth's'uchthat the eccentric fits closely therein. On shaft Ebeing rotated, the

displacement chambers I will be displaced in a vertical plane, the displacement chambers being maintained in rubbing contact with a'plate 8 under the pressure of the fluid in the pressure chamber, springs 9 being provided to maintain rubbing contact while pressure is being built up in the pressure chamber. Ports II], II, l2 and l3 are formed in the plate 8, ports iii and I2 leading directly to the suctionchamber while ports H and [3 lead through ducts He and l3a respectively in the partition wall 3.

'As the eccentric shaft rotates in a clockwise direction, eccentric 6 alternately enlarges and reduces the volume of displacement chamber 1 and simultaneously moves the displacement chamber up and down so as'to connect the displacement chamber alternately to suction or inlet ports l0, l2 and to o'utlet'or delivery ports H, l3 leading into the pressure chamber through ducts I la and l3a.v In this way liquid enters displacement chamber 1 from the suction chamber formed by cover Zand is iorced into the pressure chamber.' Eccentric 6w" operates in the same manner. I 7

According ,to one embodimentof the invention the casing l contains a separately'formed deflector or baflie l4 whichis located in position within the case by a securing screw 15 the deflector conforming to the arcuate shape of the, casing and being itself of such a cross-sectional shape as to provide a passage lBtoallow liquid to pass upwardly from the lower part of the pump casing to the pressure branch or pump outlet 4, the deflector being cut away at its upper end or so disposed with respect to the interior of the pump casing to provide an opening ll for the escape of air or vapour past the upper edge of the defiector and out of the pump outlet. The deflector is shown in the form of a separate unit but it may alternatively form part of the pump casing.

As some leakage of water from the body into any part of the passage is permissible, the deflector or baflle need not be fitted closely to the side of the pump body but may for example be an unmachined casting shaped approximately to fit the body.

The outlet 4 is situated above the pump mechanism so that when the pump is at rest, liquid is trapped in the casing but when the pump is running, any solid matter which might accumu late at the bottom of the casing will be caused to pass upwardly along the passage formed by the deflector and out of the outlet connection. 'I he deflector also has the effect of preventing stagnation of the liquid in the pump casing while, also as previously stated providing for the escape of air or vapour from the upper part of thecasing.

In the modified construction shown in 1?'ig ure 2 the passage I6 is externallyarranged and takes the form or an external pipe i8 "connecting the lower part of the pump e si g with an extension IS on the outlet pipe 4, the passage providing an escape for solid 'matte'r while the bulk of the liquid and any airor vapour will be forced into the outlet pipe direct from the pump casing, the outlet connection being again situated above the pump mechanism. I

In Figure 3 is'shownan arrangement particularly suitable for use as acombi'ned liquid pump and air or gas compressor or as a pump delivering liquid into 'a receiver or tank for storage, the pump mechanism being contained within a tank or receiver of comparatively large 'size which tank or receiver fulfils the function of the pump casing. For example, the lowerp'art of the receiver may contain pump working parts wholly or partly submerged in liquid, the upper part of the receiver acting as a receiver forthe gaseous fluid. In this arrangement an "external pipe 18 is again provided, forming a passage l6 connecting the lower part 'of the receiver with a point above the level of the liquid in the receiver when the pump is stationary. escape pipe is provided tor the outflow of air or va ours, the pipe taking the former a sm'all'diameter'branch connection 2| leading into'th'e pipe I8. I

In the constructions hereinbefore described, the minimum cross-sectional area of the passage [6 including its points of. connection with the pump casing or receiver is such that suflicient velocity of liquid flow through the passage I 6 'will prevent the deposition of. solids therein which might otherwise tend to clog the passage and prevent eillcient operationof the pump.

Although the invention has been described as applied to a pump or the kind forming the sub.- ject of my British Patent No. 592,432 wherein rotation of the eccentric'or eccentrics alternately enlarges and reduces the internal volume "offthe parts of the displacement chamber or chambers to suck in liquid from the suction side of the pump chamberand'force it under pressure into the pressure chamber or-receiver by way o'itli'e ports which are opened 'and closed as "a; result of movement of the displacement chamber 'orfcha'mbers in a vertical plane, the invention is "applicable to any other suitable construction or pumpjof the non-centrifugal type.

What I claim is: I I I 1. In a pump for delivering liquids having a casing, inlet and outlet connections leading to and from said casing and situated above the normal-level of liquid in said casing when thepum'p is stationary, pumping elements for forcing liquid entering said inlet connection. out through said outlet connection by way of said casing, a by-pass connection leading from the bottom "of said casing to said outlet connection for the passage of a proportion of the umped liquid together with any solid matter which might otherwise accumulate in the lower-part of the pump casing.

2. A pump of the non-centrifugal type for delivering liquids, comprising, in combination, a pump casing renting a pressure chamber, noncentrifugal pumping elements mounted in said casing and open to said chamber for forcing liquid into the pressure chamber, an outlet from the casing disposed above the level of said pumping elements to retain liquid in said chamber around said elements, means forming a passage extending upwardly between thelower part of the pressure] chamber'tojthe 'outle't, whereby to permit the upw mfndw or "at least "a part or the liquid and an solidlliflitter which might other wise accumulate in the lower part of the p'ump to the outlet, and means forming a second passage extending between the upper part of the pressure chamber and theoutlet at 'substan'ti'ally the same level as the outlet, whereby to permit 'the'e'sca'pe or air or'vapouri' rom the upper part of the pump casing to the outlet. ,I

3. A ump, as claimed n claim '2. wherein the first-mentioned passage forming means c'o'mprises an externallyga'rranged pipe "connecting the lower part or the chamber with the outlet con-- nection, and saidfsecond mentioned passage forming means comprises a pipe extending laterally from the chamber to said outlet connection. I I I 4. A pump, 1 claimed in claim 2, wherein said chamber comprises. afreceiyer of comparatively large dimensions," said' rirst=mentioned passage forming means'co'mprising a pipe arrangedfe'ib ternally of the receiver landconnectin'g the lower part of the receiver with the outlet connection and said second lnentioned. passage formihg means comprising a transverse pipe connecting the receiver and'the outlet'connection, above the level or the 'liquid'in the receiver.

5. pump, as"clairned in claim 2; wherein said second-mentioned passage forming means defines a passage above the bottom o'fsaid, outlet connection. I

6.; A pump, ascIaimed' in claim 2, wherein said first-mentioned passage forming means comprises a deflector mounted in. the chamber in spaced I relation to a sidewall thereof, said second mentione'd passage forming me'ans embraing the top of said deflector and the top or said chamber -cas1-ng, gthe top of said deflector being chamber to form t he se-condgmentioneid passage.

FREDERICK w 'MCCOMBIE.

REFERENCES *CI'T'IJD UNITED STATES PATENTS Number Name I I Date 2,193;020 CoHins-" Mar. 12, 1940 2,300,689 Nagle-- News, '1942 2,341,871 Karrer 1 rep. 15; 1944 2,477,079 Mueller July. 26,1949

FOREIGN PATENTS Number Country Date 206,640 Germany tab. 9, 1909

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