US2540269A - Centrifugal pump - Google Patents

Description

Feb. 6, 1951 c, c, 5, LE CLAIR 2,540,269

bENTRIFUGAL PUMP Filed Jan. 28, 1947 4 Sheets-Sheet l I t Cami/(e C/are prqzzlcliy Le 3 2 52 A ltorney Feb. 6, 1951 c, 3,5, LE CLAIR 2,540,269

CENTRIFUGAL PUMP 8 k s i e 3 2 l4 l I 6qmil/e Clare 3735;117:2

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A llorney Feb. 6, 1951 c. c. s. LE CLAIR 2,540,269

CENTRIFUGAL PUMP Filed Jan. 28, 1947 4 Sheets-Sheet 5 Patented Feb. 6, 1951 CENTRIFUGAL PUMP 1 Camille Clare Sprankling Le Clair, London, England, assignor to Tecalemit Limited, Brentford, England, a corporation of Great Britain Application January 28, 1947, Serial No. 724,817 In- Great Britain January 28, 1946' 17 Claims. (oi. 103-97) This invention relates tov centrifugal pumps, fans or blowers and also to prime movers of the turbine type WhSlTEin the energy of the fluid is used. to drive the rotor or impeller. For brevity, however, such pumps, fans, blowers and prime movers will all be referred to hereinafter simply as centrifugal pumps.

The invention relates particularly to such pumps designed todeliver a very small quantity of fluid at a very high pressure, and in which as a result the radial velocity of flow of the fluid through the rotor or impeller is relatively small in comparison with the high tangential velocity of the rotor.

It is known that in centrifugal pumps wherein the fluid delivery is extremely small, whilst the head, and hence the speed of rotation of the rotor, is relatively high, the angle at which the fluid leaves the periphery of the rotor so nearly approaches the tangent to the rotor that the design of efficient diffusing means becomes extremely difficult if not impossible.

An object of this; invention therefore is to provide a centrifugal pump in which this diifioulty is overcome and which for the purpose of this description may be referred to as a restricted output centrifugal pump.

A restricted output centrifugal pump in accordance with the present inventioncomprises a easing having an inlet passage and an outlet passage, a rotor rotatably mounted, in the casing, a number of spaced, outwardly-running fluid passages in the rotor, the inlet ends of these passages being adapted to receive fluid from the said inlet passage, a fluid inlet restriction means, or limited iiuid inlet distributor, for restricting the ingress of fluid from said inlet passage to one or more of the rotor passages while simultaneously preventing orshutting oiT the ingress of fluid to the remaining rotor passages; which are in the majority, and a fluid outlet diffuser means which permits the egress of, fluid from the, or each, rotor passage which has been or is, being supplied with fluidirom the said distributor means, while simuit :sl y preventing or shutting cit the egress of ii .dirom the said remaining rotor passages.

For output restriction purposes, that is to say, order to achieve the object of the invention, is usually desirable that the said restrictcr di user means. shall cut off all the said, rotor ges except one at a time, but at the same e, however, for balancing purposes, it is: usually desirable that at least two. passages shall be 2 left open and that these shall be equally spaced ciroumferentlally.v

Those rotor passages through which the egress of fluid takes place simultaneously will be re,- ierred; to hereinafter as operativev passages and it will be shown hereinafter that in cases in which, for balancing purposes, it is desirable ornecessary to use at least two operative passages at a time, and in which it is also desirable or necessary, for fluid output restriction purposes, to use less than two operative passages, this ef fect may be achieved by arranging the restrictor and the clifiuser means in such a manner that the. opening and closing of the inlet and outlet ends of the operative passages do not synchronise. Thus, before the. inlet end to any operative passage is fully opened, it may be arranged that the outlet end of the passage has already commenced to close, or vice versa, so that the passages become only partly operative. This arrangement will be referred to hereinafter as desynchronisation.

In a simple constructional form of the invention, the restricted output centrifugal pump comprises a casing in which the rotor is rotatably mounted. The rotor is formed with a number of spaced, curved fluid passages, the inlet ends or ports of which open into a flat port face of the rotor which rotates in cooperation with a flat port face on a part of the casing in which, two fluid inlet. passages, comn'iunicating with the fluid inlet eye, are formed. The fiat port face of the said part of the casing constitutes the fluid inlet restrictor and in it are formed the two spaced outlet ends or ports of the said fluid inlet passages.

The peripheral face of the rotor runs in contact with, or in close proximity to, a circular face in the casing, and through this latter face two spaced outwardiy-tapered curved diffuser passages are formed which communicate with the interior of a volute delivery chamber, the arrangement bein such that the fluid fed into the rotor passages from the inlet eye and the restrictor passages is discharged into the diffuser passages and thence into the delivery chamber as the rotor rotates. The delivery chamber is of volute formation, closed at" one end and communicating at its other-end with the outlet passage from the casing, l

In a modification the portv face of the fluid inlet restrictor is cylindrical and is fitted within a recess which is formed in the rotor and constitutes the port face of the latter.

In another modification, the fluid inlet restrictor is made separately from the casing and it is turnably arranged between the port face of the rotor and the inlet eye in the casing. The restrictor is thus capable of angular adjustment for the purpose of desynchronisation or the reverse as will be explained more fully hereinafter.

Ports may be provided in the resfirictor part of the casing, or in the separate restrictor, and in the rotor itself, whereby the interior of the casing may be put into communication with the inlet side of the pump, so that the suction of the pump may be used to evacuate the casing of fluid, thus allowing a large part of the rotor surfaces to run free of fluid friction.

Further constructional features of the invention will be described hereinafter.

One constructional form of the invention, applied to a centrifugal pump for pumping liquids is shown, by way of example, on the accompanying drawings, whereon:

Figure l is an elevation of one part of the pump casing with the rotor fitted therein;

Figure 2 is a transverse section of the complete P p;

Figure 3 is a transverse section of a modified D p;

Figure 3A is a fragmentary transverse section of another modified pump;

Figure 4 is a fragmentary transverse section of a pump of the type shown in Figure 2, but having an adjustable fluid inlet restrictor;

Figure 5 is a fragmentary transverse section of a pump similar to that shown in Figure 3 but having a modified form of adjustabl fluid inlet restrictor; and

Figure 5A is a fragmentary transverse section of a pump similar to that shown in Figure 5.

The restricted output centrifugal pump shown in Figures 1 and 2, comprises a casing which, for convenience, is made in two parts i and 2 adapted to be bolted together. The part I of the casing is formed centrally on one side with a liquid inlet eye 3, which is coaxial with the axis of rotation of the rotor or impeller and on the other side with the double ports I5 comprising the inlet distributor. The part 2 of the casing is formed centrally with a stuffing box 8 for the shaft and, when they are bolted together, th two part of the casing form a peripheral volute chamber 20 leading to the outlet passage 4, the axis of which is disposed at a right angle to the axis of rotation of the rotor.

The single sided rotor is in the form of a disc 5 which has a boss 6 towards the inlet side of the casing and is fixed upon a driving shaft 1 which extends out of the part 2 of the casing through a stuffing box 8. The shaft is connected to a driving means such as an electric motor or pulley, which is not shown in the drawing. The fiat machined inlet face 9 of the boss 6 of the rotor facing towards the inlet eye 3 runs in contact with a fiat machined face It on the part I of the pump casing. The flat inlet face 5 is formed with a number of circumferentially and cquidistantly spaced liquid inlet ports I I forming the inlet ends of a number of conveniently formed liquid passages 32 which terminate in the peripheral face 53 of the rotor disc. .The face I3 is spaced by a small clearance only from a cylindrical face It formed partly in the part I and partly in the part 2 of the pump casing, which face It forms the inlet face of a diffuser wall which will be referred to hereinafter.

The port face II) of the part I of the casing opposed to the port face 9 on the boss 5' of the rotor disc is formed with two diametrically opposite ports :5 which form the outlet ends or ports of two fluid inlet passages connected by a forked passage It to the inlet eye 3. The two ports i5 are thus so spaced that they are adapted to communicate with two diametrically opposite ports of the set of inlet ports II in the port face 9 on the boss 6 of the rotor, while simultaneously all the other ports II are closed by the face in of the part I of the pump casing.

Surrounding the periphery of the rotor the two parts of the pump casing together form a diffuser wall I! within the thickness of which are formed two diametrically opposed, curved diffuser passages I8 and I9, which taper from a small cross sectioned area at the inlet end to a larger area at the outlet end. The inlet end or port of each diffuser passage is formed in the cylindrical face Id in the pump casing and the outlet end or port communicates with the volute delivery chamber 20 in the casing, one end of which chamber is closed at 20A and the opposite end of which communicates with the outlet passage 4 in the casing. Each of the difiuser passages I8 and I9 is adapted to accept liquid at high speed from the operative rotor passage 62 which registers with it and, due to its increasing cross sectional area, to deliver it at the required lower velocity to the volute delivery chamber 20 and thus to the pump outlet.

As the rotor rotates, all the inlet ports I I of the passages I2 of which there may be any convenient number, for example, forty, in the rotor are in turn brought into communication two at a time with the outlet ports of the two restrictor passages communicating with the inlet eye 3. Simultaneously the outlet ends of these two passages in the periphery of the rotor are put in communication with the diffuser passages I8 and IQ. Two rotor passages I2 in turn thus become operative passages and each receives its quota of liquid to be delivered while all the remaining passages are masked so that they receive and deliver no liquid. In this manner, therefore, the

3 quantity of liquid passing under given conditions of speed of rotation (that is, under a given delivery head) and radial speed of flow will be proportionately reduced, i. e., in the ratio 40 to 2 or 20 to 1. In other words, for a given delivery the rate of radial flow will be increased twenty times and a ratio of speed of rotation to radial flow much more advantageous than those obtainable with unrestricted output centrifugal pumps of known types will be achieved.

In general, the speed of rotation of the rotor will be high and, even with the improved flow ratio described above, the inlets to the two diffuser passages I8 and I9 will be nearly tangential to the peripheral face I3 of the rotor, so that the angle of departure of the passages from the cylindrical surface I4, close to which the face I3 runs, will be small. Hence, for a given width (measured in a plane at right angles to the axis of rotation) of the diffuser passage, the length (measured circumferentially) of the inlet end or port of the passage will be fairly large and may, if desired, be enlarged still further, so that the outlet port of any individual operative rotor passage I2 will be in communication with the inlet port of the diffuser passage I8 or I9 during quite a large angle of rotation of the rotor. It is thus possible to ensure that there is a free passage for the liquid in a rotor passage during the whole of the time during which it is operative, i. e., while 5, its. inlet port isopen to the outlet port 55 of a restrictor passage.

On the other hand, it will be appreciated that, whereas the main object of this invention is to provide a restricted. output centrifugal pump capable of working at high. speeds but giving small outputs, it may be. desirable: deliberately to restrict the output additionally to the effect of the inlet restrictor already described. This may be done by making the liquid inlet restrictor part of.

the casing turnable' in such a way that the timing of the opening and closing of the inlet ports l lof the rotor passages by the restrictor passage ports it does not wholly coincide withv the opening and closing of their outlet ports by the diffuser passages 18 and i9. This, as will be ex.- plained hereinafter, can be achieved by adjusting the angular position of the restrictor part of the pump casing. By this means, the output can be regulated through the whole range, from full output right down to zero, thus giving complete control.

In the modified construction shown in Figure instead of having a flat portface H which co-- operates with the smaller or inlet port face of the rotor, the liquid inlet restrictor part of the casing is in the: form of a machined, cylindrical, open. ended, hollow boss H which fits in a central machined recess 22 in the rotor with which the. inlet ports or ends of the rotor passages communicate. In this construction, the two re stricter ports 2 3 are formed substantiallyat right anglesto the axis of rotation of the rotor through. the cylindrical wall of. the hollow boss 25. of the restrictor part, and they are arranged, in the first. described. construction, so that they communicate with the inlet ports of all the passages in the rotor in turn two at a time, the remainder of the rotor passages being kept closed and inoperative.

Referring to Figure 3A, instead of being open, the inner end of the restrictor boss. 2.! facing the rotor may be closed and formed with a wall as, which thus prevents the liquid which enters the restrictor part through the inlet eye 3 reaching the central part of the rotor in which the shaft l is keyed.

The restrictor boss 2| of the restrictor part of the casing and the recess 22 in the rotor may be conical instead of cylindrical, and, similarly, the peripheral face it of the rotor and the inner surface it of the diffuser wall 5! in which runs may also be conical.

In any pump constructed as described above, whether fitted. with the modified inlet restrl-ctor part or not, the pump casing will ultimately fill with the liquid to be pumped, and the rotor will be subject to the skin friction of the liquid.

In a further modification, therefore, also shown in Figure 3A, a small port 25 is cut through the wall of the inlet restrictor part 2! in order to put the interior of the pump casing into communication with the inlet eye 3 and inlet passage, so that the suction of the pump may be used to evacuate the interior of the. casing, thus allowing, a large part of the rotor surface to runfree of liquid friction- A similar. port 26 through. the end enclosure 24- of the said. inlet restrictor part and: a further port 26A through the rotor itself may also be: provided so that the suction oi the pump may be utilised, to evacuate the other parts of. the. casing at the. front and back; of the rotor.

It will be appreciated that there will inevitably be a time lag, even although small, between: the entry of liquid; into the: operative rotor passages l2 as permitted or controlled by the opening of their inlet ports ll by the liquid inlet. restrictor ports ['5 and the delivery of the. same quotaof liquid to the diffuser passages l8 and I9 and: that, at the high speed of rotation of the rotor, this time lag which, even although it will only be a fraction of a second, will be represented by quite appreciable angular displacement of the rotor. Hence it is desirable that the opening and closing of the rotor passage inlet ports 1 I should be in advance of the opening and closing of their outlet ports in the peripheral face I 3 of the rotor by the diffuser passages i3 and IQ- and it is obviously also desirable that the amount of the angular displacement given should be adjustable.

Hence, in a further modification of either construction described above, the liquid inlet. restrictor passages may be formed in a separate member which is; mounted within, and is capable of angularadjustment relative to, the casing and thus to the diffuser passages.

In the first modified construction shown in Figure 4, instead of cooperating directly with the flat inlet port face ll! of the rotor, as described with reference to Figure 2, the fiat port face: 2''? of the part I of the casing is spaced from it, and between the two flat port faces a separate liquid" inletre'strictor member 28 is turnably mounted. This member is formed with an inlet passage 2% which forms a continuation of the inlet? eye of the casing, and is bifurcated into two inlet passages 39' and ti, the outlet ports or ends of which cooperate with the inlet ports or ends ll of the passages l2 in the rotor.

The restrictor member 28 is turnably mounted within the casing on the axis of the rotor, and it is adapted to be turned to a desired position and then locked therein by turning and locking means which, for instance, might take the form of a worm 35 carried for rotation from the exterior of the casing by a shaft 36 and meshing with teeth 3? on the periphery of the restrictor member:

Referring to Figure 5, in this modified con-' struction a separate open-ended cylindrical or conical distributor part 23A may be constructed in like manner for angular displacement, and fitted like the hollow boss 2| within a recess 22A in the rotor as described above with reference to Figure 3; Fig. 5A. shows a modification of the construction shown in Fig. 5 in which the inner end of the restrictor boss 23A isformed with an end wall 24A. A small port 25A is out through the wall of the inlet restrictor part 28A.- to put the interior of the pump easing into communication with the inlet eye 3 and inlet passage, so that the suction of the pump may be used to ez- 'acuate the interior of he casing, thus allowing a large part of the. rotor surface to run free of liquid friction, A similar port 2613 through the end closure MA and a further port 260 through the rotor itself may also be provided so that the suction of. the pump may be utilized to evacuate the other parts of the casing at the front and back of the rotor.

Althoughv the rotor described above is singlesided it will be appreciated that it could be double-sided, with two sets of fluid outlet passages each cooperating with its own fluid inlet restrictor passage and with its own difiuser passage.

Although in the construction described above the. inlet restrictor and the outlet diffuser each have: two passages arranged so thatv two rotor passages are simultaneously operative, it will be appreciated that in a modified arrangement both restrictor and diffuser may each be provided with only one passage so that only one rotor passage is operative at a time.

Alternatively, the restrictor and diffuser might be provided With three or more passages, preferably equally spaced in the circumferential direction, such that three or more rotor passages are simultaneously operative.

Again it will be appreciated that the invention is applicable to multiple or multi-stage pumps, in which two or more rotors are mounted coaxially upon the same shaft, the outlet from one pump being led to the inlet of the next so that the fluid to be pumped passes through the rotors in series.

I claim:

1. A restricted output centrifugal pump which comprises, in combination, a casing having walls defining an interior cavity with a port face at one end thereof and main inlet and outlet passages at separated positions in the walls, a rotor mounted for rotation in the cavity of said casing and having a peripheral surface and a port face contiguous to the port face of the casing, said port face of the rotor having a plurality of ports therein in spaced relationship and communicating with fluid passages in the rotor extending outwardly thereof from the rotor ports to said peripheral surface, fluid inlet restrictor means including a plurality of fluid distributing ports at spaced positions in said port face of the casing aligned for registery with the rotor ports during rotation of the rotor and connected by passages in the casing to said main inlet so as to prevent flow from the main inlet to the rotor except when the said rotor and casing ports are in communication during the rotation of the rotor, said casing walls also including a diffuser face peripheral to the cavity and contiguous to the peripheral surface of the rotor, and fluid outlet diffuser means including said diffuser face, said peripheral surface of the rotor and outwardly extending passages in the diffuser face and communicating with the main fluid outlet, said outwardly extending passages in the difiuser face being spaced in relation to the said outwardly extending passages in the peripheral surface of the rotor so that there is flow therethrough to the main outlet from only the latter mentioned outwardly extending passages Which have been supplied from said fluid distributing ports.

2. A restricted output centrifugal pump as defined in claim 1, and wherein said fluid distributing ports are at substantially diametrically opposed positions with respect to the rotor.

3. A restricted output centrifugal pump as defined in claim 1, and wherein said restrictor means includes an element movable with reference to the casing for varying the output of the pump.

4. A restricted output centrifugal pump as defined in claim 1, and wherein the relative positions of the outwardly extending passages in the diffuser face and the casing ports are such that the opening and closing of the casing ports corre sponds only in part to the opening and closing of the outlet ends of the rotor fluid passages by the diffuser face and said outwardly extending passages.

5. A restricted output centrifugal pump as defined in claim 1, and wherein said fluid distributing ports are paired and so disposed that diametrically opposed ones of said rotor ports are opened simultaneously to the said casing ports while the others of saidrotor ports are masked by the casing port face.

6. A centrifgual pump as defined in claim 1, and wherein the number of said outwardly extending passages in the outlet difiuser means is equal to the number of fluid distributing ports in the fluid inlet restrictor means, and said outwardly extending passages communicate with the main outlet passage through a passage formed in the casing.

'7. A centrifugal pump as defined in claim 1, and wherein said port faces of the casing and rotor are plane surfaces.

8. A centrifugal pump as defined in claim 1, and wherein said port faces of the casing and rotor are cylindrical.

9. A centrifugal pump as defined in claim 1, and wherein said fluid inlet restrictor means includes a cylindrical member mounted for rotation relative to the casing and having said port face thereon and said inlet ports therein, so that rotational movement of the cylindrical member changes the time of opening and closing of the rotor ports in relation to the opening and closing of the outlet passages in the rotor.

10. A restricted output centrifugal pump which comprises a casing having an inlet passage and an outlet passage, a rotor rotatably mounted in the casing, a number of spaced, outwardly extending fluid passages in the rotor, the last mentioned passages having inlet ends adapted to receive fluid from said inlet passage, a fluid inlet restrictor means for restricting the ingress of fluid from said inlet passage to predetermined ones of the rotor passages while preventing the ingress of fluid to the remaining rotor passages, the number of said predetermined ones of the rotor passages being less than the number of the remaining rotor passages, a fluid outlet diffuser means which permits the egress of fluid from the rotor passages to which fluid has been supplied from the inlet restrictor means while preventing the egress of fluid from the remaining rotor passages, and means for varying the output of the pump, the last mentioned means including angularly adjustable means in the inlet restrictor means which varies the timed relation of the opening and closing of said rotor passages in the restrictor means with respect to the opening and closing the rotor passages in the outlet diffuser means.

11. A centrifugal pump as defined in claim 1, wherein means are provided for preventing liquid which enters said casing through said main inlet reaching the central part of said rotor.

12. A centrifugal pump as defined in claim 1, wherein means are provided whereby the suction of the pump is utilized to evacuate the interior of the casing on one side of said rotor.

13. A centrifugal pump as defined in claim 1, wherein means are provided whereby the suction of the pump is utilized to evacuate the interior of the casing on both sides of said rotor.

14. A centrifugal pump as defined in claim 1, wherein said rotor is formed with a central recess providing said port face of said rotor, and wherein said fluid restrictor means comprises a hollow restrictor member which is engaged in said recess and is formed with a port face contiguous to said port face of said rotor, said restrictor means being formed with means for preventing the liquid which enters said casing through said main inlet reaching the central part of said rotor.

15. A centrifugal pump as defined in claim 14, wherein said last mentioned means consists of an end closure wall of said restrictor member which is spaced from the central part of said rotor.

16. A centrifugal pump as defined in claim 14, wherein said last mentioned means consists of an end closure of said restrictor member, and wherein a port formed in said member provides communication between said main inlet and the interior of said casing at the front of said rotor.

17. A centrifugal pump as defined in claim 14, wherein said last mentioned means consists of an end closure of said restrictor member,- and wherein a port formed in said member provides communication between said main inlet and the interior of said casing at the front of said rotor, communication between the interior of the casing at the rear of said rotor and said main inlet being provided by a port in said end closure and a port in said rotor.

CAMILLE CLARE SPRANKLIN G LE CLAIR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,077,520 Gentil Nov. 4, 1913 FOREIGN PATENTS Number Country Date 1 4,853 Great Britain Feb. 27, 1912 340,138 Italy May 10, 1936 373,418 France May 5, 1907

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